U.S. patent application number 10/635152 was filed with the patent office on 2004-06-17 for custom orthodontic appliance forming method and apparatus.
This patent application is currently assigned to Ormco Corporation. Invention is credited to Andreiko, Craig A., Payne, Mark A..
Application Number | 20040115586 10/635152 |
Document ID | / |
Family ID | 27506046 |
Filed Date | 2004-06-17 |
United States Patent
Application |
20040115586 |
Kind Code |
A1 |
Andreiko, Craig A. ; et
al. |
June 17, 2004 |
Custom orthodontic appliance forming method and apparatus
Abstract
A system and method by which an orthodontic appliance is
automatically designed and manufactured from digital lower jaw and
tooth shape data of a patient provides for preferably scanning a
model of the patient's mouth to produce two or three dimensional
images and digitizing contours and selected points. A computer may
be programmed to construct archforms and/or to calculate finish
positions of the teeth, then to design an appliance to move the
teeth to the calculated positions. The appliance may include
archwires and brackets. Machine code is generated and appliances
are automatically produced that will straighten the teeth of the
patient. Custom placement jigs may also be automatically designed
and fabricated and are provided with the custom appliance to
position the appliance on the patient's teeth.
Inventors: |
Andreiko, Craig A.; (Alta
Loma, CA) ; Payne, Mark A.; (Whittier, CA) |
Correspondence
Address: |
WOOD, HERRON & EVANS, L.L.P.
2700 Carew Tower
441 Vine St.
Cincinnati
OH
45202
US
|
Assignee: |
Ormco Corporation
|
Family ID: |
27506046 |
Appl. No.: |
10/635152 |
Filed: |
August 6, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10635152 |
Aug 6, 2003 |
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09878801 |
Jun 11, 2001 |
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6616444 |
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09878801 |
Jun 11, 2001 |
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09431466 |
Nov 1, 1999 |
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6244861 |
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09431466 |
Nov 1, 1999 |
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08960908 |
Oct 30, 1997 |
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6015289 |
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08960908 |
Oct 30, 1997 |
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08456666 |
Jun 2, 1995 |
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5683243 |
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08456666 |
Jun 2, 1995 |
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07973973 |
Nov 9, 1992 |
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5431562 |
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08456666 |
Jun 2, 1995 |
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07973965 |
Nov 9, 1992 |
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5454717 |
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08456666 |
Jun 2, 1995 |
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07973947 |
Nov 9, 1992 |
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5447432 |
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08456666 |
Jun 2, 1995 |
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07973844 |
Nov 9, 1992 |
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5368478 |
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07973844 |
Nov 9, 1992 |
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07875663 |
Apr 29, 1992 |
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07875663 |
Apr 29, 1992 |
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07467162 |
Jan 19, 1990 |
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5139419 |
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07973965 |
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07775589 |
Oct 15, 1991 |
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Current U.S.
Class: |
433/3 ;
433/24 |
Current CPC
Class: |
A61C 7/00 20130101; B33Y
80/00 20141201; A61C 3/00 20130101; A61C 7/002 20130101; G16H 20/40
20180101; A61C 7/145 20130101; A61C 7/20 20130101; A61C 13/097
20130101; A61C 7/16 20130101; A61C 7/12 20130101; A61C 7/146
20130101; A61C 2007/004 20130101; A61C 9/0046 20130101 |
Class at
Publication: |
433/003 ;
433/024 |
International
Class: |
A61C 003/00 |
Claims
1. A method of making a custom orthodontic appliance to move teeth
of a patient from malocclused positions toward finish positions,
the method comprising the steps of: sensing the shapes of a
plurality of the teeth of a patient; from the sensed shapes,
producing three-dimensional digital tooth-shape data representing
shapes of individual teeth of the patient; from the digital tooth
shape data, producing in a digital computer, tooth finish position
defining data that locate and orient the teeth in finish positions
relative to each other; processing the three dimensional digital
tooth shape data and the tooth finish position defining data to
derive appliance design data of an orthodontic appliance for urging
the teeth of the patient from the malocclused positions toward the
finish positions, the design data including data of tooth
interconnecting appliance geometry and data of three-dimensional
tooth conforming surface geometry, the data of appliance geometry
and of tooth-conforming surface geometry being related such that,
when the orthodontic appliance having the appliance geometry is
positioned on the teeth of the patient by fitting surfaces having
the tooth conforming surface geometry to a plurality of the
patient's teeth, the appliance geometry is deformed so as to apply
forces to the teeth to urge the teeth toward the finish positions;
producing machine readable control signals containing geometric
information correlated to the results of the appliance design data
deriving step; and manufacturing, by controlling one or more
fabricating machines in response to the machine readable control
signals, the orthodontic appliance having the tooth-interconnecting
appliance geometry and the three-dimensional tooth-conforming
surface geometry.
2. A method of treating malocclused teeth comprising: mounting an
orthodontic appliance manufactured according to claim 1 on the
teeth of the patient by fitting surfaces thereof having the
three-dimensional tooth conforming geometry against the crowns of a
plurality of the patients teeth and thereby locating the appliance
on the teeth and deforming the tooth-interconnecting appliance
geometry to apply forces to the teeth; and with the appliance on
the teeth of the patient, moving the teeth away from the
malocclused positions toward the finish positions with the force
applied by the appliance having the deformed appliance
geometry.
3. The method of claim 1 wherein: the producing of the tooth finish
position defining data includes processing the three-dimensional
digital tooth-shape data in the computer to derive the tooth finish
position data.
4. The method of claim 1 wherein: the producing of the tooth finish
position defining data includes processing the three-dimensional
digital tooth-shape data in the computer to derive a mathematical
representation of an ideal dental archform for the patient, the
tooth finish position data being defined in relation to the derived
mathematical representation of the ideal dental archform.
5. The method of claim 1 wherein: the producing of the tooth finish
position defining data includes processing the three-dimensional
digital tooth-shape data in the computer to define the tooth finish
position data that includes relative positions of the teeth
arranged in a dental archform.
6. The method of claim 1 wherein: the manufacturing includes
controlling one or more fabricating machines in response to the
machine readable control signals to produce an orthodontic archwire
having the tooth-interconnecting appliance geometry.
7. The method of claim 1 wherein: the manufacturing includes
controlling one or more fabricating machines in response to the
machine readable control signals to produce orthodontic brackets
having the three-dimensional tooth-conforming surface geometry.
8. The method of claim 1 wherein: the manufacturing includes
controlling one or more fabricating machines in response to the
machine readable control signals to produce orthodontic bracket
placement jigs having the three-dimensional tooth-conforming
surface geometry.
9. A method of making a custom orthodontic appliance for moving
teeth that are initially in positions of malocclusion in the mouth
of a patient toward treatment positions tending to correct the
malocclusion, the method comprising: scanning the shapes of the
teeth while in their positions of malocclusion to generate 3-D data
of the shapes of the teeth; determining treatment positions of the
teeth that will tend to correct the malocclusion and storing data
of the determined treatment positions; processing in a computer the
stored data of treatment positions and designing thereby an
orthodontic appliance for moving the teeth of the patient toward
post appliance positions that are correlated to the determined
treatment positions; the designing of the appliance including
defining 3-D data correlated to three dimensional areas on the
teeth, at least some of said areas to be contacted by surfaces of
the appliance to apply forces to the teeth to move the teeth to the
post-appliance positions; manufacturing one or more components of
an orthodontic appliance having three dimensional surfaces thereon
that conform to three dimensional areas of a patient's teeth by
processing the defined 3-D data to operate a manufacturing
apparatus to create structural shapes correlated to the three
dimensional areas of the teeth.
10. The method of claim 9 wherein: the manufacturing includes
manufacturing a series of arch shaped appliances configured to
progressively move the teeth toward treatment positions.
11. The method of claim 10 wherein: the series of arch shaped
components is a series of archwires.
12. The method of claim 11 wherein: the series of archwires include
archwires of increasing stiffness.
13. A method of making a custom orthodontic appliance for moving
teeth that are initially in positions of malocclusion in the mouth
of a patient toward treatment positions tending to correct the
malocclusion, the method comprising: scanning the shapes of the
teeth while in their positions of malocclusion to generate 3-D data
of the shapes of each of a plurality of the teeth; relating the 3-D
data of the shapes of each of the plurality of the teeth in a
computer in positions toward which they are to be moved by an
orthodontic appliance; processing in a computer the generated data
and thereby designing geometry of the orthodontic appliance, the
designing including: defining, from the 3-D data, three dimensional
areas, on each of the plurality of the teeth, to be contacted to
locate the appliance on the teeth and to apply forces to the teeth
for urging the teeth toward the positions toward which they are to
be moved, and defining an appliance configuration that includes
surfaces conforming to a plurality of the defined three dimensional
areas and elastically deformable three dimensional structure
interconnecting at least some of said surfaces to apply forces to
the plurality of teeth; and operating manufacturing equipment to
produce a tangible form of the designed geometry and therefrom
producing an orthodontic appliance having the defined appliance
configuration.
14. The method of claim 13 wherein: the operating of manufacturing
equipment includes producing an appliance in which the surfaces
thereon that are for contacting three dimensional areas on each of
the plurality of the teeth to locate the appliance on the teeth are
located on positioning jigs that are a removable part of the
appliance.
15. The method of claim 13 wherein: the operating of manufacturing
equipment includes producing the orthodontic appliance in which the
surfaces thereon that are for contacting three dimensional areas on
each of the plurality of the teeth to apply forces thereto for
urging the teeth toward the positions toward which they are to be
moved are the bases of orthodontic brackets.
16. The method of claim 13 wherein: the operating of manufacturing
equipment includes producing the orthodontic appliance in which the
appliance configuration that includes elastically deformable three
dimensional structure interconnecting surfaces to apply forces to
the plurality of teeth includes an archwire having individualized
geometry for customizing the appliance for the patient.
17. A method of providing a custom orthodontic appliance for the
treatment of an orthodontic patient by moving teeth that are in
initial positions in the mouth of the patient toward treatment
positions, the method comprising: providing a three-dimensional
scanner at a dental facility operable for scanning
three-dimensional information of the mouth of a patient defining
shapes of the teeth of the patient while the teeth are in initial
positions; providing an appliance facility having a computer and
appliance fabrication machinery located thereat; receiving, at the
appliance facility from the dental facility, three-dimensional
digital information defining the shapes of the teeth scanned by the
scanner at dental facility; and from information received at the
appliance facility, fabricating, with the appliance fabrication
machinery, an orthodontic appliance configured for treating the
patient by moving teeth from their initial positions toward the
treatment positions.
18. The method of claim 17 wherein: the three-dimensional digital
information is received at the appliance facility over an
electronic communications network.
19. The method of claim 17 wherein: the three dimensional
information is scanned by the scanner directly from the mouth of a
patient at the dental facility.
20. The method of claim 17 further comprising: from the received
data, determining at the appliance facility optimum bracket
placement locations on each of the teeth.
21. The method of claim 17 further comprising: based on the
received data, selecting at the appliance facility an optimum set
of brackets from sets of different bracket configurations stored in
an electronic file.
22. The method of claim 17 further comprising: based on the
received data, selecting, at the appliance facility, an optimum set
of brackets from sets of different bracket profiles stored in an
electronic file.
23. The method of claim 17 further comprising: determining the
treatment positions of the teeth of the patient; and based on the
determined treatment positions, selecting one or more archwire
parameters selected from the group of parameters consisting
essentially of appliance archforms, archwire materials and archwire
cross-sections.
24. A method of fabricating a custom orthodontic appliance to
position teeth of a patient to preferred finish positions in the
mouth of the patient, the method comprising: scanning anatomical
shapes of the mouth of the patient and producing thereby anatomical
tooth-shape data; deriving an arrangement of the teeth of the
patient using the anatomical tooth-shape data with a specially
programmed computer; determining bracket mounting locations on each
of a plurality of the teeth of the patient; based on the anatomical
tooth-shape data, the determined bracket mounting locations and the
derived arrangement of the teeth, designing an orthodontic archwire
which, when engaged to brackets mounted at the bracket mounting
locations, will move the teeth to the derived arrangement;
producing machine code to implement the designed orthodontic
archwire; and fabricating an orthodontic archwire in response to
the machine code.
25. The method of claim 24 wherein: the fabricating includes the
forming of a series of bends along the length of an archwire in
response to the machine code.
26. An apparatus for manufacturing a custom orthodontic appliance,
the apparatus comprising: a scanner located at a patient
examination facility for generating data signals containing
information of anatomical shapes directly from the mouth of an
individual patient at the facility; at least one computer
programmed to calculate finish positions of the teeth of the
patient, to calculate a design of an orthodontic appliance for
placement on the teeth of the patient to move the teeth of the
patient to the calculated finish positions, and to produce machine
readable records of the calculated design; and a fabricating
machine at an appliance manufacturing facility, the machine being
responsive to the machine readable records to fabricate an
orthodontic appliance for the individual patient having the
calculated design.
27. The method of claim 26 wherein: at least one computer is
programmed to calculate finish positions of the teeth of the
patient, including deriving at least one dental archform for the
individual patient and to calculate the finish positions in
relation to the archform.
28. The method of claim 26 wherein: at least one computer is
programmed to derive at least one dental archform for the
individual patient and to calculate the finish positions of the
teeth of the patient in relation to the archform and is located at
the patient examination facility; and at least one computer is
programmed to calculate the design of an orthodontic appliance for
placement on the teeth of the patient to move the teeth of the
patient to the calculated finish positions on the derived dental
archform and to produce machine readable records of the calculated
appliance design and is located either at the patient examination
facility or at an appliance manufacturing facility.
29. A custom orthodontic archwire manufacturing apparatus
comprising: an archwire former operable in response to a wire shape
control signal communicated thereto to form a length of orthodontic
archwire material into an archwire shape; a scanner operable to
produce a digital record of anatomical shapes of the mouth of an
individual patient; and a programmed computer operative to generate
a wire shape control signal responsive to the digital record so as
to cause the archwire former to produce an orthodontic archwire
having a shape that takes into account the anatomical shapes of the
mouth of the individual patient.
30. The apparatus of claim 29 wherein: the wire shape control
signal includes wire length data that is correlated to a length
component of the archwire and wire curvature data that respectively
correspond to the wire length data; and the archwire former
includes a wire feeder operable in response to the wire length data
of the control signal to longitudinally feed the orthodontic
archwire material and wire bending elements operable in response to
the wire curvature data of the control signal to bend the archwire
material to the shape that takes into account the anatomical shapes
of the mouth of the individual patient.
31. The apparatus of claim 29 wherein: the wire length data is a
digital representation of a connected series of wire segments and
the wire curvature data are digital representations of the
curvatures of the respective wire segments; and the archwire former
is operative to longitudinally feed the series of wire segments of
the orthodontic archwire material according to the respective wire
length components and to bend segments of the orthodontic archwire
material to curvatures corresponding to the respective
curvatures.
32. The apparatus of claim 29 further comprising: a computer
programmed to calculate preferred finish positions of the teeth of
the patient from the digital record, the archwire shape control
signal being generated in response to the calculated finish
positions; and the wire shape control signal being effective to
cause the archwire former to produce an orthodontic archwire that
will urge the teeth of the individual patient toward the calculated
finish positions.
33. A method of forming an orthodontic appliance based on
individual anatomy of a patient for applying mutual forces between
or among a plurality of teeth of the patient to move teeth to
desired positions in the mouth of the patient, the method
comprising the steps of: sensing tooth shapes of a plurality of
teeth of a patient; from the sensed tooth shapes, producing tooth
shape signals containing digital three-dimensional tooth shape data
of the shapes of each of a plurality of the teeth of the patient;
producing desired tooth position signals containing digital tooth
position data of the desired positions; based on the tooth shape
data and the desired tooth position data, displaying images of the
teeth of the patient in the desired positions; calculating, from
the digital tooth shape data and digital tooth position data,
geometry for configuring an orthodontic appliance to apply mutual
forces between or among a plurality of the teeth of the patient to
move the teeth toward the desired positions; based on the results
of the calculating step, generating a machine control signal
carrying machine control instructions for producing the calculated
geometry and communicating the generated control signal to a
forming machine; and imparting an orthodontic appliance with the
calculated geometry by operating the machine in response to the
control signal to produce structure having the calculated
geometry.
34. A method of fabricating a custom orthodontic archwire
comprising: sensing anatomical shapes of an individual patient's
mouth; producing anatomical shape data corresponding to the sensed
anatomical shapes; processing the anatomical shape data to derive
data of preferred positions to which the teeth of the patients are
to be moved by the appliance; deriving digital data of an archwire
shape based on the anatomical shape data and the derived data of
the preferred positions; generating a wire shape control signal
containing information from the digital data of the archwire shape,
such that, when the control signal is communicated to an archwire
former, the archwire former produces an orthodontic archwire that
is based on the anatomical shapes of the individual patient's
mouth, and such that when the appliance is placed on the patient's
teeth, the appliance urges the teeth toward the preferred
positions; and forming, in response to the wire shape control
signal and from a length of orthodontic archwire material, an
orthodontic archwire having the archwire shape.
35. The method of claim 34 wherein: the derived digital data of
archwire shape includes wire length data and wire curvature data,
the length data and the curvature data being based on the
anatomical shapes and the curvature data being correlated to the
length data; the wire shape control signal includes a wire feed
control signal carrying the wire length data and a wire bending
control signal carrying the wire curvature data; the wire shape
control signal generating step includes the step of generating the
wire feed control signal and the step of generating the wire
bending control signal; and the archwire forming step includes the
step of longitudinally feeding the orthodontic archwire material in
response to the wire feed control signal and bending the archwire
material so fed in response to the wire bending control signal and
in synchronism with the feeding of the archwire material to thereby
form the archwire having the archwire shape.
36. The method of claim 35 wherein: the derived digital data the
archwire shape is a digital representation of a connected series of
wire segments, each having a length component and a curvature
component, the components being based on the anatomical shape data
and the preferred position data; and the feeding step includes
longitudinally feeding a series of lengths of the orthodontic
archwire material corresponding to the respective wire length
components in accordance with the wire length data and the step of
bending each length of archwire material so fed into a curvature
corresponding to the respective wire curvature component in
accordance with the wire curvature data.
37. A method of forming an individualized archwire for use with
individualized brackets based on the anatomy of the mouth of a
patient including anatomy of the individual patient's teeth, the
method comprising the steps of: sensing anatomical shapes of the
patient's mouth, including the shapes of the patient's teeth; from
the sensed anatomical shapes, producing signals containing digital
anatomical shape data, including three-dimensional tooth shape
data; establishing a digital representation of an ideal arrangement
of the patient's teeth in the mouth of the patient; establishing
bracket mounting locations on each of a plurality of the teeth of
the patient; providing orthodontic brackets for mounting on the
teeth at the established bracket mounting locations; calculating,
with a digital computer, the geometry of brackets and the shape of
an archwire such that the brackets and archwire operate in
conjunction with each other, when the brackets are mounted on the
teeth at their respective bracket mounting locations and are
interconnected by the archwire, to position the teeth in the ideal
arrangement; generating machine control signals correlated to the
calculated shape of the archwire and communicating the generated
control signals to an archwire forming machine; and operating the
archwire forming machine in response to the control signals to form
an individualized archwire having the calculated shape.
38. The method of claim 37 wherein the establishing of the digital
representation of an ideal arrangement of the patient's teeth in
the mouth of the patient includes deriving the ideal arrangement by
processing the anatomical shape data with a digital computer.
39. A method of fabricating a custom orthodontic appliance to
position teeth of a patient to preferred finish positions in the
mouth of the patient, the method comprising the steps of: sensing
anatomical shapes of the mouth of a patient; from the sensed
anatomical shapes, producing signals containing anatomical shape
data including three dimensional tooth shape data representing the
shapes of individual teeth of the patient; deriving an ideal
arrangement of the teeth of the patient by processing the
anatomical shape data contained in the signals on a digital
computer, including positioning and orienting the teeth in the
derived arrangement based at least in part upon the three
dimensional tooth shape data for the individual teeth; designing
with the computer from the three dimensional tooth shape data, an
orthodontic appliance configured to apply forces to urge the teeth
toward the ideal arrangement; producing machine readable control
signals containing geometric information correlated to the results
of the appliance designing step; and operating a machine in
response to the control signals and according to the geometric
information to carry out at least one process selected from the
group consisting of: forming an orthodontic appliance configured to
apply forces to the teeth to urge the teeth toward the ideal
arrangement, shaping three-dimensional surfaces corresponding to at
least portions of the surfaces of the teeth of the patient and
fabricating bracket positioning jigs having such surfaces thereon,
shaping three-dimensional surfaces corresponding to at least
portions of the surfaces of the teeth of the patient and
fabricating an appliance having three-dimensional tooth engaging
surfaces derived therefrom, and shaping three-dimensional surfaces
corresponding to at least portions of the surfaces of the teeth of
the patient and cutting slots in brackets positioning jigs having
such surfaces thereon.
40. A method of providing custom orthodontic treatment comprising:
providing a scanning device for producing three-dimensional digital
data of the shapes of the teeth of a patient; receiving, from a
dental practitioner, instructions relating to prescribed
orthodontic treatment of the patient; displaying three-dimensional
digital data from the scanner with a computer; interactively
selecting surface features of the patient's teeth from the data
displayed with the computer; manipulating the three-dimensional
data with a computer to position the selected surface features of
different teeth relative to each other so as to produce a digital
arrangement of the teeth in accordance with the instructions from
the dental practitioner; designing an orthodontic appliance for
moving the teeth of the patient in accordance with the digital
arrangement and the instructions from the dental practitioner; and
fabricating an orthodontic appliance as so designed.
41. The method of claim 40 wherein: the manipulating of the data to
produce the digital arrangement of the teeth includes manually
adjusting the digital arrangement on the computer.
42. The method of claim 40 wherein: the fabricating of the
orthodontic appliance includes forming an orthodontic archwire.
43. The method of claim 40 wherein: the fabricating of the
orthodontic appliance includes forming a series of bends along the
length of an orthodontic archwire.
44. The method of claim 40 further comprising: analyzing the
anatomy of the teeth from the produced three dimensional data; and
fabricating the appliance based in part on the analyzing of the
anatomy.
45. The method of claim 40 wherein: the fabricating of the custom
orthodontic appliance is based in part on identified placement
positions on the teeth of the patient and specified bracket
geometry.
46. The method of claim 40 further comprising: providing bracket
placement jigs based the three-dimensional data for the positioning
the orthodontic appliance for bonding to the teeth of the
patient.
47. A method of making a custom orthodontic appliance comprising:
capturing three-dimensional anatomical data of the teeth of a
patient while in initial positions; based on the anatomical data,
determining treatment positions of the teeth and storing data of
the determined treatment positions; processing in a computer the
stored data of treatment positions and designing thereby an
orthodontic appliance for moving the teeth of the patient toward
the determined treatment positions; and manufacturing a series of
custom orthodontic appliances for applying forces to the teeth of
the patient to move them progressively toward the determined
treatment positions.
48. The method of claim 47 wherein: the series of appliances
includes a series of archwires.
49. The method of claim 47 wherein: the series of appliances
includes a series of archwires of increasing stiffness.
50. The method of claim 47 wherein: the treatment position
determining step includes manipulating the digitized
three-dimensional data to produce a three-dimensional digital model
of the teeth in the treatment positions.
51. A method of making a custom orthodontic appliance comprising:
producing digital three-dimensional data of the shapes of the teeth
of a patient, the data including relatively simple data sets of
tooth representations and relatively high resolution data sets of
tooth representations; determining treatment positions of the teeth
and storing data in a computer the determined treatment positions
by manipulating the relatively low simple data sets of tooth
representations; processing in a computer the stored data of
treatment positions and designing thereby an orthodontic appliance
for urging the teeth of the patient toward the determined treatment
positions; and fabricating surfaces of material in accordance with
the relatively high resolution data sets of tooth representations
to conform surfaces of the material to the surfaces of the teeth
for locating the appliance on the teeth.
52. The method of claim 51 wherein: the relatively high resolution
sets of tooth representations are produced by scanning a model of
the teeth; and the relatively simple data sets of tooth
representations are produced by simplifying the data of the
relatively high resolution data sets of tooth representations.
53. The method of claim 51 wherein: the relatively high resolution
data sets of tooth representations are produced by scanning a model
of the teeth; and the surfaces fabricated in accordance with the
relatively high resolution data sets of tooth representations
include surfaces of bracket positioning jigs that conform to the
surfaces of the teeth for locating brackets on the teeth of the
patient.
54. A method of providing for the accurate placement of orthodontic
appliances on the teeth of patients comprising: providing a scanner
for producing three-dimensional data of the shapes of the teeth of
patients; defining in a computer placement positions of orthodontic
brackets on teeth; generating control signals with the computer for
controlling a fabricating machine; producing with the fabricating
machine in response to the control signals bracket placement jigs
having tooth conforming surfaces thereon defined by
three-dimensional data from the scanner for locating the
orthodontic brackets at the defined placement positions on the
teeth of patients.
Description
[0001] This application is a continuation of copending and commonly
assigned U.S. patent application Ser. No. 09/431,466, filed Nov. 1,
1999, which is a continuation of U.S. patent application Ser. No.
08/960,908, filed Oct. 30, 1997, now U.S. Pat. No. 6,015,289,
[0002] which is a continuation of U.S. patent application Ser. No.
08/456,666, filed Jun. 2, 1995, now U.S. Pat. No. 5,683,243,
[0003] which is a divisional of the following U.S. Patent
Applications, each filed Nov. 9, 1992, each by the inventors of the
present application, each commonly assigned to the assignee of the
present application, and each containing a specific reference to
the other such applications:
[0004] Ser. No. 07/973,973 entitled Method of Forming Custom
Orthodontic Appliance, now U.S. Pat. No. 5,431,562,
[0005] Ser. No. 07/973,965 entitled Custom Orthodontic Brackets and
Bracket forming Method and Apparatus, now U.S. Pat. No.
5,454,717,
[0006] Ser. No. 07/973,947 entitled Custom Orthodontic Archwire
forming Method and Apparatus, now U.S. Pat. No. 5,447,432, and
[0007] Ser. No. 07/973,844 entitled Method and Apparatus for
Forming Jigs for Custom Placement of Orthodontic Appliances on
Teeth and Jigs formed Therewith, now U.S. Pat. No. 5,368,478,
[0008] all of which are hereby expressly incorporated by reference
herein.
FIELD OF INVENTION
[0009] The present invention relates to the orthodontic treatment
of patients, particularly to the providing of orthodontic
appliances in the treatment of such patients. The invention more
particularly relates to the design, manufacture and/or use of
orthodontic appliances for the straightening of teeth, and more
particularly, to the automated design, manufacture and use of
orthodontic appliances, especially custom orthodontic appliances
based on individual patient anatomy.
BACKGROUND OF THE INVENTION
[0010] The orthodontic treatment of patients has as its fundamental
objective the repositioning or realignment of the teeth of a
patient in the patient's mouth to positions where they function
optimally together and occupy relative locations and orientations
that define a pair of opposed and cooperating planar, or nearly
planar, smooth arches. The teeth of the two arches, the maxillary
arch of the teeth of the upper jaw and the mandibular arch of the
teeth of the lower jaw, when in an optimal or ideal position,
contact the teeth of the opposite arch along a surface that is
usually flat or slightly upwardly concave and commonly referred to
as the plane of occlusion.
[0011] The treatment applied to patients who have been diagnosed as
having teeth insufficiently close to the ideal positions to require
orthodontic correction includes an initial or rough procedure to
overcome the more serious defects of tooth positioning followed by
a finish treatment designed to bring the teeth as closely as
possible or practical to their ideal positions. The rough treatment
usually involves the movement of certain teeth through the use of
any of a number of recognized techniques performed by an
orthodontist, and sometimes procedures such as the extraction of
certain teeth or surgery on the patient's jaw performed by an oral
surgeon.
[0012] In the finish treatment, the orthodontist applies an
appliance, or set of braces, to the teeth of the patient to exert
continual forces on the teeth of the patient to gradually urge them
toward their ideal positions. The application of the appliance
usually involves the attachment of brackets to the teeth, either
with the application of adhesive to the teeth or the securing of
bands around the teeth. The brackets are usually each provided with
a slot through which an archwire is extended. One archwire is
provided for the upper teeth and one for the lower teeth.
Typically, the slots in the brackets are of rectangular
cross-section and the archwire is of rectangular cross-section. The
archwire installed in the slots of the brackets interconnects the
teeth, through the brackets, and exerts forces on the teeth to
translate or rotate them toward a finish position envisioned by the
orthodontist.
[0013] It has been recognized in the design and application of
orthodontic appliances that an ideally designed and installed
orthodontic appliance will present the slots of the brackets in a
position to initially receive a pre-shaped archwire that will
elastically deform to exert corrective forces on the teeth to urge
them toward their finish positions. When in their finish positions,
the archwire of the ideally designed appliance will no longer be
elastically deformed, and will no longer exert forces upon the
teeth. Achieving this objective has been inhibited by certain
problems in the prior art.
[0014] One problem presented by the prior art is that current
orthodontic products are designed and manufactured to average
anatomy. As a result, orthodontists are faced with the need to
select what they perceive to be the brackets and archwires of the
closest design to those required by a particular patient, and to
modify the designs for treatment of the patient. Some of this
modification may be performed when the appliance is initially
installed, but almost inevitably modification is required during
the course of treatment of the patient. This modification may take
the form of the replacement of brackets, but most commonly requires
a periodic bending and reshaping of the archwire as the treatment
progresses. Thus, the treatment of the patient has become a manual
feedback system in which the orthodontist monitors the progress of
the patient's treatment and then readjusts the appliance, usually
by bending the archwires, to correct the forces being applied to
the teeth to bring the teeth to their ultimate positions, which are
less than ideal. As a result, the patient may be subjected to
treatment over a period that is longer than would be necessary if
the appliance were initially made to the optimum design. In
addition, the time required of the orthodontist for implementation
of the treatment may be several times greater than it would be if
modification of the appliance were unnecessary. Thus, the
orthodontist is able to treat fewer patients and the cost of the
treatment to the patient or to the orthodontist is increased.
[0015] Location of the connection points for the appliance to the
teeth also presents a problem in the prior art. Typically, brackets
are bonded to the teeth and then interconnected by the installation
of the archwires. This is done when the teeth are in their
maloccluded positions, with the orthodontist having only a mental
vision of where the finish positions of the teeth will be and where
the brackets are to be placed to move the teeth to those finish
positions. For more effective use of the appliance and to promote
ease in cleaning the teeth, the orthodontist prefers to locate the
brackets and archwires away from the gums. If they are placed too
close to the tips of the teeth, however, they may interfere with
the teeth of the opposite arch as the teeth approach their finish
positions.
[0016] Another problem of the prior art that has inhibited the
selection or design of an ideal orthodontic appliance for the
patient is the difficulty in arriving at an expression of the ideal
finish position of the teeth. Orthodontists typically make models
of the patient's mouth and, with the models and the aid of x-rays,
determine a treatment to move the teeth to finish tooth positions.
This process is time consuming and presents a source of error and
inaccuracy. From the measurements and based on the judgment of the
orthodontist, appliance components are selected to implement the
prescribed treatment. In reality, the treatment of patients is in
many cases more of an art than a science, with results ranging from
poor to excellent, and generally variable.
[0017] The need for custom manufactured orthodontic appliances and
the use of automatic design techniques has been recognized by some,
while others have advocated adherence to standard components and
manual techniques in view of a perceived lack of practical custom
appliance manufacturing and automated appliance design systems of
the art.
[0018] The development of automated custom appliance design systems
has encountered several difficulties. These difficulties have
included the task of developing an automated system that includes
reliable and efficient decision making algorithms and techniques
for automatically determining an ideal finish position of the
teeth. Further, these difficulties have included arriving at an
expression of appliance geometry in terms that can be efficiently
produced by automated appliance manufacturing equipment.
Furthermore, the prior art has not provided a way to accurately
manufacture an appliance on an individualized basis in accordance
with the appliance design. An additional problem in the automated
design and manufacture of orthodontic appliances lies in the
difficulty in designing the custom design system to take into
account the professionally recognized parameters and criteria,
derived over many years from the knowledge and experience of the
practicing and clinical orthodontist, upon which diagnosis and
treatment is based.
[0019] Accordingly, there is a great need in orthodontics for a
practical, reliable and efficient custom appliance automated design
and manufacturing system, and method of providing custom appliances
and treating patients therewith.
SUMMARY OF THE INVENTION
[0020] A primary objective of the present invention is to provide a
practical, reliable and efficient custom appliance automated design
and manufacturing system and methods of automatically designing
custom orthodontic appliances and treating patients therewith.
[0021] It is a particular objective of the present invention to
provide an automated custom orthodontic appliance design and
manufacturing system that can be easily and reliably used by
practicing orthodontists and that will make best use of the skills,
knowledge and experience that the orthodontist possesses. It is a
further objective of the present invention to increase the accuracy
of the orthodontist's treatment, to render the use of the
orthodontist's time more efficient, to eliminate sources of error
and guesswork from the orthodontist's treatment of patients, and to
efficiently, repeatedly and reliably perform automatically many of
the routine steps in the diagnosis, prescription and implementation
of orthodontic treatment and in the design and manufacture of
orthodontic appliances.
[0022] It is a further objective of the present invention to
improve the practice of orthodontics by aiding the practitioner in
achieving optimal finish treatment of patients and in more
accurately determining and precisely achieving the finish placement
of a patient's teeth. An additional objective of the present
invention is to provide for the accumulation of data from
individual patients for the analysis of the data to advance the
orthodontic art.
[0023] It is still another objective of the present invention to
apportion the tasks involved in the design and manufacture of
custom appliances most efficiently between orthodontist and
appliance manufacturing facility in accordance with the scale and
other particulars of the individual practitioner operation.
[0024] According to the principles of the present invention, a
system and method are provided which depart from traditional design
and manufacture by designing orthodontic appliances around the
anatomy of the individual patient. Further, unlike current
orthodontic products that are designed and manufactured to average
anatomy, the orthodontic products of the present invention and the
methods of manufacturing and using them are tailored to the
individual anatomy of the patient.
[0025] In accordance with the preferred embodiment of the present
invention, there is provided a computerized system and method with
which finish positions of the teeth of a patient are derived from
digitized information of anatomical shapes of the patient's mouth,
an orthodontic appliance is automatically designed from the
digitized shape information and the derived tooth finish positions,
machine code is generated for production of the orthodontic
appliance and communicated to NC machines, and the appliance is
automatically fabricated with the machines in response to the
machine code.
[0026] In accordance with the preferred and illustrated embodiment
of the invention, the digitized information is generated from
measurements from the mouth of the patient, either taken directly
or from a model thereof, and preferably includes information of the
shapes of the individual teeth of the patient and of the patient's
lower jaw.
[0027] In the preferred embodiment, the finish tooth position
derivation includes the derivation of one or more archforms,
preferably conforming to a skeletal archform defined by the shape
of the lower jaw. The appliance is also configured in accordance
with the shape of the derived archform, preferably with a
mandibular skeletal archform having size and shape conforming to
that of the trough of the lower jaw. In the preferred embodiments,
additional archforms are constructed using information of the
shapes of the individual teeth and the lower jaw skeletal archform
to define the positions of the buccal cusps and incisal tips of the
mandibular teeth, the marginal ridges of the upper posterior teeth,
and the lingual points of occlusion of the upper anterior teeth to
position the teeth according to a preferred treatment plan.
[0028] In certain preferred embodiments of the invention, the
digitized data is taken by measurements of the patient's individual
teeth and the data is reduced to certain landmark data that becomes
key to effective and efficient arrival at highly preferred finish
tooth positions. The individual teeth are arranged on the various
derived archforms with mesial and distal contact points of adjacent
teeth in contact. The spacing between the opposite contact points
of each tooth are preferably extracted from a computerized image
formed in horizontal plan views of the patient's teeth.
Furthermore, relative locations of the incisal tips, marginal
ridges, gingival contact points and the external surfaces of the
teeth to which the appliance connects, for example, by the mounting
of brackets, and which occlude with teeth of the opposite jaw, are
determined by digitizing vertical profiles of the surfaces of the
crowns of the teeth. This data is reduced to define contact points
of the mandibular teeth with the lower jaw, such as the gingival
center points, to define crown axes of the teeth, and other
parameters that are amenable to manipulation with a simple and
reliable algorithm in calculating the finish positions of the
teeth. The landmarks also include inter-cusp and inter-ridge
spacing measurements that provide a basis for prescribing arch
expansion treatment with exactness based on the computer aided
calculation of precise finish tooth positions. Further, the tooth
position calculations provided improve upon prior orthodontic
practice by preserving crown long axis inclination angles and
setting the teeth to preferred crown long axis inclination angles
for population groups according to seed values that are
statistically improved upon by the present invention.
[0029] In certain embodiments of the invention, images are
digitized to produce the tooth and jaw shape data. Preferably, the
images include a scanner which, in one form, generates a video
image from which selected points are digitized to produce data from
which finish tooth positioning and appliance design is carried out.
Alternatively, three dimensional imaging of the teeth and jaw of
the patient is carried out with laser or other scanner to form full
three dimensional images of the teeth and jaw of the patient. The
images may be formed from the patient's teeth and jaw or from a
model thereof. Additional data is digitized by taking vertical
profiles of the patient's teeth, either by tracing with a computer
the three dimensional images generated with other scanners, or by
scanning with a mechanical contact probe or with a non-contact
probe the individual teeth of the patient, or model thereof. The
data may be taken directly from the patient using CAT scans, MRI,
positron emission tomography or other technique.
[0030] Also in accordance with certain embodiments of the
invention, the finish tooth positioning includes the establishment
of cuspid rise criteria by rigorous calculations made from measured
and statistical anatomical data so that the height of the cuspids
and other teeth can be adjusted relative to each other so that the
teeth can be positioned to guide the jaws into proper occlusion.
With the present invention, numerical relationships are provided
for cuspid rise that are an improvement of the prior art.
[0031] In accordance with certain preferred embodiments of the
invention, an archwire forming machine that is responsive to NC
code is driven by signals generated by a computer that reads input
data of anatomical shapes of the patient's mouth, is provided to
automatically form an arcuate appliance that interconnects the
teeth to move them toward their finish positions by rotational and
translational forces applied in three dimensions each by the
arcuate appliance. Generally, the arcuate appliance is an archwire,
and the machine for forming the appliance includes an archwire
forming machine that is responsive to NC code, is driven by signals
generated by a computer that reads input data of anatomical shape
of the patient's mouth, preferably of the patient's jaw and teeth,
derives the tooth finish positions and archwire and bracket designs
that will move the teeth to the calculated finish positions, and
generates the machine code to produce the archwire in accordance
with the design. Preferably, the archwires have shapes that conform
to archforms related to the finish tooth positions, particularly to
the shape of the patient's lower jaw, and is represented as a
series of segments of a continuous archwire that each have a
constant radius of curvature over the length of the segment, and
that preferably join adjacent segments in a smooth transition, with
the segments tangent where they join.
[0032] Further in accordance with certain preferred embodiments of
the invention, a bracket fabrication machine, also responsive to NC
code, is driven by similar signals from a computer responsive to
computer generated finish tooth position calculations and digitized
tooth shape data. Preferably, the brackets have bases that mount on
computer determined positions on the teeth and have slots to
receive archwires that are inclined at computer determined angles.
The fabrication of the brackets may include the formation of a
slope and/or curvature to the mounting surfaces of the bases of the
brackets, or, as with the illustrated embodiment, by cutting custom
slots in the brackets. In the preferred embodiment, the design and
manufacture of the archwires and brackets are interrelated so that
the curve of the archwire is optimized to minimize curvature
changes and the brackets are optimize to minimize their profiles,
or the distances from the bases to the archwire slots. The
calculations provide a basis for the selection of appropriate
bracket blanks for the optimized appliance design.
[0033] Additionally, in accordance with other aspects of the
invention, one or more placement fixtures are manufactured from the
input data and the calculated tooth positions for locating points
on the teeth, preferably determined by the computer, for the
connection of the appliance to the teeth, such as for the mounting
of the brackets to the teeth. The fixtures preferably include a set
of bracket placement jigs, one for each bracket that is to be
mounted on a tooth, to position and hold the bracket to the tooth
so that it can be secured thereto in a precise mounting location.
The jigs of the preferred embodiment include a tooth profile or
three dimensional surface that fits against the tooth to precisely
locate the jig on the tooth and hold a bracket at a precise
position and inclination thereon so that it can be secured to the
tooth with adhesive.
[0034] With the present invention, a custom orthodontic appliance
is fabricated under the control of a computer directly from data
taken from the teeth and/or jaw of a patient or a model thereof.
The appliance so formed, when connected to the teeth of the
patient, moves the teeth of the patient to precise calculated
finish positions without the need for the orthodontist to bend
archwires over the course of the treatment. As a result, the
orthodontist's time is conserved, the treatment of the patient is
achieved in a shorter amount of time and the finish positions of
the teeth are more nearly ideal, and consistently so, than those
achieved with the procedures of the prior art. Furthermore, the
appliance fabricating processes result in the generation of data
useful in establishing treatment techniques and criteria that will
improve the practice of orthodontics.
[0035] Further, movement of the teeth to the finish positions
calculated in accordance with the present invention results in far
more stable placement of the teeth than with other methods of the
prior art which often experience movement of the teeth to inferior
positions after the orthodontic treatment is terminated.
[0036] These and other objectives and advantages of the present
invention will be more readily apparent from the following detailed
description of the drawings in which:
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] FIGS. 1-1F are diagrams illustrating the preferred
embodiments of the system of the present invention, of which:
[0038] FIG. 1 is a block diagram illustrating one preferred
embodiment of an automated system for the design and manufacture of
custom orthodontic appliances for the treatment of patients
therewith according to the principles of the present invention.
[0039] FIG. 1A is an elevational diagram of a video graphics image
forming embodiment of the data input portion of one embodiment of
the scanner of the system of FIG. 1.
[0040] FIG. 1B is an elevational diagram of a laser scanner version
of a three dimensional graphics imaging embodiment of a scanner of
the system of FIG. 1.
[0041] FIG. 1C is an elevational diagram of a mechanical tooth
profile probe scanner version of a two dimensional imaging portion
of one embodiment of the scanner of the system of FIG. 1.
[0042] FIG. 1D is an isometric diagram of one embodiment of a
bracket cutting device of the system of FIG. 1.
[0043] FIG. 1E is an isometric diagram of one embodiment of a wire
forming device of the system of FIG. 1.
[0044] FIG. 1F is an isometric diagram of a bracket placement jig
forming device of the system of FIG. 1.
[0045] FIGS. 2-2Z are flow chart diagrams of the preferred methods
of carrying out the present invention, of which:
[0046] FIG. 2 is a flow chart of one preferred embodiment of the
process of the present invention performed with the system of FIG.
1.
[0047] FIG. 2A is a more specific flow chart illustrating the steps
of the input procedure of automated tooth positioning and appliance
design and manufacturing operation of the process of FIG. 2.
[0048] FIG. 2B is a more specific flow chart illustrating the steps
of the analysis and tooth finish position calculating procedure of
the automated tooth positioning and appliance design and
manufacturing operation of the process of FIG. 2.
[0049] FIG. 2C is a more specific flow chart illustrating the steps
of the custom appliance design procedure of the automated appliance
design and manufacturing operation of the process of FIG. 2.
[0050] FIG. 2D is a more specific flow chart illustrating the steps
of the custom appliance manufacturing procedure of the automated
tooth positioning and appliance design and manufacturing operation
of the process of FIG. 2.
[0051] FIG. 2E is a detailed flow chart illustrating the substeps
of the identification data input step of the input procedure of
FIG. 2A.
[0052] FIG. 2F is a detailed flow chart illustrating the substeps
of the patient history and treatment data input step of the input
procedure of FIG. 2A.
[0053] FIG. 2G is a detailed flow chart illustrating the substeps
of the mandibular bone and horizontal tooth dimension data input
step of the input procedure of FIG. 2A.
[0054] FIG. 2H is a detailed flow chart illustrating the substeps
of the maxillary horizontal tooth dimension data input step of the
input procedure of FIG. 2A.
[0055] FIG. 2I is a detailed flow chart illustrating the substeps
of the individual tooth vertical profile data input step of the
input procedure of FIG. 2A.
[0056] FIG. 2J is a detailed flow chart illustrating the substeps
of the individual tooth profile analysis and landmark
identification step of the analysis procedure of FIG. 2B.
[0057] FIG. 2K is a detailed flow chart illustrating the substeps
of the cuspid rise calculation step of the analysis procedure of
FIG. 2B.
[0058] FIG. 2L is a detailed flow chart illustrating the substeps
of the mandibular preliminary horizontal tooth finish position
calculation step of the analysis procedure of FIG. 2B.
[0059] FIG. 2M is a detailed flow chart illustrating the substeps
of the best fit mandibular cusp arch equation calculation step of
the analysis procedure of FIG. 2B.
[0060] FIG. 2N is a detailed flow chart illustrating the substeps
of the calculation step of the mandibular tooth finish position on
the best fit mandibular cusp arch equation of the analysis
procedure of FIG. 2B.
[0061] FIG. 2O is a detailed flow chart illustrating the substeps
of the maxillary horizontal tooth finish position calculation step
of the analysis procedure of FIG. 2B.
[0062] FIG. 2P is a detailed flow chart illustrating the substeps
of the mandibular archwire plane calculation step of the appliance
design procedure of FIG. 2C.
[0063] FIG. 2Q is a detailed flow chart illustrating the substeps
of the mandibular bracket slot inclination calculation step of the
appliance design procedure of FIG. 2C.
[0064] FIG. 2R is a detailed flow chart illustrating the substeps
of the maxillary archwire plane calculation step of the appliance
design procedure of FIG. 2C.
[0065] FIG. 2S is a detailed flow chart illustrating the substeps
of the maxillary bracket slot inclination calculation step of the
appliance design procedure of FIG. 2C.
[0066] FIG. 2T is a detailed flow chart illustrating the substeps
of the mandibular archwire and bracket slot in-out dimension
calculation step of the appliance design procedure of FIG. 2C.
[0067] FIG. 2U is a detailed flow chart illustrating the substeps
of the maxillary archwire and bracket slot in-out dimension
calculation step of the appliance design procedure of FIG. 2C.
[0068] FIG. 2V is a detailed flow chart summarizing the substeps of
the bracket placement jig shape calculation step of the appliance
design procedure of FIG. 2C that is illustrated in more detail in
the flowchart of the jig modification step of FIG. 2Z described
below.
[0069] FIG. 2W is a detailed flow chart illustrating the substeps
of the cubic spline curve fitting, spline to circle conversion and
tooth placement calculation subroutines employed in placing teeth
on calculated archforms in certain steps of the tooth positioning
and appliance design and manufacturing operation of FIG. 2C.
[0070] FIG. 2X is a detailed flow chart illustrating the NC code
generation and slot cutting substeps of the bracket manufacturing
step of the procedure of FIG. 2D, and FIGS. 2X-1 through 2X-4 are
more detailed flowcharts illustrating substeps of FIG. 2X.
[0071] FIG. 2Y is a detailed flow chart of the substeps of the wire
bending code generation and wire manufacturing step of the
appliance manufacturing procedure of FIG. 2D.
[0072] FIG. 2Z is a detailed flow chart illustrating the substeps
of the jig manufacturing step of the appliance manufacturing
procedure of FIG. 2D. FIGS. 2Z-1 through 2Z-6 are more detailed
flowcharts illustrating details of substeps of FIG. 2Z.
[0073] FIGS. 3-3C are illustrations of graphics computer images
produced in the input procedure, in which:
[0074] FIG. 3 is an example of a computer display of a video image
generated by the scanner of the system of FIG. 1 illustrating in a
top plan view a mandibular model produced by the scanner of the
type shown in FIG. 1A.
[0075] FIG. 3A is an example of a portion of a three dimensional
digital image, illustrated in perspective, and produced by the
scanner of the type shown in FIG. 1B.
[0076] FIG. 3B is an illustration similar to FIG. 3A of another
portion of a three dimensional digital image produced by the
scanner of FIG. 1B.
[0077] FIG. 3C is an example of a set of vertical tooth profile
images produced by the scanner of FIG. 1C.
[0078] FIGS. 4-4E are plan views of the teeth of the patient on
tooth placement archforms at various stages of the tooth position
calculation procedure of FIG. 2B, of which:
[0079] FIG. 4 is a geometric diagram illustrating a horizontal plan
view data input screen showing diagrammatically the video image of
FIG. 3 used as a template, with variables relevant to the
digitization of data from the mandibular video image marked
thereon.
[0080] FIG. 4A is a geometric diagram similar to FIG. 4 for the
maxillary teeth.
[0081] FIG. 4B is a geometric diagram plotting horizontal
mandibular archforms calculated through the analysis procedure of
FIG. 2B.
[0082] FIG. 4C is a geometric diagram plotting horizontal maxillary
archforms calculated through the analysis procedure of FIG. 2B.
[0083] FIG. 4D is a horizontal plan diagram showing the maxillary
teeth in their finish positions.
[0084] FIG. 4E is a horizontal plan diagram showing the mandibular
teeth in their finish positions and with the custom appliance in
place.
[0085] FIGS. 5-5P are mathematical calculation diagrams for
reference in connection with spline to circle conversion and tooth
placement routines of FIG. 2W, in which:
[0086] FIG. 5 is a horizontal plan diagram illustrating the
placement of a tooth on an archform equation described in circle
segment form.
[0087] FIGS. 5A-5J are detailed diagrams of the spline to circle
conversion and tooth placement subroutines.
[0088] FIGS. 5K-5P are detailed diagrams of the tooth placement
subroutine.
[0089] FIGS. 6-6I are diagrams of tooth profiles illustrating
landmark determination, tooth inclination and vertical positioning,
in which:
[0090] FIG. 6 is an isometric image of a three-dimensional
computerized representation, similar to FIG. 2B, of a molar showing
the locations of alternative vertical labial-lingual profile planes
and tooth profiles.
[0091] FIG. 6A is a mathematical tooth profile plot as illustrated
on the computer screen of the system of FIG. 1 of a mandibular
molar showing selected landmark parameters.
[0092] FIG. 6B is a mathematical tooth profile plot, similar to
FIG. 6A, of a mandibular cuspid or incisor showing selected
landmark parameters.
[0093] FIG. 6C is a mathematical tooth profile plot, similar to
FIG. 6A, of a maxillary molar or bicuspid showing selected landmark
parameters.
[0094] FIG. 6D is a mathematical tooth profile plot, similar to
FIG. 6A, of a maxillary cuspid or incisor showing selected landmark
parameters relevant thereto.
[0095] FIG. 6E is representation of a display, similar to FIG. 3C,
of an array of mathematical tooth profile plots of all of the
teeth, angularly oriented, with landmark parameters marked
thereon.
[0096] FIG. 6F is representation of a display of an array of
mathematical tooth profile plots, similar to a portion of FIG. 6E,
of the mandibular teeth with working horizontal placement planes
marked thereon.
[0097] FIG. 6G is mathematical tooth profile plot, similar to FIG.
6A, of a mandibular posterior tooth with relevant dimensional
variables for placement of the tooth marked thereon.
[0098] FIG. 6H is mathematical tooth profile plot, similar to FIG.
6B, of a mandibular anterior tooth with relevant dimensional
variables for the placement of the tooth marked thereon.
[0099] FIG. 6I is mathematical tooth profile plot, similar to FIG.
6H, of the tallest mandibular tooth.
[0100] FIGS. 7-7D are diagrams for reference in connection with the
finish tooth position calculation, of which:
[0101] FIG. 7 is an elevational diagram of the relationship of the
jaws of a patient for illustration of cuspid rise occlusion
calculation.
[0102] FIG. 7A is an enlarged view of a portion of FIG. 7.
[0103] FIG. 7B is a plan mathematical diagram illustrating certain
of the mathematics of tooth placement on the mandibular offset
arch.
[0104] FIG. 7C is a perspective diagram illustrating the
relationship of the vertical tooth profile planes and relevant
horizontal arch planes in the course of tooth finish position
calculation.
[0105] FIG. 7D is a set of related elevational profiles of
mandibular and maxillary teeth showing occlusal and overlap
relationships in the course of tooth finish position
calculations.
[0106] FIGS. 8-8H are diagrams for reference in connection with the
steps of the custom appliance design procedure, of which:
[0107] FIG. 8 is a diagram similar to FIG. 7D illustrating archwire
plane and bracket slot design on positioned teeth.
[0108] FIG. 8A is an elevational diagram illustrating a bracket and
slot configuration in connection with the diagram of FIG. 8.
[0109] FIG. 8B is a top view illustrating the relation of a tooth
to an archform by placement routine of FIG. 2W.
[0110] FIG. 8C is a tooth profile diagram illustrating the slot
in-out dimension calculation.
[0111] FIG. 8D is a perspective diagram illustrating the placement
of a custom bracket onto a tooth with the use of a custom placement
jig.
[0112] FIG. 8E is a plan diagram of a custom archwire for the
appliance required to move the mandibular teeth to the finish
positions illustrated in FIG. 4E.
[0113] FIG. 8F is a plan diagram illustrating the labial installed
appliance on the teeth of the patient in their initial
positions.
[0114] FIG. 8G is a plan diagram, similar to FIG. 8F, illustrating
a lingual appliance installed on the teeth of the patient.
[0115] FIG. 8H is an elevational diagram illustrating an
orthodontic lingual bracket of the appliance of FIG. 8G.
[0116] FIG. 8I is a top view of a bracket having a base slot
curvature conforming to that of an archwire supported therein.
[0117] FIGS. 9-9W are diagrams relating to appliance manufacturing
steps, of which:
[0118] FIGS. 9-9H relate to substeps of the bracket slot cutting
code generation and bracket manufacturing step.
[0119] FIGS. 9I-9W relate to the substeps of the bracket placement
jig manufacturing step.
DETAILED DESCRIPTION OF THE DRAWINGS
[0120] The preferred embodiment of the invention provides a system
and method for designing and manufacturing orthodontic appliances
and for employing the appliances to orthodontically treat patients
for the straightening of teeth. Unlike traditional orthodontic
products, however, the appliances resulting from the practice of
the present invention are designed around the anatomy of the
individual patients. It further incorporates in its design criteria
the parameters and professional treatment approaches of the
treating orthodontists, and applies automated decision making
processes in the appliance design that take into account the
professionally recognized characteristics and anatomical landmarks
of the patients.
[0121] The overall configuration of the system 10 is illustrated
diagrammatically in FIG. 1. The overall operations of the preferred
method of the invention are illustrated in the flowchart of FIG.
2.
[0122] In accordance with the preferred embodiment of the invention
as illustrated in FIGS. 1 and 2, examination of a patient is
performed by an orthodontist at the orthodontist's office for the
purpose of assembling the information necessary to determine the
patient's condition, prescribe the appropriate treatment, and
specify the type of orthodontic appliance to implement the
treatment. The information is then communicated to a remotely
located appliance design and manufacturing facility where the
design of a custom appliance for use in administering the treatment
is carried out with the use of computer analysis. The appliance
design, together with the information necessary for the
orthodontist to install the appliance on the patient is then
transmitted back to the orthodontist, who installs the appliance
and administers the treatment in accordance with the appliance
manufacturer's instructions and his own professional expertise.
[0123] In accordance with alternative embodiments of the invention,
digitization of anatomical information for computer input is
performed either at the appliance design and manufacturing
facility, by the orthodontist at his office, or preferably divided
between the two. Similarly, the present invention contemplates the
manufacture of the appliance to be performed at either the
appliance manufacturing facility, at the orthodontist's office, or
preferably divided between the two locations and in accordance with
the analysis and design provided by the system of the present
invention.
[0124] The practice of the present invention involves the use of
certain system hardware, tangible records of information, and
communications paths described below in connection with FIG. 1 and
related illustrations, and the performance of operations,
procedures and steps described in connection with the flowchart of
FIG. 2 and related diagrams, all as set forth in detail below.
Terminology and Conventions
[0125] Throughout the description, references are made to tangible
elements illustrated in the drawings and to actions performed by
hand and by computer. In the description, numbers used to refer to
structure or other tangible items illustrated in the drawings of
the preferred embodiment appear in conventional form in the text,
while numbers that refer to method steps in the illustrated
flowchart are enclosed in parentheses in the following description.
Letter symbols are used to refer to geometric or mathematical
representations of variables, parameters, dimensions and values,
input into or calculated by a computer, tie into equations and
diagrams illustrated in the drawings, or correspond to computer
codes or conceptual items set forth in the disclosure.
[0126] Throughout this description, the various teeth of the
patient, up to thirty-two in number, may be identified as
T.sub.JSI, or T(J,S,I), where J designates the jaw (upper: J=U;
lower: J=B), where S designates the side (patient's right: S=R;
patient's left: S=L), and I designates the tooth by position
relative to the jaw centerline as follows:
1 I = 1: Central Incisor I = 2: Lateral Incisor I = 3: Cuspid I =
4: First Bicuspid I = 5: Second Bicuspid I = 6: First (6 year)
Molar I = 7: Second (12 year) Molar I = 8: Third (Wisdom Tooth)
Molar
[0127] The wisdom teeth are, however, customarily not involved in
orthodontic procedure and usually are not yet present in the mouth
of patients of treatment age. Furthermore, the second molars are
often not involved in orthodontic treatment. To simplify the
description and drawings, however, these designations are
eliminated except where they are necessary to avoid ambiguity.
Instead, the description below states verbally when it relates to,
for example, the lower jaw (thus making use of the J subscript
unnecessary) or where it relates to data or calculations relevant
to a particular or either side of a jaw (thus making use of the S
subscript unnecessary).
[0128] Further, many values are calculated or measured for each
tooth I, or for each of a limited group of teeth, as, for example,
the mesio-distal width MDW or the mesial and distal extremities
M.sub.X,Y and D.sub.X,Y as in the description of step (300) below.
Wherever possible, the I designation is also eliminated and the
description instead describes how the variables relate to the
various teeth. In addition, where some values such as MDW discussed
above relate to a tooth dimension or the distance between two
points on a tooth (and may be represented by a scalar value in a
computer), other values such as the points M.sub.X,Y and D.sub.X,Y
relate to points M and D, respectively (and may be represented by a
pair of X and Y coordinates in a computer). Usually, the subscripts
designating the two coordinates are omitted, and where helpful to
clarify the description, a single one of the subscripts X or Y may
be used, such as with D.sub.X or D.sub.Y, to designate that only
the X or Y coordinate is employed, for example, in a
calculation.
SYSTEM CONFIGURATION
[0129] Referring to the system diagram of FIG. 1, an orthodontic
appliance manufacturing and patient treatment system 10 is
illustrated. The system components are distributed between two
locations, a doctor's office 11, and an appliance design and
manufacturing facility 13. At the doctor's office 11, a patient 12,
who requires orthodontic treatment, is examined by an orthodontist
14, who makes a diagnosis 15 of the condition of the patient and of
the treatment, if any, needed. The examination involves the
traditional application of the skill, knowledge and expertise of
the orthodontist 14, and results in the preparation of detailed
records 16 of the anatomy and condition of the mouth 18 of the
patient, of the treatment proposed, and of other information
necessary to the preparation of an orthodontic appliance.
[0130] The records 16 prepared by the orthodontist include a
physical model 20 from a mold of the patient's mouth 18, which
includes a mandibular model 21 of the patient's lower jaw or
mandible 22 and a maxillary model 23 of the patient's upper jaw or
maxilla 24. The records 16 also include prescription 27 wherein the
orthodontist sets forth a treatment to be applied to the patient
and a result to be achieved by the treatment. The prescription 27
may also include a specification of techniques that are to be
included in the treatment and a designation of an orthodontic
appliance to be employed. The records 16 will further include
identification information 17 and patient history information
19.
[0131] In the illustrated embodiment of the invention, the records
16 are transmitted to the appliance manufacturing facility 13, at
which the finish position of the teeth are calculated and a custom
appliance 25 is designed and manufactured. The facility 13 is
provided with one or more trained operators 28. In some
embodiments, the physical model 20 itself is transmitted in the
information 16 to the facility 13. In such cases, one of the
primary functions of the operators 28 is to input digital
information 26 from the records 16 into a computer 30a. Another
function is to operate the same or another computer 30b to design
the custom appliance 25, and to operate NC equipment 38 controlled
by one of the same or another computer 30c to manufacture the
appliance 25. Where the inputting, design and manufacture are
performed at the appliance facility 13, the computers 30a, 30b and
30c may be the same computer 30.
[0132] In other embodiments of the invention, the orthodontist 14
digitizes data from the model 20, in which case the inputting
computer 30 is located at the orthodontist's office 11. In these
embodiments, the digitized information 26, rather than the physical
model 20, is transmitted to the appliance facility 13. The
analyzing and appliance design computer is nonetheless preferably
at the appliance facility 13.
[0133] The entry of the information into the input computer 30
involves a digitizing of the information 16 to produce the
digitized anatomical information 26 in machine readable form for
analysis by the analyzing computer 30b. The input computer 30
connected thereto by a scanner 33, which, in the alternative
embodiments of the invention, includes equipment that employs one
or more video cameras, mechanical probes, laser scanners,
ultrasonic scanners, moire image scanners or other forms of imaging
or measurement hardware that alone, or in combination with other
such components, produce anatomical geometric information that
describes the patient's teeth and jaw. The images may be
three-dimensional or be made along a plurality of planes or other
surfaces that can ultimately be combined to provide information in
three dimensions.
[0134] The combined information from the scanner 33 of the
illustrated embodiment provides a basis for three dimensional
analysis of the patient's teeth and from which calculations of
finish tooth positions can be made. From the final positional
calculations and tooth anatomy data, automatic design and
manufacture of the custom orthodontic appliance 25 is carried out.
In the illustrated embodiment, the data is imaged in a plurality of
differently oriented two dimensional planes in the computer 30,
then mathematically manipulated and combined in the computer 30b to
construct a three dimensional solution to the tooth positioning and
appliance design problems.
[0135] In a configuration in which the scanner 33 is connected to a
separate dedicated inputting computer 30 is herein described, the
functional equivalent of the inputting computer 30 may be included
in circuitry within the scanner 33 itself.
[0136] Preferably, the digital input process utilizes interactive
methods by which an operator 28 uses a pointing device and
digitizer to select particularly useful orthodontic parameters from
graphics images produced by the scanner 33 on a screen 35 of a
display connected to the inputting computer 30.
[0137] In embodiments where some or all of the extraction of the
digitized anatomical information 26 from the model 20, which may
also be derived directly from the mouth 18 of the patient 12, is
accomplished by the orthodontist 14 at the orthodontist's office
11, the information 26 is digitized by the orthodontist 14 then
transmitted as part of the information 16 to the appliance design
center 13. The transmitted information 16 is preferably transmitted
from the orthodontist's office 11 to the appliance facility 13 by
modem, but may be transmitted in any other available manner.
[0138] An analysis and design computer 30b, preferably at the
appliance design facility 13, produces an archive diskette 34 that
is formatted and written with all of the relevant information of
the analysis and the history and prescribed treatment of the
patient 14.
[0139] The computer 30b at the appliance facility 13 calculates,
based on the digitized information 26, the final position of the
patient's teeth, and the configuration of the appliance 25 required
to move the patient's teeth to this final or finish position. As a
result, calculated information for the patient is stored in a
patient data file 36. From the calculations the computer 30c
produces CNC machine readable code 42 for operating NC
manufacturing equipment 38 to produce the appliance 25. An
instruction document or file 37 is also produced, either by the
computer 30b or the computer 30c, of information to aid the
orthodontist 14 in treating the patient 14 with the custom
appliance 25.
[0140] The manufacturing equipment 38 includes an appliance bracket
cutting or forming machine 39 which produces custom brackets for
the appliance 25 by cutting slots calculated angles and to
calculated depths in slotless generic brackets. The machine 39 may
also or alternatively shape the surfaces of the bracket bases. This
provides the bracket design option of torquing the teeth by either
the bracket slot or base, as may be best for various bracket
materials.
[0141] The equipment 38 also includes an appliance archwire bending
or forming machine 40 which produces custom shaped archwires for
the appliance 25 by feeding and bending wire of any one of several
available materials and stiffnesses into the custom archwire shape.
The equipment 38 may also include a machine for forming patient
treatment components and hardware to aid in the manufacture or
installation of the appliance 25. In the illustrated embodiment,
this includes a machine 41 for the making of bracket placement
jigs, which cuts each tooth crown portion of the tooth profile into
a plastic form, along with a superimposed cutout of the positioned
bracket, for use in accurately installing the custom brackets in
their calculated positions on the teeth.
[0142] The appliance manufacturing machines 38 may be connected
directly to the analyzing computer 30b or one or more may be
connected to a separate manufacturing equipment controlling
computer or machine controller 30c. The computer 30c may be located
at the appliance facility 13 or, together with one or more of the
appliance manufacturing machines 38, 40 or 41, be located at the
orthodontist's office 11. In one preferred embodiment of the
invention, one manufacturing computer 30c and the bracket cutting
machine 40 are located at the orthodontist's office, along with the
scanner 33 and input computer 30, which may be the same computer as
the manufacturing computer 30c, while another manufacturing central
computer 30c, which may be the analyzing computer 30b, the wire
bending machine 40 and the jig forming machine 41 are located at
the appliance facility 13. The optimum distribution of the
computers 30, 30b and 30c and the scanner 33 and appliance
manufacturing machines 38, 40 and 41 will be determined by the
scale of the orthodontist's practice and the orthodontist's
preferences. In the illustrated embodiment, the computers 30-30c
are IBM PC clones, with Intel 80386 or 80486 microprocessors and
equipped with 80387 or 80487 math coprocessors, respectively.
[0143] Certain components of the system 10 of FIG. 1 are described
below in further detail.
Scanning Assembly 33
[0144] Three steps in the information input procedure (82),
described below, involve the inputting into the computer 30, for
analysis in digital form, of data concerning the shape of the mouth
18 of the patient 12 and of the shapes of the individual teeth
therein. In these steps, digitized images and measurement data of
the mouth 18 of the patient 12, preferably taken indirectly from
the model 20, and digitized to form a three dimensional
mathematical model of the patient's mouth 18. The mathematical
model includes, in the preferred embodiment of the invention, the
definition of certain parameters of the patient's lower jaw and
individual teeth, and may include some information of the initial
position and orientation of the teeth in the mouth 18 of the
patient 12 for evaluating the magnitude of the treatment.
[0145] The input information 26 is, in some embodiments of the
invention, input as a full three dimensional image, and then
simplified by reducing it to a plurality of curves in a plurality
of differently oriented planes or fairly flat curved surfaces, each
defined in the independent X-Y coordinate system of the respective
surface or plane. In subsequent analysis, these planes are
oriented, translated and rescaled with respect to each other in
arriving at a derivation of the ideal finish positions of the teeth
and the design of the custom appliance 25. In accordance with the
preferred embodiment of the invention, curves and points on the
contours of the jaw and teeth of the patient 12 are expressed in
terms of accepted or generally applicable orthodontic parameters so
that manual and automated decision making can combine and
coordinate the best of orthodontic knowledge and experience with
the efficiency and precision of computer analysis to minimize the
use of the orthodontist's time, shorten the patient's treatment
period and optimize the final treatment result.
[0146] The various types of and components of the scanner 33 of
various embodiments of the invention are described below.
[0147] Video Scanning Data Input Assembly 43:
[0148] One preferred form or component of the scanner 33 includes a
video imaging assembly 43 as illustrated in FIG. 1A. The video
imaging assembly 43 includes one or more video cameras 44 which
each produce two dimensional images of the patient's mouth 18,
preferably by forming an image of the model 20. When two or more
are used together, the video assembly 43 produces stereo images
capable of being resolved in three dimensions. In the illustrated
embodiment of the invention, a single video camera 44 is employed
to produce two dimensional video images of a plan view of the
patient's lower or upper jaws 22 and 24, from the models 21 or 23,
respectively, in generally horizontal X-Y planes. In accordance
with this embodiment, other forms or components of the scanner 33
are preferably employed to produce information in a third dimension
as described below.
[0149] Referring to FIG. 1A, the video imaging assembly 43 is shown
diagrammatically in side elevation at the appliance manufacturer's
facility 13. The video imaging assembly 43, in its preferred form,
is an operator-computer graphical interface that includes the video
camera 44 connected to a video interface board 44a in the input
computer 30. The camera 44 is mounted on a stand 45 to face
downwardly to form a top plan view of one of the halves 21 or 23 of
the model 20, shown as the mandibular portion 21 in FIG. 3, on a
horizontal support 46 attached to a base 45a of the stand 45. The
model half 21 or 23 is positioned on the support 46 such that the
teeth face upwardly toward the camera 44 and so that the tips
thereof lie generally in a horizontal plane that is maintained at a
known fixed distance from the camera 44, so that the scale of the
image formed by the camera 44 is known. This may be accomplished by
mounting the support 46 on springs 46a to urge the model half 21 or
23 upwardly against a transparent horizontal plate 45b.
[0150] The input computer 30 has connected thereto a pointing
device which may be a mouse 47a or, as shown, a mouse equipped
digitizer board 47. The camera 44 produces a graphics image display
48 on the screen 35 of the computer 30, which an operator 28 may
align with the assistance of a positioning grid G (FIG. 4A). With
the digitizer 47, the operator selects points by positioning a
curser 48a on the screen 35 with the mouse 47a. The selection
results in the storage of X,Y coordinate data for each of the
points selected. The points selected, in the description of the
preferred process below, correspond to preselected boundary points
of the teeth and, from the mandibular model 21, the lower jaw. From
these top view boundary points, tooth and mandibular jaw dimensions
are calculated. The calculated dimensions are used in analysis
steps to calculate equations for the mandibular bone structure or
mandibular trough MT and to calculate from the trough equation and
the calculated horizontal dimensions and relative positions of
features on individual teeth the finish positions of the teeth.
[0151] In the alternative to selecting points from the video image
display 48, the same points may be selected in the same manner from
a plan view video image of a digitized three-dimensional
computerized image of the teeth and jaws, such as an image formed
by a laser scanner, moire interference pattern scanner, ultrasonic
scanner, stereo video cameras, or other three-dimensional imaging
apparatus. Sectional displays 55a and 55b of such a
three-dimensional computerized image made with a laser scanner are
shown in perspective in FIGS. 3A and 3B, respectively. Such a laser
scanner is described in connection with FIG. 1B below.
[0152] Laser Three-dimensional Image Input Assembly 51:
[0153] One preferred form or component of the scanner 33 is the
laser generated three-dimensional image forming assembly 50
illustrated in FIG. 1B. Referring to FIG. 1B, one of the halves 21
and 23 of the model 20 is mounted on a support 51 while laser 52
directs a laser beam 52a onto the model 21 or 22. The laser beam
52a is reflected and the reflected beam is detected by a sensor 53
composed of a photoelectric pixel array which uses a triangulation
method to convert a change in position on the sensor into a change
in distance between the assembly 50 and the model 21 or 23 mounted
to translate parallel to the model 21 or 23 on a support 54 so as
to scan the model with the laser beam. Equipment for producing
images using laser technology in this manner is commercially
available for forming computerized representations in three
dimensions of manufactured and other objects. An example of
equipment suitable for this purpose are the Cyber Scan.TM.
Measurement System manufactured by Cyber Optics Corporation of
Minneapolis, Minn. The images formed by such equipment would
preferably include full detailed three-dimensional image data of
the patient's lower and upper jaws 22 and 24, taken from the model
20, with the teeth in their original positions. The data is written
in standard ASCII files by the equipment described and is readable
by the input computer 30a into the digitized information files
26.
[0154] Illustrated in FIGS. 3A and 3B are two sections of the
mandibular digitized model, and include a section 55a showing the
front mandibular incisors T.sub.BR1 and T.sub.BL1 of the patient
12, and a section 55b showing the right mandibular second bicuspid
T.sub.BR5 and first molar T.sub.BR6 of the patient 12. When such
images are rotated to a horizontal plan view, a derivation of the
same information that is available from the video imager 43 of FIG.
1A may be derived, and points may be selected therefrom for
digitization automatically with software, or through an
operator/computer interactive process as with the video scanner 43.
The three-dimensional image 55 may be rotated into other
orientations for the derivation of other information in various
planes such as vertical tooth profile information that is derived
with the mechanical scanner 57 described below. Additionally, other
computerized procedures may be used to automatically derive
information from the three dimensional image 55 with or without
intervention or interaction by an operator.
Mechanical Probe Digital Scanner Assembly 57:
[0155] The scanner may also include, alternatively or in
combination with other scanning equipment such as the video scanner
assembly 43 of FIG. 1A or the laser scanning assembly of FIG. 1B
above, a mechanical probe assembly 57 as illustrated in FIG. 1C.
This entire assembly 57 is used in the illustrated embodiment of
the invention in combination with the video scanner 43 to derive
labial-lingual vertical profiles of the individual teeth of the
patient from the model 20 to supplement jaw and horizontal tooth
dimensional and shape information derived from a video image
produced by the video scanner 43 from the model 20. Alternatively,
portions of this assembly can be used to produce the same
information from a three dimensional image 55 produced by equipment
such as the laser scanning assembly 50.
[0156] Referring to FIG. 1C, the probe assembly 57 includes a
measurement probe 60 which is moveable over the individual teeth of
the model 21 to produce an electrical signal that is digitized for
computer input of point locations or profiles of the surfaces of
the teeth in separate X-Y for each tooth. In the illustrated
embodiment of the process of the invention, the information 26
preferably derived from the model 21 includes the tooth profiles
curves PF.sub.1 in a labial-lingual plane viewed in a
mesial-to-distal direction.
[0157] The probe assembly 57 further includes a magnetic base 59
upon which is mounted the model 20, and from which extends an
upstanding vertical support 58 on which the probe 60 is mounted.
The probe tip 60a is freely rotatable about a vertical axis on
which its tip lies, while the probe itself is hooked to allow the
tip to track recesses in the surfaces of the teeth of the model 21.
The probe 60 is mounted on the support 58 to move in X and Y
directions in a vertical plane preferably that extends through the
support 58 and the probe 60. In this manner, the probe tip 60a is
positioned to scan the surface of a tooth of the model 21 along
this plane. The probe 60 is linked to the support 58 through a pair
of orthogonal measurement position transducers 61, which
respectively generate electrical analog measurements of the
positions of the tip of the probe 60 along respective ones of the
X-Y orthogonal coordinates. The outputs of the transducers 61 are
connected to circuitry that generates a sequence of periodic
readings of the transducer measurements of the probe tip positions
which are then digitized. These outputs are sent in along lines 61a
connected to input computer 30, preferably to a serial port
thereof.
[0158] In use, a half of the model 20, for example, the mandibular
model 21, is mounted upon the magnetic base 59 on a steel
surveyor's mount 62 which slides on the base 59 when lightly urged,
but which otherwise holds its place thereon for precise
positioning. The mount can be raised, lowered or tilted for
leveling. In operation, the probe 60 is manually moved by an
operator 28 or automatically to scan the surface of each selected
tooth of the model 21 to produce profile curves PF of a section of
each tooth as illustrated in FIG. 3C. The profile PF may be
generated by any one of a number of commercially available
off-the-shelf CAD/CAM or illustration software packages, such as
VERSACAD.TM. available from Prime Computers, Inc. of Bedford, Mass.
The computer programs described in the flowcharts herein is written
for use with VERSACAD.TM. in CPL.TM., the programming language of
therefor. The video images 63 of the profiles PF are displayed on
the screen 35 and the digitized profiles are stored as part of the
input information 26 in non-volatile memory of the computer 30.
[0159] With the curves such as the profile PF so formed, an
operator can, with the use of the pointing device 47, select, by
positioning the cursor on the formed profile on the screen 35,
point parameters of the tooth, the coordinates of which can be
thereby input digitally into the computer 30.
Appliance Manufacturing Equipment 38
[0160] The manufacturing equipment 38 of the preferred embodiment
of the invention includes: an appliance bracket cutting or forming
machine 39 that custom forms the bracket bases to mount to the
teeth and cuts archwire slots in the brackets at precise calculated
positions and angles; an appliance archwire bending or forming
machine 40 that precisely bends archwires to a shape that will
cooperate with the custom brackets to apply corrective forces to
the teeth until they are in their calculated finish positions; and
a bracket placement jig forming machine 41 that manufactures
bracket placement jigs that conform to the contours of the
patient's teeth, as recorded in the profiles PF. These jigs are
used by the orthodontist to precisely place the custom brackets at
calculated positions on the teeth.
[0161] The manufacturing equipment 38 is controlled by NC computer
generated programs based on the data from the digitized input
information files 26 and the calculated patient data files 36.
[0162] Bracket Cutting Machine 39:
[0163] Referring to FIG. 1D, a bracket slot cutting machine 39 is
illustrated. The machine 39 includes a stationary base 72 on which
is fixed a pair of upwardly extending workpiece support brackets
72a to the top of which is pivotally mounted a workpiece or bracket
support 73. On the support, a full set 80a of brackets 80 for the
custom appliance 25 is mounted, prearranged in an assembly or
cartridge of twenty or twenty-four brackets. The support 73 pivots
about an axis 73a extending between the brackets 72a. Connected to
the axis 73a is an angular positioning motor 74 which positions the
support 73, and the brackets 80 mounted thereto, to any angular
orientation with respect to the horizontal. The motor 74 has an
input connected to the computer 30c to set the inclination to the
slot inclination angle of the bracket design in response to NC
command codes.
[0164] Also fixed to the base 72 and extending upwardly therefrom
is a saw support bracket 72b. To the top of the support bracket 72b
is a saw drive motor 75 and a set of three saw blade positioning
linear drive actuator 76, including an X-drive actuator 76x, a Y
drive actuator 76y, and a Z drive actuator 76z through which a saw
support arm 77 is supported to move respectively in the X, Y and Z
directions, that is, in an X direction horizontally perpendicular
to the axis of rotation 73a of the bracket holder 73, in a Y
direction horizontally parallel to the axis of rotation 73a of the
workpiece holder 73, and in a vertical Z direction. The actuators
76 have inputs connected to the computer 30c to receive positioning
signals from the computer 30c to cut arcuate slots in the X-Y plane
of the machine 39 in response to NC commands generated in
accordance with a custom appliance design.
[0165] At the remote end of the moveable arm 77 is a slot cutter
assembly 77a, driveably linked to the motor 75. The assembly 77a
has extending downwardly therefrom a rotatable cutter blade drive
shaft 77b, which has fixed to the lower end thereof a circular slot
cutter blade 77c. The blade 77c lies in the horizontal X-Y plane
and is of the thickness of the slot needed for the thickness of
archwire selected. The archwires are typically rectangular in
cross-section so that they are able to exert torque on the bracket,
which accordingly will be provided by the saw blade 77c with a slot
of rectangular cross-section. The base of the slot will be cut, in
accordance with the command signals from the computer 30c, at an
angle in the X-Y plane of the machine 39 that is tangent to the
final curve of the archwire that it will receive. The base of the
slot will be convex to accommodate the curve of the wire in the
horizontal plane. The inclination of the bracket slot is achieved
by the angle of the support 73 in response to control signals from
the computer 30c. The computer 30c is programmed to account for
changes in elevation of the bracket 80 due to the offset of the
brackets from the support axis of rotation 73a.
[0166] Wire Bending Machine 40:
[0167] The wire bending apparatus 40 is illustrated
diagrammatically in FIG. 1E. Primary control of the apparatus 40 is
preferably by an IBM PC clone, preferably with an 80386 or 80486
microprocessor with a math coprocessor, and with motion controller
board 65 installed. The controller board 65 is, for example, an
MC300 Motion controller 3-axis card manufactured by Motion
Engineering, Inc. The MC300 is a dedicated motion control card
which sends and receives signals to and from MC-OLS stepper
interfaces 66a and 66b. MC-OLS stepper motor interfaces 66a and 66b
send control signal commands to the stepper motor power supplies
67a and 67b, such as Compumotor S-Drive stepper power supplies
#88-011483D, regarding rate and direction of motion of the
motors.
[0168] The power supply 67a has an output connected to wire feed
rollers 68, positioned on opposite sides of a wire guide 68a, which
guides archwire 69 to feed it from a continuous coil supply. The
power supply 67b has an output connected to a wire bending roller
assembly or wire anvil 70.
[0169] The controller 66b additionally is adapted to receive
feedback signals regarding position from a disc encoder 70a, such
as a Dynapar/Veeder Root #E1000A76500, which monitors the position
of wire forming roller 70b, providing closed loop control of a wire
bending roller 70b. The roller is driven by a wire anvil motor 70c,
such as a Compumotor #S/SX 57-102, through a drive screw 70d, such
as an Industrial Devices Corp. Electric cylinder
#X995A-2-M56-MT1-200-PS. The screw 70d converts the angular
position of the motor 70c into linear motion of the roller 70b to
deflect and bend the wire 69 as it is fed through the guide 68a by
the rollers 68.
[0170] By coordinating the anvil 70 and the wire feed 68, formed
archwires 64 of any planar shape are fabricated. The rollers 68
pinch the wire, forcing it to advance into the anvil 70. The roller
70b of the anvil 70 moves up and down varying the radius and thus
controlling the radius to which the wire is permanently deformed.
In the formation of archwires with inflection points, that is that
have bends in opposite directions, a second anvil would be provided
opposite the wire 69 from the anvil 70 and controlled in
synchronism therewith.
[0171] A wire position sensor 71 is provided that inspects the
finished archwire by comparing the width of the formed wire 64 to
the desired width. The sensor 71 is mounted with respect to the
anvil 70 and feed rollers 68 to detect the position of the formed
archwire 64 when it is at the end of its forming cycle. This
measurement provides a feedback signal that provides compensation
for material property variations that effect the formed shape and
the amount of over-bending required. The sensor 71 sends
information back to the computer 30c as to whether the wire 64 is
acceptable or over-bent or under-bent. If the wire is either over
or under-bent, the computer 30c calculates the correction required
and incrementally modifies the signals through the interfaces 66a
and 66b to provide compensation to progressively correct successive
archwires 64 until the result of the signal from the sensor 71 is
deemed acceptable by the computer 30c.
[0172] Bracket Placement Jig Forming Machine 41:
[0173] The bracket jig forming equipment 41 is preferably a
standard NC mill configured as illustrated in FIG. 1F. The machine
41 includes the standard mill 81, having a downwardly projecting
rotary tool head 81 a on which is mounted an endmill tool 81b of,
for example, 0.020 inches in diameter, where 0.022 inch archwire is
used, and, for example 0.016 inches in diameter where 0.018 inch
archwire is used.
[0174] The mill 81 is either connected to a controller which will
have been loaded with CNC program code 42 prepared by the computer
30c or will be directly connected to the computer 30c. The mill 81
is provided with a tool support 81c to which a set of circular ABS
plastic jig blanks 83, usually twenty or twenty-four in number, are
fed by a feeding mechanism 81d, equipped with a magazine 81e of the
sets 83a of jig blanks 83. The tool head 81a is moveable vertically
to bring the tool 81b into contact with the blanks 83 and
horizontally in the X-Y directions in accordance with the tool path
instructions from the code 42.
GENERAL OPERATIONS AND PROCEDURES
[0175] In the preferred and illustrated embodiment of the
invention, the overall configuration of which is illustrated
diagrammatically in FIG. 1, the full custom system 10 is operated
to produce the orthodontic appliance 25 based on the individual
anatomy of the patient 12. One preferred method of the invention is
represented by the operations and procedures illustrated in the
flowchart of FIG. 2.
[0176] The method of the present invention, in its preferred
embodiment, includes three general operations. The first operation,
is (85) a patient evaluation operation performed by the
orthodontist 14 at the doctor's office 11 on the patient 12. This
operation includes the traditional professional diagnosis and
general prescription of treatment. According to the present
invention, the evaluation operation (85) is followed by (87) a
computer aided analysis and appliance design and manufacturing
operation performed, preferably at least in part, at the appliance
facility 13 to produce the custom appliance 25, and in turn
followed by a patient treatment operation (89), which includes
treatment of the patient 12 by the orthodontist 14 at the doctor's
office 11, with the installation and use of the appliance 25.
(85) Patient Evaluation Operation
[0177] Referring to the system diagram of FIG. 1 and the flow chart
of FIG. 2, the orthodontic evaluation operation (85) is performed
at a doctor's office 11. The operation (85) includes the procedures
(90) of the examination of a patient 12, (91) the preparation of
the model 20 of the patient's mouth and teeth, (92) the
prescription by the orthodontist 14 of treatment, (93) and
communication with the appliance facility 13.
[0178] During the examination procedure (90) the patient 12, who
requires orthodontic treatment, is examined by an orthodontist 14,
who makes a diagnosis of the condition of the patient and of the
treatment, if any, needed. Based on the diagnosis 15, the
orthodontist or doctor 14 assembles the information 16 that is
necessary to implement the prescribed treatment.
[0179] In assembling the information 16, the orthodontist 14 (91)
prepares a model of the patient's mouth 18, usually a physical
model 20 from a mold of the patient's mouth, in its initial
condition at the time of the diagnosis 15. The model 20 includes
the mandibular model 21 of the patient's lower jaw or mandible 22
and the maxillary model 23 of the patient's upper jaw or maxilla
24.
[0180] Then, further based on the diagnosis 15, the orthodontist 14
(92) prescribes a particular treatment and generates a prescription
27 in a tangible record form.
[0181] The orthodontist 14 then (93) communicates the information
16, for example, by transmitting the model 20, the prescription for
treatment 27, a record of information 17 identifying the doctor 14
and the patient 12, together with information 19 containing
statistical and historic data of the patient 12, to an appliance
design facility 13, at some remote location. At the appliance
design facility 13, the information 16 is digitized and input into
the computer 30 for analysis.
[0182] Alternatively, the orthodontist 14 may convert the
information 16 to digital computer readable form and transmit the
digitized information to the appliance design facility 13. In this
alternative, the system 10 would be configured with the input
computer 30 located at the orthodontist's office 11, and the
orthodontist 14 or assisting personnel would perform portions of a
data input procedure (94) described below.
(87) Analysis, Design and Manufacture Operation
[0183] When the information 16, which includes, for example, the
model 20, the prescription 27 and the information 17 and 19, are
received either at the appliance system manufacturer 13 or is ready
to be digitized at the orthodontist's office 11, (87) an analysis,
finish tooth position calculation, and orthodontic appliance design
and manufacturing operation is begun. In the operation (87), the
information 16 is processed and the custom appliance 25 for moving
the patient's teeth to an optimum final or finish position in
accordance with treatment prescribed by the orthodontist 14 is
produced.
[0184] The operation (87) includes the procedures of (94) inputting
into a computer the information 16 from the orthodontist 14, in
digital form, (95) analyzing with the aid of computer 30b the input
digitized information to arrive at the finish position of the
teeth, (96) designing with a computer a custom orthodontic
appliance in accordance with the computer analysis, (97)
manufacturing the custom appliance 25 in accordance with the
computer assisted design with the aid of computer controlled
machinery, and (98) communicating the custom appliance 25 and
accompanying instructions to the orthodontist 14.
[0185] In accordance with certain embodiments of the present
invention, some or all of the appliance manufacturing step (97) can
be performed at the facilities 11 of the orthodontist 14, in which
case the communicating step (98) would involve the communication of
machine readable code, in lieu of some or all of the completed
custom appliance 25, from the design facility 13 to the
orthodontist 14.
[0186] (94) Input Procedure:
[0187] In the input procedure (90) as illustrated in the flowchart
of FIG. 2A. In the procedure (94), the received information 16 is
input, in the illustrated embodiment by operator 28 at the design
facility 13, into a computer 30 in digital form. Even where the
inputting is performed by operator at the design facility 13, some
information 16, such as the information 17 and 19, may be supplied
by the orthodontist 14 in machine readable form and input directly
into the computer 30. The input procedure (94) includes five steps
(100)-(500), the substeps of which are described in detail in
connection with the flowchart details of FIGS. 2E-2I below. The
steps of the input procedure (90), in the illustrated embodiment,
also include certain substeps that are part of the function of the
analysis step (92) but are more conveniently performed at the time
the information is entered into the computer.
[0188] The input steps (100) and (200) involve the entry of
background information assembled by the orthodontist 14. In the
input steps (300), (400) and (500), tooth and jaw positions and
profiles are defined in terms of orthodontic parameters and
landmarks that can be later analyzed by computer to best implement
the orthodontic knowledge, skill and experience embodied in the
prescription 27 and of the orthodontic profession while efficiently
automatically producing a optimum result. These steps of the input
procedure (90) include:
[0189] (100) The inputting of the doctor-patient identification
information 17 in digital form into the computer 30a:
[0190] This information is used to identify the records of the
patient and the products produced.
[0191] (200) The inputting of patient background information 19 in
digital form into the computer 30a:
[0192] This information is used in part in calculating the finish
position of the patient's teeth in accordance with genetic
characteristics. Sex and race, for example, are used to assign
certain seed values such as the inclination of the axes of the
individual teeth of the patient 12 to an arch plane in step (625),
which is used to determine an offset for tips of the teeth from the
jaw bone or gum line.
[0193] This information also includes diagnostic determinations and
treatment option decisions made by the orthodontist 14, such as
determinations to extract teeth, or employ optional treatment
norms.
[0194] (300) The inputting into the computer 30, from a top view
image of the patient's mandibular model 21, the mandibular jaw
shape and tooth dimensional information:
[0195] In implementing a treatment to correct the tooth alignment
of the patient 12, the mandible 22 is the logical starting point
because it is a solid bone and has relatively little pliancy. By
contrast, the maxilla or upper jaw 24 is composed of segments held
together by sutures which do not fuse until mid or late teens.
[0196] Furthermore, these sutures can be separated by the
orthodontist even after the point of initial fusion by simple and
commonly known clinical techniques. These anatomical factors
require that the orthodontist 14 make relatively small changes in
the mandibular bone 22 and the preponderance of skeletal changes in
the maxilla 24. For this reason, the position of the mandibular
trough MT therefore taken as a constraint on the positions of the
roots of the lower teeth.
[0197] In step (300) information is input for use, in part, to
define from the patient's lower jaw bone the shape of the
mandibular trough MT, which serves as the first constraint in
arriving at the finish position of the teeth. In one embodiment,
this is accomplished by superimposing a predefined grid G on a
video or graphics image of the mandibular trough (from FIG. 3) in
the manner illustrated in FIG. 4. In addition, the distances
between the mesio-distal extremities, or mesio-distal widths MDW,
that is, their contact points with adjacent teeth, in a horizontal
plane, are input. These determine the total length of the dental
arch and the relative center-to-center spacings of the teeth along
the arch.
[0198] A mandibular trough equation MTE is derived, and may be
converted to a symmetrical equation SMT As a starting point toward
calculating finish tooth position, the mesio-distal widths of the
mandibular teeth are mathematically placed on the trough equation.
This is explained more fully below in connection with FIG. 4.
[0199] In the above and in many archform calculations below, a
cubic spline equation form is used initially in fitting a curve to
data points, then converted to a circle segment equation that
provides advantages in the analysis and design process and in the
final calculations needed to operate NC manufacturing equipment.
This is explained below in connection with FIG. 5 et seq.
[0200] Measured initial contra-lateral cusp spacing data are
generated for use by the orthodontist 14 in evaluating the custom
design and treatment parameters resulting from the final
calculations below.
[0201] In some embodiments, horizontal profile data of the lower
jaw may be input in this step, additional landmarks in the
horizontal plane may be identified, or full three-dimensional
images of the teeth and lower jaw may be made, for example, as
discussed in the descriptions of FIGS. 1A-1C above.
[0202] (400) The inputting into the computer 30, from a bottom view
image of the patient's maxillary model 23, maxillary tooth
dimensional information:
[0203] The shape of the maxilla, which is made of a segmented bone,
is a variable capable of being altered orthodontically in response
to final tooth position calculations as set forth below. Therefore,
its initial shape and initial maxillary tooth position is relevant
only in evaluating the feasibility of the amount of alteration
required and the type of treatment to be used.
[0204] In step (400), information is input into the computer 30c of
maxillary jaw shape and tooth dimensional information from the
maxillary model 23. This information is used in part to determine
the mesiodistal widths MDW of each upper tooth, in a horizontal
plane, and to determine the total length of the dental arch and the
relative center to center spacings of the teeth along the arch.
[0205] Measured initial contra-lateral cusp and central
groove/fossa spacing data are generated for use by the orthodontist
14 in evaluating the custom design and treatment parameters
resulting from the final calculations below.
[0206] As with step (300) above, in some embodiments, horizontal
profile data of the upper jaw may be input in this step, additional
landmarks in the horizontal plane may be identified, or full
three-dimensional images of the teeth and lower jaw may be made,
for example, as discussed in the descriptions of FIGS. 1A-1C above.
In these embodiments, techniques such as those described in step
(500) may be employed in the horizontal plane in steps (300) and
(400).
[0207] (500) The inputting of individual tooth elevational profile
information from the two halves of the model 20:
[0208] The tooth profile information can be generated using
computer analysis or interactive computer imaging from
three-dimensional images, if employed, as illustrated in FIG. 3A
formed with scanners such as illustrated in FIG. 1B, or with the
use of the probe assembly 57 of FIG. 1C from the physical model 20
of the jaw. Use of the probe assembly 57 is herein described.
[0209] Rapid reduction of tooth shape information to important
dimensions and landmark data for efficient and realizable
calculations of finish tooth position is achieved by imaging
carefully selected profiles of the teeth. Profiles are produced by
outlining the tooth crown surfaces along a vertical plane or other
similarly oriented surface that extends in a labial-lingual
direction generally perpendicular to the arch of the teeth in the
respective jaw. For the single cusp anterior teeth, this surface is
generally a surface bisecting the tooth and through the crown long
axis CLA of the tooth. For multiple cusp teeth, the same generally
applies except modification or displacement of the surface is
intelligently made on some teeth to pick up the highest cusp or a
marginal ridge that is relevant to development of the proper
occlusion.
[0210] For most calculations, as set forth in the detailed
explanation below, the tooth features profile can be assumed to be
on a plane through the tooth centerline, even when they are not.
With the features selected herein, such assumptions result in
errors that are still much smaller than those accepted in
conventional methods. In other calculations, the precise position
of a feature must be considered, and provision for such
considerations are made in the certain embodiments of the
invention.
[0211] For each tooth, profile data is taken in separate X-Y
coordinates that relate only to the selected surface or plane. In
the course of the analysis and calculation of finish tooth
position, these planes are separately translated and reoriented
with respect to those of the other teeth and those of the trough
and archforms, in several steps, until the ultimate interplane
relationships are established.
[0212] (95) Analysis and Tooth Positioning Procedure:
[0213] The computer analysis procedure is illustrated in the
flowchart of FIG. 2B. In the computer analysis procedure (95), the
digitized information input by the input procedure (94) is analyzed
to calculate the finish position of the teeth, so that the custom
appliance 25 can be designed in computerized design procedure (96)
and manufactured in computer controlled manufacturing procedure
(97). The analysis procedure (95) includes six steps and
subroutines (600)-(1100), the substeps of which are described in
detail in connection with the flowchart details of FIGS. 2J-2O
below. These steps include the following:
[0214] (600) The dental analysis step in which the orthodontic
landmarks of the teeth are identified:
[0215] A minimum number of points on the tooth profiles are
selected that are sufficient for determining the contact points
between teeth that are relevant to finish tooth position
calculation and appliance design. These points are selected such
that the calculations made from them are relatively insensitive to
measurement errors in the input of the data in step (500). From the
selected points, for each tooth, other parameters are derived,
including an incisal center point ICP, a gingival center point GCP
and the crown long axis CLA through the ICP and GCP, as explained
below in connection with step (600) and FIG. 6 et seq.
[0216] In order to determine the relationship between the crown
long axes and archwire planes, twenty-four of each crown type were
removed from a set of orthodontic casts and sectioned along the
mid-sagittal plane. These crowns were then mounted and projected at
twenty times magnification on an optical comparator. Tracings were
then made of these profiles. As a result, a procedure was
determined for use to establishing the crown long axis inclination
angles to produce the desired occlusion, and seed values were
tabulated and correlated with data such as the sex and race of the
patient as entered in step (200). As a result of this analysis,
preferred crown long axis inclination angles are produced with the
present invention that are an improvement over the facial
inclination angles employed in the prior art.
[0217] From the tabulated data, angles of inclination LAIs of the
crown long axes CLAs of each of the teeth of each jaw are set
relative to the plane that contains the mandibular trough equation
MTE. This plane is parallel to a facial axis plane FAP used in
clinical studies through a clinically defined facial axis FA of a
tooth. These LAIs are later used to determine the horizontal
offsets from the MTE of the tips of the lower teeth in step (1000)
below, as well as the maxillary tooth placement in step (1100). The
rotation of the inclination angle places new Y coordinates of each
of the tooth profile planes established in step (500) parallel, and
the X axes of these planes parallel to the same plane but with
their relative horizontal orientations and relative vertical
positions yet to be determined. Once the teeth are rotated to their
finish inclinations, precise crown heights, incisal and cusp tip
locations, and other points and contours of the tooth surface are
precisely defined for intertooth contact and appliance design and
positioning calculations.
[0218] As an example, for the maxillary bicuspids and molars, a
marginal ridge elevation MRE is determined for later use in
calculations relative finish positions of the upper and lower
teeth.
[0219] (700) The cuspid rise determination step in which the
occlusion of the upper and lower teeth is defined:
[0220] The orthodontist 14 will have selected the technique to be
used to guide the teeth of the patient into occlusion as the jaws
come together. Depending on the selected occlusion technique,
either all or part of the occlusion is brought by a rise of the
cuspids above that of the other teeth, to thereby initiate contact
between the upper and lower teeth which aligns the two arches as
the jaw closes. Most orthodontists prefer to accomplish this with
the rise of the cuspids.
[0221] From anatomical studies, data is employed and the amount of
cuspid rise, or other cusp rise if selected, that is necessary to
clear the buccal cusp height BHC of the teeth, which is determined
from the landmark data of step (600).
[0222] (800) The mandibular tooth placement step in which the plane
of the mandibular teeth is defined and the teeth are positioned
with respect to the mandibular trough:
[0223] The step (800) accomplishes the preliminary mathematical
construction of the mandibular occlusion. This step first
calculates the positions of the mandibular teeth to place their
tips in an occlusal plane pending final refinement of the
placement.
[0224] The starting point for the mandibular tooth placement is to
assume tooth positions that place the teeth with their crown long
axes CLAs intersecting the plane of the mandibular trough on the
mandibular trough equation MTE. This satisfies the condition that
the mandibular teeth are set in the bone of the lower jaw. The CLAs
of the teeth are also inclined at the seed value angles LAIs
established in step (600).
[0225] Next, the positions of the teeth are adjusted vertically to
place the tips of all of the mandibular teeth, except the cuspids,
in the same plane. The tips of the mandibular cuspids are set to
extend above the plane of the tips of the other mandibular teeth by
a distance according to the cuspid rise criteria selected,
preferably by setting the distance equal to one third of the total
cuspid rise, as calculated in step (700).
[0226] Then, a horizontal OFFSET from the MTE, generally in the
labial direction, is calculated trigonometrically for each
mandibular tooth from its crown height above the mandibular trough
and its long axis inclination angle LAI. This calculation results
in a mandibular trough offset equation MO, which is an outward
radial expansion of the MTE. The MTE was defined in the form of a
series of circle segments in step (300). The expanded MO equation
is a discontinuous arch constructed by adding the respective OFFSET
of each tooth to the radius of the circle segment of the MTE with
which the midpoint of the width of the tooth is associated.
[0227] The teeth are then placed on the offset equation MO
beginning with the placement of the central with its mesial contact
point on the mandible centerline and the tooth midpoints on the MO.
Then moving distally, the remaining teeth on the same side of the
mandible are placed on the MO with their mesial contact points MCP
in contact with the distal contact point DCP of the previous tooth.
The same procedure is employed for the teeth on the other side of
the mandibular arch.
[0228] An alternative further refinement would consider the
vertical position on the teeth of their widest points and,
considering also the inclinations of the teeth, make a
trigonometric adjustment so that the tooth contact points are
spaced by the tooth widths MDW at the height of their actual widest
points, rather than assuming the teeth contact in the plane of
their tips.
[0229] (900) The best fit cusp step in which the best fit equation
is derived for mandibular arch:
[0230] In this step, a continuous curve is derived using
statistical methods to produce a best fit buccal cusp equation
BFBCE from the disconnected line segments of the MO. This is also
illustrated in FIG. 4A. In the embodiment described below, a Bezier
equation is used. A cubic equation is then generated from resulting
data points that define the best fit equation. The cubic equation
of the BFBCE is then converted to circle segment form as with the
MTE above.
[0231] (1000) The mandibular teeth placement step in which the
positions of the mandibular teeth are calculated for placement on
the best fit arch equation:
[0232] The positions of the lower teeth are then recalculated to
move the teeth horizontally, parallel to the MOC, such that the
incisal center points ICP lie on the BFBCE. For incisors and
cuspids, the ICPs are the tips of the teeth in the profile planes
of steps (500) and (600). For the bicuspids and molars, the ICPs
are the buccal cusp tips of the teeth. For purposes of placement of
the teeth on the BFBCEor other archform, the ICPs are assumed to
lie midway between the mesial and distal contact points of the
respective teeth. Accordingly, tooth placement is achieved by
moving the teeth normal to the circle segment associated with these
ICPS. This recalculation of position has the effect of moving the
roots of the teeth normal to the arch associated with their ICPs,
either labially or lingually, such that their ICPs fall on BFBCE,
when viewed from above.
[0233] This placement is the finish position of the mandibular
teeth.
[0234] (1100) The maxillary placement step in which the maxillary
arch is derived for occlusion with the placed mandibular teeth:
[0235] This step fits the positions of the maxillary teeth to the
already positioned mandibular teeth. The maxillary teeth have not
yet been positioned with respect to any equation, but the
inclination angles of their dimensions and crown long axes CLAs
have been determined in step (600). This positioning involves
setting the tips of the maxillary teeth on the BFBCE, with certain
modifications to the equation and the placement criteria to account
for the way the different types of teeth occlude.
[0236] In adjusting maxillary tooth positions, the cuspids, the
anterior teeth and the posterior teeth are treated separately to
bring their relevant contact surfaces into three different
respective arches that are then aligned relative to each other.
[0237] Since the anterior teeth do not occlude incisal edge to
incisal edge, the BFBCE is modified to take into account the
distance from the BFBCE to the labial contact points of the
mandibular incisors and laterals, plus a horizontal or labial
clearance, with the maxillary teeth. This defines the points of
occlusion with the maxillary anteriors, at the intersection of
their lingual surfaces with the plane of occlusion MOC. These
points lie in a maxillary anterior contact arch form MAAF. This
equation is calculated by expanding the BFBCE, by enlarging the
radii of the circle segments of which it is made up, to account for
these tooth dimensions and the clearances.
[0238] The vertical positioning of the maxillary anteriors and
cuspids is then performed based on the vertical occlusion methods
that have been prescribed, establishing an overlap for the incisors
and cuspid rise as determined in step (700). This defines the
vertical position of the maxillary cuspids and anteriors with
respect to the MOC, and thereby defines the incisal overlap or
overbite.
[0239] Placement of the maxillary posterior teeth places the
intersections of the marginal ridges and the central grooves from
steps (400) to (600) the cusps of the mandibular teeth with which
they will occlude. The maxillary tooth movements needed to achieve
this occlusion are applied to calculate a central groove marginal
ridge arch form CGMRAF by modifying the BFBCE. The cusp tips of the
maxillary cuspids are placed between the archforms of the incisors
and of the posteriors, for example, by averaging the distance from
the BFBCE to the MAAF and to the buccal cusp of the first maxillary
bicuspid, by placing the cuspid mesial and distal contact points in
contact with the adjacent teeth, by calculating a clearance as was
done for the incisors or by some other criteria. The archforms for
the maxillary tooth placement are illustrated in FIG. 4B.
[0240] The vertical positioning of the remaining teeth takes into
account the occlusion and other prescription information input in
step (200). The remaining calculations are set forth in detail
below.
[0241] (96) Appliance Design Procedure:
[0242] The appliance design procedure (96), as illustrated in the
flowchart of FIG. 2C, calculates the dimensions of the appliance
components in a form capable of being translated into NC codes for
operating NC machinery for production of the appliance components,
such as the brackets and archwires and also placement jigs for
installing the brackets in the proper positions on the teeth of the
patient. The appliance design procedure (96) includes the following
steps (1200) through (1800), which are further illustrated in the
detailed flowcharts of FIGS. 2P-2V:
[0243] (1200) The mandibular archwire plane step in which the plane
of the archwire for the mandibular teeth is defined in relation to
the teeth of the mandible:
[0244] Where labial brackets are to be applied, as illustrated in
FIG. 8, a plane is selected for the mandibular archwire that avoids
interference with the mandibular archwire and brackets with the
maxillary teeth, which overlap on the labial side of the mandibular
teeth. Where lingual brackets are to be applied, this step is
performed to define a maxillary archwire plane to avoid
interference between the lingually mounted maxillary archwires and
brackets with the mandibular teeth that overlap on the lingual side
of the maxillary teeth.
[0245] This step involves the selection of the archwire plane and
defines it in mathematical relation to the MOC. Once defined, the
bracket positions on the teeth are determined such that the
archwire slots will lie within the dimensional limits of the
bracket. Where possible, it is preferable that the archwire lie in
a literally flat plane and be symmetrical about the midline of the
arch. As such, the archwire will be properly shaped for
installation with either side facing upward.
[0246] (1300) The mandibular slot inclination step in which the
angles of the slots of the mandibular tooth brackets of the
appliance are calculated:
[0247] The slot inclination angle for the mandibular brackets is
calculated from the angle between the mandibular archwire plane and
the angle of the mandibular tooth surface to which the base of the
bracket is to be mounted. The slot inclination angle may be
achieved by cutting the full angle into the slot, by inclining the
bracket base, or by both of these methods.
[0248] (1400) The maxillary archwire plane step in which the plane
of the archwire for the maxillary teeth is defined in relation to
the teeth of the maxilla:
[0249] The maxillary archwire plane in the case of labial
appliances, and the mandibular archwire plane in the case of
lingual appliances, has few constraints on its position and may be
selected based on cosmetic considerations. It is usually selected
as a plane midway on the crown of the maxillary teeth. It is
therefore normally not parallel to the mandibular archwire plane.
Once defined, the bracket positions on the teeth are determined
such that the archwire slots will lie within the dimensional limits
of the bracket.
[0250] (1500) The maxillary slot inclination step in which the
angles of the slots of the maxillary tooth brackets of the
appliance are calculated:
[0251] The slot inclination angle for the maxillary brackets is
calculated from the angle between the maxillary archwire plane and
the angle of the maxillary tooth surface to which the base of the
bracket is to be mounted. The slot inclination angle may be
achieved by cutting the full angle into the slot, by inclining the
bracket base, or by both of these methods.
[0252] (1600) The mandibular archwire and bracket in-out dimension
calculation step in which the slot depth and bracket geometry is
calculated for the mandibular tooth brackets:
[0253] For each bracket, the deepest and shallowest slot depths is
determined to develop a window into which the archwire must pass,
as illustrated in FIG. 8A. Then the smoothest archwire curve that
will pass between the depth limits is determined. The smoothest
curve is considered to be one with the least variation in radius
changes along the curve, and preferably with no inflection points.
A cubic spline equation is used to fit the points and the equation
is then converted to one of circle segment form.
[0254] (1700) The maxillary archwire and bracket in-out dimension
calculation step in which the slot depth and bracket geometry is
calculated for the maxillary tooth brackets:
[0255] As with the mandibular slot depth calculations, for each
maxillary bracket, the deepest and shallowest slot depths is
determined to develop a window into which the archwire must pass.
Then the smoothest archwire curve that will pass between the depth
limits is determined. Here to, the smoothest curve is considered to
be one with the least variation in radius changes along the curve.
A curve with no, or the least number of inflection points is
preferred. A cubic spline equation is used to fit the points and
the equation is then converted to one of circle segment form.
[0256] (1800) The bracket placement jig designing step in which
placement jigs are designed for use in properly positioning the
custom designed brackets on the patient's teeth:
[0257] After the brackets and archwires are completely defined as
in the above steps, with the depth and angle of the slots finalized
for the positioning of the brackets on the teeth and the shape of
the desired archwires are described mathematically, bracket
placement jigs are designed that will be used to assist the
orthodontist in placing the brackets at the proper locations on the
teeth. The designing of the jigs, in the preferred embodiment, is
carried out in the software that generates the NC machine code in
the performance of the jig manufacturing step (3500) below. This
deferring of the jig design allows for consideration of appliance
hardware modifications that may be made in the course of the
bracket and archwire forming steps (3000) and (3200),
respectively.
[0258] The provision of the bracket placement jigs furthers a goal
of the practice of orthodontics to treat cases to occlusal
perfection with the least amount of effort, discomfort and time
expended. The portion of this goal that can be accomplished by
appliance design and manufacture has been described above. While
the individualized appliance geometries thus defined will be
fabricated, the ability to place the bracket portion of the
appliance system on the teeth with sufficient accuracy to allow the
appliance system to deliver the desired orthodontic relationship,
heretofore not realized clinically, is provided as follows:
[0259] The brackets are placed according to the three criteria:
[0260] 1. Height: The height is established so that the appliance
causes the upper and lower teeth to contact each other in the
prescribed manner.
[0261] 2. Mesio-Distally: The mesio-distal location is established
so that the mesial and distal ridges of the teeth are parallel to
the archform for that patient.
[0262] 3. Long Axis: The bracket is aligned relative to the long
axis of the tooth so that the appliance system tips the tooth to
the desired angle relative to the archwire.
[0263] From the vertical profile data of step (500), and horizontal
or three dimensional profile data of steps (300) and (400), the
shape and size of each tooth is extracted, including particularly
the profile in a mesio-distal view at the height of contour or
along a plane perpendicular to the greatest prominence of the
central developmental lobe of each tooth. Additionally, the
geometry of the archwire slot has been accurately related to the
respective teeth. This geometry includes the intersection of the
archwire plane with the tooth profile curve, the slot inclination
angle and the slot in-out dimensions. In addition, the wire size
and bracket geometry information are assembled, and tool size and
clearance information are taken into account.
[0264] With this information, a bracket placement jig is designed
for NC controlled manufacture to position the slot, and thereby the
bracket, precisely on the tooth.
[0265] In FIG. 8D, a plastic jig 82 is shown which engages the
walls and bottom of the bracket slot fully. Additionally, the
portion of the jig 82 contacting the tooth designed to be formed to
precisely fit the known contour of the tooth, as determined by the
profiles input in step (500). This assures that the bracket slot
and hence the bracket is placed at precisely the correct height
when bonded to the tooth.
[0266] Brackets are placed so that the slots are not necessarily
perpendicular to the long axis of the tooth but at varying degrees
of cant. The jig 82 accomplishes this goal by the use of an adapter
84 that fits into the bracket slot 82b and a coplanar slot 84a
(FIG. 9T) to engage the plastic blade jig 82, as illustrated in
FIG. 8D. The jig design substeps, which are preferably performed in
step (3500) and included in the detailed flowchart of the jig
manufacturing step of FIG. 2Z, are summarized in the flowchart of
FIG. 2V. The design is converted into CNC code in step (3500) for
controlling the jig forming machinery 41 primarily to cut a
contoured surface that conforms the profiles of the tooth so that
the jig fits in a precise position on the tooth to position the
bracket for adhesion to the teeth.
[0267] In installation performed in the treatment operation (89),
the jig 82 is lined up with the long axis of the tooth crown when
viewed from either the front or facial surface of the tooth and
from the biting or occlusal surface. A plastic blade form of jig 82
offers visual reference to the height of contour of the tooth and
alignment of the bracket with the marginal ridges.
[0268] (97) Appliance Manufacturing Procedure:
[0269] The appliance manufacturing procedure (97), as illustrated
in the flowchart of FIG. 2D, entails the generation of controller
codes for NC machinery to produce the brackets, archwires and
bracket placement jigs designed in the appliance design procedure
(96), and the manufacture of the appliance components with the use
of the machinery controlled by the codes. The procedure (97)
includes the steps of:
[0270] (3000) Controlling and operating the bracket forming
machinery 39 to produce the custom brackets:
[0271] The bracket manufacturing procedure of the preferred
embodiment involves the generation of NC code for the bracket slot
cutting mill 39 of FIG. 1D, as illustrated in the flowchart of FIG.
2X. The step involves the geometric relating of the tooth profile
information PF for each tooth, and other tooth contour information
of the shape of the surface of the tooth to which the bracket is to
be attached from steps (300) and (400), and the archwire plane,
slot inclination angle and slot depth information from steps (1200)
through (1700). In addition, the bracket forming step performs the
function of selecting the bracket blank from which the bracket is
to be fabricated. The bracket blank is made up of a base or pad
that is attached to the tooth and an outwardly projecting support
into which an archwire slot is formed.
[0272] The preferred embodiment includes the forming of brackets by
cutting custom slots in bracket blanks while preserving the base
inclination angle. Brackets could be alternatively fabricated by
inclining the bracket bases or pads. Additionally, bracket bases
may be contoured to conform to the surfaces of the teeth, or a
bonding agent may fill the space between the bracket base and the
tooth. Furthermore, while in the preferred embodiments, a
mechanical cutter blade forms the bracket, other means such as wire
EDM, machining, casting or stereo lithography may be employed.
[0273] (3200) Controlling and operating the Wire-bending machinery
40 to produce the custom archwires:
[0274] The software that operates the computer 30c to drive the
wire bending apparatus 40 reads data files generated for the
mandibular and maxillary archwires in steps (1600) and (1700)
respectively. Also read by the computer 30c are data on the
characteristics of the unformed wire 69, including that relating to
the material of which the wire is made, as well as its
cross-sectional shape and dimension. The file that is read contains
coordinated data regarding calculated archwire segment lengths and
radii which cumulatively describes geometrically the desired
archwire shapes. As explained above, the archwires consist of a
sequence of tangential arc segments with each segment a particular
length and radius.
[0275] The arch forming software determines the position of the
roller 70b of the anvil 70 that is required to produce a given
radius in the particular wire material and cross-section by going
to a look-up table, previously derived and stored in a file
accessible by the computer 30c, containing constants necessary to
correct for each wire material and cross-section. The anvil 70 is
driven to the desired position to produce the required radius and
the feed roll motor 70c is driven to create the desired length of
wire at that radius. By adjusting the position of the anvil roller
70b and length of wire fed with the roller 70b so adjusted,
archwires 64 of the calculated final sequential tangential radii
are fabricated.
[0276] (3500) Controlling and operating the jig forming machinery
41 to make custom placement jigs for the location of the brackets
on the patient's teeth:
[0277] The machine control codes for controlling the jig forming
machinery 41 are produced directly from the tooth profiles
generated in step 500 and from the archwire plane location of steps
(1200) and (1400), the slot inclination steps (1300) and (1500),
and the slot in-out dimensions from the steps (1600) and (1700). As
stated above, the jig design step (1800) is preferably performed in
the course of, and is described herein as part of, the jig
manufacturing step.
[0278] The profile data, which represents the profile curves with a
fairly high resolution of data points is a series of straight line
segments for developing the codes for driving the NC equipment.
Tool and bracket dimensions and design clearances are also taken
into account, and CNC codes are generated to cut jigs from circular
plastic wafers on a standard CNC mill using a small carbide endmill
tool. The details of the substeps of the step (3500) are included
in the flowchart of FIG. 2Z.
[0279] (98) Appliance Transmission Procedure:
[0280] One of the ultimate objectives is to place the custom
orthodontic appliance into the hands of the orthodontist 14, along
with the tools and information necessary for the proper
installation of the appliance 25 in the mouth of the patient 12 to
treat the patient by moving the patient's teeth to the calculated
finish positions. This is best understood by reference to FIG.
1.
[0281] Referring to FIG. 1, as set forth above, the configuration
of the preferred system 10 will vary depending on the nature and
scale of the orthodontist's practice. Preferably, all or much of
the appliance design portion of the procedure (87) takes place at
an appliance design facility 13, although in a large scale
orthodontic clinic, the entire process could be carried out at the
patient treatment location. Usually, however, the functions
performed in the design computer 30b, or design portion of the
computer 30, are carried out at the appliance facility 13, together
with some of the manufacturing functions performed by the
manufacturing control computer 30c and the appliance manufacturing
equipment 38.
[0282] In the configuration where, as illustrated, some or all of
the appliance 25 is made at the appliance facility 13, the custom
appliance 25 is transmitted to the orthodontist 14. Along with the
appliance 25 is communicated documentation in the form of a hard
copy printout of information 37 generated by the design computer
30b, which could also include documentation of the input data that
made up the data 26 and the prescription information 27, and a
printout of parameters recorded by the manufacturing computer
30c.
[0283] The transmitted appliance 25 includes a set of archwires 64,
as illustrated in FIGS. 8E and 8F, a complete set of custom
brackets 80, as illustrated in FIGS. 8D and 8F, and the placement
jigs as illustrated in FIGS. 8D and 9T through 9W. Along with the
jigs 82 are included a set of adapters 84 that are used to align
the slots 80b of the brackets 80 with coplaner slots 84a of the
jigs 82. The appliance and the bracket placement jigs therefor are
similar in the case of lingual appliances, a bracket for which is
illustrated on a tooth in FIG. 8G while the lingual appliance is
shown positioned on the mandibular teeth in FIG. 8H.
[0284] In addition, custom archwires 64 are transmitted to the
orthodontist 14. These archwires include archwires in the exact
form, as illustrated in FIG. 8E, to move the teeth to their finish
calculated positions, as illustrated, for example for the lower
teeth, in FIG. 4D. In FIG. 4D, the archwire 64 is shown in the
unstressed state (or having nominal residual stress sometimes
motivating some orthodontists to prescribe overcorrection) that it
will attain when the appliance 25 has moved the patient's teeth to
the calculated finish positions. This is the same shape as the
archwire of FIG. 8E shipped to the orthodontist 14. This finish
archwire will be of a material and stiffness determined to be
appropriate for the final positioning of the teeth. Depending on
the severity of the initial malpositioning of the patient's teeth,
however, less stiff archwires, or temporary archwires may be
desired for beginning the orthodontic treatment. Thus, additional
archwires 64 of various properties but in the shape shown in FIG.
8E will be provided the orthodontist 14. In addition or in the
alternative to the provision of these additional archwires, an
actual size drawing or template having thereon the shape shown in
FIG. 8E will be provided the orthodontist 14 to enable him to form
archwires for preliminary treatment and rough positioning.
[0285] In alternative configurations, information may be sent from
the design computer 30b in machine readable form, for example by
diskette 34 or modem, to a manufacturing computer 30c to which is
attached one or more of the appliance component manufacturing
machines 38.
(89) Patient Treatment Operation
[0286] The patient treatment involves, first, the assembly of the
respective bracket 80, jig 82 and adapter 84 combinations, as
illustrated in FIG. 8D, and the application of the brackets 80
thereby to the patient's teeth. This involves the application of
adhesive to the area generally in the center of the face of the
tooth, either labial or lingual, to which the brackets 80 are to be
applied. This is illustrated in FIG. 8D, for example, with the
application of a bracket 80 to the labial face of a maxillary
incisor T.sub.U,1. The assembly is positioned on the tooth with the
blade of the jig 82 positioned on a generally vertical labial
lingual cross section through the approximate center of the tooth,
in the plane that may be said to contain the crown long axis CLA of
the tooth.
[0287] When the bracket adhesive has set, the bracket placement jig
82 is removed by first sliding out the adapter 84 mesiodistally and
then sliding the jig 82 off of the incisal edge of the tooth,
leaving the bracket in the calculated position.
[0288] Then, with the brackets 80 set on the teeth the archwire 64
is installed. Often, the first archwire installed will be one of
lower stiffness than the final archwire. In the example of FIG. 8F,
the mandibular teeth in their initial position as illustrated in
FIGS. 4 and 4A are shown. The brackets 80 are positioned on the
teeth in the exact same positions as shown in the calculated finish
position diagram of FIG. 4D. Because the teeth are not yet in this
ideal finish position, the archwire 64, when inserted into the
archwire slots and tied to the brackets 80, will be stressed into
the elastically deformed condition shown in FIG. 8F. This stressed
condition of the archwire 64 operates, without the need of the
orthodontist to artfully bend the wire, to apply the forces to the
teeth to urge them toward the ideal positions of FIG. 4D. This
force will continue to be applied until the teeth have moved to the
finish positions. In some prescribed forms of treatment, the wire
and brackets are designed to move the teeth to a slightly
overcorrected position to allow for a relaxation movement of the
teeth when the appliance 25 is removed.
DETAILS OF STEPS OF APPLIANCE ANALYSIS, TOOTH POSITION CALCULATION,
AND APPLIANCE DESIGN AND MANUFACTURING OPERATION (87)
[0289] The analysis, design and manufacturing operation (87), as
stated above, includes the (94) input, (95) analysis, (96) design,
(97) manufacturing, and (98) transmission procedures of a
computerized custom designed appliance manufacturing operation. The
steps of those procedures, as outlined above, include the
following:
Digitized Input Procedure (94)
[0290] The input of digitized information includes the (100) input
of patient and doctor identifying information, (200) the input of
patient background information, (300) the input of digitized
information of the horizontal dimensions of the mandibular teeth
and the mandibular bone, (400) the input of horizontal dimensions
of the maxillary teeth, and (500) the input of vertical
labial-lingual profile information of each of the individual
teeth.
[0291] (100) Identification Information Input Step:
[0292] The first step in the procedure (82), as illustrated in.
flowchart of FIG. 2A, is (100) to input the doctor-patient
identification information 17. This step (100), as illustrated in
the detailed flowchart of FIG. 2E, includes the substeps, performed
by an operator 28 in response to prompts for text input at a
terminal of the computer 30, of (105) input of the doctor's name,
(110) input of the doctor's identification number, and (115) input
of the patient's name. Then, the computer 30 (120) assigns a
patient identification number. With this information, (125) a
patient-specific floppy disk or diskette 34 is automatically
formatted.
[0293] (200) Patient Background Input Step:
[0294] The next step in the information input procedure (94), as
illustrated in FIG. 2A, is (200) the entry, in response to prompts,
of the patient background information 19, and the prescribed
treatment information 27 from the doctor. This step, as illustrated
in the detailed flowchart of FIG. 2F, involves the substeps of
(205) entering, from the background information 19, the patient's
age as numerical data, and selecting (210) the patient's sex and
(215) the patient's race from options on the screen. Then, from the
prescription information 27, the data are entered, by selecting
choices from multiple choice prompts, from information such as the
following:
[0295] (220) Whether or not the treatment is to include an
extraction, and if so, which teeth are to be extracted;
[0296] (225) Whether the occlusion type is a group function or a
cuspid rise, and if a cuspid rise, whether averages or individual
head film is to be used;
[0297] (230) Whether the prescribed procedure is to preserve lower
intercuspid distance or allow expansion, and if expansion is to be
allowed, how much expansion;
[0298] (235) Whether or not the occlusion is mutilated;
[0299] (240) Whether a Steiner compromise is to be allowed to
accommodate skeletal discrepancy;
[0300] (245) Whether a Roth or Ricketts inset is to be used on
upper laterals, and if so which;
[0301] (250) Whether a Roth or Andrews upper lateral overbite is
indicated, and if so, which;
[0302] (255) Which is the preferred slot size, from traditional
sizes 0.018" or 0.022" (0.45 mm or 0.55 mm), or other available
size, of which 0.20" (0.50 mm) would often be acceptable;
[0303] (260) Whether the case is to be treated with labial or
lingual appliances;
[0304] (265) Whether the case is to be diagnosed using symmetry or
not;
[0305] (270) How inter-incisal angle is to be determined, using the
Andrews Norms, the Parallel Upper Central to Facial Axis Norm, or
Ricketts Norm.
[0306] (300) Mandible Digitized Video Input Step:
[0307] The forming of the computerized mathematical model of the
teeth of the patient 12 begins with (300) the inputting of video or
other graphics top view image of the patient's lower jaw, including
the teeth, as illustrated in the detailed flowchart of FIG. 2G.
Such an image as input by the video scanner 43, is illustrated in
FIG. 3.
[0308] The step (300) includes the digitizing and processing of the
data of the widths of the mandibular teeth and size and shape of
the mandibular bone or bone of the lower jaw 22 of the patient 12
from the horizontal plan view of the lower jaw as in FIG. 4. The
mandible 22 is composed of hard or cortical bone on the external
surface and soft or cancellous bone in the interior. This bone is
not as orthodontically alterable as is the maxilla. Since the lower
teeth must remain in the mandible, determination of its shape and
boundaries is made so that a skeletal arch can be defined to be
used as a starting point in the calculation of the finish position
of the teeth.
[0309] The lower teeth must lie on the mandible 22 in an arch that
may be defined as the mandibular trough MT, as illustrated in FIG.
4. The roots of the lower teeth of the patient are contained within
the mandibular trough MT, which is defined as the space between
boundaries B.sub.L and B.sub.B of FIG. 4. The outer, or buccal, and
inner, or lingual, boundaries B.sub.B and B.sub.L, respectively,
are preferably digitized by interactive selection by the operator
28 from an image 48 of the cortical bone of the mandible 22 on the
screen 35. Furthermore, the mandibular teeth must lie in the arch
in contact with one another. They each occupy a portion of the arch
equal to the distances between their mesial and distal contact
points with the adjacent teeth. These tooth extremities are also
preferably digitized by interactive selection from the image
48.
[0310] To (300) input data of the patient's mandibular teeth and
lower jaw 22, as illustrated in the detail flow chart of FIG. 2G,
(305) a video graphics image 48 (FIG. 3) of mandibular model 21 is
first input to the screen 35 of the computer 30c. Then (310) a grid
G is overlaid on the video image of the mandibular 22 as
illustrated in FIG. 4. The grid G presents grid lines that
intersect the image 48 on the screen. The operator 28 (315) resizes
the grid G, if necessary, and orients the image relative to grid G
to define X,Y coordinates with a Y axis on a midline ML of the
lower jaw 22 and an X axis perpendicular to the Y axis through a
selected intersection point or origin 0,0, preferably set at the
mesial contact points of the lower central incisors.
[0311] Next, the computer 30 prompts the operator sequentially to
select each point, first for the individual tooth contact points,
then the jaw bone boundaries. With the pointing device 47, (320)
the operator 28 moves the cursor on the screen 35 and selects
(e.g., clicks with a mouse on) the prompted point, thereby
initiating the software for digitizing the X,Y Cartesian
coordinates of the mesial and distal extremities M.sub.X,Y
D.sub.X,Y, respectively, for each mandibular tooth. The mesial
extremity M.sub.X,Y of a tooth is the point on its surface closest
the midline ML along the mandibular arch (the mesial direction m)
while distal extremity of a tooth is the point on its surface
closest the rear of the mouth along the mandibular arch (the distal
direction d). From the X, Y coordinates of M.sub.X,Y, M.sub.X and
M.sub.Y, and of D.sub.X,Y, D.sub.X and D.sub.Y, (325) the
mesio-distal width MDW.sub.I of each tooth I, on each side of the
mandible 22, is calculated using Pythagorean theorem: 1 MDW = ( M X
+ D X ) 2 + ( M Y + D Y ) 2
[0312] where:
[0313] M.sub.X is mandibular X coordinate.
[0314] M.sub.Y is mandibular Y coordinate.
[0315] D.sub.X is distal X coordinate.
[0316] D.sub.Y is distal Y coordinate.
[0317] These widths are then summed to calculate the total length
MAL required of the arch to accommodate the mandibular teeth. Since
all of the teeth will be finally positioned to be in contact with
the adjacent teeth, this length remains a constant length of any
arch on which the mandibular teeth are placed in the
calculations.
[0318] Then, by moving the pointing device 47 to the intersections
of the lines of the grid G with the visible boundaries B.sub.B and
B.sub.L and selecting the intersection points, data is input for
determination of the shape of the mandibular trough MT. The point
selection function can be made with conventionally available
CAD/CAM, imaging or illustration software and the pointing device
47. (330) From the selected intersections of the lines of the grid
G with the mandible boundaries B.sub.B and B.sub.L, Cartesian
coordinates La.sub.X,Y and Li.sub.X,Y of labial and lingual limits,
respectively, of cortical bone on both sides of mandibular jaw are
generated. The X, Y coordinates La and Li so chosen are digitized
as above on the boundary lines B.sub.L and B.sub.B of the cortical
bone, between and interproximate the teeth.
[0319] After the points La and Li are chosen representing the
cortical bone limits, (335) midpoint coordinates MP.sub.XY are
calculated between each of the individual labio-lingual pairs of La
and Li. Also, calculated are the bone width distances between each
of the respective labio-lingual pair DLL, as follows: 2 MP X = La X
+ Li X - La X 2 ; MP Y = La Y + Li Y - La Y 2 DLL = ( La X + Li X )
2 + ( La Y + Li Y ) 2
[0320] where:
[0321] La.sub.X is labial X coordinate of point La.
[0322] La.sub.Y is labial Y coordinate of point La.
[0323] Li.sub.X is lingual X coordinate of point Li.
[0324] Li.sub.Y is lingual Y coordinate of point Li.
[0325] These midpoints MP.sub.X,Y one of which is the designated
origin MP.sub.0,0, lie on an arch that describes the size and shape
of the center of the cancellous portion of the mandibular bone
22.
[0326] At this point, the beginning of the analysis for the
calculation of the finish positions of the teeth is carried out.
The coordinates of points MP.sub.X,Y are recalculated relative to a
new origin 0,0 at the calculated midpoint between the mandibular
centrals, to normalize the mandibular trough equation to its own
independent midpoint when calculated below. The sum of the
individual mandibular tooth widths MDW equals the total dental
length or mandibular arch length MAL contained in the mandibular
trough equation MTE that will be constructed through the points
MP.sub.X,Y. MAL is referred to as the arch perimeter.
[0327] At this stage, (340) the midpoints are typically averaged
right to left to eliminate any asymmetry that may be present due to
slight measurement errors. If, however, the patient has been
diagnosed by the orthodontist 14 to be of asymmetrical anatomy, the
averaging process is not performed. Such a determination will have
been made by the orthodontist 14 in the examination procedure (90)
described above and specified of the prescription 27 in step (265)
of the procedure (92) described above. An advantage of the
averaging process is that, when used, it assists the final
positioning of the teeth symmetrically about the midline ML and
will make it easier for an archwire to be produced that is
symmetrical from right to left, and thus can be made such that it
can be installed in inverted orientation.
[0328] The midline ML shown in FIG. 4 is the axis of such symmetry
corrections. These corrections for each point MP.sub.X,Y are
calculated as follows: 3 S X = MP X + PR X - PL X 2 ; S Y = MP Y +
PR Y - PL Y 2
[0329] where:
[0330] S.sub.X,Y is the symmetricalized point MP.sub.X,Y
[0331] MP.sub.X,Y is mid-point of mandibular trough
[0332] PR.sub.X,Y is a point MP.sub.X,Y on the right side
[0333] PL.sub.X,Y is the corresponding point on left side of the
trough
[0334] With the completion of this symmetricalization process, a
mathematical equation MTE, which describes the size and shape of
the mandibular trough according to steps (345), (350) and (355), is
derived by fitting a curve to the points MP.sub.X,Y. Preferably,
this curve is derived by fitting a series of cubic equations, such
as a cubic spline equation, to pass smoothly through the points,
for example, through the averaged midpoints S.sub.X,Y. The cubic
equations allow the determination of the slope of the curve at each
of the midpoints.
[0335] The cubic equations are then preferably converted in form to
a series of segments of tangent circle equations with slopes equal
to the slopes of the cubic spline at the midpoints, and equal to
the slopes of the adjacent circle segments at the segment end
points, or their points of intersection, along the curve. To fit a
cubic equation with quadratics, two circles CS and CL are used to
describe each segment of the MTE between midpoints, as illustrated
in FIG. 5. This allows a smooth curve consisting of tangential
circles to represent the mandibular trough.
[0336] The cubic equation calculations are preferably those
performed by (345) calculating cubic spline parameters required to
pass a smooth curves through symmetricalized midpoints S.sub.X,Y as
illustrated in FIG. 5A. This includes (350) calculating the slope
of the cubic spline curve at each symmetricalized mid-point
S.sub.X,Y or S.sub.X,Y, and (355) calculating a series of
tangential circle equations whose slopes are equal at the
mid-points and at points of intersection along the curve.
[0337] (345) The cubic spline method preferred uses a cubic, or
third degree, polynomial to interpolate between each pair of data
points S.sub.X,Y. A different polynomial is used for each interval,
and each one is constrained to pass through the original data with
the same slope as the data. (350) The slopes of the cubic equation
are computed by solving the slope of a parabola that passes through
each data point and its two nearest neighbors points. The cubic
spline method is described in more detail in the discussion of the
cubic spline subroutine (2000) below.
[0338] (355) Any point on the cubic spline equation can now be
calculated by using a cubic spline interpolation. Using this, the
cubic spline equation is subjected to a circle segment conversion
by which the form of the equation MTE is converted to a series of
circle segments that interconnect tangentially. Once the spline
equation is derived, the slopes at each data point are calculated
using the point slope method. These slopes are utilized to derive,
between each pair of data points on the spline equation, the
description of two circle segments, each from one of two circles as
illustrated in FIG. 5, to convert the MTE to a series of circle
segments throughout its length. This facilitates the setup of the
teeth, the description of the configuration of archwires, and the
generation of NC code for the manufacture of the appliance. The
spline-to-circle conversion routine is described in further detail
under routine (2100) below.
[0339] The input procedure continues. (360) Cartesian coordinates
are input for right and left mandibular cuspid cusp tips CR and CL,
respectively, as illustrated in FIG. 4. (365) A distance DCT
between the cusp tips CR and CL of the two mandibular cuspids is
then calculated: 4 DCT = ( CR X + CL X ) 2 + ( CR Y + CL Y ) 2
[0340] where:
[0341] CR.sub.X=right cuspid X coordinate.
[0342] CR.sub.Y=right cuspid Y coordinate.
[0343] CL.sub.X=left cuspid X coordinate.
[0344] CL.sub.Y=left cuspid Y coordinate.
[0345] This information is used to calculate if and how much the
mandibular intercuspid distance is to be altered, and to evaluate
whether the calculated final position is acceptable. Similarly,
(370) Cartesian coordinates or right and left mesio-buccal cusp
tips, MR and ML, respectively, of mandibular first molars are
calculated, and (375) the distance between these points DMT is
calculated: 5 DMT = ( MR X + ML X ) 2 + ( MR Y + ML Y ) 2
[0346] where:
[0347] MR.sub.X=right first molar cusp X coordinate.
[0348] MR.sub.Y=right first molar cusp Y coordinate.
[0349] ML.sub.X=left first molar cusp X coordinate.
[0350] ML.sub.Y=left first molar cusp Y coordinate.
[0351] This information is used to determine if and how much the
mandibular intermolar distance is to be altered.
[0352] (400) Maxilla Digitized Video Input Step:
[0353] As with the mandibular jaw information described in
connection with FIG. 4, (400) a computer image is made from input
in the same manner from the upper model 23 of the maxillary jaw 24
of the patient 12, as illustrated in the flowchart detail of FIG.
2H. This involves the substeps of (405) inputting a video image 48a
of maxillary model 23 to the computer screen 35. The image 48a is
illustrated in FIG. 4A. With the maxilla, it is not necessary to
overlay the grid G on maxillary image on the screen, since the bone
of the maxilla is a variable that will be altered orthodontically
to accommodate the finish positions of the teeth. The orientation
of the axes and position of the origin are immaterial to the
calculation of the relative distances such as MDW of the teeth.
Only the scale must be maintained. As with the mandibular
information, the image of the maxillary jaw 24 is displayed at a
scale predetermined by the scanner 33. The scale is involved in the
calculation of the maxillary tooth widths MDW.
[0354] (420) Cartesian coordinates of mesial and distal extremities
M.sub.x,y and D.sub.x,y of each maxillary tooth are then input as
with the mandibular teeth and (425) the mesio-distal width MDW of
each maxillary tooth is calculated using Pythagorean theorem, thus:
6 MDW = ( M X + D X ) 2 + ( R Y + L Y ) 2
[0355] where:
[0356] M.sub.X is mesial X coordinate.
[0357] M.sub.Y is mesial Y coordinate.
[0358] D.sub.X is distal X coordinate.
[0359] D.sub.Y is distal Y coordinate.
[0360] This information is used first to determine whether the
maxillary and mandibular teeth are correct in proportion to the
mesiodistal widths MDW of the other. If the proportions are
incorrect, a tooth size discrepancy TDS is said to exist, and the
information is recorded to report to the orthodontist. The MDWs of
the maxillary teeth are later used to place the maxillary teeth
upon the mandibular arch.
[0361] Next, (430) coordinates of the central fossae of right and
left maxillary first molars are input. Then, (435) the distance
between central fossae DCF is calculated as follows: 7 DCF = ( R X
+ L X ) 2 + ( R Y + L Y ) 2
[0362] where:
[0363] R.sub.X is right side central fossa X coordinate.
[0364] R.sub.Y is right side central fossa Y coordinate.
[0365] L.sub.X is left side central fossa X coordinate.
[0366] L.sub.Y is left side central fossa Y coordinate.
[0367] This information is recalculated after the tooth finish
positions are calculated to coincide with the DMT spacing of the
mandibular first molars, and compared with this initial measurement
as an indicator of whether the intermolar width will be changed by
treatment and the amount of such change, if any.
[0368] (500) Digitized Probe Tooth Profile Input Step:
[0369] The next input step (500) involves an analysis of the
dentition, as illustrated in the detailed flowchart of FIG. 21. In
this step, selected profiles of each of the teeth are generated
from either the model 20, or from a digitized three dimensional
representation of the patient's teeth or the model 20 as
illustrated in FIGS. 3A and 3B. In the illustrated embodiment, the
use of the probe assembly 57 of FIG. 1C is used in this step.
[0370] Where the full three dimensional scan has been employed in
step (300), as could be produced with the use of the laser image
generator (FIG. 1B), or as could be produced with moire image
generator or other technique, a digitized computer model is
produced. From such a computer model, which is an electronic
version of the model 20 in the form illustrated in FIGS. 3A and 3B,
planes or other cross-sections through the teeth are selected that
contain extremities of the teeth. The three dimensional images may
be displayed on the screen 35 and profiles generated either with
the pointing device 47 in a manner similar to the use of the
mechanical probe described below, or automatically using available
CAD or illustration imaging software. Whether the profiles are
generated from a physical model 20 or an electronic version
thereof, much of the input step (500) and/or the landmark selection
step (600) may be similarly employed.
[0371] In the preferred use of the information from the probe
assembly 57, a single digitized profile curve PFis constructed for
each tooth in a generally vertical plane extending in an
approximately labial-lingual orientation generally along the
central developmental lobe perpendicular to the marginal ridges.
While other profiles can be taken, the need to do so is reduced by
intelligent plane selection made with an understanding of tooth
anatomy, depending on the data required by the tooth positioning
and appliance design criteria employed. The selection of the
profile plane is illustrated in FIG. 6 where a first profile
PF.sub.A through the center of the tooth is shown as missing the
buccal cusp tip which is the maximum crown highpoint of the tooth.
Profile PF.sub.B is then selected to include the buccal cusp, and
the ridge of the profile is found to generally align with the
lowpoint of PF.sub.A. Alternatively, the profile may be non-planar
to pick the important features of both planes. As such, the profile
produced will be comparable to a projection onto a plane of the
relevant tooth extremities.
[0372] The step (500) of analysis of the dentition includes, first
(505) examination, by the operator 28 of the computer 30a, of the
marginal ridges of the upper central and upper lateral teeth. If
ridges are excessive, a determination is made to take a profile
twice with the probe 60, once by smoothing the teeth, for example
with wax, for arch coordination and once without smoothing for
placement jig geometry. Otherwise, a single profile taken across
the buccal cusp will contain information of the crown height of the
tooth as well as approximating the profile of the tooth through its
mesiodistal center with accuracy that is usually sufficient. Then,
(510) a determination is made as to whether one or two traces of
maxillary incisor teeth are to be input as in step (505) above.
[0373] (515) The computer 30a is configured to receive sequential
Cartesian coordinate pairs through an RS-232C serial port
representing tooth profile anatomy from the orthogonally positioned
displacement transducers 61. (520) The computer 30a prompts the
operator 28 to enter the profiles of each tooth sequentially. In
response to the prompts, data points of each tooth are input,
beginning with lower left molar T(B,L,6) and ending with upper
right molar T(U,R,6), and a display 63 of profile PF.sub.I image is
generated. The output circuits associated with the transducers 61
are configured to digitize data values at periodic time intervals
as the probe 60 is moved across the teeth from the time the probe
first starts to move across the tooth until the operator enters a
command or key stroke indicating that the scan is complete. Then
(525) the input profile data of each of the teeth is stored in
memory by the computer 30. The resulting profiles PF, are
illustrated in FIG. 3C. These profiles, at this stage, are not
related to the positions of the teeth within the mouth or with
respect to other teeth. Thus, each of the X-Y coordinates of the
individual tooth profiles are independent of each other. In step
(600) below, the coordinate axes of each tooth will be oriented
with respect to each other, and thereafter, in later steps
(800)-(1100), the coordinates of each profile are translated
vertically for proper occlusion and horizontally for placement on
their respective arches.
(95) Analysis and Finish Tooth Position Calculation Procedure
[0374] The calculation of the finish positions of the teeth, as
illustrated in the flowchart of FIG. 2B, includes (600) determining
the relative positions of geometric landmarks on the surfaces of
the teeth and establishing the axis inclinations of the teeth,
(700) calculating cuspid rise, (800) initially positioning the
mandibular teeth vertically and in relation to the mandibular
trough, (900) calculating a best fit cusp tip equation for the
mandibular teeth, (1000) calculating the finish positions of the
mandibular teeth on the best fit equation, and (1100) calculating
the finish positions of the maxillary teeth on three arches related
to the best fit equation.
[0375] (600) Tooth Landmark Identification Analysis Step:
[0376] After the individual teeth have been digitized, the
inputting of tooth shape data (94) is complete, with the digitized
information 26 stored a file. Then, referring again to the
flowchart of FIG. 2, (95) the input data 26 is analyzed to develop
or derive further parameters for calculating the final positions of
the teeth and for (96) the design of the appliance 25. In the tooth
positioning analysis (95), as illustrated in the flowchart of FIG.
2B, (600) a tooth profile analysis is made in which, for example,
certain anatomical landmarks are chosen, depending on the tooth to
be analyzed. The details of the tooth profile analysis are
illustrated in the flowchart of FIG. 2J.
[0377] In the tooth profile analysis step, (605) individual images
63 of the profile curves PF.sub.I of each tooth (FIG. 3C) are
recalled separately to the screen of the computer 30b for selection
of the landmarks.
[0378] Using the displayed images 63 of the profile curves
PF.sub.I, (610) specific landmark points are chosen, first on the
mandibular molars and bicuspids. The selected points are digitized
as illustrated in FIG. 6. The selected points are:
[0379] Point P.sub.1: The Lingual (tongue side) gum/tooth
intersection.
[0380] Point P.sub.2: The prominence of the lingual cusp.
[0381] Point P.sub.3: The prominence of the buccal (cheek side)
cusp.
[0382] Point P.sub.4: The buccal gum/tooth intersection.
[0383] From these landmarks, (615) the crown long axis CLA of each
molar and bicuspid profiled is determined. The determination is
made by constructing a first line L.sub.1 between points P.sub.2
and P.sub.3 and a second line L.sub.2 between points P.sub.1 and
P.sub.4. The crown long axis CLA of a tooth is the line between the
midpoints of L.sub.1 and L.sub.2.
[0384] Line L.sub.1 is constructed through point P.sub.2 and point
P.sub.3 by the following equation: 8 Y - Y 2 X - X 2 = Y 3 - Y 2 X
3 - X 2
[0385] where:
[0386] X.sub.2, Y.sub.2=X and Y coordinates of point P.sub.2.
[0387] X.sub.3, Y.sub.3=X and Y coordinates of point P.sub.3.
[0388] Line L.sub.2 is constructed through point P.sub.1 and point
P.sub.4 by the following equation: 9 Y - Y 1 X - X 1 = Y 4 - Y 1 X
4 - X 1
[0389] where:
[0390] X.sub.1, Y.sub.1=X and Y coordinates of point P.sub.1.
[0391] X.sub.4, Y.sub.4=X and Y coordinates of point P.sub.4.
[0392] A point equidistant between points P.sub.2 and P.sub.3 along
line L.sub.1 is then calculated and defined as P.sub.2-3: 10 P 2 -
3 X , Y = X 2 + X 3 2 ; Y 2 + Y 3 2
[0393] where:
[0394] X.sub.2, Y.sub.2=X and Y coordinates of point P.sub.2.
[0395] X.sub.3, Y.sub.3=X and Y coordinates of point P.sub.3.
[0396] A point equidistant between points P.sub.1 and P.sub.4 along
line L.sub.2 is also calculated and defined as the Gingival Center
Point GCP: 11 GCP X , Y = X 1 + X 4 2 ; Y 1 + Y 4 2
[0397] where:
[0398] X.sub.1, Y.sub.1=X and Y coordinates of point P.sub.1.
[0399] X.sub.4, Y.sub.4=X and Y coordinates of point P.sub.4.
[0400] The line defining the crown long axis CLA is constructed
using the following equation: 12 Y - Y 2 - 3 X - X 2 - 3 = Y GCP -
Y 2 - 3 X GCP - X 2 - 3
[0401] where:
[0402] X.sub.2-3, Y.sub.2-3=X and Y coordinates of the center point
P.sub.2-3.
[0403] X.sub.GCP, Y.sub.GCP=X and Y coordinates of gingival center
point GCP.sub.X,Y.
[0404] For molars and bicuspids, point P.sub.3, the buccal cusp
tip, is defined as the Incisal Center Point ICP.
[0405] Similarly, (610) the anatomical landmarks and crown long
axis CLA for the mandibular cuspids, laterals and central teeth are
determined, as illustrated in FIG. 6B. The points P.sub.1 through
P.sub.4, as labeled in FIG. 6B, are selected as follows:
[0406] Point P.sub.1: The lingual gum/tooth intersection.
[0407] Point P.sub.2: The lingual aspect of the incisal edge.
[0408] Point P.sub.3: The buccal aspect of the incisal edge.
[0409] Point P.sub.4: The facial gum/tooth intersection.
[0410] As with the bicuspids and molars, lines L.sub.1 and L.sub.2
are constructed. The landmarks in the cases of the teeth as
illustrated in FIG. 6B, are chosen because they are relatively
tolerant to operator error in selection. This can be seen by the
set of broken lines that are possible alternatives to L.sub.2 in
FIG. 6B. From these landmarks (615) the crown long axis CLA is
determined as defined above, by connection of the midpoints of
L.sub.1 and L.sub.2.
[0411] The next step in the analysis is the determination of
maxillary dentition for each upper molar and bicuspid. (610)
Anatomical landmarks are identified and chosen as illustrated in
FIG. 6C, which requires (612) the selection of a fifth point,
P.sub.5, defined as follows:
[0412] Point P.sub.1: The lingual gum/tooth intersection.
[0413] Point P.sub.2: The prominence of the lingual cusp.
[0414] Point P.sub.3: The prominence of the buccal cusp.
[0415] Point P.sub.4: The buccal gum/tooth intersection.
[0416] Point P.sub.5: The mesial marginal ridge of the tooth at
central groove.
[0417] Referring to FIG. 6C, from the landmarks, (615) the crown
long axis CLA of each applicable maxillary tooth is determined.
[0418] The (610) anatomical landmarks for the maxillary cuspids,
laterals and central teeth are determined as illustrated in FIG.
6D. The points labeled P.sub.1 through P.sub.4 are selected, as
follows as illustrated in FIG. 6D:
[0419] Point P.sub.1: The lingual gum/tooth intersection.
[0420] Point P.sub.2: The lingual aspect of the incisal edge.
[0421] Point P.sub.3: The buccal aspect of the incisal edge.
[0422] Point P.sub.4: The facial gum/tooth intersection.
[0423] From each of these sets of landmarks, the crown long axis
CLA of each such tooth is also determined as described (615)
above.
[0424] This completes the loop (620) for all of the teeth.
[0425] Next, as further illustrated in FIG. 6D, (620) seed values
for setting the crown long axis inclinations LAI of the teeth.
Initially, such seed values may be derived from analyses that
identified the facial axis plane FAP through the facial axis point
FA of the tooth (the midpoints of the height of the clinical crowns
along the facial axes of the clinical crowns) as described by Dr.
Lawrence Andrews. It is, however, contemplated that CLA seed values
for various population groups will be statistically derived in the
course of the practice of the present invention, and will produce
improved treatment results.
[0426] The seed values shown in Table 1 below are typical for
Caucasian males. These seed values for tooth LAI, tabulated in
degrees from the horizontal lingual (-X) axis, will vary to reflect
known variations due to such things as sex,
[0427] The preferred seed values are shown in Table 1 below are
typical for Caucasian males. These seed values will vary to reflect
known variations due to such things as sex, race or treatment
plan.
2TABLE 1 Tooth Maxillary Mandibular Type Crown LAI Crown LAI
Central 117 107 Lateral 112 107 Cuspid 108 100 1.sup.st Bicuspid 94
83 2.sup.nd Bicuspid 94 80 1.sup.st Molar x x 2.sup.nd Molar x
x
[0428] The computer images as summarized in FIG. 3C for each tooth
(630) are then rotated so that the CLA is oriented at the angle
LAI, the long axis inclination angle, to the mandibular trough
plane MT according to the values in Table 1. This computes the
final inclinations of the teeth that will be preserved in the
calculations below. This produces the oriented profiles PF
summarized in FIG. 6E.
[0429] In the analyses of Andrews referred to above, the LAIS were
established with a line L.sub.FA drawn tangent to the facial
surface at FA, and line representing the relative inclination of
the archwire plane drawn through FA point. The angle between the
lines was established at the inclinations reported by Andrews for
patients with no skeletal discrepancies. The angle LAI between the
crown long axis CLA and a line representing the maxillary arch
plane in which lies the mandibular trough equation MTE is related
to the facial inclination angles of Andrews' studies by taking into
account statistically the thicknesses and contours of the teeth.
Table 1 above was derived, after statistical processing, to produce
the seed value used for the final inclination of the crown long
axis in preferred occlusal design.
[0430] Once the tooth profiles have been rotated to the inclination
angles LAI, certain precise vertical dimensions and extremities can
be determined. From the digitized profile curves, which are stored
in memory in the form of a series of closely spaced points, the
precise incisal tip IC, as illustrated in FIGS. 6F, 6H and 6I, are
identified on the cuspids, laterals and centrals.
[0431] Additionally the elevation of the marginal ridge P.sub.5 is
identified. The marginal ridge elevation MRE, which is the vertical
distance from P.sub.3 to P.sub.5, is identified on the maxillary
posterior teeth because they are the centric stops for the buccal
cusps of the mandibular molars and bicuspids. In other words, point
P.sub.3 on the mandibular molars and bicuspids contacts point
P.sub.5 on the maxillary molars and bicuspids when the teeth are
together, as illustrated in phantom line PH.sub.1, in FIG. 6C. For
a more precise placement in a less common case where the maxillary
ridge is narrow in relation to the mandibular tip (phantom line
PH.sub.2), a more detailed three dimensional analysis of the tooth
shape can take into account additional correction needed. The
calculation of MRE (FIG. 6C) is made after rotation of the teeth to
their proper LAI inclinations so that MRE will be a vertical
distance, where LAI is measured relative to the plane of the dental
arch. The MRE is used as the buccal cusp height BCH in the
calculation of cuspid rise and archwire plane placement as
described below in the discussion of FIGS. 7A and 8, 471
respectively.
[0432] (700) Cuspid Rise Determination Step:
[0433] The next step of the analysis procedure (87) is (700) the
calculation of cuspid rise, illustrated in detail in the flowchart
of FIG. 2K.
[0434] Most orthodontists currently desire a cuspid rise occlusion,
in which, in lateral movement of the lower jaw, the cuspids cause
the other teeth to disclude or to come apart. In order for this to
happen, the overlap of the cuspids must be greater than that of the
other teeth when the teeth are together. This is complicated by the
fact that the cuspids (I=3) are close to the front of the mouth and
are therefore further from the condyle or pivot point PP of the jaw
than are the posterior teeth (I>3), as illustrated by distances
DJ.sub.I in FIG. 7. This results in the teeth closer to the back of
the mouth moving less than the cuspids on opening. This
differential rate of movement must be included in the calculation
of cuspid rise or the back teeth will remain in contact after the
cuspids have cleared each other. Also, the distance DPP from the
occlusal plane to the pivot point PP of the condyle of the jaws
must be considered, as illustrated in FIG. 7. A failure to provide
for this distance results in what is known as working
interferences.
[0435] According to the preferred embodiment of the present
invention, where cuspid rise is prescribed to control occlusion,
the contribution of cuspid rise is distributed between the
maxillary and mandibular cuspids, with two parts of the cuspid rise
provided by the maxillary cuspids and one part by the mandibular
cuspids. This distribution is applicable where occlusion is solely
to be a cuspid rise function. Where occlusion is to be a group
function, as specified by the orthodontist 14 in the prescription
27, the distribution between the upper and lower teeth is generally
equal.
[0436] In the substeps performed in the calculation of the cuspid
rise (700), illustrated in detail in the flowchart of FIG. 2K, the
first substep is (705) to acquire the initial vertical distance or
buccal cusp height BCH from P.sub.3 to the marginal ridge for each
of the right and left maxillary first bicuspids T(U,4), second
bicuspids T(U,5), first molars T(U,6), and second molars T(U,7), as
illustrated in FIG. 6C. This is the marginal ridge elevation MRE
calculated for each of these teeth in substep (615) of step (600).
Then, from anatomical study, (710) the ues in Table 2.
3 TABLE 2 1.67 .times. BCH of T(U,7) 1.50 .times. BCH of T(U,6)
1.36 .times. BCH of T(U,5) and 1.20 .times. BCH of T(U,4).
[0437] Then, (715) from the products of the buccal cuspid rise
vertical height CR required to clear each respective pair of teeth
is determined by first computing the values in Table 2, which are
derived from the jaw dimensions DPP and DJ.sub.I in FIG. 7.
required to clear each respective pair of teeth is determined by
first computing the val height BCH for each such tooth multiplied
by the rise factor listed above, the largest value is selected.
This selected product is the cuspid rise required to clear the most
prominent cusp and provide group function occlusion. This is
illustrated as BCH.sub.6 in FIG. 7A for the case where the first
molars are the last to clear.
[0438] (720) If the group function has been selected in the
prescription 27 provided by the orthodontist 14, the calculated
rise is used as is. If cuspid guidance has been selected in the
prescription 27 of the orthodontist 14, the calculated cuspid rise
factor must further be modified to give typically 0.5 to 0.75 mm of
clearance over the largest rise factor by multiplying the buccal
cusp height BCH for each tooth by the rise factor listed above and
selecting the largest figure, then adding 0.5 to 0.75 mm additional
cuspid overlap to obtain and adjusted cuspid guidance cuspid
rise.
[0439] (725) Calculation of cuspid overlap or cuspid rise CR for
maxillary and mandibular cuspids is preferably as follows: If group
function has been selected, mandibular rise equals 50% total group
function rise, and maxillary rise equals 50% of the total group
function rise. If cuspid function has been selected, mandibular
rise equals 34% of the total cuspid guidance rise, and maxillary
rise equals 66% of the total cuspid guidance rise.
[0440] (800) Mandibular Tooth Placement Step:
[0441] The next step in the analysis procedure (87) is (800) the
mathematical construction of the mandibular occlusion to calculate
the position of the mandibular teeth. The details of this step are
illustrated in the flowchart of FIG. 2L. The first calculation
places the tips of the mandibular teeth on an occlusal plane
pending final refinement of the placement, as diagrammatically
illustrated in FIG. 6E. In this step, the inclinations of the
mandibular tooth crown long axes CLA are preserved, and the teeth
are moved upward along their CLA's until their tips are in
alignment with the plane of the top of the tallest tooth. The CLA's
are placed to intersect the MTE below the tooth GCP. Because the
teeth are inclined at different LAIs, or long axis inclination
angles, the tooth tips will each be differently offset from the
MTE, and thus not in a smooth arch.
[0442] The substeps of the mandibular placement step (800),
illustrated in the flowchart of FIG. 2L, are as follows:
[0443] (805) The tallest mandibular tooth, with the exception of
the cuspids, is identified. In FIG. 6F this is illustrated as the
left mandibular central. The tallest tooth is the tooth with the
greatest crown height CH. The crown height CH is the distance, in
the Y direction (with the teeth profiles oriented as described in
step (600), from the GCP, the point of intersection of line L.sub.2
and crown long axis CLA, to highest point on buccal cusp, e.g.
P.sub.3 (for posterior teeth) as illustrated in FIG. 6F and (for
the anterior teeth) to either the incisal center point ICP or,
preferably to the incisal tip IC, as illustrated in FIG. 6G. The
crown height CH of the tallest tooth, shown as the left mandibular
central incisor in FIG. 6F, is the maximum crown height MCH of the
mandibular teeth.
[0444] Then, (810) three parallel planes are established:
[0445] a) an MCH reference plane MCHP parallel to the X-axis, and
passing through an origin 0,0, set at the GCP of the tallest tooth
(FIGS. 6F and 6I);
[0446] b) a Buccal Cusp Plane BCP parallel to X-axis and passing
through coordinates 0, MCH on the tallest tooth (FIGS. 6F and 6I);
and
[0447] c) a Cuspid Rise Plane CRP parallel to X-axis and passing
through coordinates 0, where CR is the cuspid rise calculated in
step (700), where the cuspid rise option has been selected.
[0448] With the planes defined, (815) the oriented mandibular teeth
are placed such that the highest point on buccal cusp tip P.sub.3
or incisal tip IC of each contacts the buccal cusp plane BCP, for
all teeth except the cuspids, as illustrated further in FIG. 6F.
The BCP thereby is established as the occlusal plane MOC. The
reference plane MCHP is set equal to the plane of the mandibular
trough MT This sets the GCP of the tallest tooth on the MT, with
the GCPs of the remaining mandibular teeth above it. It also sets
the occlusal plane MOC a distance MCH from the mandibular trough
MT. The absolute highest point on a tooth crown is preferably used
to align the teeth with the BCP. Such a point can be determined by
additional point selection in step (500), such as by the direct
selecting of the point IC for the precise incisal tip, or
preferably by calculating the highest point directly from the
profiles of FIG. 3C or from three dimensional images as in FIGS.
2A, 2B after rotation of the teeth to their final inclination
angles LAI, at the end of step (600).
[0449] The next stage in this step is to establish the mandibular
component of cuspid rise. This involves (820) vertically moving the
cuspids by, for example, sliding the cuspids along their crown long
axes, such that the cuspid cusp tips are at the appropriate height
above the mandibular occlusal plane, that is, in the plane CRP.
[0450] At this stage, the vertical positions of the mandibular
teeth relative to each other are calculated, providing a basis for
relating the Y coordinates of the individual mandibular tooth
profiles with respect to each other as illustrated in FIGS. 6F and
7C.
[0451] Then, with the mandibular teeth vertically positioned, the
teeth are horizontally set at temporary positions with respect to
the MTE, which lies in the plane of the mandibular trough MT
(MCHP). This horizontal positioning, in effect, relates the X axes
of the individual tooth profiles in a horizontal in-out direction
with respect to the mandibular arch and special mesiodistally along
the mandibular arch.
[0452] Because the preferred goal, however, is to position the tips
of the teeth in the smoothest arch in an occlusal plane MOC rather
than their gingival aspects in a smooth arch at the mandibular
trough MT, (825), a horizontal distance OFFSET for each tooth is
calculated, based on the tooth and the crown long axis inclination
LAI determined in step (600). This offset is the horizontal
distance from the MTEto the tooth tips when their GCPs are placed
on the MTE.
[0453] For mandibular centrals and laterals and cuspids, the OFFSET
is calculated by dividing, by the tangent of LAI, the vertical
distance from (1) the intersection of crown long axis CLA and the
incisal tip IC to (2) the intersection of CLA and maximum cusp
height reference plane MCHP. The vertical distance may be
calculated from the IC to the MCHP (equal to the Y coordinate of
point IC, producing the incisal center vertical distance ICD.) For
mandibular laterals and centrals, ICD equals MCH. For mandibular
cuspids, ICD equals the mandibular cuspid rise component, which is
MCH+(Total CR)/3 when cuspid rise function occlusion has been
selected. The calculation of the OFFSET for centrals, laterals and
cuspids would thus be as follows for the incisors and laterals:
OFFSET=ICD/tan(LAI)
[0454] (831) For mandibular bicuspids and molars, referring to FIG.
6F, the OFFSET is calculated as the horizontal distance from point
P.sub.3 to the intersection of the CLA and the MCHP as follows:
OFFSET=[MCH/tan (LAI)]+HD
[0455] where HD equals the horizontal distance from point P.sub.3
to incisal center point ICP.
[0456] Then, (835) the mandibular trough placement point MTPP is
defined as the intersection of MCHP and CLA, as illustrated in
FIGS. 6G and 6H. For the tallest tooth, MTPP is its GCP, as
illustrated in FIG. 6I. The MCHP is at the level of the mandibular
trough and contains the MTE. The MTPP is the point on the tooth
that is initially placed on the MTE.
[0457] Next, referring to FIGS. 7B and 7C, the teeth are placed
with their MTPPs on the mandibular trough, one side at a time. To
achieve this, (840) the subroutine (2200) is called twice, once for
the left side, and once for the right side, as follows:
[0458] The mandibular trough equation MTE is first adjusted for the
mandibular centrals to increase the radii by the amount of the
central OFFSET for that particular tooth, as defined above, to form
a mandibular trough offset curve MO(1) of FIG. 4B. The radii of the
MTE referred to are those of the MTE defined in the circle segment
form of the equation generated in step (300) with the spline to
circle conversion routine (2100). Since the OFFSETs of the teeth
differ, the MO may be viewed as a discontinuous equation when
constructed in this manner, made up of segments, each containing
the tip of one tooth and spaced labial-lingually from the MTE by
the amount of the individual tooth's OFFSET
[0459] Beginning with the left side, the central is placed, as
illustrated in FIG. 7B, by placing its mesial contact point MCP at
the intersection of the midline ML with the offset curve MO for the
tooth. This has the effect of the placing MTPP of the tooth, which
is the intersection of the CLA with the MCHP or MT, on the MTE and
the incisal tip IC of the tooth on MO.sub.1. The tooth placement on
the circle segment form of an equation is explained in detail in
the description of the tooth placement routine (2200) below. In the
placement of the central, a circle C.sub.1 is constructed with a
radius equal to the mesiodistal width MDW.sub.1 of the central
tooth and with the center of the circle C.sub.1 at the mesial
contact point MCP of the tooth at intersection of the midline ML
with the offset curve MO.sub.1. Then, circle C.sub.2 is constructed
with a radius equal to MDW/2 and with its center coincident with
the center of circle C.sub.1. Then, the intersections of trough
offset curve MO with the circles C.sub.1 and C.sub.2 are found, its
intersection with the circle C.sub.1 being the distal contact point
DCP of the tooth and its intersection with the C.sub.2 being the
tooth midpoint TMP of the central tooth. The tooth midpoint TMP is
here defined as the midpoint of the mesiodistal width of the tooth
placed on an archform, which is the intersection of the archform
with a vertical labial-lingual plane that contains the CLA. This
mid-point TMP of the central tooth on the MO is the approximate
position of the incisal tip IC.
[0460] Determining the intersections of the circles with the offset
trough curve MO, or expanded mandibular trough, requires
identification of which circle sector lines (FIG. 5) the circles
C.sub.1 and C.sub.2 intersect. These are identified by comparison
of the X coordinates of the intersections with the X coordinates of
the distal contact points DCP of each of the central teeth to
determine which segments of the trough equation will be used, as
explained more fully in the description of the tooth placement
routine (2200) below.
[0461] Finally, a distal contact point line DCPL is constructed for
the central tooth through the DCP, at the intersection of circle
C.sub.1 with the MO, and through the center of the identified
circle segment of the MO, the expanded MTE, on which the DCP of the
tooth lies. This line lies along a radius of the circle segment of
the MO curve through the distal contact point of the central tooth.
Similar lines DTMP are constructed for the center of the tooth
TMP.
[0462] (845) For each of the remaining mandibular teeth on the same
side of the arch, in distal sequence, a new mandibular trough
offset MO.sub.1 is calculated, by expanding the MTE with radii of
curvature increased by the amount of the next tooth's OFFSET and
with center of the circles C.sub.1 and C.sub.2 moved labially or
outwardly from the MTE along the prior tooth's distal contact point
line DCPL by the amount of the current tooth's OFFSET This is the
MCP for the next tooth. Circle C.sub.1 for the tooth is constructed
with a radius equal to the mesiodistal width of the tooth and with
its center at their center point MCP. Circle C.sub.2 is constructed
with a radius equal to MDW/2 and with centers coincident with
circles C1.
[0463] For bicuspids and molars, the tooth midpoints TMP can be
considered as their points P.sub.3. Then, as with the central, the
intersections of MO and circles C.sub.1 and C.sub.2 are calculated
for these teeth. The distal contact points DCT of these teeth are
at the intersections of MO for the tooth and the respective
C.sub.1s. The centers of the teeth TMP are at the intersections of
MO for the tooth and the respective circles C.sub.2. The MO sector
segments which the circles intersect are identified. Selection of
the segments is made by comparing the X and Y coordinates of
intersections to X and Y coordinates of distal contact points DCPs.
Finally, a distal contact point line DCPL is constructed from
selected segment center to the plane DCP. The same is done for the
centers of the teeth TMP.
[0464] (848) The substeps (842) are repeated for all of the
remaining mandibular teeth on the same side of the arch. Then,
(849) substeps (840)-(848) are repeated for the teeth on the
opposite side of arch.
[0465] (900) Best Fit Mandibular Arch Equation Step:
[0466] The above step (800) leaves the crown long axes CLA of the
mandibular teeth intersecting the MCHP reference plane, which is at
the level of the mandibular trough MT at or just below the gingival
center points GCP of the teeth, along the mandibular trough
equation MTE. The discontinuous offset equation MO, however,
contains the approximate tips of the teeth in the occlusal plane
MOC, with the teeth irregularly offset as represented by the
discontinuous MO lines in FIG. 4B. To place the tips of the teeth
into an ideal arch, (900) a final equation for better placement of
the buccal cusp tips and incisal edges of the mandibular teeth in a
continuous arch is developed. The development of the best fit
equation is illustrated in the detailed flowchart of FIG. 2M.
[0467] When viewed perpendicularly to the occlusal plane as in
FIGS. 4B and 7B, it can be seen that the buccal cusp tips and
incisal tips of all of the individual teeth do not lie along either
the mandibular trough equation or the same geometrical expansion of
that equation. In fact, due to small anatomical variations, it is
unlikely that the tips will fall on any smooth curve when the tooth
CLAs intersect a smooth curve at the mandibular trough in the MCHP
and the LAIs are preserved. To remedy this, the equation is
statistically developed that best fits the cusp tips and incisal
edges of the individual teeth; a Best Fit Buccal Cusp Equation
BFBCE. In the formulation of the equation, the coordinates of the
right and left tooth midpoints TMP, the ICPs or ICs in FIG. 7B, are
preferably averaged. The equation BFBCE may be obtained (910) by
use of polynomial or other bezier or least square statistical
techniques to arrive at a best fit equation. These are available in
any of a number of off-the-shelf software packages.
[0468] Such a BFBCE equation is plotted in FIG. 4B. Once the BFBCE
is determined, it may be (915) converted to a circle segment
equation in a manner such as with the spline to circle conversion
routine (2100). This equation provides a basis for moving the teeth
labially or lingually from the discontinuous offset equation MO to
place the tips of the mandibular teeth in a smooth arch in the
occlusal plane CP, as illustrated in FIG. 7C. To do this, in the
next step the profile planes will be translated bodily in their own
horizontal X-directions (which is an X-Y movement in the
coordinates of the horizontal planes), moving their MTPPs off of
the MTE in the MCHP (or MT).
[0469] (1000) Mandibular Best Fit Arch Placement Step:
[0470] After statistically deriving a best fit equation BFBCE,
(1000) positions of the individual mandibular teeth are calculated
to translate then facially, either labially or lingually, so that
their tips fall on the best fit curve. This step is illustrated in
detail in the flowchart of FIG. 2N.
[0471] To achieve this, (1005) the mesiodistal contact point of the
mandibular central, the point MCP, as in FIG. 7B, is first placed
on the intersection of the midline ML with the BFBCE in the same
manner as it was placed on the MO in step (800). Then (1010)
circles C1 and C2, as defined above, for the tooth are constructed
and their intersections with the BFBCE curve are found. As with the
placement in step (800) above, the intersection of C.sub.1 with
BFBCE is the distal contact point DCP of the tooth, and the
intersection of C.sub.2 with the BFBCE curve, is the center point
TMP (which aligns with IC) of the tooth. This, in effect, moves the
tooth normal to the circle segment of the BFBCE associated with the
TMP. Then, (1015) new circles C.sub.1 and C.sub.2 are constructed
with centers at the distal center points DCP and (1020) substeps
(1005) and (1015) are repeated for all teeth on the same side of
the mandibular arch. Then, (1025) steps (1005) through (1020) are
repeated for the teeth on the other side of the mandibular arch.
The placement uses the tooth placement routine (2200), the
description of which below explains in detail the placement of the
mandibular teeth on the BFBCE.
[0472] This step bodily translates the teeth in a generally
horizontal direction, and rotates the teeth of the mandible about
their CLAs to place incisal edges and cusp tips, as determined in
step (800), on the BFBCE. With the completion of this step the
finished positions of the mandibular teeth are calculated and the
mandibular occlusion is finalized. At this point the mandibular
occlusion can be envisioned as an ideal setup cast in stone, to
which the maxillary occlusion will be fitted and related.
[0473] The finish positions of the mandibular teeth are illustrated
in FIG. 7C in which the X-Y coordinates are those of the horizontal
arch planes. A vertical Z coordinate, perpendicular to the
horizontal X-Y plane, is aligned with the Y axes of the individual
tooth profile planes. The X coordinates of the profile planes are
aligned with the labial-lingual directions La-Li in FIG. 7B.
[0474] (1100) Maxillary Tooth Placement Step:
[0475] The construction of occlusion requires (1100) the fitting of
the maxillary teeth to the already positioned mandibular teeth.
This is accomplished by deriving a modified best fit buccal cusp
equation BFBCE for the maxillary teeth in the step illustrated in
detail in the flowchart of FIG. 2O. Unlike with the mandibular
teeth, with the maxillary teeth, the cusp tips of the posterior
teeth and incisal edges of the anterior teeth are not set in a
single arch. The maxillary teeth are rather set: (1) with the
central groove-marginal ridge points of the maxillary bicuspids and
molars on the BFBCE, (2) with the maxillary anteriors spaced
labially off of the BFBCE to allow for incisal overlap and a
clearance between the lingual surfaces thereof and the labial
surfaces of the mandibular teeth, and (3) with the cuspid tips in
the arch generally between the first maxillary bicuspid and the
lateral incisor. The arches on which the maxillary teeth are placed
as illustrated in FIG. 4C, as explained above.
[0476] For the maxillary incisors, the modification of the BFBCE
first involves averaging the distances from point P.sub.2 to point
P.sub.3 on the mandibular incisor incisal edge, and dividing by
two, to locate the arch that will contain the labial surface of the
tooth adjacent the incisal center point ICP of the tooth, which is
generally the point P.sub.3. This produces a uniform distance from
the best fit equation to the contact point of the facial surface on
the labial side of the mandibular anterior teeth with the facial
point on the lingual side of the maxillary anterior teeth. An
additional distance, of typically one-quarter millimeter, is added
to the averaged distance to provide a slight Clearance between the
upper and lower anterior teeth. This is illustrated in FIG. 7D.
[0477] The maxillary anterior dentition is set for vertical
position relative to the occlusal plane MOC according to occlusion
criteria selected to provide a predetermined overlap. From the
cuspid rise calculation of step (700), the vertical positions of
the maxillary cuspids are known relative to the mandibular occlusal
plane MOC. For maxillary laterals and centrals, the vertical
positions provide the overlaps according to the prescribed
criteria, putting their lingual facial contact points with their
mandibular counterparts on the MOC plane. All teeth are inclined at
the prescribed crown long axis CLA inclination values LAI from
Table 1 in step (600).
[0478] In the (1100) placement of the teeth of the maxilla, or
upper jaw 24, with respect to those of the mandibular, or lower jaw
22, (1105) three arch forms are mathematically defined. These are
(1106) the maxillary anterior arch form MAAF, (1110) the central
groove marginal ridge arch form CGMRAF, and (1115) the maxillary
cuspid arch form MCAF, as illustrated in FIG. 4B. The MAAF is
established to position the maxillary incisors with respect to the
BFBCE so that their lingual faces contact or clear the labial faces
of the mandibular incisors. The CGMRAF is established separate from
the MAAF because the maxillary bicuspids and molars contact their
mandibular counterparts with their central groove marginal ridge
intersection points juxtaposed on the mandibular buccal cusps. The
MCAF is established separate from the MAAF and the CGMRAF because
the cuspids have a still different relation to their mandibular
counterparts.
[0479] (1106) Location of the MAAF relative to the BFBCE requires a
circle segment radius expansion of the BFBCE equation such that the
lingual surfaces of the maxillary incisors, after being adjusted
vertically to provide a predetermined overlap, will contact the
labial face of the mandibular incisors at points spaced labially
from the BFBCE with the predetermined Clearance. This expansion is
calculated as the average distance between points P.sub.3 and
P.sub.2 on the four maxillary incisors and adding the predetermined
Clearance of typically 0.25 mm. This expansion, so calculated, is
added to the BFBCE circle segment radii to define the maxillary
anterior contact arch form MAAF. The MAAF is thus also expressed as
a circle segment equation.
[0480] The calculation of the amount of circle segment radius
expansion of the BFBCE needed to define the MAAF is made at the
midpoint of the mesiodistal width of either maxillary central,
TMP.sub.1 in FIG. 4C. This would be the intersection with BFBCE of
circle C.sub.2 in FIG. 7C. The tooth is placed on the maxillary
contact arch form equation MAAF such that the mesial contact point
of the tooth is on intersection of the midline ML and the maxillary
contact arch form MAAF (FIG. 4C).
[0481] (1108) The MAAF is defined as follows with respect to upper
laterals and centrals: 13 MAAF = BFBCE + { t } P 3 X - P 2 X { Avg
} + Clearance
[0482] where:
[0483] t=number of teeth (4),
[0484] Avg=2 (to find midpoint), and
[0485] Clearance=0.25 mm, typically.
[0486] P.sub.2 and P.sub.3 are points on the maxillary central as
defined in step (600). As described above, the crown long axes CLA
of these teeth are angulated relative to the occlusal plane at the
crown long axis seed values stated in Table 1.
[0487] (1109) The tooth placement proceeds in accordance with the
tooth placement routine (2200) described below. The placement
positions the lingual faces of the central teeth on the MAAF, with
the central mesial contact point MCP.sub.1 on ML. The midpoint
TMP.sub.2 of the mesiodistal width of the next maxillary tooth is
then placed on the maxillary contact arch equation MAAF such that
the mesial contact point MCP.sub.2 touches a line normal to the
curve MAAF and through the distal contact point DCP.sub.1 of the
previous tooth. This procedure applies on one side of the occlusion
up to the cuspid. The other maxillary side is constructed
similarly.
[0488] The next substep in the construction of the maxillary
occlusion is (1110) the definition of the location of the arch for
horizontal placement of the posterior teeth. The teeth are again
set at the LAI values of Table 1 from step (600). (1111) The
intersections of the marginal ridge and the central groove, which,
if not separately selected in step (600) may be taken as point
P.sub.5 in FIG. 6C, are placed over the buccal cusp of the
appropriate mandibular tooth whose cusps were previously positioned
on the best fit buccal cusp equation BFBCE. Thus, the CGMRAF
coincides with the BCBFE as shown in FIG. 4B.
[0489] For the maxillary cuspids, (1115) the cusp tips are placed
on some smooth arch between the MAAF and the CGMRAF Preferably,
their tips are placed on the BFBCE expanded by the average of the
distances therefrom to the incisal tip of the lateral and to the
buccal cusp tips of the first maxillary bicuspids. This labial
distance from this point to the buccal cusp tip of the first
bicuspid may alternatively be used to place the distal contact
point of the cuspid, with its mesial contact point in contact with
the distal contact point of the lateral. The point to which the
BFBCE must be expanded to locate the buccal cusp tip of the first
bicuspid for the two above alternatives is
P.sub.3X(U,4)-P.sub.5X(U,4). The cuspids will thereby be spaced out
from the BFBCE by the average of a distance equal to the horizontal
or X distance from P.sub.5 to P.sub.3 on the first maxillary molar,
as illustrated in FIG. 6C, and the MAAF.
[0490] Alternatively, the cuspids may be placed with their mesial
contact points MCP.sub.3 on the MAAF and with their distal contact
points DCP in line with the mesial contact points or with the
buccal cusp tips of the first maxillary bicuspids.
[0491] A third alternative in placing the cuspids is to use the
same criteria for clearance with the mandibular teeth used for the
definition of the MAAF. Following the determination of the MCAF,
the cuspids placed adjacent the laterals with the tips thereof on
the MCAF, followed by the successive placement of the posterior
teeth with the marginal ridges thereof on the CGMRAF (BFBCE), all
according to routine (2200).
[0492] In relating the profile and archform drawings and equations
above, it should be noted that the X dimension of the profiles on
which P.sub.3 and P.sub.5 are defined are vertical planes, and that
the X direction in these planes corresponds to the labial direction
in the horizontal planes of the archforms, as was explained for the
mandibular teeth in connection with FIG. 7C. Thus, addition of an X
component of a point on a tooth profile to an archform curve
results in a labial expansion of the archform, or an increase in
the radius of the corresponding circle segment of the archform
circle series equation.
[0493] At this point, information from the prescription 27 from the
orthodontist 14 is retrieved to determine (1120) which maxillary
anterior vertical occlusion method has been selected. The methods
may include, for example, (1121) Roth occlusion, (1122) Ricketts
occlusion, or (1123) the preferred method, referred to by the
inventors as Elan occlusion. These are discussed below.
[0494] Where (1121) Roth occlusion has been selected, the maxillary
cuspids will extend a distance CR.sub.U3 equal to the cuspid rise
CR below the occlusal plane MOC, and for laterals and centrals, the
teeth will extend a distance CR.sub.U2 equal to 0.5 the cuspid rise
beyond the occlusal plane, as illustrated in FIG. 7D. From step
(725), the treatment is selected to apply either group function or
cuspid rise function, and the respective cuspid rise quantities for
maxillary cuspids are determined. From the lowest point on buccal
(facial) cusp, a distance is measure vertically upward equal to 0.5
CR to find the intersection of occlusal plane MOC and central and
lateral teeth if two profiles were taken, the profile that includes
marginal ridges is used. The intersections of MOC with each
maxillary incisor are defined as follows:
[0495] Facial intersection with MOC=FIMOC,
[0496] Lingual intersection with MOC=LIMOC,
[0497] The distance from LIMOC to FIMOC, DLF, is computed as
follows:
DLF=/X.sub.FIMOC-X.sub.LIMOC/
[0498] where LIMOC is the contact point with MAAF.
[0499] Where (1122) Ricketts occlusion is prescribed, the maxillary
cuspids also extend below the MOC by a distance CR.sub.U3 equal to
the cuspid rise CR. The laterals are positioned such that the tips
are the distance CR.sub.U2 of 1.0 mm above the cuspid tips, and the
distance CR.sub.U1 is such that the tips of the centrals are 0.5 mm
above the cuspid tips. From step (725), in which either group
function or cuspid rise function were selected, the respective
cuspid rise quantities are applied for the maxillary cuspids. Then,
from lowest point on buccal (facial) cusp, a distance of 1.0 mm is
measured upward on the laterals and a distance of 0.4 mm is
measured upward on centrals to find the intersection of MOC with
the central and lateral teeth. If two profiles were taken, a
profile that includes the marginal ridges is used. A line is then
constructed through the points on the buccal cusps parallel to the
MOC. The intersections with the teeth are defined as follows:
[0500] Facial intersection with MOC=FIMOC
[0501] Lingual intersection with MOC=LIMOC
[0502] Distance DLF from LIMOC to
FIMOC=/X.sub.FIMOC-X.sub.LIMOC/
[0503] where LIMOC is contact point with MAAF
[0504] Where (1123) Elan occlusion has been selected, the maxillary
cuspids will extend a distance CR.sub.U3 equal to 0.67 of the
cuspid rise CR below the occlusal plane MOC, laterals extend a
distance CR.sub.U2 equal to 0.33 of the cuspid rise CR below the
plane MOC, and the centrals extend a distance CR.sub.U1 equal to
0.50 of the cuspid rise CR below the plane MOC. As with the above,
from step (725), in which either group function or cuspid rise
function were selected, the respective cuspid rise quantities are
applied for the maxillary cuspids. Then, from the lowest point on
buccal (facial) cusp, a distance of 0.33 of the cuspid rise CR is
measured upward on the laterals, and a distance of 0.50 of the
cuspid rise CR is measured upward on the centrals, and the
intersection of the teeth with the plane MOC is found. If two
profiles were taken, a profile that includes marginal ridges is
used. The MOC plane and the intersections with the teeth are
defined as follows, as illustrated on the cuspid in FIG. 7D:
[0505] Facial intersection with MOC=FIMOC.
[0506] Lingual intersection with MOC=LIMOC.
[0507] Distance DLF from LIMOC to
FIMOC=/X.sub.FIMOC-X.sub.LIMOC/.
[0508] LIMOC is contact point with MAAF
[0509] The (1125) elected horizontal occlusion is selected. If
(1126) the Roth maxillary anterior horizontal occlusion has been
selected, no further changes are required. This results in the
lingual surfaces of the teeth forming a smooth arc. If (1127) the
Ricketts maxillary anterior horizontal occlusion has been selected,
changes are made to cause the labial surfaces of the teeth to form
a smooth arc. This requires finding the largest DLF, or LIMOC-FIMOC
distance for the centrals, subtracting the other LIMOC-FIMOC
distances of the incisors from this largest distance, adding the
respective differences to each tooth to extend the LIMOC point
lingually along line LIMOC-FIMOC, and establishing a new point at
which the LIMOC is to intersect the MOC.
[0510] If (1128) the Elan horizontal occlusion is selected, which
is the preferred and illustrated embodiment, the horizontal tooth
placement proceeds as set forth below. Because, given the overlap
of the maxillary incisors, the labial-lingual thicknesses of the
anterior teeth are greater in the plane of occlusion than the
distance P.sub.3-P.sub.2 used to calculate the MAAF and the MCAF,
offsets must be calculated and the maxillary teeth placed again on
the offset versions of these archforms.
[0511] First, in calculating the positions of the teeth to provide
the horizontal occlusion, (1130) a distance is calculated from
LIMOC to ICP for the maxillary centrals and the laterals. This
distance is referred to as the maxillary anterior offset MAO, thus:
14 ICP = X 2 + X 3 2 ; Y 2 + Y 3 2
MAO=/LIMOC.sub.X-ICP.sub.X/
[0512] (1135) The maxillary first bicuspid offset MBO is
calculated:
MBO=/P.sub.5X-P.sub.3X/
[0513] (1140) The maxillary tooth positions are then recalculated,
one side at a time, with respect to the offset maxillary arch forms
defined above that contain the buccal cusp tips and incisal edges
of the maxillary teeth. This is achieved by sending the relevant
parameters to the placement routine (2200) and calculating
placement in the same manner as shown in FIG. 7B for the mandibular
teeth. For the maxillary centrals, (1141) MAAF is adjusted such
that the MAAF radii are increased by the amount of the MAO. This
curve is now called maxillary contact archform offset MAAFO and is
illustrated in FIG. 4C.
[0514] Calculation of the positions of the maxillary incisors on
the MAAFO, preferably in accordance with the tooth placement
routine (2200), closes the spaces between the teeth that results
from expanding MAAF to MAAFO.
[0515] The intersection of MAAFO and the arch midline ML is the
mesial contact point MCP of the tooth. A circle C.sub.1 is
constructed with a radius equal to the mesiodistal width MDW of the
central incisor. Its center is at the intersection point of MAAFO
and ML. The intersection of the circle C.sub.1 with MAAFO is the
distal contact point DCP. Then, circle C.sub.2 is constructed with
a radius equal to MDW/2, that is half the mesiodistal width MDW.
Its center is coincidental with that of C.sub.1. The intersection
of the circle C.sub.2 with the MAFFO curve is the mid-point of
tooth TMP and the incisal center point ICP.
[0516] The intersection of MAAFO and circles C.sub.1 and C.sub.2
are then constructed. The curve defined by MAAFO and the
intersection of circle C.sub.1 is the distal contact point DCP. The
intersections of MAAFO and MAAFO circle segment lines are found.
The X coordinates of the intersections are compared to the X
coordinates of DCP to determine which segment's center will be
used.
[0517] A distal contact point line DCPL is constructed from the
selected segment center to the DCP. Similarly a center of tooth
line TMPL is constructed from the sector center to the TMP. Thus,
the tooth LIMOC is on MAAF and the tooth mesiodistal width line is
on the MAAFO arch. The location of FIMOC is accordingly determined
by adding DFL to the MAFFO circle segment radius through the
TMP.
[0518] The MAAFO, like the MO for the mandibular teeth, is
discontinuous, with the archform being offset differently for the
different maxillary teeth. Accordingly, for the maxillary laterals,
the prior MAAFO is replaced with the MAAF adjusted such that the
MAAF radii are increased by amount of MAO for lateral. The tooth's
MCP is the tooth's MAO distance from the MAAF along the prior
tooth's distal contact point line DCPL. Circle C.sub.1 is
constructed with a radius the mesiodistal width of the tooth and
with a center at the tooth's MCP. The intersection of C.sub.1 with
the MAAFO is the tooth's DCP. Circle C.sub.2 is constructed with a
radius equal to half of the tooth's MDW and with a center
coincident with that of circle C.sub.1. The intersection of circle
C.sub.2 with MAAFO is the tooth's ICP.
[0519] Then, the intersections of MAAFO and the MAAFO sector lines
are found. The X and Y coordinates of intersections are compared to
the X and Y coordinates of DCP to determine which segment's center
will be used. A distal contact point line DCP is constructed from
the selected segment center to the DCP. Similarly a center of tooth
line TMPL is constructed from the sector to the TMP.
[0520] For the maxillary cuspids, the prior MAAFO is eliminated. A
new arch form, the maxillary cuspid arch form MCAF, is computed to
place the cuspid between the lateral and the first bicuspid. In one
preferred approach, the MCAF is constructed offset from the BFBCE
by the average of the OFFSETs of the first bicuspid and the
lateral, as calculated in substep (1135) above. With exception of a
new arch radius, the cuspid is placed as above.
[0521] For the maxillary bicuspids and molars, the arch form
CGMRAF, which is the BFBCE, is offset by MBO. CGMRAF is adjusted by
adding MBO for the respective teeth. The cuspid tips on the MCAF,
which was offset from the BFBCE to align with the buccal cusp tips
of the first bicuspids in (1115) above, are thus in line with the
posterior buccal cusp tips. From the cuspid DCP, circles C.sub.1
and C.sub.2 are constructed and DCPLs are established. This
sequence is repeated for remainder of the teeth, completing the
relation of the maxillary and mandibular occlusions. The finish
positions of the maxillary teeth are illustrated FIG. 4D.
[0522] At this point, the final positions of the maxillary teeth
have been calculated, and thus, the finish positions of all of the
teeth.
Appliance Design Procedure (96)
[0523] The appliance design procedure includes the steps of (1200)
determining the location of the mandibular archwire plane relative
to the calculated finish positions of the mandibular teeth, (1300)
calculating the angle of each mandibular bracket slot relative to
the mounting surface of the respective tooth, (1400) determining
the location of the maxillary archwire plane relative to the
calculated finish positions of the maxillary teeth, (1500)
calculating the angle of each maxillary bracket slot relative to
the mounting surface of the respective tooth, (1600) calculating
the shape of the mandibular archwire and the slot in-out dimension
of each mandibular bracket, (1700) calculating the shape of the
maxillary archwire and the slot in-out dimension of each maxillary
bracket, and (1800) calculating the contours of bracket placement
jigs for each tooth.
[0524] (1200) Mandibular Archwire Plane Step:
[0525] The next step is (1200) to establish the position of the
archwire plane for the mandibular teeth, which is illustrated in
detail in the flowchart of FIG. 2P. The archwire plane can be
located in an infinite number of vertical positions since the
brackets and archwire will be designed to accommodate any chosen
location. Since the overlap of the maxillary teeth is known, for
labial bracket placement, the mandibular archwire plane is set to
provide bracket clearance for the maxillary teeth in the finished
occlusion. For lingual bracket placement, this consideration is
given to the maxillary archwire plane instead, in step (1300)
below.
[0526] Since the maxillary teeth do not pose a bracket interference
dilemma with labial bracket placement, the brackets can be
positioned for ease of placement, cosmetic considerations and
gingival health. This applies to the mandibular bracket positioning
where lingual bracket placement is used. Typically, these brackets
are located more centrally than the brackets of the other arch.
[0527] More particularly, as illustrated in the flowchart of FIG.
2P and FIG. 8, (1200) to establish the archwire plane, (1205) the
selected vertical occlusion and respective vertical overlap from
MOC for cuspids, laterals and centrals is recalled from (1110).
Then, (1210) with the information from (705), the buccal cusp
height BCH is recalled for each bicuspid and molar. Next, (1215)
the maximum BCH or anterior vertical overlap is chosen as the
maximum vertical overlap MVO. Then, (1220) a distance equal to the
MVO is measured downward from the MOC. Finally, (1225) half of the
bracket height (typically 3.0 mm) plus an additional 0.75 mm is
added for occlusal clearance. This defines the mandibular archwire
plane MAWP. This places brackets as occlusal as possible with an
0.75 mm clearance from the worst case from the maxillary
occlusion.
[0528] (1300) Mandibular Slot Inclination Step:
[0529] Once the archwire planes have been defined with respect to
the teeth, as illustrated in the flowchart of FIG. 2Q, (1300) the
angle between the bracket mounting surface of the teeth and
archwire plane is determined. This angle minus 90.degree. is the
facial torque or inclination angle to be formed into the brackets.
This also defines the bracket slot placement height which is the
distance from the top of the incisal edge to the archwire plane.
This distance is calculated perpendicular to the archwire
plane.
[0530] Slotless bracket bodies (vanilla brackets) have now been
positioned appropriately. A smooth archwire is then designed such
that it will pass through the bodies of the brackets. The archwire
must not cut too deeply into the bracket or pass even partially
outside the face of the brackets. Brackets are chosen having
different heights according to need. Without modifying buccal tube
assemblies, standard bracket distances from the tooth surface to
the center of the slot may be used as a seed values. The archwire
equation is then mathematically derived from cubic spline and
tangential circle techniques as previously described and provided
in the routines (2000) and (2100). Both archwires are developed
similarly.
[0531] Bracket angle determination (1300), more particularly, is
achieved by (1305) taking the intersection of the MA WP and labial
(buccal) surface of each mandibular tooth in the case of labial
appliances. and the intersection of the MAWP with the lingual
surface of each tooth in the case of lingual appliances. Then,
(1310) circles are constructed with centers at the intersections
and with diameters that represent the occluso-gingival (vertical)
dimensions of the bracket bonding pad (typically 3.0 mm). Then,
(1315) X, Y coordinates of the circle intersections with labial
(buccal) tooth surface are taken, and, with the equations:
R.sup.2=(X.sub.1-h).sup.2+(Y.sub.1-K).sup.2
Y.sub.2=mX.sub.2+b.sub.2
Y.sub.3=mX.sub.3+b.sub.3
[0532] (1320) The slopes between the points of intersection are
calculated to produce the facial inclination angle FIA, where:
[0533] h,k=coordinates of circle center
[0534] X.sub.1, Y.sub.2, b.sub.2=definition of first line
segment
[0535] X.sub.3, Y.sub.3, b.sub.3=definition of second line
segment
[0536] Then, as illustrated in FIG. 8A for labial appliances,
.pi./2 radians are then subtracted to produce the slot inclination
angle SIA: 15 FIA = Y 2 - Y 3 X 2 - X 3
SIA=FIA-.pi./2
[0537] (1400) Maxillary Archwire Plane Step:
[0538] The next step is (1400) locating the maxillary archwire
plane as illustrated in the flowchart of FIG. 2R and diagram of
FIG. 8. For the maxillary centrals, this involves (1405) finding
the vertical distance from incisal edge to point P.sub.4. (1410)
The smallest value is selected and divided by two to produce the
slot placement height for the maxillary centrals. (1415) For
terminal maxillary bicuspids the vertical distance from buccal cusp
to point P.sub.4 is found. (1420) Again, the smallest value is
selected and divided by two. This produces the slot placement
height SPH for the terminal maxillary bicuspids.
[0539] For maxillary centrals, (1425) the Y value of FIMOC is
subtracted from the Y value for the slot placement height SPH. This
is the distance from MOC to the slot centerline. For terminal
maxillary bicuspids, (1430) the Y value of MOC is subtracted from
the Y value for the slot placement height SPH. This is the distance
from MOC to the slot centerline. Then, (1435) the SPH for the
terminal bicuspid from SPH for the maxillary centrals. This is
elevation change DH of the maxillary archwire relative to the MOC
from the centrals to the terminal maxillary bicuspids. (1440) The
elevation of the maxillary archwire MXAWP from the MOC, or archwire
height AHTon each tooth, is calculated as follows:
AHT=K+DH+SPH-MOC.sub.Y+Vertical overlap from (1110)
[0540] where K is the conversion factor from Table 3.
4 TABLE 3 Extraction Non- (e.g. 2nd Tooth Type Extraction Bicuspid)
Maxillary Central 0.0 0.0 Maxillary Lateral -0.19 -0.28 Maxillary
Cuspid -0.42 -0.62 Maxillary First Bicuspid -0.68 -1.00 Maxillary
Second Bicuspid -1.00 NA Maxillary First Molar -1.32 -1.46
[0541] (1500) Maxillary Slot Inclination Step:
[0542] Once the archwire plane is determined, as illustrated in the
flowchart of FIG. 2S, (1500) the slot inclination angle SAI for
each of the maxillary tooth brackets is determined in a manner
similar to the slot inclination determination step for the
mandibular brackets (1300). This step (1505) begins by finding the
intersection of the maxillary archwire plane MXAWP with the labial
or buccal surface of each maxillary tooth. Then, (1510) circles are
described, for each maxillary tooth, having centers at this
intersection point and having diameters equal to the
occluso-gingival, or vertical, dimensions of the bracket bonding
pad, which is typically 4.0 mm. From these circles, (1515) X, Y
coordinates of the intersections of the circles with the labial or
buccal tooth surface are found, as follows:
R.sup.2=(X.sub.1-h).sup.2+(Y.sub.1-k).sup.2
Y.sub.2=mX.sub.2+b.sub.2
Y.sub.3=mX.sub.3+b.sub.3
[0543] Where: h,k=coordinates of the circle center
[0544] X.sub.1, Y.sub.1=possible coordinates on the circle
[0545] X.sub.2, Y.sub.2, b.sub.2=definition of a first line
segment
[0546] X.sub.3, Y.sub.3, b.sub.3=definition of a second line
segment
[0547] Then, as illustrated in FIG. 8A, (1520) .pi./2 radians are
then subtracted to produce the slot inclination angle SIA: 16 FIA =
Y 2 - Y 3 X 2 - X 3
SIA=FIA-.pi./2
[0548] (1600) Mandibular Archwire and Slot Depth Step:
[0549] The next step, as illustrated in the flowchart of FIG. 2T,
is (1600) to determine the mandibular archwire and bracket in-out
dimension. First, (1605) the circle segment of the BFBCE with which
the ICP of the right central is associated is determined, as
illustrated in FIG. 8B. Then, (1610) the incisal center point and
circle segment center point plane ICPCDCPP is created normal to the
arch planes. An incisal center point line ICPL is struck that will
pass through the ICP and a particular circle segment center point
CSCP associated with the tooth. Then (1615) the Pythagorean
distance PD from CSCP to ICP is determined. Then, (1620) viewing
the tooth in the ICPCSCPP, as illustrated in FIG. 8C, a line NL is
struck normal to the BFBCE plane through the ICP, which is the
intersection of CLA and BFBCE. Next, (1625) still viewing the tooth
in this plane, the intersection point XP of NL and MAWP is
determined.
[0550] Still viewing the tooth in the ICPCSCPP, (1630) the X
distance XD to the labial surface of the tooth from the XP is
determined, and (1635) PD is added to XD and the lower limit of the
bracket slot LLBS. The LLBS is a distance associated with the
particular bracket that will be placed on this tooth. It is the
deepest slot allowable for that bracket. Then, the lower limit LL
is calculated thus:
LL=PD+XD+LLBS
[0551] Similarly, (1640) PD is added to the XD and the upper limit
of the bracket slot ULBS. The ULBS is also a distance associated
with the particular bracket that will be placed on this tooth. It
is the shallowest slot allowable for that bracket. The, the upper
limit UL is calculated thus:
UL=PD+XD+ULBS
[0552] (1645) Then, viewing the mandibular occlusion in a plan view
and moving out along the ICPL from its CSCP by the LL distance, X
and Y points, AWLL.sub.X,Y, are determined relative to an origin at
the intersection of BFBCE and the mandibular midline ML. Then,
(1650) viewing the mandibular occlusion in a plan view and moving
out along the ICPL from its CSCP by the UL distance, X and Y
points, AWUL.sub.X,Y are determined relative to the intersection of
BFBCE and the mandibular midline ML. Then, (1655) the mid-point of
AWLL.sub.X,Y and AWUL.sub.X<Y is found and steps (1605) through
(1650) are then repeated for all mandibular teeth.
[0553] Then, (1660) the average mid-point and distance from right
to left is calculated to force mandibular archwire symmetry: 17 S X
= MP X + PR X - PL X 2 S Y = MP Y + PR Y + PL Y 2
[0554] Where:
[0555] S.sub.X,Y is the symmetricalized point.
[0556] MP is the mid-point of BCBCE.
[0557] PR is a point on the right side of the midline.
[0558] PL is a point on the left side of the midline.
[0559] The smoothest curve SC that will pass between all
AWLL.sub.X,Y and AWUL.sub.X,Y points is then determined, as
illustrated in FIG. 4E. This is accomplished by the following
procedure:
[0560] a) The mid-point of each AWLL.sub.X,Y and AWUK.sub.X,Y pair
is found.
[0561] b) Then, as described above, a cubic spline equation is
passed through these points.
[0562] c) The existence of any inflection points is determined.
[0563] d) The curve with the least variation in radius changes
along the curve is considered the smoothest curve. Preferably, it
has no inflection points. If there are one or more inflection
points, a logical alternative bracket solution will be derived
based upon where the inflection occurred.
[0564] Then, (1665) the intersection point XSCICPL of the
mandibular right central's ICPL is determined as well the smoothest
curve as defined above in substep (1660). Next, (1670) the in-out
IO of that particular tooth is determined as the distance along
ICPL from ICP to XSCICPL minus that tooth's XD. Then, (1675) steps
(1665) and (1670) are repeated until all in-out dimensions are
calculated.
[0565] Finally, (1675) all XCSICPL points are passed into the cubic
spline routine (2000) and to circle routine (2100) and (1680) all
circle segment information gathered therefrom are converted to
linear distance LD moves needed to bend the appropriate wire, as
will be further explained in connection with the wire bending step
(3200) below. The bracket slot cutting is described in connection
with step (3000) below.
[0566] (1700) Maxillary Archwire and Slot Depth Step:
[0567] The next step, as illustrated in the flowchart of FIG. 2U,
is (1700) to determine the maxillary archwire and bracket in-out
dimension. As with the mandibular determination step (1600), (1705)
the circle segment of the BFBCE with which the ICP of the right
central is associated is determined. The step is similar to that
for the mandibular slot in-out dimension calculation of FIGS. 4E
and 8C, except that the maxillary centrals and laterals are
associated with the MAAF rather than the BFBCE, the maxillary
cuspids are associated with MCAF, and teeth posterior to the cuspid
are associated with the BFBCE.
[0568] The calculation proceeds with (1710) the incisal center
point and circle segment center point plane ICPCDCPP being created,
with a line being struck that will pass through the incisal center
point line ICPL which will pass through the ICP and a particular
circle segment center point CSCP associated with the tooth. The
plane passing through the ICP and the CSCP and normal to the
mandibular trough MT is the ICPCSCPP. Then (1715) the Pythagorean
distance PD from CSCP to ICP is determined. Then, (1720) viewing
the tooth in the ICPCSCPP, a line NL is struck normal to the BFBCE
through the intersection of CLA and BFBCE. Next, (1725) still
viewing the tooth in this plane, the intersection point XP of NL
and MAWP is determined.
[0569] Still viewing the tooth in the ICPCSCPP, (1730) the X
distance XD to the labial surface of the tooth from the XP is
determined, and (1735) PD is added to XD and the lower limit of the
bracket slot LLBS. The LLBS is a distance associated with the
particular bracket that will be placed on this tooth. It is the
deepest slot allowable for that bracket. Then, the lower limit LL
is calculated thus:
LL=PD+XD+LLBS
[0570] Similarly, (1740) PD is added to the XD and the upper limit
of the bracket slot ULBS. The ULBS is also a distance associated
with the particular bracket that will be placed on this tooth. It
is the shallowest slot allowable for that bracket. Then, the upper
limit UL is calculated thus:
UL=PD+XD+ULBS
[0571] (1745) Then, viewing the mandibular occlusion in a plan view
and moving out along the ICPL from its CSCP by the LL distance, X
and Y points, AWLL.sub.X,Y, are determined relative to the
intersection of BFBCE and the mandibular midline ML. Then, (1750)
viewing the mandibular occlusion in a plan view and moving out
along the ICPL from its CSCP by the UL distance, X and Y points,
AWUL.sub.X,Y are determined relative to the intersection of BFBCE
and the mandibular midline ML. Then, (1755) The mid-point of
AWLL.sub.X,Y and AWUL.sub.X,Y is found and steps (1705) through
(1750) are then repeated for all mandibular teeth.
[0572] Then, (1760) the average mid-point and distance from right
to left is calculated to force mandibular archwire symmetry: 18 S X
= MP X PR X - PL X 2 S Y = MP Y PR Y + PL Y 2
[0573] Where:
[0574] S.sub.X,Y=the symmetricalized point.
[0575] MP=the mid-point of BCBCE.
[0576] PR=a point on the right side of the midline.
[0577] PL=a point on the left side of the midline.
[0578] Then the smoothest curve SC that will pass between all
AWLL.sub.X,Y and AWUL.sub.X,Y points is determined. This is
accomplished by the following procedure:
[0579] a) The mid-point of each AWLL.sub.X,Y and AWUK.sub.X,Y pair
is found.
[0580] b) Then, as described above, a cubic spline equation is
passed through these points.
[0581] c) The existence of any inflection points is determined.
[0582] d) If there are no inflection points, this is considered the
smoothest curve. If there is an inflection point, a logical
alternative bracket solution will be derived based upon where the
inflection occurred. The relevant information necessary to
determine a new pair of AWLL.sub.X,Y and AWUL.sub.S,Y and their
midpoints is undertaken. It should be noted that there are varying
LLBS and ULBS possibilities available for each tooth.
[0583] Then, (1765) the intersection point XSCICPL of the
mandibular right central's ICPL is determined as well as the
smoothest curve as defined above in substep (1760). Next, (1770)
the in-out of that particular tooth is determined as the distance
along ICPL from ICP to XSCICPL minus that tooth's XD. Then, (1775)
steps (1765) and (1770) are repeated until all in-out dimensions
are calculated.
[0584] Finally, (1775) all XCSICPL points are passed into the
spline to circle program and (1780) all circle segment information
gathered therefrom are converted to linear distance LD moves needed
to bend the appropriate wire, as will be further explained in
connection with the wire bending step (3200) below. The bracket
slot cutting is described in the discussion of step (3000)
below.
[0585] (1800) Placement Jig Design Step:
[0586] With the shapes of the individual teeth determined, their
finish positions calculated, and the brackets designed and their
places on the individual teeth determined, the information
necessary for the design of bracket placement jigs to aid the
orthodontist in positioning the brackets in their proper positions
on the individual teeth is available. In the preferred embodiment
of the invention, the design of the placement jigs is carried out
in the software associated with the jig manufacturing step (3500)
described below, following a loading of the appropriate files with
the necessary data from the calculations described above into the
manufacturing control computer 30c. An abbreviated presentation of
the jig design substeps is set forth in the flowchart of FIG.
2V.
[0587] Referring to FIG. 2V, (1805) a file containing data of the
individual tooth profiles, the archwire plane location including
data relating each of the tooth profiles to the relevant archwire
plane, the bracket profiles relevant to each tooth, and the bracket
design data including the slot size, inclination and depth, are
prepared. Then, (1810) the tools that will form the jig are
determined, and (1815) clearances are established. Then, (1820)
data needed for instructions to cut an internal profile into each
jig is assembled to hold a bracket and to locate the bracket at the
proper position on the tooth by precise fitting of the jig over the
tooth profile along a labial-lingual plane through the tooth
midpoint TMP.
[0588] The details of the jig design step, as it is performed along
with the jig manufacturing step, is described in detail in
connection with the description of the flowchart of FIG. 2Z under
step (3500) below.
Subroutines
[0589] Three subroutines are used in calculating various archforms
and calculating the positions of the teeth thereon. These are
(2000) the cubic spline equation curve calculation subroutine,
(2100) the spline equation to circle segment equation conversion
subroutine, and (2200) the tooth placement subroutine. These are
illustrated in the flowchart of FIG. 2W.
[0590] (2000) Cubic Spline Equation Fitting Subroutine:
[0591] In the cubic spline interpolation, symmetrical data points
are interpolated and a cubic spline equation is derived. As
illustrated in FIG. 5A, a symmetrical mandibular trough or cubic
spline equation SMT is shown for one side of the lower jaw. In FIG.
5A, the point M.sub.X,M.sub.Y represents the intersection of the
curve and the midline ML. The points SI.sub.X,SI.sub.Y for I=1 to 6
represent the symmetricized points X.sub.ML referred to above.
[0592] The cubic spline method uses a cubic (3rd degree) polynomial
to interpolate between each pair of data points. A different
polynomial is used for each interval, and each one is constrained
to pass through the original data points with the same slope as the
data. At these points, slopes are computed by finding the slope of
the parabola that passes through each data point and its two
nearest neighbors.
[0593] The iterations necessary to compute the cubic polynomial are
as follows:
[0594] 1) For each data point, the X and Ycoordinates are made
equal to zero and all other data points evaluated relative to this
new original.
[0595] 2) The slopes of the cubic spline are computed by first
computing the coefficients of the above described parabola, then a
first point of a slope array is filled followed by the remaining
points through the final slope array point.
[0596] 3) The spline coefficients are computed.
[0597] 4) The polynomial is evaluated.
[0598] These steps are described in Science and Engineering
Programs, Apple II Edition, Edited by John Heilborn, and published
by Asborne/McGraw-Hill. Copyright, 1981, McGraw-Hill, Inc., and
incorporated herein by reference.
[0599] Once the polynomial has been evaluated, it is possible to
acquire additional data points. A Y value can be determined for any
given X value, with the constraint that additional data points be
within the upper and lower limits of the original X values. The
following iterations are performed before circle conversion:
[0600] 1) Determination of X and Y points on each side of the
original data points. This is done by taking X points that are one
thousandth (0.001) to each side of original X data points. Then X
values two thousandths (0.002) less than the last data point are
taken. Then Y points are determined for each arrayed X point by
evaluation of the polynomial equation discussed above. Then the Y
points of the array are calculated.
[0601] 2) The slope array is then filled with slopes corresponding
to data points on either side of the original data points.
[0602] 3) The slope of the curve at each of the original data
points is calculated. This involves retrieving X and Y points on
either side of original data points, and calculating the slope at
the original data points using the Point Slope method according to:
19 SLOPE = Y 2 - Y 1 X 2 - X 1
[0603] Where:
[0604] SLOPE=the slope of the curve at that point.
[0605] X1=the X point 0.001 to left of original data point.
[0606] Y1=the Y point associated with X1.
[0607] X2=the X point 0.001 to right of original data point.
[0608] Y2=the Y point associated with X2.
[0609] The slope is calculated using the arrayed point that is
0.002 less than the last data point and the last data point, and
the slope is calculated using the point slope method as all array
slopes are calculated.
[0610] (2100) Circle Segment Conversion Subroutine:
[0611] The circle segment conversion typically fits two circle
segments into one spline segment. A spline segment is defined as
the interpolated cubic spline equation which describes the shape of
the curve between two original data points. A circle segment is
defined as the arc associated with a beginning point, or end point,
and the slope of tangency at that point. Two configurations of
circle segments are possible when converting a spline segment into
two circle segments, one where the first circle is larger than the
second (FIG. 5B) and the other where the first circle is smaller
than the second circle FIG. 5C, the variables in which are
identified below. The iterations necessary to convert a spline
segment into two circle segments are illustrated in FIG. 5D in
which:
[0612] P1.sub.X, P1.sub.Y=the beginning point of spline segment
[0613] P2.sub.X, P2.sub.Y=end point of spline segment
[0614] MT1=tangent slope of spline at point P1.sub.X, P1.sub.Y
[0615] MN1=normal slope of MT1
[0616] MT2=tangent slope at point P2.sub.X, P2.sub.Y
[0617] MN2=normal slope of MN2
[0618] P3.sub.X, P3.sub.Y=intersection of a line through point
P1.sub.X, P1.sub.Y with a slope of MT1 and a line though point
P2.sub.X, P2.sub.Y with a slope of MT2
[0619] CL=a Cord Line, a line connecting points P1.sub.X, P1.sub.Y
and P2.sub.X, P2.sub.Y
[0620] CNL=a Cord Normal Line, a line normal to CL through
P3.sub.X, P3.sub.Y
[0621] hs,ks=the center of the smaller of the two circle
segments
[0622] The iterations to convert a spline segment into two circle
segments are, as follows:
[0623] 1) Determine MN1 and MN2. They are the negative inverse of
MN1 and MT2, respectively.
[0624] 2) Determine the intersection point P3.sub.X, P3.sub.Y.
[0625] 3) Determine the slope of the CL.
[0626] 4) Determine the slope of CLN.
[0627] 5) Determine the distance from P1.sub.X, P1.sub.Y to
P.sup.3.sub.X, P3.sub.Y. This is defined as test one.
[0628] 6) Determine the distance from P2.sub.X, P2.sub.Y to
P3.sub.X, P3Y. This is defined as test two.
[0629] 7) Test to determine which length is smaller. If the test
one result is shorter than the test result, the smaller circle is
associated with P1.sub.X, P2.sub.Y, otherwise, the smaller circle
is associated with P2.sub.X, P2.sub.Y.
[0630] 8) Rename the variable associating to the size of the
circle. See FIG. 5B in which:
[0631] P1.sub.X, P2.sub.Y=the beginning point of spline segment
[0632] P2.sub.X, P2.sub.Y=the end point of spline segment
[0633] MNS=the normal slope of small circle segment, equivalent to
MN1 or MN2 depending on the relative results of test one and test
two
[0634] MNL=normal slope of large circle segment
[0635] hs,ks=the center of the smaller of the two circle
segments
[0636] hl,kl=the center of the larger of the two circle
segments
[0637] P6.sub.X, P6.sub.Y=a distance, defined by the radius of the
small circle, to a point along MNL from the spline segment point
associated with it
[0638] MNF=is the slope of the final line
[0639] 9) Determine the intersection of the line described by slope
of CNL and passing through P3.sub.X, P3.sub.Y and the line
described by MNS through the spline segment point associated with
it. The intersection point of these two lines is the center of the
smaller circle hs,ks.
[0640] 10) Determine the Pythagorean distance from the small circle
center hs,ks to the spline segment points associated with it. This
distance is the radius of the small circle rs.
[0641] 11) Move along the line described by MNL and passing through
the spline segment point associated with it by the radius of the
smaller circle rs. This point is P6.sub.X, P6.sub.Y.
[0642] 12) Strike a line from P6.sub.X, P6.sub.Y to hs,ks.
[0643] 13) The negative inverse of the slope of the line from
P6.sub.X, P6.sub.Y and hs,ks is mnf.
[0644] 14) Determine the midpoint of the line from P6.sub.X,
P6.sub.Y to hs,ks.
[0645] 15) Determine the intersection of the line described by a
slope of mnf and passing the point described in step 14 and the
line described by MNL and through the spline segment point
associated with it. The intersection point of these two lines is
the center of the larger circle hl,kl.
[0646] 16) Determine the Pythagorean distance from the large circle
center hs,ks to the spline segment points associated with it. This
distance is the radius of the larger circle rl.
[0647] 17) The intersection of the two circles is defined as the
intersection of the line going through the large circle center
hl,kl and the small circle center hs,ks and either of the circles.
At this point the tangency of the two circles are equivalent.
[0648] 18) Accommodate an arc length calculation dependent upon
which spline point is closer to P3.sub.X, P3.sub.Y:
[0649] If the test one result is greater than that of test two,
then:
[0650] Theta1=A TN(m)-ATN(MSI)
[0651] Theta2=ATN(MLI)-ATN(m)
[0652] otherwise:
[0653] Theta1=A TN(msl)-ATN(m)
[0654] Theta2=A TN(m)-ATN(mll)
[0655] where: 20 m = k1 - ks h1 - hs
[0656] Theta1=the arc angle of the smaller circle
[0657] Theta2=the arc angle of the larger circle.
[0658] 19) Calculate arc length for each segment.
[0659] s1=rs (Theta1)
[0660] s2=rl (Theta2)
[0661] where:
[0662] s1=arc length of smaller segment
[0663] s2=arc length of larger segment
[0664] 20) Calculate the running arc length.
[0665] 21) Continue distally until all spline segments are
converted.
[0666] FIGS. 5E-5J illustrate the building of the mandibular trough
data points into circle segments.
[0667] (2200) Tooth Placement on Curve Subroutine:
[0668] The individual tooth placement upon an equation is required
in many steps of the tooth finish position calculation procedure
(94). The preferred method is described here in connection with the
first occurrence in the procedure for the placement of the
mandibular teeth.
[0669] There are four alternative equations upon which teeth can be
placed: the mandibular trough MT equation, the maxillary anterior
arch form MAAF equation, the maxillary cuspid arch form MCAF
equation, and the central groove marginal ridge arch form MGMRAF
equation. All occlusion equations will have been converted to
circle segments before teeth are placed upon them. A typical tooth
placement is illustrated in FIG. 5N, in which:
[0670] DCP=Distal Contact Point
[0671] ICP=Incisal Center Point
[0672] MCP=Mesial Contact Point
[0673] MCPL=is the Mesial Contact Point Line.
[0674] The DCP is the point at which the tooth contacts the
proceeding tooth. The ICP is the center of the tooth being placed.
The MCP is the point at which the tooth contacts the preceding
tooth. The MCPL is defined as the line through the DCP of the tooth
being placed and the center of the circle segment associated with
the DCP. The MCPL is the line upon which the DCP of the proceeding
tooth will be found.
[0675] The iterations to place the teeth onto the circle segments
are:
[0676] 1) Determine the offset distance for the mandibular central
tooth on the side of the jaw under consideration.
[0677] 2) Expand all circle segments about their centers by the
offset amount.
[0678] 3) Determine the intersection of the first circle segment
and the midline. This is the mesial contact point MCP of the
central, as illustrated in FIG. 5K.
[0679] 4) Place the first circle C.sub.1, whose radius is the
mesio-distal width of the tooth, at MCP, as illustrated in FIG.
5K.
[0680] 5) Determine which circle segment in the distal direction
circle C.sub.1 intersects and identify the intersection point. This
is accomplished by performing an iteration which begins by
transferring the coordinate system to the beginning point of the
circle segment, as illustrated in FIG. 5L, in which:
[0681] X.sub.BEG, Y.sub.BEG=beginning coordinates of the circle
segment
[0682] X.sub.END, Y.sub.END=End points of the circle segment
[0683] X.sub.INT, Y.sub.INT=coordinates of circle intersection
[0684] X and Y axes are oriented at X.sub.BEG, Y.sub.BEG.
[0685] The two following circle equations are then solved
simultaneously:
R.sub.1.sup.2=(x-h1)+(y-k1)
R.sub.2.sup.2=(x-h2)+(y-k2)
[0686] Where:
[0687] h1,k1=the center coordinates of the first circle
[0688] h2,k2=the center coordinates of the second circle
[0689] R.sub.1=the radius of the first circle C.sub.1
[0690] R.sub.2=the radius of a second circle C.sub.2
[0691] X,Y=coordinates of possible intersection points
[0692] The following solutions are possible: (1) two real solutions
which are labeled X1.sub.INT, Y1.sub.INT and X2.sub.INT,
Y2.sub.INT, respectively. (2) imaginary solutions, which are
discarded, whereupon the next circle segment is evaluated. If
intersections are real, the circle segment is rotated, as
illustrated in FIG. 2M, such that X.sub.END, Y.sub.END is placed on
the X axis. Then, X.sub.BEG, Y.sub.BEG is subtracted from the
rotated X intersection point X1.sub.INT or X2.sub.INT, and rotated
X.sub.END is subtracted from the rotated X intersection point
X1.sub.INT or X2.sub.INT. If the signs of the results of the two
subtractions are opposite, the rotated intersection point is tested
for a value less than zero. If it is not less than zero, the other
rotated intersection point is tested to determine if it is valid.
The testing continues until a segment is found such that the
subtractions produce opposite sign results and the associated
rotated Y intersection point is less than zero. This is the distal
contact point DCP of the tooth, as illustrated in FIG. 5N.
[0693] 6) Construct a line passing through the DCP and the center
of the circle segment that intersects C.sub.1.
[0694] 7) Place circle C.sub.2, whose radius is one half the
mesio-distal width MDW of the tooth, at the MCP.
[0695] 8) Determine which circle segment in the distal direction
intersects circle C.sub.2 and identify the intersection point. This
is the incisal center point ICP of the tooth, as illustrated in
FIG. 5N.
[0696] 9) Eliminate all expanded circle segments.
[0697] 10) Determine the offset distance for the mandibular
lateral.
[0698] 11) Expand all circle segments about their centers by the
offset amount.
[0699] 12) Determine the intersection point of the expanded circle
segment ECS associated with the DCP MCP Line. The intersection
point is the mesial contact point MCP of the lateral, as
illustrated in FIG. 5O.
[0700] 13) Place circle C.sub.1, with radius the mesio-distal width
MDW of the lateral, at the current MCP point.
[0701] 14) Determine which circle segment in the distal direction
circle C.sub.1 intersects and identify the intersection point,
which is the DCP of the lateral.
[0702] 15) Construct a line passing through the DCP and the center
of the circle segment that intersects C.sub.1.
[0703] 16) Place circle C.sub.2, whose radius is one half the
mesio-distal width MDW of the tooth, at the MCP.
[0704] 17) Determine which circle segment in the distal direction
intersects circle C.sub.2 and identify the intersection point. This
is the incisal center point ICP of the tooth, as illustrated in
FIG. 5P.
[0705] 18) Continue distally until all teeth are placed.
[0706] 19) Perform the same iterations for the co-lateral side of
the arch.
(97) Appliance Manufacturing Procedure
[0707] The appliance manufacturing procedure (97) includes the
steps of (3000) manufacture of the custom brackets, (3200)
manufacture of the custom archwires and (3500) manufacture of
custom placement jigs for placement of the custom brackets on the
patient's teeth. These steps are described in detail below for the
embodiment in which all of the manufacturing is carried out at the
appliance design facility 13.
[0708] (3000) Bracket Manufacturing Step:
[0709] The bracket manufacturing step (3000) produces the custom
brackets, preferably by selecting bracket blanks and cutting a
torque slot in the bracket for the archwire 64. This utilizes the
modified CNC mill 40 illustrated in FIG. 2D. The bracket slot
cutting step is illustrated in the detailed flowchart of FIG.
2X.
[0710] Referring to FIG. 2X, the bracket manufacturing step (3000)
begins with the computer 30c (3005) loading the data for each
bracket from the patient data file 36.
[0711] For each tooth and bracket, as a default or initial
selection, (3010) low profile brackets are assumed. Then, the slot
angle FAI and the slot in-out dimension IO are read. Also, (3020)
the radius of the archwire at the tooth midpoint is determined.
[0712] Then, (3025) a main CNC program is created and (3030) the
program loops to generate the code for the cutting of each bracket,
beginning with the calculation of the variables for the bracket,
(3040) assigning the variables for each bracket to (3045)-(3050)
set the cutting of the slot at the appropriate angle by rotating
the bracket support 73 and setting the cutter 77c to a cooperating
height Z and horizontal X position. If the position of the slot
lies outside of the area of the bracket, a bracket of the
appropriate higher profile is called for by the program, and
loaded, either automatically or by an operator. The code is then
generated (3055) to control the path of the cutter in the Y
direction to cut the archwire radius in the slot bottom. (3060)
then, the NC code is combined with the calculated variable values
for the tooth and bracket and a subroutine is generated for the
bracket, with (3065) the P-codes subroutines written the file.
(3068) The program loops until codes for all of the brackets are
complete.
[0713] Then, (3070) the CNC code is preferably downloaded to an NC
controller and the brackets are formed by the cutting of the slots
in the series of bracket blanks, and (3080) a report is
written.
[0714] (3200) Arch wire Manufacturing Step:
[0715] The archwire manufacturing step (3200) produces the archwire
64, as illustrated in FIG. 2E, preferably that is symmetrical about
its archwire midline AML, having the appropriate terminal leg span
TLS, formed of a series of circle segments.
[0716] As illustrated in the flowchart of FIG. 2Y, the archwire
manufacturing step (3200) executes a program with the manufacturing
control computer 30c to generate a CNC code to operate the wire
forming machine 40. The program begins by (3215) opening one or
more files from the calculated patient data 36 and reads therefrom
the wire alloy and the wire cross-section prescribed, and an array
of data that contains a series of j sets of data including the
radius and sector length of each circle segment of which the
archwire curve is formed, and the calculated total cumulative
archwire length. To the archwire equation, (3220) a radii and
sector lengths are added to produce a one half inch of straight
segment at each end of the wire to form parallel terminal leg
extensions. Then, calculating the cumulative slopes and sector
lengths of the wire along the equation, (3225) the terminal leg
span TLS is calculated.
[0717] Based upon the wire type selected, (3230) one of several
data files or tables are read. For rectangle wire, for example,
four files would include: (1) 0.022" thickness stainless steel
(SS), (2) 0.025" thickness SS, (3) 0.022" thickness titanium
molybdenum alloy (TMA), and (4) 0.025" thickness TMA. Other files
are provided for round wires of various diameters and types.
[0718] Then, using the cubic spline subroutine (2000), (3235) the
slopes of the cubic spline equation describing wire behavior are
calculated by: (1) computing the coefficients of a parabola, (2)
filling the first point of a slope array, (3) filling the
intermediate points of the slope array, and (4) filling the last
point of the slope array. Then, (3240) the cubic spline
coefficients are calculated. Then, (3245) the vertical displacement
of the bending lever arm LA (FIG. 2E) between the contact points of
the roller 70b with the wire 69 and the contact point of the
rollers 68 with the wire 69 is determined for each circle segment
of the archwire equation, and data added to the array.
[0719] Then, (3255) temporary variables are defined for the sector
length, lever arm displacement, radius and terminal leg span across
the straight segments of the archwire, (3260) the controller card
65 of the computer 30c is initialized, (3265) the controller base
address is set, and (3270) default parameters are set. Then, (3275)
a sequential series of sector lengths and lever arm displacements
are sent respectively (1) through the circuits 66a and 67a to the
drive of the feed rolls 68, and (2) through the circuits 66b and
67b to the anvil assembly 70.
[0720] When all circle segments have been formed, (3280) the lever
arm displacement is zeroed and (3285) the wire leg location is read
by the sensor 71. This reading converted to a numerical value in
the computer 30b and any difference in the actual measured terminal
leg span and the desired terminal leg span TLS is calculated. If
(3290) the difference is out of tolerance, a correction is made and
another wire is formed.
[0721] (3500) Jig Manufacturing Step:
[0722] The jig manufacturing step (3500) produces bracket placement
jigs custom designed for each tooth to aid in the placement of the
custom designed brackets in the proper positions on the teeth so
that the custom designed archwire will, when installed in the
custom designed and custom placed brackets, move the teeth to their
calculated finish positions.
[0723] The information necessary for the design of the custom
placement jigs is contained in the patient data file of the
calculations made in the appliance design procedure (96) and in the
tooth profile data file of digitized information read in step
(500), in the illustrated embodiment of the invention. The design
of the custom jigs involves, primarily, an assembly of the
information already generated, and, in the preferred embodiment,
takes place in the course of generating the code for control of the
NC controlled manufacturing equipment 41 that produces the
jigs.
[0724] In the preferred and illustrated embodiment, the jig
manufacturing equipment 41 is a standard CNC mill equipped with a
small carbide endmill tool of, for example, 0.020 inches in
diameter (FIG. 1F). The jigs themselves 82 are made from circular
ABS plastic wafers 83 of approximately one inch in diameter and
approximately 0.040 inches in thickness, though considerable
variation in size is acceptable.
[0725] The jig manufacturing step (3500), as illustrated in the
detailed flowchart of FIG. 2Z, begins with the execution of a
program or routine in the manufacturing computer 30b and the input
of parameters identifying the patient or case. Upon beginning of
the execution of the program, (3515) the file of patient data 36
generated in the tooth position calculation and analysis procedure
(95) and the appliance design procedure (96) is opened and
information is read for each tooth, as illustrated in the diagram
of FIG. 9I, in relation to a tooth profile PF The variables read
are (a) the intersection of the archwire plane and the labial (or
lingual, if prescribed) surface of the tooth TS, which is in the
form of a pair of X, Y coordinates TS.sub.X,Y in the tooth profile
vertical-labial/lingual plane, (b) the slot in-out dimension Elan
or IO, (c) the type of bracket, which provides access to the
appropriate place in a lookup table of bracket dimensions, such as
bracket base thickness BRel and bracket pad height BPH, and (d) the
torque slot width, 0.018 or 0.022 from the prescription.
[0726] Then, (3520) the bracket data file is opened and the bracket
base thickness read, as illustrated in FIG. 9J. Then, a file name
is assigned, (3530) a CNC file is created, and (3535) a CNC "main"
program is written to it, as set forth, for example, in the
flowchart of FIG. 2Z-1.
[0727] Then, (3540) a sequential file is identified that contains
the beginning and ending object number for each tooth profile, and
(3545) a CAD program file containing the tooth profiles PF, is
loaded. The profiles PF, as illustrated in FIG. 3C, are made up of
a series of closely spaced points in the profile plane, each
represented by X,Y coordinates, connected by straight line segments
to define the profile curve PF. The endmill tool diameter Endmill
is also entered, which must be less than the archwire diameter or
archwire slot width (0.018 or 0.022). Constants are declared,
including the diameter of the jig blank 83, the cut clearance on
the outside of the jig, the number of loops, set at 23, and the
counter initial settings.
[0728] Then, (3560) the CNC P-code is generated for each tooth, by
looping through substeps (3560) through (3639) until the code for
each of the jigs 82 is generated. The loop begins by (3560)
incrementing the tooth and P-code counters by 1. The loop begins
with the lower left bicuspid, as brackets are usually not used on
the molars, and proceeds left to right. Thus, (3565), when the
incrementing of the counter advances the count to the lower right
molar, (3565) the counter is advanced to skip to the upper left
bicuspid.
[0729] Then, (3570) the parameters for the particular tooth are set
up as illustrated in the flowchart detail of FIG. 2Z-2. This is
followed by creating the profile and bracket clearance compensation
tool paths ITP and BCTP, respectively, as illustrated in the
flowchart detail of FIG. 2Z-3. This involves (3590) the creation of
an initial inside tool path line IITP made up of a series of
straight line segments, one parallel to each of the line segments
of the tooth profile curve, spaced a distance equal to the tool
radius on the inside of the profile curve, as illustrated in FIG.
9K, (3595) the creation of an initial bracket base compensation
tool path line IBCTP made up of a series of straight line segments,
one parallel to each of the line segments of the tooth profile
curve, spaced a distance equal to the bracket base dimension minus
the tool radius outside of the profile curve, as illustrated in
FIG. 9L, and (3600) creation of the final bracket base compensation
tool path (d) to cut from the inside tool path line to the base
compensation line at the top of the bracket base pad to cut off the
jig at the bottom of the pad, as illustrated in FIG. 9M ("top" and
"bottom" being used as an example for the lower teeth, and being
opposite for the upper teeth).
[0730] Next, (3605) the archwire slot tool path ASTP is created as
illustrated in the flowchart detail of FIG. 2Z-4, which can be
understood from the sequence set forth in the flowchart with
reference to the diagrams of FIGS. 9N, 9O and 9P. Then, as set
forth in the flowchart detail of FIG. 2Z-5, (3610) a reference tool
path RefP is created on an image of a jig blank 83, as illustrated
in FIG. 9Q, and with reference to it, (3615) the outside jig
boundary cutout CTP is added as illustrated in FIG. 2R, and (3620)
the actual tool path TP is then generated as illustrated in FIG.
9S.
[0731] Then, (3625) the CNC machine code is generated, as
illustrated in the detailed flowchart of FIG. 2Z-6, and written to
the output file. Then, (3630) the variables are reset, (3635) the
final results are displayed, and (3640) the program loops back to
substep (3560) until all of the bracket jig code have been
generated. Then, (3645) the completed CNC file is sent to the
controller of the CNC mill and a pallet of wafers 83a (FIG. 1F) is
cut into a set of bracket placement jigs 82. An example of one of
the jigs is illustrated in FIGS. 9T through 9W.
[0732] What is described above includes the preferred embodiments
of the invention. Those skilled in the art will appreciate that
additions to and modifications of the system and method of the
invention, and the detailed manifestations thereof, may be made
without departing from the principles of the inventive concepts set
forth herein. Accordingly, the following is claimed:
* * * * *