U.S. patent application number 10/404178 was filed with the patent office on 2004-02-05 for system and methods for dental treatment planning.
This patent application is currently assigned to ALIGN TECHNOLOGY, INC.. Invention is credited to Chishti, Muhammad, Miller, Ross J., Wen, Huafeng.
Application Number | 20040023183 10/404178 |
Document ID | / |
Family ID | 31191997 |
Filed Date | 2004-02-05 |
United States Patent
Application |
20040023183 |
Kind Code |
A1 |
Miller, Ross J. ; et
al. |
February 5, 2004 |
System and methods for dental treatment planning
Abstract
Computer-implemented systems and methods implement a dental
treatment plan by specifying tooth movement patterns using a
two-dimensional array; and generating treatment paths to move the
teeth in accordance with the specified pattern.
Inventors: |
Miller, Ross J.; (Sunnyvale,
CA) ; Chishti, Muhammad; (Sunnyvale, CA) ;
Wen, Huafeng; (Redwood Shores, CA) |
Correspondence
Address: |
TOWNSEND AND TOWNSEND AND CREW, LLP
TWO EMBARCADERO CENTER
EIGHTH FLOOR
SAN FRANCISCO
CA
94111-3834
US
|
Assignee: |
ALIGN TECHNOLOGY, INC.
Santa Clara
CA
|
Family ID: |
31191997 |
Appl. No.: |
10/404178 |
Filed: |
March 31, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10404178 |
Mar 31, 2003 |
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09843246 |
Apr 25, 2001 |
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6602070 |
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10404178 |
Mar 31, 2003 |
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09313289 |
May 13, 1999 |
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6318994 |
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60199610 |
Apr 25, 2000 |
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Current U.S.
Class: |
433/24 ;
705/2 |
Current CPC
Class: |
A61C 7/002 20130101;
A61C 7/00 20130101; A61C 9/004 20130101; G16H 50/50 20180101; G16H
20/40 20180101; A61C 9/0053 20130101; A61C 7/146 20130101 |
Class at
Publication: |
433/24 ;
705/2 |
International
Class: |
G06F 017/60; A61C
003/00 |
Claims
What is claimed is:
1. A virtual health-care electronic commerce community, comprising:
a network to communicate information relating to the community; one
or more patients coupled to the network; one or more treating
professionals coupled to the network; and a server coupled to the
network, the server storing data for each patient and performing
patient data visualization in response to a user request.
2. The community of claim 1, wherein the treating professional
views one or more of the following patient data visualization over
the network: a right buccal view; a left buccal view; a posterior
view; an anterior view; a mandibular occlusal view; a maxillary
occlusal view; an overjet view; a left distal molar view; a left
lingual view; a lingual incisor view; a right lingual view; a right
distal molar view; an upper jaw view; and a lower jaw view.
3. The community of claim 1, wherein the treating professionals
include dentists or orthodontists.
4. The community of claim 1, further comprising one or more
partners coupled to the network.
5. The community of claim 4, wherein the partners include a
financing partner.
6. The community of claim 4, wherein the partners include a
supplier.
7. The community of claim 4, wherein the partners include a
delivery company.
8. The community of claim 1, wherein the treating professionals
perform office management operations using the server.
9. The community of claim 8, wherein the office management
operations include one or more of the following: patient
scheduling, patient accounting, and claim processing.
10. The community of claim 1, wherein the patients and the treating
professionals access the server using browsers.
11. A computer-implemented method for performing dental-related
electronic commerce, comprising: transmitting teeth data associated
with a patient from a dental server to a treating professional
computer over the internet upon an authorized request; displaying a
three-dimensional computer model of the teeth at the treating
professional computer using a browser; allowing a treating
professional to manipulate the three-dimensional computer model of
the teeth using the browser; transmitting the computer model from
the treating professional computer to the server; and generating an
appliance to treat the patient based on the computer model of the
teeth.
12. The method of claim 11, further comprising providing financing
options for the patient using one or more financing partners.
13. The method of claim 11, further comprising offering an on-line
shop geared to the patient's dental requirements.
14. The method of claim 11, further comprising providing office
management utilities for the treating professional.
15. The method of claim 13, wherein the office management utilities
include one or more of the following: patient scheduling, patient
accounting, and claim processing.
16. The method of claim 11, wherein allowing a treating
professional to manipulate the three-dimensional computer model of
the teeth using the browser further comprises displaying a
plurality of dental views.
17. The method of claim 15, wherein the dental views include one or
more of the following: a right buccal view; a left buccal view; a
posterior view; an anterior view; a mandibular occlusal view; a
maxillary occlusal view; an overjet view; a left distal molar view;
a left lingual view; a lingual incisor view; a right lingual view;
a right distal molar view; an upper jaw view; and a lower jaw
view.
18. The method of claim 11, wherein allowing a treating
professional to manipulate the three-dimensional computer model of
the teeth using the browser further comprises clicking on a tooth
to adjust its position.
19. The method of claim 18, further comprising displaying x, y and
z axis to allow the treating professional to adjust the position of
the tooth.
20. The method of claim 11, further comprising providing
supplemental services to the patient, including teeth whitening
services.
21. A server to support a health-care electronic commerce community
with one or more patients and one or more service providers,
comprising: a processor adapted to communicate with a network; a
data storage device coupled to the processor and adapted to store
data for each patient; and software to communicate 3D patient data
in response to a client request.
22. The server of claim 21, further comprising a browser adapted to
receive the client request and transmitting the request to the
server.
23. The server of claim 22, wherein the browser further comprises a
viewer plug-in to visualize patient data in 3D.
24. The server of claim 21, wherein the providers service one or
more of the following heath-care applications: dentistry
applications, cosmetic augmentation, hair-care enhancements,
liposuction, plastic or reconstructive surgery.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application is a divisional of application Ser. No.
09/843,246 (Attorney Docket No. 018563-004010US/AT-00039.1), filed
Apr. 25, 2001, which claimed priority from Provisional Application
Serial No. 60/199,610 (Attorney Docket No.
018563-004000US/AT-00039), filed Apr. 25, 2000, which was a
continuation-in-part of application Ser. No. 09/313,289 (Attorney
Docket No. 018563-005200US/AT-00110), filed May 13, 1999, the full
disclosures of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates generally to the field of orthodontics
and, more particularly, to computer-automated development of an
orthodontic treatment plan and appliance.
[0004] Repositioning teeth for aesthetic or other reasons is
accomplished conventionally by wearing what are commonly referred
to as "braces." Braces comprise a variety of appliances such as
brackets, archwires, ligatures, and O-rings. Attaching the
appliances to a patient's teeth is a tedious and time-consuming
enterprise requiring many meetings with the treating orthodontist.
Consequently, conventional orthodontic treatment limits an
orthodontist's patient capacity and makes orthodontic treatment
quite expensive. As such, the use of conventional braces is a
tedious and time consuming process and requires many visits to the
orthodontist's office. Moreover, from the patient's perspective,
the use of braces is unsightly, uncomfortable, presents a risk of
infection, and makes brushing, flossing, and other dental hygiene
procedures difficult.
[0005] 2. Description of the Background Art
[0006] Tooth positioners for finishing orthodontic treatment are
described by Kesling in the Am. J. Orthod. Oral. Surg. 31:297-304
(1945) and 32:285-293 (1946). The use of silicone positioners for
the comprehensive orthodontic realignment of a patient's teeth is
described in Warunek et al. (1989) J. Clin. Orthod. 23:694-700.
Clear plastic retainers for finishing and maintaining tooth
positions are commercially available from Raintree Essix, Inc., New
Orleans, La. 70125, and Tru-Tain Plastics, Rochester, Minn. 55902.
The manufacture of orthodontic positioners is described in U.S.
Pat. Nos. 5,186,623; 5,059,118; 5,055,039; 5,035,613; 4,856,991;
4,798,534; and 4,755,139.
[0007] Other publications describing the fabrication and use of
dental positioners include Kleemann and Janssen (1996) J. Clin.
Orthodon. 30:673-680; Cureton (1996) J. Clin. Orthodon. 30:390-395;
Chiappone (1980) J. Clin. Orthodon. 14:121-133; Shilliday (1971)
Am. J. Orthodontics 59:596-599; Wells (1970) Am. J. Orthodontics
58:351-366; and Cottingham (1969) Am. J. Orthodontics 55:23-31.
[0008] Kuroda et al. (1996) Am. J. Orthodontics 110:365-369
describes a method for laser scanning a plaster dental cast to
produce a digital image of the cast. See also U.S. Pat. No.
5,605,459.
[0009] U.S. Pat. Nos. 5,533,895; 5,474,448; 5,454,717; 5,447,432;
5,431,562; 5,395,238; 5,368,478; and 5,139,419, assigned to Ormco
Corporation, describe methods for manipulating digital images of
teeth for designing orthodontic appliances.
[0010] U.S. Pat. No. 5,011,405 describes a method for digitally
imaging a tooth and determining optimum bracket positioning for
orthodontic treatment. Laser scanning of a molded tooth to produce
a three-dimensional model is described in U.S. Pat. No. 5,338,198.
U.S. Pat. No. 5,452,219 describes a method for laser scanning a
tooth model and milling a tooth mold. Digital computer manipulation
of tooth contours is described in U.S. Pat. Nos. 5,607,305 and
5,587,912. Computerized digital imaging of the jaw is described in
U.S. Pat. Nos. 5,342,202 and 5,340,309. Other patents of interest
include U.S. Pat. Nos. 5,549,476; 5,382,164; 5,273,429; 4,936,862;
3,860,803; 3,660,900; 5,645,421; 5,055,039; 4,798,534; 4,856,991;
5,035,613; 5,059,118; 5,186,623; and 4,755,139.
BRIEF SUMMARY OF THE INVENTION
[0011] In one aspect, computer-implemented systems and methods
implement a dental treatment plan by specifying tooth movement
patterns using a two-dimensional array; and generating treatment
paths to move the teeth in accordance with the specified
pattern.
[0012] Implementations of the invention include one or more of the
following. One dimension of the array identifies each stage in the
teeth movement and one dimension of the array identifies a unique
tooth. Tooth movement is specified by indicating a start stage and
an end stage for a tooth. One or more tooth paths is determined
based on the selected tooth movement pattern. The method includes
selecting one or more clinical treatment prescriptions that include
at least one of the following: space closure, reproximation, dental
expansion, flaring, distalization, and lower incisor extraction. An
appliance is fabricated for each treatment stage. The appliance can
be either a removable appliance or a fixed appliance. The method
also includes generating a three-dimensional model for the teeth
for each treatment stage.
[0013] The system can conform to one or more constraints. The
constraints relates to teeth crowding, teeth spacing, teeth
extraction, teeth stripping, teeth rotation, and teeth movement.
The teeth can be rotated approximately five and ten degrees (per
stage) and can be incrementally moved in one or more stages (per
stage), each stage moving each tooth approximately 0.2 mm to
approximately 0.4 mm. The constraints can be stored in an array
with one dimension of the array identifying each stage in the teeth
movement. The treatment paths can include determining the minimum
amount of transformation required to move each tooth from the
initial position to the final position and creating each treatment
path to require only the minimum amount of movement. Additionally,
intermediate positions can be generated for at least one tooth
between which the tooth undergoes translational movements of equal
sizes. Further, intermediate positions can be generated for at
least one tooth between which the tooth undergoes translational
movements of unequal sizes. A set of rules can be applied to detect
any collisions that will occur as the patient's teeth move along
the treatment paths. Collisions can be detected by calculating
distances between a first tooth and a second tooth by establishing
a neutral projection plane between the first tooth and the second
tooth, establishing a z-axis that is normal to the plane and that
has a positive direction and a negative direction from each of a
set of base points on the projection plane, computing a pair of
signed distances comprising a first signed distance to the first
tooth and a second signed distance to the second tooth, the signed
distances being measured on a line through the base points and
parallel to the z-axis, and determining that a collision occurs if
any of the pair of signed distances indicates a collision. Where
the positive direction for the first distance is opposite the
positive direction for the second distance, a collision is detected
if the sum of any pair of signed distances is less than or equal to
zero. Information indicating whether the patient's teeth are
following the treatment paths can be used to revise the treatment
paths. More than one candidate treatment path for each tooth can be
generated and graphically displayed for each candidate treatment
path to a human user for selection. A set of rules can be applied
to detect any collisions that will occur as the patient's teeth
move along the treatment paths. Collisions can be detected by
calculating distances between a first tooth and a second tooth by:
establishing a neutral projection plane between the first tooth and
the second tooth, establishing a z-axis that is normal to the plane
and that has a positive direction and a negative direction from
each of a set of base points on the projection plane, computing a
pair of signed distances comprising a first signed distance to the
first tooth and a second signed distance to the second tooth, the
signed distances being measured on a line through the base points
and parallel to the z-axis, and determining that a collision occurs
if any of the pair of signed distances indicates a collision. A
collision can also be detected if the sum of any pair of signed
distances is less than or equal to zero. A set of rules can be
applied to detect any improper bite occlusions that will occur as
the patient's teeth move along the treatment paths. A value for a
malocclusion index can be computed and the value displayed to a
human user. The treatment paths can be generated by receiving data
indicating restraints on movement of the patient's teeth and
applying the data to generate the treatment paths. A
three-dimensional (3D) graphical representation of the teeth at the
positions corresponding to a selected data set can be rendered. The
graphical representation of the teeth to provide a visual display
of the movement of the teeth along the treatment paths can be
generated. A graphical interface, with components representing the
control buttons on a videocassette recorder, which a human user can
manipulate to control the animation, can be generated. A portion of
the data in the selected data set may be used to render the
graphical representation of the teeth. A level-of-detail
compression can be applied to the data set to render the graphical
representation of the teeth. A human user can modify the graphical
representation of the teeth and the selected data set can be
modified in response to the user's request. A human user can select
a tooth in the graphical representation and, in response,
information about the tooth can be displayed. The information can
relate to the motion that the tooth will experience while moving
along the treatment path. The information can also indicate a
linear distance between the tooth and another tooth selected in the
graphical representation. The teeth can be rendered at a selected
one of multiple viewing orthodontic-specific viewing angles. A user
interface through which a human user can provide text-based
comments after viewing the graphical representation of the
patient's teeth can be provided. The graphical representation data
can be downloaded to a remote computer at which a human view wishes
to view the graphical representation. An input signal from a 3D
gyroscopic input device controlled by a human user can be applied
to alter the orientation of the teeth in the graphical
representation.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is an elevational diagram showing the anatomical
relationship of the jaws of a patient.
[0015] FIG. 2A illustrates in more detail the patient's lower jaw
and provides a general indication of how teeth may be moved by the
methods and apparatus of the present invention.
[0016] FIG. 2B illustrates a single tooth from FIG. 2A and defines
how tooth movement distances are determined.
[0017] FIG. 2C illustrates the jaw of FIG. 2A together with an
incremental position adjustment appliance which has been configured
according to the methods and apparatus of the present
invention.
[0018] FIG. 3 is a block diagram illustrating a process for
producing incremental position adjustment appliances.
[0019] FIG. 4 is a flow chart illustrating a process for optimizing
a final placement of the patient's teeth.
[0020] FIG. 5 is a flow chart illustrating the positioning of teeth
at various steps of an orthodontic treatment plan.
[0021] FIG. 6 is a flow chart of a process for determining a
tooth's path among intermediate positions during an orthodontic
treatment plan.
[0022] FIG. 7 is a flow chart of a process for optimizing the path
of a tooth from an initial position to a final position during an
orthodontic treatment plan.
[0023] FIG. 8 is a diagram illustrating a buffering technique for
use in a collision detection algorithm.
[0024] FIG. 9 is a flow chart for a collision detection
technique.
[0025] FIG. 10 is a block diagram illustrating a system for
generating appliances in accordance with the present invention.
[0026] FIG. 11 is a diagram of a set of teeth that need to be moved
in an expansion pattern.
[0027] FIG. 12 is an exemplary two-dimensional diagram illustrating
the movement of each tooth in the diagram of FIG. 11.
[0028] FIG. 13 shows an exemplary X-type movement.
[0029] FIG. 14 shows an exemplary A-type movement.
[0030] FIG. 15 shows an exemplary V-type movement.
[0031] FIG. 16 shows an exemplary XX-type movement.
DETAILED DESCRIPTION OF THE INVENTION
[0032] FIG. 1 shows a skull 10 with an upper jawbone 22 and a
lowerjawbone 20. The lower jawbone 20 hinges at a joint 30 to the
skull 10. The joint 30 is called a temporomandibularjoint (TMJ).
The upper jawbone 22 is associated with an upper jaw 101, while the
lower jawbone 20 is associated with a lower jaw 100.
[0033] A computer model of the jaws 100 and 101 is generated, and a
computer simulation models interactions among the teeth on the jaws
100 and 101. The computer simulation allows the system to focus on
motions involving contacts between teeth mounted on the jaws. The
computer simulation allows the system to render realistic jaw
movements which are physically correct when the jaws 100 and 101
contact each other. The model of the jaw places the individual
teeth in a treated position. Further, the model can be used to
simulate jaw movements including protrusive motions, lateral
motions, and "tooth guided" motions where the path of the lower jaw
100 is guided by teeth contacts rather than by anatomical limits of
the jaws 100 and 101. Motions are applied to one jaw, but may also
be applied to both jaws. Based on the occlusion determination, the
final position of the teeth can be ascertained.
[0034] Referring now to FIG. 2A, the lower jaw 100 includes a
plurality of teeth 102, for example. At least some of these teeth
may be moved from an initial tooth arrangement to a final tooth
arrangement. As a frame of reference describing how a tooth may be
moved, an arbitrary centerline (CL) may be drawn through the tooth
102. With reference to this centerline (CL), each tooth may be
moved in orthogonal directions represented by axes 104, 106, and
108 (where 104 is the centerline). The centerline may be rotated
about the axis 108 (root angulation) and the axis 104 (torque) as
indicated by arrows 110 and 112, respectively. Additionally, the
tooth may be rotated about the centerline, as represented by an
arrow 114. Thus, all possible free-form motions of the tooth can be
performed.
[0035] FIG. 2B shows how the magnitude of any tooth movement may be
defined in terms of a maximum linear translation of any point P on
a tooth 102. Each point P1 will undergo a cumulative translation as
that tooth is moved in any of the orthogonal or rotational
directions defined in FIG. 2A. That is, while the point will
usually follow a nonlinear path, there is a linear distance between
any point in the tooth when determined at any two times during the
treatment. Thus, an arbitrary point P1 may in fact undergo a true
side-to-side translation as indicated by arrow d1, while a second
arbitration point P2 may travel along an arcuate path, resulting in
a final translation d2. Many aspects of the present invention are
defined in terms of the maximum permissible movement of a point P1
induced on any particular tooth. Such maximum tooth movement, in
turn, is defined as the maximum linear translation of that point P1
on the tooth which undergoes the maximum movement for that tooth in
any treatment step.
[0036] FIG. 2C shows one adjustment appliance 111 which is worn by
the patient in order to achieve an incremental repositioning of
individual teeth in the jaw as described generally above. The
appliance is a polymeric shell having a teeth receiving cavity.
This is described in U.S. application Ser. No. 09/169,036, filed
Oct. 8, 1998, which claims priority from U.S. application Ser. No.
08/947,080, filed Oct. 8, 1997, which in turn claims priority from
provisional application No. 06/050,352, filed Jun. 20, 1997
(collectively the "prior applications"), the full disclosures of
which are incorporated by reference.
[0037] As set forth in the prior applications, each polymeric shell
may be configured so that its tooth receiving cavity has a geometry
corresponding to an intermediate or final tooth arrangement
intended for the appliance. The patient's teeth are repositioned
from their initial tooth arrangement to a final tooth arrangement
by placing a series of incremental position adjustment appliances
over the patient's teeth. The adjustment appliances are generated
at the beginning of the treatment, and the patient wears each
appliance until the pressure of each appliance on the teeth can no
longer be felt. At that point, the patient replaces the current
adjustment appliance with the next adjustment appliance in the
series until no more appliance remains. Conveniently, the
appliances are generally not affixed to the teeth and the patient
may place and replace the appliances at any time during the
procedure. The final appliance or several appliances in the series
may have a geometry or geometries selected to overcorrect the tooth
arrangement, i.e., have a geometry which would (if fully achieved)
move individual teeth beyond the tooth arrangement which has been
selected as the "final." Such overcorrection may be desirable in
order to offset potential relapse after the repositioning method
has been terminated, i.e., to permit some movement of individual
teeth back toward their precorrected positions. Overcorrection may
also be beneficial to speed the rate of correction, i.e., by having
an appliance with a geometry that is positioned beyond a desired
intermediate or final position, the individual teeth will be
shifted toward the position at a greater rate. In such cases, the
use of an appliance can be terminated before the teeth reach the
positions defined by the appliance.
[0038] The polymeric shell 111 can fit over all teeth present in
the upper or lower jaw. Often, only certain one(s) of the teeth
will be repositioned while others of the teeth will provide a base
or an anchor region for holding the appliance 111 in place as the
appliance 111 applies a resilient repositioning force against the
tooth or teeth to be repositioned. In complex cases, however,
multiple teeth may be repositioned at some point during the
treatment. In such cases, the teeth which are moved can also serve
as a base or anchor region for holding the repositioning
appliance.
[0039] The polymeric appliance 111 of FIG. 2C may be formed from a
thin sheet of a suitable elastomeric polymer, such as Tru-Tain 0.03
in, thermal forming dental material, available from Tru-Tain
Plastics, Rochester, Minn. Usually, no wires or other means will be
provided for holding the appliance in place over the teeth. In some
cases, however, it will be desirable or necessary to provide
individual anchors on teeth with corresponding receptacles or
apertures in the appliance 100 so that the appliance can apply an
upward force on the tooth which would not be possible in the
absence of such an anchor.
[0040] FIG. 3 shows a process 200 for producing the incremental
position adjustment appliances for subsequent use by a patient to
reposition the patient's teeth. As a first step, an initial digital
data set (IDDS) representing an initial tooth arrangement is
obtained (step 202).
[0041] In some implementations, the IDDS includes data obtained by
scanning a physical model of the patient's teeth, such as by
scanning a positive impression or a negative impression of the
patient's teeth with a laser scanner or a destructive scanner. The
positive and negative impression may be scanned while interlocked
with each other to provide more accurate data. The initial digital
data set also may include volume image data of the patient's teeth,
which the computer can convert into a 3D geometric model of the
tooth surfaces, for example using a conventional marching cubes
technique. In some embodiments, the individual tooth models include
data representing hidden tooth surfaces, such as roots imaged
through x-ray, CT scan, or MRI techniques. Tooth roots and hidden
surfaces also can be extrapolated from the visible surfaces of the
patient's teeth. The IDDS is then manipulated using a computer
having a suitable graphical user interface (GUI) and software
appropriate for viewing and modifying the images. More specific
aspects of this process will be described in detail below.
[0042] Individual tooth and other components may be segmented or
isolated in the model to permit their individual repositioning or
removal from the digital model. After segmenting or isolating the
components, the user will often reposition the tooth in the model
by following a prescription or other written specification provided
by the treating professional. Alternatively, the user may
reposition one or more teeth based on a visual appearance or based
on rules and algorithms programmed into the computer. Once the user
is satisfied, the final teeth arrangement is incorporated into a
final digital data set (FDDS) (step 204).
[0043] In step 204, final positions for the upper and lower teeth
in a masticatory system of a patient are determined by generating a
computer representation of the masticatory system. An occlusion of
the upper and lower teeth is computed from the computer
representation; and a functional occlusion is computed based on
interactions in the computer representation of the masticatory
system. The occlusion may be determined by generating a set of
ideal models of the teeth. Each ideal model in the set of ideal
models is an abstract model of idealized teeth placement which is
customized to the patient's teeth, as discussed below. After
applying the ideal model to the computer representation, and the
position of the teeth is optimized to fit the ideal model. The
ideal model may be specified by one or more arch forms, or may be
specified using various features associated with the teeth.
[0044] The FDDS is created by following the orthodontists'
prescription to move the teeth in the model to their final
positions. In one embodiment, the prescription is entered into a
computer, which automatically computes the final positions of the
teeth. In alternative other embodiments, a user moves the teeth
into their final positions by independently manipulating one or
more teeth while satisfying the constraints of the prescription.
Various combinations of the above described techniques may also be
used to arrive at the final tooth positions.
[0045] One method for creating the FDDS involves moving the teeth
in a specified sequence. First, the centers of each tooth model may
be aligned using a number of methods. One method is a standard
arch. Then, the teeth models are rotated until their roots are in
the proper vertical position. Next, the teeth models are rotated
around their vertical axis into the proper orientation. The teeth
models are then observed from the side, and translated vertically
into their proper vertical position. Finally, the two arches are
placed together, and the teeth models moved slightly to ensure that
the upper and lower arches properly mesh together. The meshing of
the upper and lower arches together is visualized using a collision
detection process to highlight the contacting points of the
teeth.
[0046] Based on both the IDDS and the FDDS, a plurality of
intermediate digital data sets (INTDDSs) are defined to correspond
to incrementally adjusted appliances (step 206). Finally, a set of
incremental position adjustment appliances are produced based on
the INTDDs and the FDDS (step 208).
[0047] After the teeth and other components have been placed or
removed to produce a model of the final tooth arrangement, it is
necessary to generate a treatment plan which produces a series of
INTDDS's and FDDS as described previously. To produce these data
sets, it is necessary to define or map the movement of selected
individual teeth from the initial position to the final position
over a series of successive steps. In addition, it may be necessary
to add other features to the data sets in order to produce desired
features in the treatment appliances. For example, it may be
desirable to add wax patches to the image in order to define
cavities or recesses for particular purposes, such as to maintain a
space between the appliance and particular regions of the teeth or
jaw in order to reduce soreness of the gums, avoid periodontal
problems, allow for a cap, and the like. Additionally, it will
often be necessary to provide a receptacle or aperture intended to
accommodate an anchor which is to be placed on a tooth in order to
permit the tooth to be manipulated in a manner that requires the
anchor, e.g., to be lifted relative to the jaw.
[0048] In the manner discussed above, information on how the
patient's teeth should move from an initial, untreated state to a
final, treated state is used to generate a prescription, or
treatment plan. The prescription takes into consideration the
following:
[0049] 1. Initial Position: a detailed description of the initial
maloclussion.
[0050] 2. Final Position: a detailed description of treatment goals
for the patient.
[0051] 3. Movement: a detailed, sequential description of how the
patient's teeth should be moved in order to accomplish the desired
goals for final placement.
[0052] 1. Initial Position
[0053] The initial position section describes in detail the
patient's malocclusion. Considerations include:
[0054] Crowding
[0055] Spacing
[0056] Extraction
[0057] Stripping
[0058] Additionally, considerations for the Final Position
discussed below may also be used.
[0059] 2. Final Position
[0060] This section is a detailed description of your final
position objectives and treatment goals--both static and
functional. These considerations include
[0061] Overjet
[0062] Overbite
[0063] Midlines
[0064] Functional Occlusion
[0065] Classification
[0066] Torque
[0067] Tip
[0068] Rotations
[0069] Lingual/Palatal
[0070] Buccal/Facial
[0071] Intercuspation
[0072] Initial Position of the Occlusion--CR/CO Considerations
[0073] Interarch Issues
[0074] Intra-arch Issues
[0075] Space
[0076] 3. Movement
[0077] The movement section specifies an order in moving the
patient's teeth in order to achieve the goals for final placement.
In this process, the orthodontist has precise control over which
teeth the orthodontist wants to move and which teeth to anchor (not
move), thereby breaking the treatment down into discrete stages.
The movement order information is captured for both the upper and
the lower arches.
[0078] At each stage, major and minor tooth movements are analyzed.
Major movements usually occur at the beginning of a tooth's
movement. Minor movements usually occur as "detailing" movements
that occur toward the end of treatment. On average, each aligner
should be able to accomplish move about 0.25-0.33 mm and to rotate
about 5-10 degrees within a 2-week period. However, biologic
variability, patient and clinician preferences are also taken into
consideration. Additionally, various movements such as
distalization, tip, and torque can have separate parameters.
[0079] Based on these considerations, a plan is generated for
moving teeth. FIG. 4 illustrates a process 300 for generating tooth
movements while minimizing teeth indices, as discussed in copending
U.S. application Ser. No. 09/169,034, the content of which is
hereby incorporated by reference. First, the process 300
automatically or, with human assistance, identifies various
features associated with each tooth to arrive at a model of the
teeth (step 302). An ideal model set of teeth is then generated
either from casts of the patient's teeth or from patients with a
known acceptable occlusion (step 303).
[0080] From step 302, the process 300 positions the model of the
teeth in its approximate final position based on a correspondence
of features to the ideal model (step 304). In that step, each tooth
model is moved so that its features are aligned to the features of
a corresponding tooth in the ideal model. The features may be based
on cusps, fossae, ridges, distance-based metrics, or shape-based
metrics. Shape-based metrics may be expressed as a function of the
patient's arches, among others.
[0081] Next, the process 300 computes an orthodontic/occlusion
index (step 306). One index which may be used is the PAR (Peer
Assessment Rating) index. In addition to PAR, other metrics such as
shape-based metrics or distance-based metrics may be used. The PAR
index identifies how far a tooth is from a good occlusion. A score
is assigned to various occlusal traits which make up a
malocclusion. The individual scores are summed to obtain an overall
total, representing the degree a case deviates from normal
alignment and occlusion. Normal occlusion and alignment is defined
as all anatomical contact points being adjacent, with a good
intercuspal mesh between upper and lower buccal teeth, and with
nonexcessive overjet and overbite.
[0082] In PAR, a score of zero would indicate good alignment, and
higher scores would indicate increased levels of irregularity. The
overall score is recorded on pre- and posttreatment dental casts.
The difference between these scores represents the degree of
improvement as a result of orthodontic intervention and active
treatment. The eleven components of the PAR Index are: upper right
segment; upper anterior segment; upper left segment; lower right
segment; lower anterior segment; lower left segment; right buccal
occlusion; overjet; overbite; centerline; and left buccal
occlusion. In addition to the PAR index, other indices may be based
on distances of the features on the tooth from their ideal
positions or ideal shapes.
[0083] From step 306, the process 300 determines whether additional
index-reducing movements are possible (step 308). Here, all
possible movements are attempted, including small movements along
each major axis as well as small movements with minor rotations. An
index value is computed after each small movement and the movement
with the best result is selected. In this context, the best result
is the result that minimizes one or more metrics such as PAR-based
metrics, shape-based metrics or distance-based metrics. The
optimization may use a number of techniques, including simulated
annealing technique, hill climbing technique, best-first technique,
Powell method, and heuristics technique, among others. Simulated
annealing techniques may be used where the index is temporarily
increased so that another path in the search space with a lower
minimum may be found. However, by starting with the teeth in an
almost ideal position, any decrease in the index should converge to
the best result.
[0084] In step 308,if the index can be optimized by moving the
tooth, incremental index-reducing movement inputs are added (step
310) and the process loops back to step 306 to continue computing
the orthodontic/occlusion index. Alternatively, in the event that
the index cannot be further optimized, the process 300 exits (step
312).
[0085] In generating the index reducing movements of step 310, the
process considers a set of movement constraints which affect the
tooth path movement plan. In one embodiment, movement information
for about fifty discrete stages is specified. Each stage represents
a single aligner, which is expected to be replaced about every two
weeks. Thus, each stage represents about a two-week period. In one
embodiment, a two-dimensional array is used to track specific
movements for each tooth at a specific period of time. One
dimension of this array relates to teeth identification, while the
second dimension relates to the time periods or stages.
Considerations on when a tooth may be moved include the
following:
[0086] Mesial
[0087] Distal
[0088] Buccal/Facial
[0089] Lingual/Palatial
[0090] Expansion
[0091] Space
[0092] Teeth moving past each other
[0093] Intrusion
[0094] Extrusion
[0095] Rotations
[0096] Which teeth are moving when?
[0097] Which teeth move first?
[0098] Which teeth need to be moved before others are moved?
[0099] What movements are easily done?
[0100] Anchorage
[0101] The orthodontist user's philosophy on distalization of
molars and minor expansion in adults
[0102] In one embodiment, the user can change the number of desired
treatment stages from the initial to the target states of the
teeth. Any component that is not moved is assumed to remain
stationary, and thus its final position is assumed to be the same
as the initial position (likewise for all intermediate positions,
unless one or more key frames are defined for that component).
[0103] The user may also specify "key frames" by selecting an
intermediate state and making changes to component position(s). In
some embodiments, unless instructed otherwise, the software
automatically linearly interpolates between all user-specified
positions (including the initial position, all key frame positions,
and the target position). For example, if only a final position is
defined for a particular component, each subsequent stage after the
initial stage will simply show the component an equal linear
distance and rotation (specified by a quatemion) closer to the
final position. If the user specifies two key frames for that
component, the component will "move" linearly from the initial
position through different stages to the position defined by the
first key frame. It will then move, possibly in a different
direction, linearly to the position defined by the second key
frame. Finally, it will move, possibly in yet a different
direction, linearly to the target position.
[0104] These operations may be done independently to each
component, so that a key frame for one component will not affect
another component, unless the other component is also moved by the
user in that key frame. One component may accelerate along a curve
between one pair of stages (e.g., stages 3 and 8 in a treatment
plan having that many stages), while another moves linearly between
another pair of stages (e.g., stages 1 to 5), and then changes
direction suddenly and slows down along a linear path to a later
stage (e.g., stage 10). This flexibility allows a great deal of
freedom in planning a patient's treatment.
[0105] In some implementations, non-linear interpolation is used
instead of or in addition to linear interpolation to construct a
treatment path among key frames. In general, a non-linear path,
such as a spline curve, created to fit among selected points is
shorter than a path formed from straight line segments connecting
the points. A "treatment path" describes the transformation curve
applied to a particular tooth to move the tooth from its initial
position to its final position. A typical treatment path includes
some combination of rotational and translational movement of the
corresponding tooth, as described above.
[0106] FIG. 5 shows step 310 in more detail. Initially, a first
tooth is selected (step 311). Next, constraints associated with the
tooth is retrieved for the current stage or period (step 312).
Thus, for the embodiment which keeps a two-dimensional array to
track specific movements for each tooth at a specific period of
time, the tooth identification and the time period or stage
information are used to index into the array to retrieve the
constraints associated with the current tooth.
[0107] Next, a tooth movement plan which takes into consideration
the constraints is generated (step 313). The process of FIG. 5 then
detects whether the planned movements would cause collisions with
neighboring teeth (step 314). The collision detection process
determines if any of the geometries describing the tooth surfaces
intersect. If there are no obstructions, the space is considered
free; otherwise it is obstructed. Suitable collision detection
algorithms are discussed in more detail below.
[0108] If a collision occurs, a "push" vector is created to shift
the path of the planned movement (step 315). Based on the push
vector, the current tooth "bounces" from the collision and a new
tooth movement is generated (step 316). From step 314 or 316, the
movement of the current tooth is finalized.
[0109] Next, the process of FIG. 5 determines whether tooth
movement plans have been generated for all teeth (step 317), and if
so, the process exits. Alternatively, the next tooth in the
treatment plan is selected (318), and the process of FIG. 5 loops
back to step 312 to continue generating tooth movement plans.
[0110] The resulting final path consists of a series of vectors,
each of which represents a group of values of the interpolation
parameters of the translational and rotational components of the
transformations of the moving teeth. Taken together, these
constitute a schedule of tooth movement which avoids tooth-to-tooth
interferences. Pseudo code for generating the tooth path in view of
specified constraints is shown below:
[0111] For each tooth path model
[0112] For each path increment
[0113] Load constrains associated with each tooth
[0114] Move the tooth in view of constraint
[0115] Perform tooth collision detection
[0116] If collision occurs, for associated colliding teeth create
"push" vector and "bounce" back from collision to avoid
collision
[0117] end for
[0118] end tooth path model
[0119] FIG. 6 is a flow chart of a computer-implemented process for
generating non-linear treatment paths along which a patient's teeth
will travel during treatment. The non-linear paths usually are
generated automatically by computer program, in some cases with
human assistance. The program receives as input the initial and
final positions of the patient's teeth and uses this information to
select intermediate positions for each tooth to be moved (step
1600). The program then applies a conventional spline curve
calculation algorithm to create a spline curve connecting each
tooth's initial position to the tooth's final position (step 1602).
In many situations, the curve is constrained to follow the shortest
path between the intermediate positions. The program then samples
each spline curve between the intermediate positions (step 1604)
and applies the collision detection algorithm to the samples (step
1606). If any collisions are detected, the program alters the path
of at least one tooth in each colliding pair by selecting a new
position for one of the intermediate steps (step 1608) and creating
a new spline curve (1602). The program then samples the new path
(1604) and again applies the collision detection algorithm (1606).
The program continues in this manner until no collisions are
detected. The routine then stores the paths, e.g., by saving the
coordinates of each point in the tooth at each position on the path
in an electronic storage device, such as a hard disk (step
1610).
[0120] The path-generating program, whether using linear or
non-linear interpolation, selects the treatment positions so that
the tooth's treatment path has approximately equal lengths between
each adjacent pair of treatment steps. The program also avoids
treatment positions that force portions of a tooth to move with
more than a given maximum velocity. For example, a tooth can be
scheduled to move along a first path T1 from an initial position
T11 to a final position T13 through an intermediate position T12,
which lies closer to the final position T13. Another tooth is
scheduled to move along a shorter path T2 from an initial position
T21 to a final position T23 through an intermediate position T22,
which is equidistant from the initial and final positions T21, T23.
In this situation, the program may choose to insert a second
intermediate position T14 along the first path T1 that is
approximately equidistant from the initial position T11 and the
intermediate position T12 and that is separated from these two
positions by approximately the same distance that separates the
intermediate position T12 from the final position T13. Altering the
first path T1 in this manner ensures that the first tooth will move
in steps of equal size. However, altering the first path T1 also
introduces an additional treatment step having no counterpart in
the second path T2. The program can respond to this situation in a
variety of ways, such as by allowing the second tooth to remain
stationary during the second treatment step (i.e., as the first
tooth moves from one intermediate position T14 to the other
intermediate position T13) or by altering the second path T2 to
include four equidistant treatment positions. The program
determines how to respond by applying a set of orthodontic
constraints that restrict the movement of the teeth.
[0121] Orthodontic constraints that may be applied by the
path-generating program include the minimum and maximum distances
allowed between adjacent teeth at any given time, the maximum
linear or rotational velocity at which a tooth should move, the
maximum distance over which a tooth should move between treatment
steps, the shapes of the teeth, the characteristics of the tissue
and bone surrounding the teeth (e.g., ankylose teeth cannot move at
all), and the characteristics of the aligner material (e.g., the
maximum distance that the aligner can move a given tooth over a
given period of time). For example, the patient's age and jawbone
density may dictate certain "safe limits" beyond which the
patient's teeth should not forced to move. In general, a gap
between two adjacent, relatively vertical and non-tipped central
and lateral teeth should not close by more than about 1 mm every
seven weeks. The material properties of the orthodontic appliance
also limit the amount by which the appliance can move a tooth. For
example, conventional retainer materials usually limit individual
tooth movement to approximately 0.5 mm between treatment steps. The
constraints have default values that apply unless patient-specific
values are calculated or provided by a user. Constraint information
is available from a variety of sources, including text books and
treating clinicians.
[0122] In selecting the intermediate positions for each tooth, the
path-generating program invokes the collision detection program to
determine whether collisions will occur along the chosen paths. The
program also inspects the patient's occlusion at each treatment
step along the path to ensure that the teeth align to form an
acceptable bite throughout the course of treatment. If collisions
or an unacceptable bite will occur, or if a required constraint
cannot be satisfied, the program iteratively alters the offending
tooth path until all conditions are met. The virtual articulator
described above is one tool for testing bite occlusion of the
intermediate treatment positions.
[0123] As shown in FIG. 7, once the path-generating program has
established collision-free paths for each tooth to be moved, the
program calls an optimization routine that attempts to make the
transformation curve for each tooth between the initial and final
positions more linear. The routine begins by sampling each
treatment path at points between treatment steps (step 1702), e.g.,
by placing two sample points between each treatment step, and
calculating for each tooth a more linear treatment path that fits
among the sample points (step 1704). The routine then applies the
collision detection algorithm to determine whether collisions
result from the altered paths (step 1706). If so, the routine
resamples the altered paths (step 1708) and then constructs for
each tooth an alternative path among the samples (step 1710). The
routine continues in this manner until no collisions occur (step
1712).
[0124] In some embodiments, as alluded to above, the software
automatically computes the treatment path, based upon the IDDS and
the FDDS. This is accomplished using a path scheduling algorithm
which determines the rate at which each component, i.e., each
tooth, moves along the path from the initial position to the final
position. The path scheduling algorithm determines the treatment
path while avoiding "round-tripping," i.e., while avoiding moving a
tooth along a distance greater than absolutely necessary to
straighten the teeth. Such motion is highly undesirable, and has
potential negative effects on the patient.
[0125] One implementation of the path scheduling algorithm attempts
first to schedule or stage the movements of the teeth by
constraining each tooth to the most linear treatment path between
the initial and final positions. The algorithm then resorts to less
direct routes to the final positions only if collisions will occur
between teeth along the linear paths or if mandatory constraints
will be violated. The algorithm applies one of the path-generation
processes described above, if necessary, to construct a path for
which the intermediate treatment steps do not lie along a linear
transformation curve between the initial and final positions.
Alternatively, the algorithm schedules treatment paths by drawing
upon a database of preferred treatments for exemplary tooth
arrangements. This database can be constructed over time by
observing various courses of treatment and identifying the
treatment plans that prove most successful with each general class
of initial tooth arrangements. The path scheduling algorithm can
create several alternative paths and present each path graphically
to the user. The algorithm provides as output the path selected by
the user.
[0126] In other implementations, the path scheduling algorithm
utilizes a stochastic search technique to find an unobstructed path
through a configuration space which describes possible treatment
plans. One approach to scheduling motion between two user defined
global key frames is described below. Scheduling over a time
interval which includes intermediate key frames is accomplished by
dividing the time interval into subintervals which do not include
intermediate key frames, scheduling each of these intervals
independently, and then concatenating the resulting schedules.
[0127] A collision or interference detection algorithm employed in
one embodiment is based on the algorithm described in SIGGRAPH
article, Stefan Gottschalk et al. (1996): "OBBTree: A Hierarchical
Structure for Rapid Interference Detection." The contents of the
SIGGRAPH article are herein incorporated by reference.
[0128] The algorithm is centered around a recursive subdivision of
the space occupied by an object, which is organized in a
binary-tree like fashion. Triangles are used to represent the teeth
in the DDS. Each node of the tree is referred to as an oriented
bounding box (OBB) and contains a subset of triangles appearing in
the node's parent. The children of a parent node contain between
them all of the triangle data stored in the parent node.
[0129] The bounding box of a node is oriented so it tightly fits
around all of the triangles in that node. Leaf nodes in the tree
ideally contain a single triangle, but can possibly contain more
than one triangle. Detecting collisions between two objects
involves determining if the OBB trees of the objects intersect. If
the OBBs of the root nodes of the trees overlap, the root's
children are checked for overlap. The algorithm proceeds in a
recursive fashion until the leaf nodes are reached. At this point,
a robust triangle intersection routine is used to determine if the
triangles at the leaves are involved in a collision.
[0130] The collision detection technique described here provides
several enhancements to the collision detection algorithm described
in the SIGGRAPH article. For example, OBB trees can be built in a
lazy fashion to save memory and time. This approach stems from the
observation that some parts of the model will never be involved in
a collision, and consequently the OBB tree for such parts of the
model need not be computed. The OBB trees are expanded by splitting
the internal nodes of the tree as necessary during the recursive
collision determination algorithm.
[0131] Moreover, the triangles in the model which are not required
for collision data may also be specifically excluded from
consideration when building an OBB tree. For instance, motion may
be viewed at two levels. Objects may be conceptualized as "moving"
in a global sense, or they may be conceptualized as "moving"
relative to other objects. The additional information improves the
time taken for the collision detection by avoiding recomputation of
collision information between objects which are at rest relative to
each other since the state of the collision between such objects
does not change.
[0132] FIG. 8 illustrates an alternative collision detection
scheme, one which calculates a "collision buffer" oriented along a
z-axis 1802 along which two teeth 1804, 1806 lie. The collision
buffer is calculated for each treatment step or at each position
along a treatment path for which collision detection is required.
To create the buffer, an x,y plane 1808 is defined between the
teeth 1804, 1806. The plane must be "neutral" with respect to the
two teeth. Ideally, the neutral plane is positioned so that it does
not intersect either tooth. If intersection with one or both teeth
is inevitable, the neutral plane is oriented such that the teeth
lie, as much as possible, on opposite sides of the plane. In other
words, the neutral plane minimizes the amount of each tooth's
surface area that lies on the same side of the plane as the other
tooth.
[0133] In the plane 1808 is a grid of discrete points, the
resolution of which depends upon the required resolution for the
collision detection routine. A typical high-resolution collision
buffer includes a 400.times.400 grid; a typical low-resolution
buffer includes a 20.times.20 grid. The z-axis 1802 is defined by a
line normal to the plane 1808.
[0134] The relative positions of the teeth 1804, 1806 are
determined by calculating, for each of the points in the grid, the
linear distance parallel to the z-axis 1802 between the plane 1808
and the nearest surface of each tooth 1804, 1806. For example, at
any given grid point (M,N), the plane 1808 and the nearest surface
of the rear tooth 1804 are separated by a distance represented by
the value Z1(M,N), while the plane 1808 and the nearest surface of
the front tooth 1806 are separated by a distance represented by the
value Z2(M,N). If the collision buffer is defined such that the
plane 1808 lies at z=0 and positive values of z lie toward the back
tooth 1804, then the teeth 1804, 1806 collide when
Z1(M,N).quadrature.Z2(M,N) at any grid point (M,N) on the plane
1808.
[0135] FIG. 9 is a flow chart of a collision detection routine
implementing this collision buffer scheme. The routine first
receives data from one of the digital data sets indicating the
positions of the surfaces of the teeth to be tested (step 1900).
The routine then defines the neutral x,y-plane (step 1902) and
creates the z-axis normal to the plane (step 1904).
[0136] The routine then determines for the x,y-position of the
first grid point on the plane the linear distance in the
z-direction between the plane and the nearest surface of each tooth
(step 1906). To detect a collision at that x,y-position, the
routine determines whether the z-position of the nearest surface of
the rear tooth is less than or equal to the z-position of the
nearest surface of the front tooth (step 1908). If so, the routine
creates an error message, for display to a user or for feedback to
the path-generating program, indicating that a collision will occur
(step 1910). The routine then determines whether it has tested all
x,y-positions associated with grid points on the plane (step 1912)
and, if not, repeats the steps above for each remaining grid point.
The collision detection routine is performed for each pair of
adjacent teeth in the patient's mouth at each treatment step.
[0137] The system may also incorporate and the user may at any
point use a "movie" feature to show an animation of the movement
from initial to target states. This is helpful for visualizing
overall component movement throughout the treatment process.
[0138] As described above, one suitable user interface for
component identification is a three dimensional interactive
graphical user interface (GUI). A three-dimensional GUI is also
advantageous for component manipulation. Such an interface provides
the treating professional or user with instant and visual
interaction with the digital model components. The
three-dimensional GUI provides advantages over interfaces that
permit only simple low-level commands for directing the computer to
manipulate a particular segment. In other words, a GUI adapted for
manipulation is better in many ways than an interface that accepts
directives, for example, only of the sort: "translate this
component by 0.1 mm to the right." Such low-level commands are
useful for fine-tuning, but, if they were the sole interface, the
processes of component manipulation would become a tiresome and
time-consuming interaction.
[0139] Before or during the manipulation process, one or more tooth
components may be augmented with template models of tooth roots.
Manipulation of a tooth model augmented with a root template is
useful, for example, in situations where impacting of teeth below
the gumline is a concern. These template models could, for example,
comprise a digitized representation of the patient's teeth
x-rays.
[0140] The software also allows for adding annotations to the data
sets which can comprise text and/or the sequence number of the
apparatus. The annotation is added as recessed text (i.e., it is
3-D geometry), so that it will appear on the printed positive
model. If the annotation can be placed on a part of the mouth that
will be covered by a repositioning appliance, but is unimportant
for the tooth motion, the annotation may appear on the delivered
repositioning appliance(s).
[0141] The above-described component identification and component
manipulation software is designed to operate at a sophistication
commensurate with the operator's training level. For example, the
component manipulation software can assist a computer operator,
lacking orthodontic training, by providing feedback regarding
permissible and forbidden manipulations of the teeth. On the other
hand, an orthodontist, having greater skill in intraoral physiology
and teeth-moving dynamics, can simply use the component
identification and manipulation software as a tool and disable or
otherwise ignore the advice.
[0142] FIG. 10 is a simplified block diagram of a data processing
system 500. Data processing system 500 typically includes at least
one processor 502 which communicates with a number of peripheral
devices over bus subsystem 504. These peripheral devices typically
include a storage subsystem 506 (memory subsystem 508 and file
storage subsystem 514), a set of user interface input and output
devices 518, and an interface to outside networks 516, including
the public switched telephone network. This interface is shown
schematically as "Modems and Network Interface" block 516, and is
coupled to corresponding interface devices in other data processing
systems over communication network interface 524. Data processing
system 500 may include a terminal or a low-end personal computer or
a high-end personal computer, workstation or mainframe.
[0143] The user interface input devices typically include a
keyboard and may further include a pointing device and a scanner.
The pointing device may be an indirect pointing device such as a
mouse, trackball, touchpad, or graphics tablet, or a direct
pointing device such as a touchscreen incorporated into the
display. Other types of user interface input devices, such as voice
recognition systems, may be used.
[0144] User interface output devices may include a printer and a
display subsystem, which includes a display controller and a
display device coupled to the controller. The display device may be
a cathode ray tube (CRT), a flat-panel device such as a liquid
crystal display (LCD), or a projection device. The display
subsystem may also provide nonvisual display such as audio
output.
[0145] Storage subsystem 506 maintains the basic programming and
data constructs that provide the functionality of the present
invention. The software modules discussed above are typically
stored in storage subsystem 506. Storage subsystem 506 typically
comprises memory subsystem 508 and file storage subsystem 514.
[0146] Memory subsystem 508 typically includes a number of memories
including a main random access memory (RAM) 510 for storage of
instructions and data during program execution and a read only
memory (ROM) 512 in which fixed instructions are stored. In the
case of Macintosh-compatible personal computers the ROM would
include portions of the operating system; in the case of
IBM-compatible personal computers, this would include the BIOS
(basic input/output system).
[0147] File storage subsystem 514 provides persistent (nonvolatile)
storage for program and data files, and typically includes at least
one hard disk drive and at least one floppy disk drive (with
associated removable media). There may also be other devices such
as a CD-ROM drive and optical drives (all with their associated
removable media). Additionally, the system may include drives of
the type with removable media cartridges. The removable media
cartridges may, for example be hard disk cartridges, such as those
marketed by Syquest and others, and flexible disk cartridges, such
as those marketed by Iomega. One or more of the drives may be
located at a remote location, such as in a server on a local area
network or at a site on the Internet's World Wide Web.
[0148] In this context, the term "bus subsystem" is used
generically so as to include any mechanism for letting the various
components and subsystems communicate with each other as intended.
With the exception of the input devices and the display, the other
components need not be at the same physical location. Thus, for
example, portions of the file storage system could be connected
over various local-area or wide-area network media, including
telephone lines. Similarly, the input devices and display need not
be at the same location as the processor, although it is
anticipated that the present invention will most often be
implemented in the context of PCS and workstations.
[0149] Bus subsystem 504 is shown schematically as a single bus,
but a typical system has a number of buses such as a local bus and
one or more expansion buses (e.g., ADB, SCSI, ISA, EISA, MCA,
NuBus, or PCI), as well as serial and parallel ports. Network
connections are usually established through a device such as a
network adapter on one of these expansion buses or a modem on a
serial port. The client computer may be a desktop system or a
portable system.
[0150] Scanner 520 is responsible for scanning casts of the
patient's teeth obtained either from the patient or from an
orthodontist and providing the scanned digital data set information
to data processing system 500 for further processing. In a
distributed environment, scanner 520 may be located at a remote
location and communicate scanned digital data set information to
data processing system 500 over network interface 524.
[0151] Fabrication machine 522 fabricates dental appliances based
on intermediate and final data set information received from data
processing system 500. In a distributed environment, fabrication
machine 522 may be located at a remote location and receive data
set information from data processing system 500 over network
interface 524.
[0152] The system of FIG. 10 can generate a series of appliances as
defined by a treatment plan. The treatment plan can be specified by
a treating professional such as a dentist or an orthodontist, among
others. FIGS. 11-16 illustrate exemplary treatment specifications
using a tooth movement planning system. FIG. 11 shows an exemplary
set of fourteen teeth numbered 601, 602, 604, 606, 608, 610, 612,
614, 616, 618, 620, 622, 624 and 625. In the example of FIG. 11,
teeth 601, 602, 604 need to move or expand toward the left side of
the diagram, while teeth 606, 608, 610 and 612 need a curvilinear
expansion movement toward the left also. Correspondingly, teeth
614, 616 and 618 need to moved to the right side of the diagram in
a curvilinear expansion, and teeth 618, 620, 622, 624 and 625 need
to be moved to the right. The end result of the prescription
exemplified in FIG. 11 is that teeth are moved in an expansion
pattern.
[0153] Turning now to FIG. 12, a diagrammatic illustration of the
movement of FIG. 11 as specified on a two-dimensional array is
shown. In FIG. 12, the top row identifies the tooth identification,
while the left column number shows the stage sequence for each
tooth. In this case, each stage takes approximately two weeks,
although the duration can be increased or decreased. In the example
of FIG. 12, the tooth 601 is moved between stages 1-10. Similarly,
teeth 602, 604, 606 are moved between stages 1-10. In stages 10-20,
tooth 608 is moved. Further, in stages 20-30, teeth 610-616 are
moved. Tooth 618 is moved between stages 10-20. Also, teeth 620,
622, 624 and 625 are moved in stages 1-10. The net result as
specified by the two-dimensional array is an expansion movement
pattern.
[0154] Although FIGS. 13-16 show an exemplary expansion movement
pattern, other patterns can be specified using the two-dimensional
array as well. These patterns can be incorporated into a library of
movements. For a given initial position of patient teeth and a
final corrected position, the system generates in-between stages by
finding the stage positions of each tooth in accordance with a
selected movement. FIGS. 13-16 show exemplary movement patterns,
namely an X-type movement, an A-type movement, a V-type movement,
and an XX-type movement, among others. These exemplary movement
patterns will be discussed next.
[0155] An exemplary X-type movement is shown in FIG. 13. The X-type
movement is also known as an `All Equal Movement`. In this
movement, all teeth in a given group are moving at the same time.
The tooth path is determined by dividing a starting frame
containing the teeth into half frames and recursively determines
intermediate paths in each half. The recursion stops when the
moving distance in each frame meets a given criterion. Once the
movements are done, the system adjusts teeth movements so that each
frame does not exceed one or more distance constraints.
[0156] Next, the A-type movement is discussed. In this type of
movement, the anterior tooth moves first, followed by the posterior
teeth. The movement looks like an A character as the front tooth is
moving ahead of the next tooth. In each tooth, the next tooth
starts to move when the current tooth reaches midway to the current
tooth's goal position. The diagram of the A type movement is shown
in FIG. 14.
[0157] The V-type movement is shown in FIG. 15. Conceptually, the V
type movement is reverse of A type movement: the rear teeth move
first then the next front teeth follow. In one implementation, a
reverse A movement is done for posterior teeth, while the anterior
teeth go through an X type movement.
[0158] FIG. 16 shows an XX type movement, which involves two all
equal movement. Posterior teeth go through an all equal movement
(X-type) first and the anterior teeth go through the all equal
movement.
[0159] Various alternatives, modifications, and equivalents may be
used in lieu of the above components. Although the final position
of the teeth may be determined using computer-aided techniques, a
user may move the teeth into their final positions by independently
manipulating one or more teeth while satisfying the constraints of
the prescription.
[0160] Additionally, the techniques described here may be
implemented in hardware or software, or a combination of the two.
The techniques may be implemented in computer programs executing on
programmable computers that each includes a processor, a storage
medium readable by the processor (including volatile and
nonvolatile memory and/or storage elements), and suitable input and
output devices. Program code is applied to data entered using an
input device to perform the functions described and to generate
output information. The output information is applied to one or
more output devices.
[0161] Each program can be implemented in a high level procedural
or object-oriented programming language to operate in conjunction
with a computer system. However, the programs can be implemented in
assembly or machine language, if desired. In any case, the language
may be a compiled or interpreted language.
[0162] Each such computer program can be stored on a storage medium
or device (e.g., CD-ROM, hard disk or magnetic diskette) that is
readable by a general or special purpose programmable computer for
configuring and operating the computer when the storage medium or
device is read by the computer to perform the procedures described.
The system also may be implemented as a computer-readable storage
medium, configured with a computer program, where the storage
medium so configured causes a computer to operate in a specific and
predefined manner.
[0163] The invention has been described in terms of particular
embodiments. Other embodiments are within the scope of the
following claims. For example, the three-dimensional scanning
techniques described above may be used to analyze material
characteristics, such as shrinkage and expansion, of the materials
that form the tooth castings and the aligners. Also, the 3D tooth
models and the graphical interface described above may be used to
assist clinicians that treat patients with conventional braces or
other conventional orthodontic appliances, in which case the
constraints applied to tooth movement would be modified
accordingly. Moreover, the tooth models may be posted on a
hypertext transfer protocol (http) web site for limited access by
the corresponding patients and treating clinicians.
[0164] Further, while the invention has been shown and described
with reference to an embodiment thereof, those skilled in the art
will understand that the above and other changes in form and detail
may be made without departing from the spirit and scope of the
following claims.
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