U.S. patent application number 11/881528 was filed with the patent office on 2009-01-29 for orthodontic force measurement system.
Invention is credited to Heng Cao.
Application Number | 20090030347 11/881528 |
Document ID | / |
Family ID | 40275322 |
Filed Date | 2009-01-29 |
United States Patent
Application |
20090030347 |
Kind Code |
A1 |
Cao; Heng |
January 29, 2009 |
ORTHODONTIC FORCE MEASUREMENT SYSTEM
Abstract
A method for concurrently measuring a force exerted upon each of
a plurality of teeth is disclosed. A dentition crown connecting rod
associated with a force gauge is positioned such that a dentition
crown coupled to the dentition crown connecting rod may be received
within a corresponding cavity of a reference aligner. A measurement
aligner is then applied to the dentition crown, wherein the
dentition crown is positioned to be received within a corresponding
cavity of a reference aligner. A force exerted on the dentition
crown by the measurement aligner is then calculated.
Inventors: |
Cao; Heng; (Santa Clara,
CA) |
Correspondence
Address: |
ALIGN TECHNOLOGY C/O WAGNER BLECHER LLP
123 WESTRIDGE DRIVE
WATSONVILLE
CA
95076
US
|
Family ID: |
40275322 |
Appl. No.: |
11/881528 |
Filed: |
July 27, 2007 |
Current U.S.
Class: |
600/590 ; 433/18;
433/24 |
Current CPC
Class: |
A61C 19/04 20130101;
G01L 5/1627 20200101; A61C 7/00 20130101 |
Class at
Publication: |
600/590 ; 433/18;
433/24 |
International
Class: |
A61B 5/103 20060101
A61B005/103; A61C 3/00 20060101 A61C003/00 |
Claims
1. A force gauge comprising: a frame coupled to a first end of a
plurality of beams, wherein said frame is configured to provide a
stable body to which said first end of each of said plurality of
beams is coupled; and a fixture coupled to a second end of said
plurality of beams, wherein said fixture is configured to receive a
dentition crown connecting rod, each of said plurality of beams
configured to have at least one strain gauge coupled thereto, said
at least one strain gauge configured to sense a force exerted upon
a dentition crown when said dentition crown is coupled to said
dentition crown connecting rod.
2. The force gauge of claim 1, wherein said force is measured by
six components representing the tilt and rotation of an X, Y, and Z
axis.
3. The force gauge of claim 1, wherein said plurality of beams is
three beams such that said frame is coupled to a first end of each
of said three beams and said fixture is coupled to a second end of
said each of said three beams.
4. The force gauge of claim 1, wherein said frame further
comprises: a width less than a length of said frame, and said width
less than a height of said frame.
5. The force gauge of claim 1, wherein any dimension of said each
of said plurality of beams is less than a corresponding dimension
of said frame.
6. The force gauge of claim 1, wherein said plurality of beams are
within a size box of said frame.
7. The force gauge of claim 1, wherein said fixture further
comprises: a width that is not greater than a width of a dentition
crown associated with said fixture; a fixture hole configured to
receive an associated dentition crown connecting rod and a screw
such that a fixture gap may be reduced by tightening a clamp.
8. The force gauge of claim 1, wherein said dentition crown
connecting rod is vertical, and said dentition crown connecting rod
is perpendicular to a horizontal plane of a top surface of a
platform, wherein said platform is configured to stabilize said
frame of said force gauge.
9. The thin frame force gauge of claim 1, wherein said dentition
crown connecting rod further comprises: a stopper configured to
limit downward movement and to maintain a position of a dentition
crown such that said dentition crown is located in said position
corresponding to a position of an original digital model of said
dentition crown within a jaw.
10. A force measurement system for concurrently measuring a force
exerted upon each of a plurality of teeth, said system comprising:
a plurality of dentition crown connecting rods operatively coupled
to a dental appliance; a plurality of force gauges, wherein each of
said plurality of force gauges is coupled to a plurality of strain
gauges, each of said plurality of strain gauges configured to sense
a force exerted on each of a plurality of dentition crowns by said
dental appliance; a force determiner coupled to said each of said
plurality of strain gauges, wherein said force determiner is
configured to calculate said force exerted on said each of said
plurality of dentition crowns by said dental appliance; and a
platform coupled to said each of said plurality of force gauges,
wherein said platform is configured to stabilize a frame of said
each of said plurality of force gauges.
11. The force measurement system of claim 10, wherein said force is
measured by six components representing the tilt and rotation of an
X, Y, and Z axis.
12. The force measurement system of claim 10, wherein said
plurality of dentition crowns represent an entire set of dentition
crowns within a jaw such that the force exerted on each of said
entire set of dentition crowns within a jaw is concurrently
measured.
13. The force measurement system as recited in claim 10, wherein
each of said plurality of force gauges further comprises: a frame
coupled to a first end of a plurality of beams, wherein said frame
is configured to provide a stable body to which said first end of a
plurality of beams is coupled.
14. The force measurement system as recited in claim 13, wherein
said plurality of beams is three beams such that said frame is
coupled to a first end of each of said three beams and a fixture is
coupled to a second end of said each of said three beams.
15. The force measurement system as recited in claim 10, wherein
said plurality of strain gauges is coupled to each of a plurality
of beams.
16. The force measurement system as recited in claim 10, wherein
each of said plurality of force gauges further comprises: a fixture
coupled to one of said plurality of dentition crown connecting
rods, and said fixture coupled to a second end of a plurality of
beams, wherein said fixture is configured to receive said one of
said plurality of dentition crown connecting rods.
17. The force measurement system as recited in claim 16, wherein
said fixture further comprises: a width that is not greater than a
width of a dentition crown associated with said fixture; and a
fixture hole configured to receive an associated dentition crown
connecting rod and a screw such that a fixture gap may be reduced
by tightening a clamp.
18. The force measurement system as recited in claim 10, wherein
said each of said plurality of dentition crown connecting rods
further comprises: a stopper configured to limit downward movement
and to maintain a position of a dentition crown such that said
dentition crown is located in said position corresponding to a
position of an original digital model of said dentition crown
within a jaw.
19. The force measurement system as recited in claim 10, wherein
said platform is a magnetic table.
20. A method for concurrently measuring a force exerted upon each
of a plurality of teeth, said method comprising: positioning a
dentition crown connecting rod associated with a force gauge such
that a dentition crown coupled to said dentition crown connecting
rod may be received within a corresponding cavity of a reference
aligner; applying a measurement aligner to said dentition crown,
wherein said dentition crown is positioned to be said received
within a corresponding cavity of a reference aligner; and
calculating a force exerted on said dentition crown by said
measurement aligner.
21. The method of claim 20, wherein said dentition crown connecting
rod is a plurality of dentition crown connecting rods.
22. The method of claim 21, wherein said plurality of dentition
crowns represent an entire set of dentition crowns within a jaw
such that the force exerted on each of said entire set of dentition
crowns within a jaw is concurrently measured.
23. The method of claim 20, wherein said positioning a dentition
crown connecting rod associated with said force gauge such that a
dentition crown coupled to said dentition crown connecting rod may
be received within a corresponding cavity of a reference aligner
further comprises: calculating said force exerted upon said
dentition crown by said reference aligner, wherein said calculated
force is shown on a monitor in real time; adjusting a position of
said dentition crown connecting rod until said calculated force
exerted upon said dentition crown reaches a tolerance of
approximately zero; and in response to said calculated force
exerted upon said dentition crown reaching said tolerance of
approximately zero, locking said dentition crown connecting rod
into fixture.
24. The method of claim 20, wherein said applying a measurement
aligner to said dentition crown, wherein said dentition crown of
said dentition crown is positioned to be said received within a
corresponding cavity of a reference aligner further comprises:
utilizing a measurement aligner, wherein said measurement aligner
represents a position of each said dentition crown incorporating
targeted orthodontic movement.
25. The method of claim 20, wherein said calculating a force
exerted on said dentition crown by said measurement aligner further
comprises: sensing a strain on two adjacent surfaces of each beam
of said force gauge by a strain gauge; recording voltage output;
transferring said recorded voltage output to a force determiner;
utilizing by said force determiner said recorded voltage output to
calculate said force exerted on said dentition crown by said
measurement aligner.
26. The method of claim 20, further comprising: transforming said
calculated force to a tooth coordinate system, wherein said tooth
coordinate system is defined based on a geometry of said dentition
crown.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to the field of
orthodontics.
BACKGROUND OF THE INVENTION
[0002] Orthodontic treatments involve repositioning misaligned
teeth and improving bite configurations for improved cosmetic
appearance and dental function. Repositioning is typically
accomplished by a dentist or orthodontist (hereinafter
practitioner) applying gentle forces by a dental appliance (e.g.,
braces or positioning appliances) to a patient's teeth over an
extended period of time. Due to the limited space within the oral
cavity and extensive movements that some teeth must undergo, the
teeth will often be moved throughout a series of intermediate
patterns to properly arrange the teeth.
[0003] Braces comprise a variety of appliances such as brackets,
bands, archwires, ligatures, and O-rings. After the brackets are
bonded to the teeth, periodic meetings with the treating
practitioner are required to allow them to reactively adjust the
braces. This generally involves installing different archwires
having different force-inducing properties, and/or replacing or
tightening existing ligatures.
[0004] In contrast, positioning appliances or aligners are
comprised of a thin shell of material that generally conforms to a
patient's teeth but each appliance provides a teeth receiving
cavity geometry that is slightly out of alignment with the initial
tooth configuration. Placement of the aligner over the teeth
applies controlled forces in specific locations to gradually move
the teeth into a new configuration of a predetermined treatment
plan. Repetition of this process with successive aligners, each
providing a new unique teeth receiving cavity, eventually moves the
teeth through a series of intermediate arrangements to a final
desired arrangement in accordance with the predetermined treatment
plan.
[0005] The force that will be generated by braces or an aligner
system to teeth can be calculated by finite element analysis
modeling. Currently, the systems that exist for obtaining such
measurements suffer from issues of inaccuracy and their ability to
look at multiple teeth and their movements relative to each other.
Thus, it takes much time and effort to obtain a force measurement
for multiple teeth within the jaw structure, and any result can
rarely be replicated.
SUMMARY
[0006] A method for concurrently measuring a force exerted upon
each of a plurality of teeth is disclosed. A dentition crown
connecting rod associated with a force gauge is positioned such
that a dentition crown coupled to the dentition crown connecting
rod may be received within a corresponding cavity of a reference
aligner. A measurement aligner is then applied to the dentition
crown, wherein the dentition crown is positioned to be received
within a corresponding cavity of a reference aligner. A force
exerted on the dentition crown by the measurement aligner is then
calculated.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a perspective view of a force gauge coupled to a
force determiner, according to one embodiment.
[0008] FIG. 2 is a perspective view of a force gauge coupled to a
dentition crown connecting rod, according to one embodiment.
[0009] FIG. 3 is a top perspective view of a plurality of force
gauges, each force gauge coupled to a dentition crown connecting
rod, according to one embodiment.
[0010] FIG. 4 is a flow diagram of an example method for
concurrently measuring a force exerted upon each of a plurality of
teeth by a dental appliance, according to one embodiment.
[0011] FIG. 5 is a representation of the force gauge coordinate
system, with forces x, y, z, a, b, and c, caused by the pulling,
compressing and/twisting of beams, whose origin can be fixed at a
certain point in three dimensional space.
[0012] The drawings referred to in this description should not be
understood as being drawn to scale unless specifically noted.
DETAILED DESCRIPTION OF THE INVENTION
[0013] Before the present force gauge tool, force measurement
systems and methods are described, it is to be understood that this
invention is not limited to particular tools, systems and methods
specifically described, as such may, of course, vary. It is also to
be understood that the terminology used herein is for the purpose
of describing particular embodiments only, and is not intended to
be limiting, since the scope of the present invention will be
limited only by the appended claims.
[0014] Unless defined otherwise, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which this invention belongs. Although
any methods and materials similar or equivalent to those described
herein can be used in the practice or testing of the present
invention, some potential and preferred methods and materials are
now described.
[0015] It must be noted that as used herein and in the appended
claims, the singular forms "a", "an", and "the" include plural
referents unless the context clearly dictates otherwise. Thus, for
example, reference to "a tooth" includes a plurality of such teeth,
and reference to "the appliance" includes reference to one or more
appliances and equivalents thereof known to those skilled in the
art, and so forth.
[0016] While specific reference may be made to a user, patient,
practitioner, or other person using the disclosed tools and
systems, and practicing the disclosed methods, it is to be
understood that such terms are meant to be inclusive of all such
users, unless the context clearly dictates otherwise.
[0017] The discussion will begin with an overview of the general
process of measuring a force exerted upon an individual tooth, and
the limitations of this process. The discussion will then focus on
embodiments of the present technology that provide a force gauge
for measuring a force exerted upon a tooth, and that provide a
force measurement system for concurrently measuring a force exerted
upon each of a plurality of teeth. The discussion will then focus
on the method for concurrently measuring a force exerted upon each
of a plurality of teeth.
Overview
[0018] An aligner may be placed on the tooth crown so as to
reposition misaligned teeth. This aligner delivers a force to the
tooth crown in order to move the tooth to the intended position. A
certain amount of force is necessary to move this tooth to its
intended position.
[0019] Due to the varied size, shape and narrow spacing around each
tooth, off-the-shelf force gauges are incapable of being fit into
an arrangement to concurrently measure the in vitro force on each
tooth in a jaw.
[0020] Embodiments of the present technology provide a method for
concurrently measuring how much force a dental appliance (e.g.,
braces or aligner) exerts upon each of a plurality of teeth. For
example, a model of a tooth is coupled via a dentition crown
connecting rod to a three dimensional force gauge. An aligner is
then placed over this tooth model. The force exerted upon the tooth
model by the aligner may then be measured by six components of
force (x, y, z, a, b, and c, wherein a, b, and c represent the
rotation about the X, Y, and Z axis respectively).
[0021] By calculating the force exerted upon a tooth by a dental
appliance (e.g. aligner, braces) using the disclosed force gauge,
it is possible to concurrently determine the force exerted upon
each of a plurality of teeth. In this manner, a dental appliance
may be tested to determine if it satisfactorily performs its
intended function of re-aligning teeth to a predetermined position.
Additionally, new products and new materials for re-aligning teeth
may be efficiently tested.
Structure
[0022] With reference now to FIG. 1, a perspective view of a force
gauge 100 is shown. In this embodiment, force gauge 100 comprises
frame 105, beams 110, 115, and 120, fixture 125, and fixture hole
130. Additionally, beams 110, 115, and 120 are configured to have
at least one of strain gauges 135, 140, and 145 coupled thereto.
Furthermore, FIG. 100 shows strain gauges 135, 140, and 145 coupled
to force determiner 150.
[0023] The above assembled components enable force gauge 100 to
sense a force exerted upon a dentition crown by a dental appliance.
For example, a three dimensional model of a tooth is made. This
`dentition crown` (model of a tooth) is coupled to a dentition
crown connecting rod. The dentition crown connecting rod is coupled
to fixture 125 when inserted into fixture hole 130 and locked into
place at a starting or original position. An aligner is then placed
over the dentition crown to apply a force to the dentition crown
locked into the starting position. The force applied to the
dentition crown travels from the dentition crown to the dentition
crown connecting rod, and then to fixture 125. This force is then
transferred from fixture 125 beam 110, beam 115, and beam 120.
[0024] Beams 110, 115, and 120 realize a force causing deformation
in the x, y, and z direction, as well as a rotational force
(torque) causing deformation in the a, b, and c direction (wherein
a, b, and c are rotational forces about the x, y, and z axes,
respectively). Sensing this deformation, strain gauges 135, 140,
and 145 output a respective voltage to force determiner 150. The
voltage output is then recorded, measured, and converted to force
measurements by force determiner 150. Consequently, in one
embodiment, force gauge 100, as will be described in greater detail
in the Operation section herein, enables the measurement of force
as exerted by an aligner onto a dentition crown in the x, y, z, a,
b, and c direction.
[0025] Referring now to FIG. 5, a representation of a force gauge
coordinate system of x, y, and z is shown, whose origin can be
fixed at a certain point in three dimensional space. The origin of
this force gauge coordinate system is located at the intersection
point of beams 110, 115, and 120. Beams 110, 115, and 120 are
pulled, compressed and/or torqued in response to a dental appliance
being applied to dentition crown 220. Strain gauges 135, 140, and
145, attached to beams 110, 115, and 120 respectively, sense the
strain put upon beams 110, 115, and 120, and each output voltage to
force determiner 150 proportional to the deformation of the area to
which it is attached.
[0026] Frame 105 is configured to provide a stable body to which
the first end of beam 110, beam 115, and beam 120 is coupled.
Additionally, the body of frame 105 may be of an elastic nature,
such that frame 105 remains a stable body for the first end of beam
110, beam 115, and beam 120, but may provide enough flexibility to
allow for in vitro positioning of force gauge 100.
[0027] With reference now to FIG. 2, the force gauge 100 of FIG. 1
is shown for sensing a force exerted upon dentition crown 220.
Fixture 125 is configured to receive dentition crown connecting rod
225 which is coupled to dentition crown 220. Although FIGS. 1 and 2
show force gauge 100 with a plurality of strain gauges 135, 140,
and 145 coupled to beams 110, 115, and 120 respectively, it is
appreciated that force gauge 100 may have at least one strain gauge
coupled to each of beams 110, 115, and 120. Each of the plurality
of strain gauges 135, 140, and 145 are configured to sense a force
exerted upon the respective beams to which they are coupled. This
force was transferred from dentition crown 220 to dentition crown
connecting rod 225 to fixture 125, to strain gauges 134, 140, and
145. Consequently, each of plurality of strain gauges 135, 140, and
145 are configured to sense a force exerted by a dental appliance
upon dentition crown 220.
[0028] FIGS. 1 and 2 display frame 105 as being in a U-shape.
However, it is appreciated that frame 105 may be in any shape to
which the first end of three beams 110, 115, and 120 may be coupled
to frame 105 as well as to fixture 125. Additionally, the three
beams must also be configured so as to have a plurality of strain
gauges 135, 140, and 145 coupled thereto such that a force exerted
upon dentition crown 220 may be sensed. Moreover, the base of frame
105 may partially or wholly be comprised of a type of material
which has an attraction to a magnetic table, such as iron or
stainless steel.
[0029] In an example of the present technology, dentition crown 220
is a three dimensional object, such as a model of a tooth crown,
representing any number of sources. For example, dentition crown
220 may be a model of a patient's tooth crown (based upon a digital
model), or may be a model of an ideal tooth crown within an
arrangement of a plurality of ideal tooth crowns. In this instance,
the term `ideal` refers to a pre-determined desired position for a
generic set of teeth. Dentition crown 220 and dentition crown
connecting rod 225 are coupled to each other so that both objects
are a single body, for force measurement purposes.
[0030] Dentition crown 220 and dentition crown connecting rod 225
can be two parts formed using different techniques and then jointed
together. In one example, a ceramic dentition crown 220 may be
bonded by glue to a stainless steel dentition crown connecting rod
225. The bonding may be removed by removing the glue material. In
another example, a stainless steel dentition crown 220 may be
welded to a stainless steel dentition crown connecting rod 225. In
order to separate these parts, machining off the welding may be
necessary.
[0031] Strain gauges 135, 140, and 145 may be made out of silicon
or any other material which would allow for sensing a force exerted
upon dentition crown 220. Moreover, strain gauges 135, 140, and 145
may be one of any number of shapes, simple or complex, including
but not limited to: rectangular, square, round, oval or some
variation thereof. Strain gauges 135, 140, and 145 may be shear
strain gauges configured to consider the angular distortion of an
object, such as a beam, under stress. An example of gauges 135,
140, and 145 suitable for use in the present technology are sold
under the trademark ESB-020.TM., and are available for purchase
from companies such as Measurement Specialties, located at 1000
Lucas Way, Hampton, Va. 23666. Additionally, strain gauges 135,
140, and 145 are attached to beams 110, 115, and 120 and coupled to
force determiner 150, respectively, in any manner recognized in the
state of the art of applying and using strain gauges.
[0032] Force determiner 150 may be comprised of any number of
devices configured to calculate a force exerted upon dentition
crown 220.
[0033] Referring again to the embodiment of FIG. 2, frame 105 has
width 205 which is less than length 215, and width 205 which is
less than height 210. This configuration enables frame 105 to be
placed in close proximity with other frames 105, while still
permitting a force to be sensed by strain gauges 135, 140, and 145.
For example, if width 205 is greater than length 215, then length
would have to be very small in order to couple a plurality of
frames 105 to a model of a set of teeth. If the length of frame 105
was small enough to allow each of a plurality of force gauges 100
with widths 205 greater than lengths 215 to be coupled to each of a
plurality of adjacent dentition crown connecting rods 225, then
there would not be enough space within the size box of frame 105
(description of size box to follow herein) to accommodate beams
110, 115, and 120 as well as strain gauges 135, 140, and 145.
Hence, by limiting the dimensions of width 205 to be less than
length 215 and height 210, force gauge 100 is enabled to be coupled
to each of a plurality of dentition crown connecting rods 225 and
to have beams 110, 115, and 120 configured to be coupled to strain
gauges 135, 140, and 145.
[0034] In another embodiment, any dimension of each of the three
beams 110, 115, and 120, is less than a corresponding dimension of
frame 105 so that beams 110, 115, and 120 together fit within frame
105 according to force gauge's 100 disclosed configuration. For
example, the length of beam 110 is less than length 215 of frame
105. The width of beam 115 is less than width 205 of frame 105. The
height of beam 120 is less the height 210 of frame 105. This
configuration enables beams 110, 115, and 120 to have a deformation
to be sensed by strain gauges 135, 140, and 145.
[0035] In an example of the present technology, the combination of
all three beams 110, 115, and 120, are within a size box of frame
105. For example, FIG. 1 displays frame 105 as being in a U-shape,
with a left side as well as a top and bottom of what could be a
rectangular box if a right side were added. A size box of frame 105
would be the result of having closed off the open portion of
frame's 105 U-shape. For instance, suppose that an imaginary line
was drawn from the outside open edge of the top portion of frame
105 to the outside open edge of the bottom portion of frame 105.
The resulting shape, including the side, top, bottom, and imaginary
line portion, creates a size box. Beam 110, beam 115, and beam 120
lie fully within this size box.
[0036] In yet another embodiment, fixture 125 has a width that is
not greater than a width of dentition crown 220 associated with
fixture 125. For example, if the dentition crown 220 is four
millimeters, then the width of fixture 125 to which dentition crown
220 is attached via dentition crown connecting rod 225 has a width
that is not greater than four millimeters. Additionally, fixture
125 also includes a fixture hole 130 configured to receive an
associated dentition crown connecting rod 225, and a screw, such
that fixture gap 230 may be reduced by tightening a clamp. Fixture
hole 130 would be large enough for dentition crown connecting rod
225 to fit within fixture hole 130. A screw is then placed within
screw holes 235 such that a bolt may be placed upon the screw and
tightened. The tightening of the bolt on the screw forms a clamp,
forcing the reduction in fixture gap 230, and thus locking
dentition crown connecting rod 225 into place.
[0037] In another embodiment, dentition crown connecting rod 225 is
positioned vertically, while dentition crown connecting rod 225 is
also perpendicular to a horizontal plane of a top surface of a
platform. For instance, frame's 105 base is coupled to a platform
such that frame 105 does not move when a force is exerted upon
dentition crown 220. The platform may be made out of any material
that supports frame's 105 immovability when a force is exerted upon
dentition crown 220. The platform is configured to stabilize frame
105 of force gauge 100. In one instance, the platform is a magnetic
table.
[0038] In yet another embodiment, dentition crown connecting rod
225 comprises stopper 240. Stopper 240 is configured to limit
downward movement of dentition crown 220. Stopper 240 is also
configured to maintain a position of dentition crown 220. By
limiting the downward movement and maintaining a position of
dentition crown 220, dentition crown 220 is located in a position
corresponding to a position of an original digital model of a
dentition crown within a jaw. Stopper 240 surrounds connecting
rod's 225 circumference. In another embodiment dentition crown
connecting rod 225 is configured to couple dentition crown 220
directly to fixture 125.
[0039] Referring now to FIG. 3, a perspective view of a force
measurement system 300 is shown wherein a plurality of force gauges
100 (see FIGS. 1 and 2) are coupled to dentition crown connecting
rod 225. In one embodiment 305, force measurement system 300
includes eight force gauges 100 attached to eight dentition crown
connecting rods 225 corresponding to posterior dentition crowns
220. In another embodiment 310, force measurement system 300
includes six force gauges 100 attached to six dentition crown
connecting rods 225 corresponding to anterior dentition crowns 220.
FIG. 3 shows an example of force gauges 100 varying in their widths
to accommodate the varying widths of posterior versus anterior
dentition crowns. Additionally, FIG. 3 shows an example of each
dentition crown of an entire set of either the upper or lower jaw
array of dentition crowns within a jaw, being coupled to force
gauges 100. Thus, each of an entire set of upper or lower jaw
dentition crowns 220 may be attached to one of a plurality of force
gauges 100 and their respective force determiner 150 via dentition
crown connecting rods 225, such that the force exerted on each or
all of the entire set of lower and/or upper jaw dentition crowns
220 may be measured.
[0040] Frame 105 of force measurement system 300 may provide a
width 205 that varies with the width of dentition crown 220. The
dental appliance may be, but is not limited to the following: a
reference aligner, a measurement aligner, and braces. In addition,
a platform is coupled to each of a plurality of force gauges 100,
wherein a platform is configured to stabilize frame 105 of each of
the plurality of force gauges 100.
[0041] Using techniques known in the state of the art of
orthodontics, a reference aligner is made from a mold, which mold
was formed based upon an original digital model of a set of teeth.
The reference aligner is used to fit over a set of teeth (either a
three dimensional model or a person's set of teeth), and to realign
this set of teeth so that they match the original digital model of
a set of teeth.
[0042] For example, a model of each dentition crown of a set of
teeth is formed. Each resulting dentition crown model is then
aligned to be in a position matching its corresponding position
within a set of teeth. A reference aligner is placed over the
aligned dentition crown models. The aligned dentition crown models
are then repositioned so as to fit within their corresponding
cavity within the reference aligner. Consequently, the reference
aligner is used to reposition dentition crown models of a set of
teeth so that the set of dentition crown models replicate the
positioning of the set of teeth.
[0043] A measurement aligner is a variation of the reference
aligner described herein, and is formed based upon the original
digital model of a set of teeth. However, the measurement aligner
represents a mold which is designed to fit a set of teeth (either a
three dimensional model or a person's set of teeth) in such a way
as to realign the set of teeth to the targeted position of the
cavities spaces within the measurement aligner.
Operation
[0044] Turning now to FIG. 4, a flowchart 400 is shown of an
example method for concurrently measuring a force exerted upon each
of a plurality of teeth. With reference to FIGS. 1-3, step 405
recites how a dentition crown connecting rod 225 associated with
force gauge 100 is positioned such that dentition crown 220 coupled
to dentition crown connecting rod 225 may be received within a
corresponding cavity of a reference aligner.
[0045] The plurality of dentition crowns 220 may represent an
entire set of dentition crowns 220 within a jaw (or a subset of an
entire set) such that the force exerted on each of the entire set
of dentition crowns 220 within a jaw is concurrently measured.
[0046] In one embodiment, positioning dentition crown connecting
rod 225 associated with force gauge 100 described herein further
comprises: calculating a force exerted upon dentition crown 220 by
a reference aligner, wherein the calculated force is shown on a
monitor in real time; adjusting a position of dentition crown
connecting rod 225 until the force exerted upon dentition crown 220
reaches a tolerance of approximately zero; and in response to the
force exerted upon dentition crown 220 reaching a tolerance of
approximately zero, locking dentition crown connecting rod 225 into
fixture 125.
[0047] In one instance, calculating a force exerted upon dentition
crown 220 by the reference aligner involves: sensing a strain on
two adjacent surfaces of beams 110, 115, and 120 of force gauge 100
by a plurality of strain gauges 135, 140, and 145; recording
voltage output; transferring the recorded voltage output to force
determiner 150; and utilizing by force determiner 150 the recorded
voltage output to calculate the force exerted on dentition crown
220 by a reference aligner.
[0048] For example, a reference aligner exerts a force on dentition
crown 220 once it is placed upon dentition crown 220. For instance,
if a dentition crown 220 is leaning against the reference aligner,
then the reference aligner is exerting a force against dentition
crown 225. This force is transferred to dentition crown connecting
rod 225, which is transferred to fixture 125, which in turn is
transferred to beams 110, 115, and 120.
[0049] Strain gauges 135, 140, and 145 sense the strain placed upon
beams 110, 115, and 120, and output a voltage corresponding to the
deformation that it senses. For example, the deformation that
strain gauges 135, 140, and 145 sense is due to beams 110, 115, and
120 being twisted, compressed, and/or pulled. This twisting,
compressing, and/or pulling may occur in the a, b, c, x, y, and/or
z direction. In one instance, strain gauges 135, 140, and 145 are
coupled to a voltage measurement circuit as known in the art via
wire or some other connection apparatus. It is appreciated that the
voltage measurement circuit may be part of force determiner 150 or
separate from force determiner 150, while in both instances being
communicatively coupled thereto.
[0050] The voltage output of strain gauges 135, 140, and 145 is
then determined by a voltage measurement circuit. The voltage
measurement circuit is communicatively coupled to force determiner
150. Force determiner 150 records the voltage output determined by
the voltage meter. Force determiner 150 then utilizes this recorded
voltage output to calculate the force exerted on dentition crown
220 by the reference aligner with a standard linear algebra
technique.
[0051] In one embodiment, a position of dentition crown connecting
rod 225 is adjusted (e.g., by moving rod 225 left, right, forward,
backward or by rotating the rod within the fixture hole 130 of
FIGS. 1 and 2) until the calculated force exerted upon dentition
crown 220 reaches a tolerance of approximately zero. Additionally,
force gauge 105 may also be moved to aid in achieving a tolerance
reading of approximately zero for the force exerted upon dentition
crown 220.
[0052] In response to a calculated force being exerted upon
dentition crown 220 reaching a tolerance of approximately zero,
dentition crown connecting rod 225 is locked into fixture 125. For
example, dentition crown connecting rod 225 may be locked into
fixture 125 by tightening a bolt onto a screw placed in screw holes
235. The tightening of the bolt on the screw forms a clamp, forcing
the reduction in fixture gap 230 and also resulting in the locking
of dentition crown connecting rod 225 into place. After being
locked into place, connecting rod's 225 position may be changed due
to the clamping force, which may in turn change the calculated
force reading. However, the position of dentition crown connecting
rod 225 can still be adjusted by changing the position of frame 105
as it is set on a platform in order to bring the calculated force
reading to approximately zero.
[0053] Referring again to FIG. 4, step 410 provides that a
measurement aligner is applied to dentition crown 220, wherein
dentition crown 220 is positioned to be received within a
corresponding cavity of a reference aligner. In one embodiment, a
pre-set measurement aligner is utilized, wherein the measurement
aligner is built to represent the position of each dentition crown
220 incorporating targeted orthodontic movement. For example, while
a reference aligner mimics the original position of a tooth or a
set of teeth, a measurement aligner mimics the desired position of
a tooth or a set of teeth. The reference aligner and the
measurement aligner represent two different positions of a tooth or
a set of teeth. This difference represents the targeted orthodontic
movement.
[0054] The measurement aligner is designed by any number of methods
which results in an aligner representing the targeted position of a
tooth or set of teeth. This may be through computer (digital)
methods, manual methods, or a combination thereof. The measurement
aligner is placed upon a model of the original positioning of the
teeth.
[0055] Referring again to FIG. 4 as well as to FIGS. 1-3, step 415
provides that a force exerted on dentition crown 220 by the
measurement aligner is calculated. This force is calculated via the
method described herein for calculating the force exerted upon
dentition crown 220 by the reference aligner.
[0056] Furthermore, in one embodiment, the calculated force may be
transformed into a tooth coordinate system, wherein the tooth
coordinate system is defined based on a geometry of dentition crown
220. For instance, an orthodontic practitioner or an engineer might
want to look at a three dimensional viewpoint of the forces exerted
on dentition crown 220. However, the calibration matrix obtained
via force gauge coordinate system is based upon the strain
experienced by beams 110, 115, and 120 and corresponding strain
gauges 135, 140, and 145. In other words, while the tooth
coordinate system is determined by tooth geometry, the force gauge
coordinate system is determined, independent of tooth geometry, by
a calibration matrix.
[0057] The resulting force calculation from a force exerted by a
dental appliance upon dentition crown 220 may not be easily
comprehensible to an orthodontic practitioner or an engineer, due
to its being designed to be independent of the tooth coordinate
system. For example, an orthodontic practitioner is familiar with
the tooth coordinate system, which has its own x, y, and z
coordinates associated with tooth geometry. According to
technologies within the art, these calculations may be transformed
into a three dimensional system, thereby making the force
calculations more understandable to some practitioners and
engineers.
[0058] By calculating the force exerted upon a tooth by a dental
appliance (e.g. aligner, braces) using the disclosed force gauge,
it is possible to concurrently determine the force exerted upon
each of a plurality of teeth. In this manner, a dental appliance
may be tested to determine if it satisfactorily performs its
intended function of re-aligning teeth to a predetermined position.
Additionally, new products and new materials for re-aligning teeth
may be efficiently tested. Furthermore, to aid in a practitioner's
or engineer's comprehension, the calculated force may be
transformed into a tooth coordinate system, wherein the tooth
coordinate system is defined based on a geometry of dentition crown
220.
[0059] In calculating the force exerted upon dentition crown 220 by
the reference aligner using the disclosed force gauge 100, it is
possible to concurrently determine the force exerted upon each of a
plurality of teeth. In this manner, it is possible to determine the
force a measurement aligner delivers to each dentition crown 220.
This force measurement enables a cost beneficial method of testing
a measurement aligner's ability to satisfactorily perform its
intended function.
[0060] All statements herein reciting principles, aspects, and
embodiments of the invention as well as specific examples thereof,
are intended to encompass both structural and functional
equivalents thereof. Additionally, it is intended that such
equivalents include both currently known equivalents and
equivalents developed in the future, i.e., any elements developed
that perform the same function, regardless of structure. The scope
of the present invention, therefore, is not intended to be limited
to the exemplary embodiments shown and described herein. Rather,
the scope and spirit of present invention is embodied by the
appended claims.
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