U.S. patent application number 16/817132 was filed with the patent office on 2020-09-17 for thermoforming multiple aligners in parallel.
The applicant listed for this patent is Align Technology, Inc.. Invention is credited to David Aguilar Mendez, Luis Carlos Martinez Gonzalez, Mario Alfonso Rito Martinez.
Application Number | 20200290262 16/817132 |
Document ID | / |
Family ID | 1000004736105 |
Filed Date | 2020-09-17 |
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United States Patent
Application |
20200290262 |
Kind Code |
A1 |
Aguilar Mendez; David ; et
al. |
September 17, 2020 |
THERMOFORMING MULTIPLE ALIGNERS IN PARALLEL
Abstract
Embodiments relate to thermoforming multiple aligners
simultaneously. In one embodiment, an aligner manufacturing system
includes a plate, a heating section, and a thermoforming chamber.
The plate is configured to secure a first mold of a first dental
arch and a second mold of a second dental arch. The heating section
is configured to heat a sheet of plastic to generate a heated
sheet. The thermoforming chamber is configured to simultaneously
thermoform the heated sheet over the first mold of the first dental
arch and the second mold of the second dental arch to form a first
aligner shaped to fit the first dental arch and a second aligner
shaped to fit the second dental arch.
Inventors: |
Aguilar Mendez; David;
(Ciudad Juarez, MX) ; Martinez Gonzalez; Luis Carlos;
(Ciudad Juarez, MX) ; Rito Martinez; Mario Alfonso;
(Ciudad Juarez, MX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Align Technology, Inc. |
San Jose |
CA |
US |
|
|
Family ID: |
1000004736105 |
Appl. No.: |
16/817132 |
Filed: |
March 12, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62818848 |
Mar 15, 2019 |
|
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|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61C 7/08 20130101; B29C
51/426 20130101; B29C 51/14 20130101; B29K 2101/12 20130101; B29C
51/46 20130101; B29K 2075/00 20130101; B29C 51/261 20130101; B29L
2031/753 20130101 |
International
Class: |
B29C 51/26 20060101
B29C051/26; A61C 7/08 20060101 A61C007/08; B29C 51/42 20060101
B29C051/42; B29C 51/46 20060101 B29C051/46; B29C 51/14 20060101
B29C051/14 |
Claims
1. An aligner manufacturing system comprising: a plate configured
to secure a first mold of a first dental arch and a second mold of
a second dental arch; a heating section configured to heat a sheet
of plastic to generate a heated sheet; and a thermoforming chamber
configured to simultaneously thermoform the heated sheet over the
first mold of the first dental arch and the second mold of the
second dental arch to form a first aligner shaped to fit the first
dental arch and a second aligner shaped to fit the second dental
arch.
2. The aligner manufacturing system of claim 1, wherein the plate
is to secure each of the first mold and the second mold via: a
corresponding pin to secure a corresponding mold in an x-direction
and a y-direction; a corresponding locking mechanism to secure the
corresponding mold in a z-direction; and a corresponding keyway to
maintain orientation of the corresponding mold.
3. The aligner manufacturing system of claim 1, wherein the plate
is to secure each of the first mold and the second mold in a
predetermined position, a predetermined orientation, and
predetermined distances from inner walls of the thermoforming
chamber.
4. The aligner manufacturing system of claim 1 further comprising:
a pallet comprising a plurality of holding pins to pierce the sheet
of plastic to secure the sheet of plastic to the pallet during
heating via the heating section and thermoforming via the
thermoforming chamber.
5. The aligner manufacturing system of claim 4, wherein the
plurality of holding pins comprises a corresponding holding pin at
each corner of the sheet of plastic.
6. The aligner manufacturing system of claim 1, wherein the heating
section comprises: a mask to surround the sheet of plastic during
heating of the sheet of plastic to minimize heat transfer from the
heating section to other sheets of plastic.
7. The aligner manufacturing system of claim 6, wherein the mask is
heat resistant up to about 500 degrees Fahrenheit, is an insulator,
and does not adhere to the heated sheet.
8. The aligner manufacturing system of claim 6, wherein the mask
comprises polytetrafluoroethylene (PTFE).
9. The aligner manufacturing system of claim 1, wherein the heating
section comprises a ceramic heater, a convection oven, or an
infrared heater.
10. The aligner manufacturing system of claim 1, wherein: a maximum
profile of each of the first mold and the second mold has a maximum
length and a maximum width; and the sheet of plastic has a first
length that is about twice the maximum length and a first width
that is about 1.4 times the maximum width.
11. The aligner manufacturing system of claim 10, wherein: a
distance from an inner wall of the thermoforming chamber that
surrounds the first mold and the second mold to a perimeter edge of
the sheet of plastic is at least 1.8% of the first length or at
least 3.1% of the first width to avoid air leakage during
thermoforming via the thermoforming chamber.
12. The aligner manufacturing system of claim 10, wherein: a
minimum distance from an inner wall of the thermoforming chamber to
the maximum profile is about 4.2-4.5% of the first length or about
7-7.2% of the first width to maintain thickness of the first
aligner and the second aligner.
13. The aligner manufacturing system of claim 10, wherein: each of
the first mold and the second mold is at about a 25-degree to a
40-degree angle from a first edge of the sheet of plastic that has
the first length.
14. The aligner manufacturing system of claim 10, wherein: a
distance between a first line tangent to molar sections of the
maximum profile corresponding to the first mold and a second line
tangent to molar sections of the maximum profile corresponding to
the second mold is about 3-4% of the first length or 5-6% of the
first width to avoid forming defects.
15. The aligner manufacturing system of claim 10, wherein: a
distance between a first molar section of a first maximum profile
and a second molar section of a second maximum profile is about
9-10% of the first length or 16-17% of the first width to avoid
forming defects.
16. The aligner manufacturing system of claim 1, wherein the sheet
of plastic is sized to fit only the first mold and the second
mold.
17. The aligner manufacturing system of claim 1, wherein the first
aligner and the second aligner each comprise: at least two outer
layers, wherein each of the at least two outer layers comprises a
thermoplastic polymer; and a middle layer comprising a polyurethane
elastomer.
18. The aligner manufacturing system of claim 17, wherein the
thermoplastic polymer has a flexural modulus of from about 1,000
MPa to 2,500 MPa and a glass transition temperature and/or melting
point of from about 80.degree. C. to about 180.degree. C.
19. The aligner manufacturing system of claim 17, wherein the
polyurethane elastomer has a flexural modulus of from about 50 MPa
to 500 MPa and one or more of a glass transition temperature and/or
melting point of from about 90.degree. C. to about 220.degree.
C.
20. The aligner manufacturing system of claim 17, wherein each of
the first aligner and the second aligner has a combined thickness
of the at least two outer layers and the middle layer from 250
microns to 2,000 microns and a flexural modulus of from 500 MPa to
1,500 MPa.
21. The aligner manufacturing system of claim 1, wherein the first
aligner and the second aligner each comprise: a hard inner polymer
layer comprising a co-polyester and having a hard polymer layer
elastic modulus; and a first soft outer polymer layer and a second
soft outer polymer layer each comprising a thermoplastic
polyurethane elastomer and each having a soft polymer elastic
modulus less than the hard polymer layer elastic modulus.
22. The aligner manufacturing system of claim 20, wherein the first
soft outer polymer layer and the second soft outer polymer layer
each have a flexural modulus of greater than about 35,000 psi, a
hardness of about 60A to about 85D, and a thickness in a range from
25 microns to 100 microns.
23. The aligner manufacturing system of claim 20, wherein the hard
inner polymer layer comprises a blend of polymeric materials
including the co-polyester and one or more of: a polyester, a
thermoplastic polyurethane, a polypropylene, a polyethylene, a
polypropylene and polyethylene copolymer, an acrylic, a
polyetheretherketone, a polyamide, a polyethylene terephthalate, a
polybutylene terephthalate, a polyetherimide, a polyethersulfone, a
polytrimethylene terephthalate, or a combination thereof.
24. A method comprising: securing a first mold of a first dental
arch and a second mold of a second dental arch to a plate; heating
a sheet of plastic to generate a heated sheet; and simultaneously
thermoforming the heated sheet over the first mold of the first
dental arch and the second mold of the second dental arch to form a
first aligner shaped to fit the first dental arch and a second
aligner shaped to fit the second dental arch.
25. The method of claim 24 further comprising: determining whether
a size of a third mold of a third dental arch is below a threshold
size; responsive to determining the size is below the threshold
size, thermoforming a third aligner shaped to fit the third dental
arch simultaneously with another aligner; and responsive to
determining the size is above the threshold size, thermoforming the
third aligner by itself.
26. The method of claim 24 further comprising: piercing, using a
plurality of holding pins of a pallet, the sheet of plastic to
secure the sheet of plastic to the pallet during the heating and
the thermoforming.
27. The method of claim 24 further comprising: surrounding the
sheet of plastic with a mask during the heating of the sheet of
plastic to minimize heat transfer to other sheets of plastic.
28. A method comprising: determining a first size of a first mold
of a first dental arch and a second size of a second mold of a
second dental arch; selecting a first plate, a first sheet of
plastic, and a first pallet based on at least one of the first size
or the second size; causing the first mold and the second mold to
be secured to the first plate; causing the first sheet of plastic
to be heated to generate a first heated sheet; and causing the
first heated sheet to be simultaneously thermoformed over the first
mold of the first dental arch and the second mold of the second
dental arch to form a first aligner shaped to fit the first dental
arch and a second aligner shaped to fit the second dental arch.
29. The method of claim 28 further comprising: determining a third
size of a third mold of a third dental arch and a fourth size of a
fourth mold of a fourth dental arch; selecting a second plate, a
second sheet of plastic, and a second pallet based on at least one
of the third size or the fourth size, wherein the second plate has
a different size than the first plate, the second sheet of plastic
has a different size than the first sheet of plastic, and the
second pallet has a different size than the first pallet; and
causing, using the second plate, the second sheet of plastic, and
the second pallet, a third aligner and a fourth aligner to be
formed.
30. The method of claim 28 further comprising laterally moving, via
a conveyor system, the first plate to a loading station to receive
the first sheet of plastic, to a heating station to heat the first
sheet of plastic, and to a thermoforming station to thermoform the
first heated sheet.
31. The method of claim 28 further comprising rotationally moving,
via a dial system, the first plate to a loading station to receive
the first sheet of plastic, to a heating station to heat the first
sheet of plastic, and to a thermoforming station to thermoform the
first heated sheet.
32. A heat mask comprising: an upper surface configured to couple
with a heater of an aligner manufacturing system a lower surface
configured to be disposed on a sheet of plastic, wherein the sheet
of plastic is to be disposed between a pallet and the lower surface
of the heat mask, wherein the heat mask is to minimize heat
transfer from the heater to other sheets of plastic; and a
plurality of inner sidewalls forming recesses, wherein a first
portion of the sheet of plastic that is disposed on the pallet is
exposed by the recesses to the heat transfer from the heater, and
wherein the heat mask is to minimize the heat transfer from the
heater to a second portion of the sheet of plastic that is disposed
on the pallet and is covered by heat mask.
33. The heat mask of claim 32, wherein the recesses are
substantially uniformly formed along the plurality of inner
sidewalls to provide the heat transfer from the heater to the first
portion of the sheet of plastic to seal the sheet of plastic to the
pallet for thermoforming of the sheet of plastic over a first mold
of a first dental arch and a second mold of a second dental arch to
form a first aligner shaped to fit the first dental arch and a
second aligner shaped to fit the second dental arch.
34. A pallet of an aligner manufacturing system, the pallet
comprising: an upper surface configured to receive a sheet of
plastic to be heated and to be thermoformed over a first mold of a
first dental arch and a second mold of a second dental arch to form
a first aligner shaped to fit the first dental arch and a second
aligner shaped to fit the second dental arch; a plurality of inner
sidewalls sized and shaped to receive a plate securing the first
mold and the second mold for thermoforming of the sheet of plastic;
a plurality of holding pins disposed on the upper surface, wherein
the plurality of holding pins are configured to pierce the sheet of
plastic to secure the sheet of plastic during heating and the
thermoforming.
35. The pallet of claim 34, wherein the plurality of inner
sidewalls form a first inner corner of the pallet, a second inner
corner of the pallet, a third inner corner of the pallet, and a
fourth inner corner of the pallet, wherein the plurality of holding
pins comprise: a first holding pin located on the upper surface
proximate the first inner corner; a second holding pin located on
the upper surface proximate the second inner corner; a third
holding pin located on the upper surface proximate the third inner
corner; and a fourth holding pin located on the upper surface
proximate the fourth inner corner.
36. The pallet of claim 35, wherein the plurality of holding pins
further comprise: a fifth holding pin located on the upper surface
between the first holding pin and the second holding pin; a sixth
holding pin located on the upper surface between the second holding
pin and the third holding pin; a seventh holding pin located on the
upper surface between the third holding pin and the fourth holding
pin; and an eighth holding pin located on the upper surface between
the fourth holding pin and the first holding pin.
Description
RELATED APPLICATION
[0001] This application claims the benefit of Provisional
Application No. 62/818,848, filed Mar. 15, 2019, the entire content
of which is incorporated by reference herein.
TECHNICAL FIELD
[0002] The technical field relates to the field of manufacturing
dental appliances and, in particular, to thermoforming multiple
aligners in parallel (e.g., simultaneously).
BACKGROUND
[0003] For some applications, shells are formed around molds to
achieve a negative of the mold. The shells are then removed from
the molds to be further used for various applications. One example
application in which a shell is formed around a mold and then later
used is corrective dentistry or orthodontic treatment. In such an
application, the mold is of a dental arch for a patient and the
shell is an aligner to be used for aligning one or more teeth of
the patient.
[0004] Molds may be formed using rapid prototyping equipment such
as 3D printers, which may manufacture the molds using additive
manufacturing techniques (e.g., stereolithography) or subtractive
manufacturing techniques (e.g., milling). The aligners may then be
formed over the molds one at a time using thermoforming equipment.
The forming of aligners one at a time using thermoforming equipment
may result in a bottleneck in the aligner production process and
may damage the aligners.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] The present invention is illustrated by way of example, and
not by way of limitation, in the figures of the accompanying
drawings.
[0006] FIGS. 1A-B illustrate aligner manufacturing systems,
according to certain embodiments.
[0007] FIGS. 2A-B illustrate heating sections of aligner
manufacturing systems, according to certain embodiments.
[0008] FIG. 2C illustrates a pallet, sheet of plastic, and mask of
an aligner manufacturing system, according to certain
embodiments.
[0009] FIG. 2D illustrates a pallet, sheet of plastic, and mask of
an aligner manufacturing system, according to certain
embodiments.
[0010] FIG. 2E illustrates a pallet, according to certain
embodiments.
[0011] FIG. 3 illustrates a thermoforming chamber of an aligner
manufacturing system, according to certain embodiments.
[0012] FIG. 4A illustrates a plate of an aligner manufacturing
system, according to certain embodiments.
[0013] FIG. 4B illustrates molds on a plate of an aligner
manufacturing system, according to certain embodiments.
[0014] FIG. 4C illustrates a profile of a mold, according to
certain embodiments.
[0015] FIG. 5A-B illustrate flow diagrams for methods of
thermoforming multiple aligners simultaneously, according to
certain embodiments.
[0016] FIG. 6 illustrates a block diagram of an example computing
device, according to certain embodiments.
[0017] FIG. 7A illustrates a tooth repositioning appliance,
according to certain embodiments.
[0018] FIG. 7B illustrates a tooth repositioning system, according
to certain embodiments.
[0019] FIG. 7C illustrates a method of orthodontic treatment using
a plurality of appliances, according to certain embodiments.
[0020] FIG. 8 illustrates a method for designing an orthodontic
appliance, according to certain embodiments.
[0021] FIG. 9 illustrates a method for digitally planning an
orthodontic treatment, according to certain embodiments.
DETAILED DESCRIPTION
[0022] Described herein are embodiments of simultaneously
thermoforming multiple polymeric aligners (also referred to as an
aligner, a shell, a plastic aligner, a plastic shell, an appliance,
and an orthodontic appliance) or otherwise forming multiple
polymeric aligners in parallel using a single thermoforming
apparatus. Conventionally, automated production of aligners
includes attaching a long continuous roll of plastic to a conveyor
system, pulling the roll of plastic so that a first portion of the
roll is heated at a first station, and pulling the roll of plastic
further so that the heated first portion is thermoformed over a
single mold at a second station (e.g., to form an aligner). The
thermoformed first portion is later removed from the roll. As the
roll of plastic is pulled so that the heated first portion enters
the second station, a second portion enters the first station, and
so forth. As a portion of the roll is heated at the first station,
adjacent portions of the roll may also become heated (e.g., via
convection, conduction, radiation, etc.) which may damage and
reduce performance of the aligners. Thermoforming a portion of the
roll over a single mold may result in wasted plastic (e.g., the
remaining part of the portion of the roll that does not become the
aligner). For example, about 70% of the plastic roll may be wasted
by thermoforming a single aligner at a time. Thermoforming a single
aligner at a time may become a bottleneck in the aligner production
process.
[0023] Embodiments described herein enable simultaneous and/or
parallel thermoforming of multiple aligners together in a single
apparatus. An aligner manufacturing system may perform simultaneous
and/or parallel thermoforming of multiple aligners in a single
apparatus. A plate of the aligner manufacturing system may secure a
first mold of a first dental arch and a second mold of a second
dental arch to a plate. A heating section of the aligner
manufacturing system may heat a sheet of plastic to generate a
heated sheet. A thermoforming chamber of the aligner manufacturing
system may simultaneously (e.g., at the same time) thermoform the
heated sheet over the first mold of the first dental arch and the
second mold of the second dental arch to form a first aligner
shaped to fit the first dental arch and a second aligner shaped to
fit the second dental arch.
[0024] In some embodiments, the plate may secure each mold in a
predetermined position, a predetermined orientation, and
predetermined distances from inner walls of the thermoforming
chamber and/or predetermined distances from each other. For each
mold, the plate includes a corresponding pin, a corresponding
locking mechanism, and a corresponding keyway. Each pin may secure
a corresponding mold in an x-direction and a y-direction. Each
locking mechanism may secure a corresponding mold in the
z-direction. Each keyway may maintain orientation of a
corresponding mold.
[0025] In some embodiments, the aligner manufacturing system
includes a pallet to secure the sheet of plastic. The pallet may
include holding pins to pierce the sheet of plastic to secure the
sheet of plastic during heating (e.g., via the heating section) and
thermoforming (e.g., via the thermoforming chamber). Each corner of
the pallet may have a corresponding holding pin to pierce the sheet
of plastic.
[0026] In some embodiments, the heating section may include a mask
to surround the sheet of plastic during heating of the sheet of
plastic to minimize heat transfer from the heating section to other
sheets of plastic. The mask may be heat resistant up to about 500
degrees Fahrenheit (.degree. F.), may be an insulator, and may not
adhere to the heated sheet of plastic. The mask may include
polytetrafluoroethylene (PTFE). The heating section may include a
ceramic heater, a convection oven, or an infrared heater, in
embodiments.
[0027] In some embodiments, the sheet of plastic is sized to fit
only the first mold and the second mold. The first mold and second
mold may have minimum distances, ranges of distances, and/or ratios
of distances from each other and from the inner walls of the
thermoforming chamber. Alternatively, the sheet of plastic may be a
large sheet of plastic that is rolled into a plastic roll.
[0028] Aspects of the present disclosure result in technological
advantages of significant reduction in wasted plastic, significant
increase in throughput, and significant improvement in quality. By
thermoforming at least two aligners on a single sheet of plastic,
the present disclosure results in significant reduction in wasted
plastic. For example, the present disclosure may have more than 30%
reduction in wasted plastic compared to conventional automated
systems. By thermoforming at least two aligners on a single sheet
of plastic, the present disclosure results in significant increase
in throughput. For example, the present disclosure may have an 80%
increased capacity compared to conventional automated systems. By
using a mask to surround the sheet of plastic during heating, the
present disclosure minimizes heat transfer to other sheets of
plastic and improves quality of the aligners compared to
conventional automated systems. Also, by using the dimensions,
ranges, and/or ratios disclosed herein, the present disclosure may
improve quality of the aligners compared to conventional automated
systems. Aspects of the present disclosure may be provided in a new
aligner manufacturing system. In some embodiments, an aligner
manufacturing system may be retrofit (e.g., upgraded, modified)
with aspects of the present disclosure.
[0029] FIG. 1A illustrate aligner manufacturing systems 100A-B
(hereinafter aligner manufacturing systems 100), according to
certain embodiments. FIG. 1A illustrates an aligner manufacturing
system 100A, according to certain embodiments. The aligner
manufacturing system 100 may include a loading station 110, a
heating section 120, and a thermoforming chamber 130. A conveyor
system 140 (e.g., conveyor belt, chain conveyor system, etc.) may
move pallets 150 (e.g., pallets 150A-C, chain conveyor pallets)
through the loading station 110, heating section 120, and
thermoforming chamber 130. In some embodiments, two or more of the
loading station 110, heating section 120, and thermoforming chamber
130 may be combined. In some embodiments, additional stations may
be included before, after, or during the loading station 110,
heating section 120, and/or thermoforming chamber 130.
[0030] In some embodiments, each pallet 150 may include holding
pins 152. In the loading station 110, a sheet of plastic 154 may be
placed on the holding pins 152 to pierce the sheet of plastic 154
with the holding pins to secure the sheet of plastic 154 to the
pallet 150. For example, the loading station 110 may include a
robot that activates a vacuum of the robot to pick up the sheet of
plastic 154. The robot may push the sheet of plastic onto the
holding pins 152, and the robot may deactivate the vacuum to leave
the sheet of plastic secured to the pallet 150. The sheet of
plastic may remain secured to the pallet 150 during heating via the
heating section 120 and during thermoforming via the thermoforming
chamber 130. In some embodiments, the pallet 150 has an upper
surface that has a substantially rectangular surface area that
forms four corners. The pallet 150 may include a holding pin 152 on
the upper surface at each corner. The pallet 150 may include a
holding pin 152 on the upper surface at a midpoint between each set
of adjacent corners and/or at other positions along a perimeter of
the pallet 150. The pallet 150 may have multiple holding pins 152
(e.g., six holding pins, eight holding pins) on the upper surface
of the pallet 150 in some embodiments. The holding pins may have
sharp points, and may pierce the sheet of plastic 154B to secure
the sheet of plastic 154B in embodiments.
[0031] After the loading station 110, the conveyor system 140 may
move a pallet 150 to the heating section 120. The heating section
120 may include a heater 122 and a mask 124 (e.g., heater mask
124). The heater 122 may be a ceramic heater, a convection oven, or
an infrared heater in embodiments. The mask 124 may be heat
resistant up to about 500.degree. F. in embodiments. The mask 124
may be an insulator. The mask 124 may not adhere to the sheet of
plastic 154 when the mask 124 and sheet of plastic 154 are heated.
The mask may include polytetrafluoroethylene (PTFE) (e.g.,
Teflon.TM.) in embodiments. Other materials that are heat
resistant, have low thermal conductivity, and that will not adhere
to the plastic sheet may also be used.
[0032] In some embodiments, the heating section 126 includes one or
more heaters 122 (e.g., three heaters), where each heater 122
(e.g., heating element, infrared heater) heats a corresponding
zone. The heating section 126 may include one or more sensors 170
(e.g., to measure temperature). In some embodiments, there is at
least one sensor 170 per heater 122 (e.g., at least one sensor 170
per zone). A sensor 170 may be located below each heater 122 (e.g.,
below the sheet of plastic 154). The sensors 170 may determine the
temperature of the sheet of plastic 154 and/or the air around the
sheet of plastic 154. A heating profile of the sheet of plastic 154
may be determined based on sensor data from the sensors 170.
[0033] In some embodiments, one or more sensors 170 may be disposed
in the heating section 120 (e.g., in the heating chamber, above the
sheet of plastic 154, etc.). In some embodiments, a corresponding
sensor 170 is located above or below each corner of the sheet of
plastic 154 (e.g., within the heating space, within the interior
perimeter of the mask 124). In some embodiments, one or more
sensors 170 are located above or below a middle portion of the
sheet of plastic 154 (e.g., between a first mold and a second
mold).
[0034] In some embodiments, the sensors 170 may be disposed below
the sheet of plastic 154. One or more sensors 170 may be disposed
in a first plane and the sheet of plastic 154 may be disposed in a
second plane. The second plane may be substantially parallel to the
first plane. The second plane may be a distance above the first
plane. The distance between a first sensor 170 and a second sensor
170 may be less than the distance between the first plane and the
second plane. In some embodiments, the distance between a first
sensor 170 and a second sensor 170 is about one tenth the distance
between the first plane and the second plane (e.g., sensor spacing
is about one tenth the spacing between a sensor 170 and the sheet
of plastic 154).
[0035] A processing device may receive the sensor data from the
sensors 170. The processing device may determine whether one or
more temperatures associated with the sheet of plastic 154 meet one
or more threshold values (e.g., high enough of temperature, not too
high of temperature, total time of heating, rate of increase of
temperature, temperature in each of the zones is substantially the
same, etc.). Responsive to determining that the one or more
temperatures associated with the sheet of plastic 154 meet the one
or more threshold values, the processing device may allow the
heated sheet of plastic continue being formed into an aligner.
Responsive to determining that one or more temperatures associated
with the sheet of plastic 154 do not meet one or more threshold
values (e.g., uneven temperature, overheating, underheating, etc.),
the processing device may perform a corrective action. A corrective
action may include one or more of causing the heated sheet of
plastic 154 to be discarded, causing the sheet of plastic 154 to be
reheated, recalibrating the heaters 122, interrupting one or more
components (e.g., heaters 122) the aligner manufacturing system
100, providing an alert, changing the manufacturing parameters
(e.g., controlling power fed to the heaters 122, controlling the
heat to be in an acceptable range, controlling total time of
heating, etc.), and/or the like.
[0036] The heating section 120 may move (e.g., via a pneumatic
cylinder of the heating section 120) the mask 124 to interface with
the sheet of plastic 154 on the pallet 150. The mask 124 may
include features so that the mask 124 avoids interfacing with the
holding pins 152 while the mask 124 surrounds the sheet of plastic
154. The mask 124 may surround the sheet of plastic 154 to minimize
heat transfer from the heating section to other sheets of plastic
154. The heater 122 may heat the sheet of plastic 154 to about
336.degree. F. without hanging of the sheet of plastic 154 (e.g.,
without sagging portions of the sheet of plastic) by using the mask
124. For example, the mask may surround a perimeter of the sheet of
plastic and provide a force sandwiching the sheet of plastic
between the mask 124 and the pallet 150B. The force may be applied
approximately uniformly about the perimeter of the sheet of
plastic, and may prevent or mitigate sagging and/or warping of the
sheet of plastic during the heating process. By avoiding generation
of hanging or sagging portions of the sheet of plastic 154, air
leaks may be avoided during the thermoforming. The mask 124 may be
removed from the sheet of plastic 154 after the heating is
completed.
[0037] After the heating section 120, the conveyor system 140 may
move the pallet 150 (e.g., with the heated sheet of plastic 154
secured to the pallet 150 via the holding pins 152) to the
thermoforming chamber 130. The thermoforming chamber 130 may
include a pressure device 132. In some embodiments, the pressure
device 132 may be lowered to interface with at least a portion
(e.g., of an upper surface of the heated sheet of plastic 154
and/or of an upper surface of the pallet 150 proximate the
perimeter of the pallet 150). Molds 160 (e.g., at least a first
mold 160A and a second mold 160B) may be secured to a plate 162
that is disposed on a lifting device 164. The pallet 150 may form a
border, where the molds 160A-B and/or plate 162 may pass through
the pallet (e.g., the pallet 150 creates a channel from the lower
surface to the upper surface of the pallet 150 sized for the molds
160 and/or plate 162 to pass through the channel).
[0038] The lifting device 164 may lift the molds 160A-B and plate
162 to interface with a lower surface of the heated sheet of
plastic 154 in the thermoforming chamber 130. The pressure device
132 may maintain a pressure level (e.g., high pressure, lower
pressure, vacuum, substantially vacuum, etc.) at the upper surface
of the heated sheet of plastic 154. The lifting device 164 may push
the molds 160A-B against the lower surface of the heated sheet of
plastic 154 to thermoform the heated sheet of plastic 154 to form
aligners. Subsequent to thermoforming the heated sheet of plastic
154, the lifting device 164 may lower to allow the conveyor system
140 to move the pallet 150 and thermoformed sheet of plastic 154
out of the thermoforming chamber 130.
[0039] After the thermoforming chamber 130, the thermoformed sheet
of plastic 154 may be moved (e.g., via conveyor system 140) to
other sections of the aligner manufacturing system 100 for one or
more of reading identifiers on the aligners, marking the aligners,
dividing the aligners, trimming the aligners, etc.
[0040] The conveyor system 140 may continue to move pallets 150
from the loading station 110, to the heating section 120, and to
the thermoforming chamber 130 to thermoform additional sets of
aligners in parallel (e.g., simultaneously). For example, there may
be a pallet 150A in the loading station 110, pallet 150B in the
heating section 120, and a pallet 150C in the thermoforming chamber
130 at substantially the same time.
[0041] Embodiments are discussed with reference to simultaneous
processing of pairs of aligners (e.g., using first mold 160A and
second mold 160B). However, it should be understood that in
alternative embodiments more than two aligners may be formed
together using a single sheet of plastic. For example, three
aligners, four aligners, five aligners, etc. may be formed in
parallel on a single sheet of plastic. Additionally, embodiments
are discussed with reference to the simultaneous thermoforming of
multiple aligners. It should be understood that in some embodiments
there may be a slight delay between the beginning of thermoforming
a first aligner and thermoforming a second aligner and/or between
the ending of thermoforming a first aligner and ending of
thermoforming a second aligner. For example, first mold 160A may be
slightly vertically offset from second mold 160B, which may cause
the thermoforming of a first aligner by first mold 160A to start
and end at a slightly different time from the thermoforming of a
second aligner by second mold 160B. Accordingly, it should be
understood that embodiments that are discussed with reference to
simultaneous processing or manufacturing also include parallel
processing or manufacturing that may not be simultaneous.
[0042] FIG. 1B illustrates an aligner manufacturing system 100B,
according to certain embodiments. Elements with the same or similar
numbering may have the same or similar functionality as those
described in FIG. 1A. The aligner manufacturing system 100B may
include a loading station 110, a heating station 126 (e.g., heating
section 120), a thermoforming station 136 (e.g., one or more
thermoforming chambers 130), and an unloading station 180. One or
more dial systems 190 may be used to form the aligners. A dial
system 190A may rotate to move pallets 150 (e.g., pallets 150A-C)
through the loading station 110, heating station 126, thermoforming
station 136, and unloading station 180. A dial system 190B may be
used to load the plate 162 and/or molds 160 onto a lifting device
164. In some embodiments, two or more of the loading station 110,
heating station 126, thermoforming station 136, and unloading
station 180 may be combined. In some embodiments, additional
stations may be included before, after, or during the loading
station 110, heating station 126, thermoforming station 136, and/or
unloading station 180.
[0043] The dial system 190A be configured to receive different
sizes of pallets 150 (e.g., three sizes of pallets). Each pallet
150 may be configured for multiple molds (e.g., two molds). A size
of pallet 150 may be selected based on the size of the largest mold
to be used with the pallet 150. Responsive to the largest mold to
be used with the pallet 150 meeting a first threshold size, a first
size of pallet 150 may be selected. Responsive to the largest mold
to be used with the pallet 150 meeting a second threshold size, a
second size of pallet 150 may be selected. Responsive to the
largest mold to be used with the pallet 150 meeting a third
threshold size, a third size of pallet 150 may be selected. For
each size of pallet 150, there may be a corresponding size of sheet
of plastic 154, a corresponding pressure device 132, a
corresponding plate 162, a corresponding lifting device 164, and/or
the like.
[0044] In some embodiments, groups of two or more pallets 150
(e.g., three pallets 150) of different sizes are located on the
dial system 190A proximate each other. Responsive to the dial
system 190A rotating, a first group of the two or more pallets 150
is moved into the loading station 110. Responsive to the largest
mold to be used meeting a threshold size, a particular size of
sheet of plastic 154 is placed on a particular size of pallet
150.
[0045] After securing the sheet of plastic 154 to the pallet 150,
the dial system 190A is rotated and the first group of two or more
pallets 150 of different sizes is moved into the heating station
126. A heater 122 and mask 124 are moved to heat the sheet of
plastic 154 secured to the pallet 150. In some embodiments, the
same heater 122 and mask 124 are used to heat a sheet of plastic
154 secured to any of the two or more pallets 150. In some
embodiments, there are three heaters 122 and three masks 124 that
each correspond to a different sized pallet 150 and only the heater
122 above the pallet 150 that is securing a sheet of plastic 1548
is actuated (e.g., lowered, caused to perform a heating function,
etc.).
[0046] After heating the sheet of plastic 154 that is secured to
the pallet 150, the dial system 190A is rotated and the first group
of two or more pallets 150 of different sizes is moved into the
thermoforming station 136. The thermoforming station may include
the same number of thermoforming chambers 130, pressure devices
132, plates 162, and/or lifting devices 164 as the number of
pallets 150. Each thermoforming chamber 130, pressure device 132,
plate 162, and/or lifting device 164 may be sized for the
corresponding pallet 150. In some embodiments, only the
thermoforming chamber 130, pressure device 132, and/or lifting
device 164 corresponding to the pallet 150 securing a heated sheet
of plastic 154 are actuated. A single lifting device 164 may be
used for the two or more pallets 150. In some embodiments, the
lifting device 164 is configured to receive and lift two or more
plates 162, each sized for a corresponding pallet 150 (e.g., all
two or more plates 162 are lifted at the same time by the lifting
device 164). In some embodiments, the lifting device 164 is
configured to receive a single plate 162 and move the plate 162 to
the corresponding pallet 150 that is securing a sheet of plastic.
In some embodiments, the thermoforming station 136 has two or more
thermoforming chambers 130. In some embodiments, the thermoforming
station 136 has a single thermoforming chamber 130 that is aligned
with the pallet 150 that is securing a sheet of plastic 154.
[0047] After thermoforming the heated sheet of plastic 154 that is
secured to the pallet 150, the dial system is rotated and the first
group of two or more pallets 150 of different sizes is moved into
the unloading station 180. The unloading station 180 may one or
more of read one or more identifiers (e.g., patient identifier
(PID, stage, etc.), laser mark the thermoformed sheet of plastic
154 (e.g., aligner), trim the one or more aligners form the
thermoformed sheet of plastic 154, unload the thermoformed sheet of
plastic 154 (e.g., aligners) from the plate 162, and/or the like.
In some embodiments, the unloading station 180 may include one or
more substations and the dial system 190A may be rotated to move
the first group of two or more pallets 150 from one substation to
another. For example, one or more identifiers of the thermoformed
sheet of plastic 154 may be read at a first substation, the dial
system 190A is rotated, the thermoformed sheet of plastic 154 is
laser marked at a second substation, the dial system 190A is again
rotated, the thermoformed sheet of plastic 154 is unloaded (e.g.,
along with the molds, without the molds) from the plate 162, and
the dial system 190A is again rotated (e.g., to locate the first
group of two or more pallets 150 in the loading station 110).
[0048] In some embodiments, the aligner manufacturing system 100B
includes multiple dial systems 190. A dial system 190B may be
located under the dial system 190A. The dial system 190B may be
used to locate the lifting device 164, plate 162, and/or one or
more molds 160 under the corresponding pallet 150 securing a sheet
of plastic 154 in the thermoforming station 136. The lifting device
164 may lift the plate 162 securing one or more molds 160 to the
pallet 150 securing the sheet of plastic 154 to thermoform the
sheet of plastic 154 on the one or more molds. The dial system 190B
may rotate through one or more different stations. In some
embodiments, a plate 162 may be loaded to the dial system 190B at a
station of the dial system 190B. In some embodiments, one or more
molds 160 may be loaded on a plate 162 at a station of the dial
system 190B. In some embodiments, the one or more molds 160 and/or
the plate 162 are unloaded from the dial system 190B at a station
of the dial system 190B. In some embodiments, the lifting device
164 remains located under the thermoforming station 136 and the
lifting device 164 lifts the plate 162 securing the molds 160 from
the dial system 190B to the pallet 150 securing the sheet of
plastic 154. In some embodiments, the lifting device 164 rotates
with the dial system 190B.
[0049] In some embodiments, the dial system 190A and the dial
system 190B rotate in the same direction (e.g., both clockwise,
both counter-clockwise). In some embodiments, the dial system 190A
and the dial system 190B rotate in opposite directions. In some
embodiments, the dial system 190A and the dial system 190B rotate
simultaneously or substantially simultaneously (e.g., at the same
speed, etc.). In some embodiments, the dial system 190A and the
dial system 190B are rotated separately (e.g., the pallet 150
securing a sheet of plastic 150 may be rotated to the thermoforming
station 136 at a time different than the plate 162 securing the one
or more molds 160 is rotated under the thermoforming station
136).
[0050] In some embodiments, the dial system 190A may include
multiple groups of two or more pallets 150. A first group may be
located in the loading station 110, a second station may be located
at the heating station 126, a third group may be located in the
thermoforming station 136, and a fourth group may be located in the
unloading station 180. In some embodiments, different stations of
the dial system 190A are being interacted with at substantially the
same time. In some embodiments, a sheet of plastic 154A is being
placed on a pallet 150A, a heater 122 is heating the sheet of
plastic 154B loaded on a pallet 150B, and a pressure device 132 is
thermoforming a heated sheet of plastic 154C secured to a pallet
150C at substantially the same time. In some embodiments, different
stations of the dial system 190B are being interacted with at
substantially the same time.
[0051] The operations of forming an aligner by using a conveyor
belt 140 may be applied to forming an aligner by using one or more
dial systems 190A-B.
[0052] FIGS. 2A-B illustrate heating sections 120 of aligner
manufacturing systems 100, according to certain embodiments. The
heating section 120 may include a pneumatic cylinder 210, a heater
122, a mask 124, a sheet of plastic 154 inserted into the heating
section 120, and a pallet 150. As shown in FIG. 2A, the heater 122
may be located proximate the sheet of plastic 154 disposed on a
pallet 150. As shown in FIG. 2A, the mask 124 may be disposed
between the heater 122 and the sheet of plastic disposed on the
pallet 150. The mask 124 may lower to interface with the sheet of
plastic 154 disposed on the pallet 150.
[0053] FIG. 2C illustrates a pallet 150, sheet of plastic 154, and
mask 124 of an aligner manufacturing system 100, according to
certain embodiments. The mask 124 may provide a thermal seal
between the heater 122 and the sheet of plastic 154 on the pallet
150. The mask 124 may be a border that forms a channel from the
lower surface to the upper surface of the mask 124. The channel of
the mask 124 may be substantially similar in size to the channel of
the pallet 150. The mask 124 may be shaped to not interfere with
the holding pins 152 (e.g., the mask 154 may have recesses to go
around the holding pins 152). In some embodiments, the mask 124
substantially covers the pallet 150 so that the mask 124 is
disposed on substantially all portions of the sheet of plastic 154
that are disposed on the pallet 150.
[0054] FIG. 2D illustrates a pallet 150, sheet of plastic 154, and
mask 124 of an aligner manufacturing system, according to certain
embodiments. The mask 124 may have an upper surface configured to
couple with a heater of an aligner manufacturing system 100. The
mask 124 may have a lower surface configured to be disposed on a
sheet of plastic 154. The sheet of plastic is to be disposed
between a pallet 150 and the lower surface of the mask 124. The
mask may have inner sidewalls forming recesses 220 (e.g., cut-outs,
indents, etc.). A first portion of the sheet of plastic 154 that is
disposed on the pallet 150 is exposed by the recesses 220 to heat
transfer from the heater (e.g., the first portion is heated by the
heater). The heated first portion of the sheet of plastic 154
provide a seal between the sheet of plastic 154 and the pallet 150
and/or one or more portions of the thermoforming chamber 130. The
mask 124 is to minimize the heat transfer from the heater to a
second portion of the sheet of plastic 154 that is disposed on the
pallet and is covered by heat mask 124 (e.g., portions that are not
exposed by the recesses).
[0055] The recesses 220 may be substantially uniformly formed
(e.g., substantially evenly spaced) along the inner sidewalls to
provide the heat transfer from the heater to the first portion of
the sheet of plastic 154 to seal the sheet of plastic to the pallet
for thermoforming. The recesses substantially uniformly formed
recesses may provide for substantially uniform heating to provide
an improved seal.
[0056] In some embodiments, the recesses 220 have substantially
vertical sidewalls. In some embodiments, the recesses 220 have
planar (e.g., planar vertical) sidewalls. In some embodiments, the
recesses 220 have curved (e.g., curved vertical, rounded vertical)
sidewalls.
[0057] FIG. 2E illustrates a pallet 150, according to certain
embodiments. The pallet 150 has an upper surface configured to
receive a sheet of plastic 154. The pallet 150 also includes inner
sidewalls sized and shaped to receive a plate 162 securing the
first mold and the second mold for thermoforming of the sheet of
plastic 154. The pallet 150 also includes holding pins 152 disposed
on the upper surface of the pallet. The holding pins 152 are
configured to pierce the sheet of plastic 154 to secure the sheet
of plastic 154 during heating and thermoforming.
[0058] The inner sidewalls form a first inner corner of the pallet
150, a second inner corner of the pallet 150, a third inner corner
of the pallet 150, and a fourth inner corner of the pallet 150. The
holding pins 152 include a first holding pin 152A located on the
upper surface proximate the first inner corner, a second holding
pin 152B located on the upper surface proximate the second inner
corner, a third holding pin 152C located on the upper surface
proximate the third inner corner, and a fourth holding pin 152D
located on the upper surface proximate the fourth inner corner. The
holding pins 152 may also include a fifth holding pin 152E located
on the upper surface between (e.g., substantially midway between)
the first holding pin 152A and the second holding pin 152B, a sixth
holding pin 152F located on the upper surface between (e.g.,
substantially midway between) the second holding pin 152B and the
third holding pin 152C, a seventh holding pin 152G located on the
upper surface between (e.g., substantially midway between) the
third holding pin 152C and the fourth holding pin 152D, and an
eighth holding pin 152H located on the upper surface between (e.g.,
substantially midway between) the fourth holding pin 152D and the
first holding pin 152A.
[0059] In some embodiments, the pallet 150 has at least four
holding pins 152. In some embodiments, the pallet 150 has at least
six holding pins 152. In some embodiments, the pallet 150 has at
least eight holding pins 152. The holding pins 152 may hold the
sheet of plastic 154 in place (e.g., during heating and
thermoforming).
[0060] FIG. 3 illustrates a thermoforming chamber 130 of an aligner
manufacturing system 100, according to certain embodiments. A
heated sheet of plastic 154 may be secured to a pallet 150 by one
or more holding pins 152 on the upper surface of the pallet 150.
Molds 160A-B may be secured to an upper surface of a plate 162 that
is coupled to a lifting device 164. A pressure device 132 of the
thermoforming chamber 130 may lower onto an upper surface of an
outer perimeter of the heated sheet of plastic 154 and/or pallet
150. The lifting device 164 may lift the plate 162 so that the
molds 160A-B press against the lower surface of the heated sheet of
plastic 154 with a specified amount of force while the pressure
device 132 maintains a pressure (e.g., substantially vacuum). After
a threshold amount of time, the lifting device 164 lowers plate
162, the pressure device 132 may lift from the sheet of plastic 154
secured to the pallet 150, and the pallet 150 (with the
thermoformed sheet of plastic 154 secured to the upper surface of
the pallet 150) may leave the thermoforming chamber 130.
[0061] FIG. 4A illustrates a plate 162 of an aligner manufacturing
system 100, according to certain embodiments. In some embodiments,
for each mold, a plate 162 may include corresponding features
including a corresponding keyway 402A-B, corresponding pin 404A-B,
and corresponding locking mechanism 406A-B. The plate 162 may
secure each mold 160A-B in a predetermined position, a
predetermined orientation, and predetermined distances from inner
walls of the thermoforming chamber 130 and/or from each other using
the features.
[0062] Each keyway 402 may maintain orientation of a corresponding
mold 160A-B. A lower surface of the mold 160A-B may have a feature
(e.g., protrusion, recess) that interfaces with the keyway 402A-B
so that the mold does not change orientation.
[0063] Each pin 404A-B may secure a corresponding mold 160A-B in an
x-direction and a y-direction. Each mold 160A-B may have a recess
(e.g., pin hole) formed by a lower surface of the mold 160A-B that
interfaces with the pin 404A-B. The pin 404A-B interfacing with the
recess may cause the mold 160A-B to not move in the x- and
y-directions.
[0064] Each locking mechanism 406A-B may secure a corresponding
mold 160A-B in the z-direction. For example, the locking mechanism
may overlap an upper surface of the mold 160A-B so that the mold
160A-B does not move away from the plate 162. Each mold may form a
hole (e.g., proximate a flat identification portion of the mold)
that corresponds to the locking mechanism 406A-B. The mold 160A-B
may be placed on the plate 162 so that a top portion of the locking
mechanism 406A-B sticks through the hole and the top portion of the
locking mechanism may be rotated to lock the mold 160A-B in the
z-direction.
[0065] FIG. 4B illustrates molds 160A-B on a plate 162 of an
aligner manufacturing system 100, according to certain embodiments.
The plate 162 may secure molds 160A-B in predetermined positions,
predetermined orientations, and predetermined distances from inner
walls 420 of the thermoforming chamber 130. The plate 162 may be
sized to receive two molds 160A-B that each fit within a
corresponding profile 410A-B (e.g., are not greater than a maximum
mold size). The predetermined positions, orientations, and
distances of each mold 160A-B and/or each profile 410A-B may
improve the quality of the aligners (e.g., reduce defects). The
dimensions described herein may have a tolerance that substantially
matches the tolerance of the tooling (e.g., aligner manufacturing
system 100, thermoforming chamber 130, etc.). In some embodiments,
the tolerance of the dimensions described herein and/or the
tolerances of the tooling may be at least 3 thousandths of an inch.
In some embodiments, the profiles 410A-B are each the same size.
Alternatively, profile 410A may have a different size (e.g., one or
more different dimensions) than profile 410B.
[0066] FIG. 4C illustrates the profile 410 of a mold 160, according
to certain embodiments. In some embodiments, two or more molds 160
that fit within the size of the profile 410 may used on the same
plate 162 to simultaneously thermoform multiple aligners. In some
embodiments, molds 160 that do not fit within the dimensions of the
profile 410 are to be used to thermoform one aligner at a time. A
maximum profile 410 of each mold may have a maximum length (e.g.,
72 mm) and a maximum width (e.g., 62.5 mm) in one embodiment.
[0067] Returning to FIG. 4B, the sheet of plastic 154 may have a
first length (e.g., 148 mm) that is about twice the maximum length
(e.g., 72 mm) of the profile 410 and the sheet of plastic may have
a first width (e.g., 90 mm) that is about 1.4 times the maximum
width (e.g., 62.5 mm) of the profile 410.
[0068] A distance from an inner wall 420 of the thermoforming
chamber 130 that surrounds the molds 160 to a perimeter edge of the
sheet of plastic 154 may be at least 1.8% of the first length of
the sheet of plastic 154 or at least 3.1% of the first width of the
sheet of plastic 154 to avoid air leakage during thermoforming via
the thermoforming chamber 130. For example, the distance from the
inner wall 420 of the thermoforming chamber 130 to the perimeter of
the sheet of plastic 154 may be about 2.75 mm. The portion of the
sheet of plastic 154 corresponding to the distance from the inner
wall 420 of the thermoforming chamber 130 to the perimeter edge of
the sheet of plastic 154 may be used to hold the sheet of plastic
154 in place while being processed (e.g., heated, thermoformed,
etc.). This distance may allow the sheet of plastic 154 to be held
in place correctly so that the sheet of plastic 154 does not hang
during heating (e.g., hanging may cause an air leak when
forming).
[0069] A minimum distance from an inner wall 420 of the
thermoforming chamber 130 to the maximum profile 410 (e.g.,
projection tangent) may be about 4.2-4.5% the first length of the
sheet of plastic 154 or about 7-7.2% of the first width of the
sheet of plastic 154. For example, the distance from the inner wall
420 of the thermoforming chamber 130 to the perimeter of the sheet
of plastic 154 may be about 6.34-6.82 mm (e.g., about 6.55 mm from
the first edge of the sheet of plastic that has the first length
and about 6.34 mm from the second edge of the sheet that has the
first width). The minimum distance between the inner walls 420 of
the thermoforming chamber 130 and the profile 410 may be used to
generate (e.g., via thermoforming) aligners with a threshold
thickness (e.g., to provide the force necessary to move teeth). The
minimum distance may be used to define the position and orientation
of the features (e.g., keyway 402, pin 404, locking mechanism 406,
etc.) of the plate 162 where the mold 160 is fixed while being
processed.
[0070] Each mold 160A-B may be at about a 25 degree (.degree.) to a
40.degree. angle from a first edge of the sheet of plastic 154 that
has the first length. For example, each mold may be at about a
32.degree. angle from a first edge of the sheet of plastic 154 that
has the first length.
[0071] A distance between a first line 412A tangent to molar
sections of the maximum profile 410A corresponding to the first
mold 160A and a second line 412B tangent to molar sections of the
maximum profile 410B corresponding to the second mold 160B may be
about 3-4% of the first length of the sheet of plastic 154 or 5-6%
of the first width of the sheet of plastic 154 to avoid forming
defects. For example, the distance between the first line tangent
412A to molar sections of the profile 410A and the second line
tangent 412B to the molar sections of the profile 410B may be about
5 mm.
[0072] A distance between a first molar section of a first maximum
profile 410A and a second molar section of a second maximum profile
410B may be about 9-10% of the first length of the sheet of plastic
154 or 16-17% of the first width of the sheet of plastic 154 to
avoid forming defects. For example, the distance between the first
molar section and the second molar section may be about 13.59-14.56
mm. The distance between the molar sections (e.g., separation
between molar sections of the molds 160) of the profiles 410 may
prevent forming defects such as webbing (e.g., thermoformed sheet
of plastic 154 creating a bridge from one mold 160 to another mold
160) and thickness defects (e.g., non-uniform thickness, overly
thin thickness, overly thick thickness, etc.).
[0073] The sheet of plastic 154 may be sized to fit only the first
mold 160A and the second mold 160B. For example, the sheet of
plastic 154 may be sized to fit two molds without having space for
a third mold. The sheet of plastic 154 may be sized to fit the
first and second molds 160A-B with only the distances between the
molds 160, distances between the molds 160 and inner wall 420 of
the thermoforming chamber 130, and distances between the outer
perimeter of the sheet of plastic 154 and the inner walls 420 of
the thermoforming chamber 130 as described herein. Sized to fit may
refer to fitting two profiles 410 with one or more of the following
distances as described herein: distance from an inner wall 420 of
the thermoforming chamber 130 that surrounds the molds 160 to a
perimeter edge of the sheet of plastic 154; minimum distance from
an inner wall 420 of the thermoforming chamber 130 to the maximum
profile 410; each of mold 160 may be at about a 25.degree. to a
40.degree. angle from a first edge of the sheet of plastic 154 that
has the first length; distance between a first line tangent 412A to
molar sections of the profile 410A corresponding to the first mold
160A and a second line 412B tangent to molar sections of the
profile 410B corresponding to the second mold 160B; and/or a
distance between a first molar section of a first maximum profile
410A and a second molar section of a second maximum profile
410B.
[0074] FIGS. 5A-B illustrate flow diagrams for method 500A-B of
thermoforming multiple aligners simultaneously (or otherwise in
parallel), according to certain embodiments. In some embodiments,
one or more operations of methods 500A-B are performed by a
processing logic of a computing device to automate one or more
operations of forming an aligner. The processing logic may include
hardware (e.g., circuitry, dedicated logic, programmable logic,
microcode, etc.), software (e.g., instructions executed by a
processing device), firmware, or a combination thereof. For
example, one or more operations of methods 500A-B may be performed
by a processing device executing a program or module, such as
aligner generator 650 of FIG. 6.
[0075] Referring to FIG. 5A, at block 502 of method 500A, a
corresponding digital model for each mold is generated. For
example, a first digital model of a first mold and a second digital
model of a second mold may be generated. A shape of a dental arch
for a patient at a treatment stage may be determined based on a
treatment plan to generate the digital model of the mold. In the
example of orthodontics, the treatment plan may be generated based
on an intraoral scan of a dental arch to be modeled. The intraoral
scan of a patient's dental arch may be performed to generate a
three dimensional (3D) virtual model of the patient's dental arch.
For example, a full scan of the mandibular and/or maxillary arches
of a patient may be performed to generate 3D virtual models
thereof. The intraoral scan may be performed by creating multiple
overlapping intraoral images from different scanning stations and
then stitching together the intraoral images to provide a composite
3D virtual model. In other applications, virtual 3D models may also
be generated based on scans of an object to be modeled or based on
use of computer aided drafting techniques (e.g., to design the
virtual 3D mold). Alternatively, an initial negative mold may be
generated from an actual object to be modeled. The negative mold
may then be scanned to determine a shape of a positive mold that
will be produced.
[0076] Once the virtual 3D model of the patient's dental arch is
generated, a dental practitioner may determine a desired treatment
outcome, which includes final positions and orientations for the
patient's teeth. Processing logic may then determine a number of
treatment stages to cause the teeth to progress from starting
positions and orientations to the target final positions and
orientations. The shape of the final virtual 3D model and each
intermediate virtual 3D model may be determined by computing the
progression of tooth movement throughout orthodontic treatment from
initial tooth placement and orientation to final corrected tooth
placement and orientation. For each treatment stage, a separate
virtual 3D model of the patient's dental arch at that treatment
stage may be generated. The shape of each virtual 3D model will be
different. The original virtual 3D model, the final virtual 3D
model and each intermediate virtual 3D model is unique and
customized to the patient.
[0077] The processing logic may determine an initial shape for a
mold of the patient's dental arch at a treatment stage based on the
digital model of the dental arch at that treatment stage.
Processing logic may additionally determine one or more features to
add to the mold that will cause the aligner formed over the mold to
have the determined markings and/or elements.
[0078] The processing logic may determine a final shape for the
mold and may generate a digital model of the mold. Alternatively,
the digital model may have already been generated. In such an
instance, processing logic updates the already generated digital
model to include the determined features for the mold. The digital
model may be represented in a file such as a computer aided
drafting (CAD) file or a 3D printable file such as a
stereolithography (STL) file. The digital model may include
instructions that will control a fabrication system or device in
order to produce the mold with specified geometries.
[0079] At block 504, a corresponding mold is generated based on
each digital model. For example, a first mold may be generated for
a first digital model and a second mold may be generated for a
second digital model. Each virtual 3D model of a patient's dental
arch may be used to generate a unique customized mold of the dental
arch at a particular stage of treatment. The shape of the mold may
be at least in part based on the shape of the virtual 3D model for
that treatment stage. The mold may correspond to a dental arch of a
patient and the mold may include a sloping portion that commences
below a gum line of the dental arch and extends away from the
dental arch to a lower portion of the mold. A portion of the
thermoformed sheet of plastic 154 that is disposed on the sloping
portion of the mold is to be trimmed (e.g., at block 518 to trim
the aligners from the thermoformed sheet of plastic). In some
embodiments, at block 504, the mold is generated with the sloping
portion commencing below the gum line to assist in the release of
the thermoformed sheet of plastic from the mold. The mold may be
formed using a rapid prototyping equipment (e.g., 3D printers) to
manufacture the mold using additive manufacturing techniques (e.g.,
stereolithography) or subtractive manufacturing techniques (e.g.,
milling). The digital model may be input into a rapid prototyping
machine. The rapid prototyping machine then manufactures the mold
using the digital model. One example of a rapid prototyping
manufacturing machine is a 3D printer. 3D Printing includes any
layer-based additive manufacturing processes. 3D printing may be
achieved using an additive process, where successive layers of
material are formed in proscribed shapes. 3D printing may be
performed using extrusion deposition, granular materials binding,
lamination, photopolymerization, continuous liquid interface
production (CLIP), or other techniques. 3D printing may also be
achieved using a subtractive process, such as milling.
[0080] In one embodiment, stereolithography (SLA), also known as
optical fabrication solid imaging, is used to fabricate an SLA
mold. In SLA, the mold is fabricated by successively printing thin
layers of a photo-curable material (e.g., a polymeric resin) on top
of one another. A platform rests in a bath of a liquid photopolymer
or resin just below a surface of the bath. A light source (e.g., an
ultraviolet laser) traces a pattern over the platform, curing the
photopolymer where the light source is directed, to form a first
layer of the mold. The platform is lowered incrementally, and the
light source traces a new pattern over the platform to form another
layer of the mold at each increment. This process repeats until the
mold is completely fabricated. Once all of the layers of the mold
are formed, the mold may be cleaned and cured.
[0081] Materials such as a polyester, a co-polyester, a
polycarbonate, a polycarbonate, a thermoplastic polyurethane, a
polypropylene, a polyethylene, a polypropylene and polyethylene
copolymer, an acrylic, a cyclic block copolymer, a
polyetheretherketone, a polyamide, a polyethylene terephthalate, a
polybutylene terephthalate, a polyetherimide, a polyethersulfone, a
polytrimethylene terephthalate, a styrenic block copolymer (SBC), a
silicone rubber, an elastomeric alloy, a thermoplastic elastomer
(TPE), a thermoplastic vulcanizate (TPV) elastomer, a polyurethane
elastomer, a block copolymer elastomer, a polyolefin blend
elastomer, a thermoplastic co-polyester elastomer, a thermoplastic
polyamide elastomer, or combinations thereof, may be used to
directly form the mold. The materials used for fabrication of the
mold can be provided in an uncured form (e.g., as a liquid, resin,
powder, etc.) and can be cured (e.g., by photopolymerization, light
curing, gas curing, laser curing, crosslinking, etc.). The
properties of the material before curing may differ from the
properties of the material after curing.
[0082] Optionally, the rapid prototyping techniques described
herein allow for fabrication of a mold including multiple
materials, referred to herein as "multi-material direct
fabrication." In some embodiments, a multi-material direct
fabrication method involves concurrently forming an object from
multiple materials in a single manufacturing step. For instance, a
multi-tip extrusion apparatus can be used to selectively dispense
multiple types of materials (e.g., resins, liquid, solids, or
combinations thereof) from distinct material supply sources in
order to fabricate an object from a plurality of different
materials. Alternatively or in combination, a multi-material direct
fabrication method can involve forming an object from multiple
materials in a plurality of sequential manufacturing steps. For
instance, a first portion of the object (e.g., a main portion of
the mold) can be formed from a first material in accordance with
any of the direct fabrication methods herein, then a second portion
of the object (e.g., complex features added to the mold) can be
formed from a second material in accordance with methods herein,
and so on, until the entirety of the object has been formed. The
relative arrangement of the first and second portions can be varied
as desired. In one embodiment, multi-material direct fabrication is
used to cause a first material to be used for the markings of the
cut line on the mold, and to cause one or more additional materials
to be used for the remainder of the mold.
[0083] Aligners may be formed from each mold to provide forces to
move the patient's teeth. The shape of each aligner is unique and
customized for a particular patient and a particular treatment
stage. In an example, the aligners can be pressure formed or
thermoformed over the molds. Each mold may be used to fabricate an
aligner that will apply forces to the patient's teeth at a
particular stage of the orthodontic treatment. The aligners each
have teeth-receiving cavities that receive and resiliently
reposition the teeth in accordance with a particular treatment
stage.
[0084] At block 506, whether a first mold and a second mold are
below a threshold size (e.g., maximum profile 410 of FIGS. 4B-C) is
determined. Responsive to determining a size of a mold is below the
threshold size, flow continues to block 508 (e.g., the
corresponding aligner may be thermoformed simultaneously (or in
parallel) with another aligner). Responsive to determining the size
of a mold is above the threshold size, flow continues to block 520
where a single aligner at a time is generated for each mold greater
than the threshold size (e.g., instead of simultaneously
thermoforming the aligner with another aligner, at a standard
thermoforming apparatus).
[0085] At block 508, the first mold and the second mold are secured
to a plate (see FIGS. 4A-B). The first and second molds may be
secured to the plate via fasteners such as a pin, a keyway, and a
locking mechanism. The first and second molds may be secured to the
plate to avoid movement in the x-, y-, and z-direction and to avoid
rotation (e.g., change in angle) of the molds.
[0086] At block 510, a sheet of plastic is secured to a pallet (see
FIGS. 1 and 2A-C). The sheet of plastic may be an elastic
thermoplastic, a sheet of polymeric material, etc. The sheet of
plastic may be lowered onto the pallet so that holding pins of the
pallet pierce the sheet of plastic to secure the sheet of plastic
to the pallet.
[0087] At block 512, the sheet of plastic secured to the pallet is
surrounded by a mask (see FIGS. 1 and 2A-C). A pressurized cylinder
may lower the mask onto the sheet of plastic secured to the
pallet.
[0088] At block 514, the sheet of plastic is heated. The sheet of
plastic may be heated to a temperature at which the sheet of
plastic becomes pliable. The sheet of plastic may be heated using a
ceramic heater, convection oven, or infrared heater. The mask may
allow the sheet of plastic to be heated to 336.degree. F. without
hanging to avoid air leaks.
[0089] At block 516, the heated sheet of plastic is simultaneously
thermoformed to the first mold and the second mold that are secured
to the plate. To thermoform the heated sheet of plastic over the
two molds, pressure may concurrently be applied to the sheet of
plastic to form the now pliable sheet of plastic around the two
molds (e.g., with features that will imprint markings and/or
elements in the aligners formed on the molds). Once the sheet
cools, it will have a shape that conforms to both molds. In one
embodiment, a release agent (e.g., a non-stick material) is applied
to the molds before forming the aligners (e.g., shells). This may
facilitate later removal of the molds from the shells. In some
embodiments, the sheet of plastic is pressure formed over the first
mold and the second mold simultaneously.
[0090] At block 518, a first aligner and a second aligner are
trimmed from the thermoformed sheet of plastic. The thermoformed
sheet of plastic may be removed from the molds (e.g., using a shell
removal device). The thermoformed sheet of plastic may be trimmed
to generate the first and second aligners. In some embodiments, for
each mold, the portion of thermoformed sheet of plastic that is
disposed on a portion of the corresponding mold that slopes outward
below the gum line is removed during the trimming of the
thermoformed sheet of plastic to generate the aligners. After the
thermoformed sheet of plastic is removed from the mold for a
treatment stage, the thermoformed sheet of plastic is subsequently
trimmed along one or more cut lines (also referred to as a trim
line). The cut line may be a gingival cut line that represents an
interface between an aligner and a patient's gingiva. In one
embodiment, the aligner is manually cut by a technician using
scissors, a bur, a cutting wheel, a scalpel, or any other cutting
implement. In another embodiment, the aligner is cut by a computer
controlled trimming machine such as a CNC machine or a laser
trimming machine. The computer controlled trimming machine may
control an angle and position of a cutting tool of the trimming
machine to trim the thermoformed sheet of plastic. In some
embodiments, the thermoformed sheet of plastic is divided into two
parts (each part corresponding to a respective aligner) prior to
the trimming of thermoformed sheet of plastic to generate the
aligners.
[0091] Referring to FIG. 5B, at block 540 of method 500B, a first
size of a first mold of a first dental arch and a second size of a
second mold of a second dental arch are determined. In some
embodiments, the first and second sizes may be determined based on
digital models of the first mold and the second mold. In some
embodiments, the first and second sizes may be determined by
measuring the first mold and the second mold (e.g., via automated
optical measurement, manually, etc.). In some embodiments, the
sizes of the molds are compared to threshold sizes.
[0092] At block 542, a first plate, a first sheet of plastic, and a
first pallet are selected based on at least one of the first size
or the second size. In some embodiments, if the larger of the first
mold and the second mold meets a first threshold size, a first size
of plate, sheet of plastic, and/or pallet are selected. If the
larger of the first mold and the second mold meets a different
threshold size, a second size of plate, sheet of plastic, and/or
pallet are selected. In some embodiments, if the first mold and the
second mold in combination meet a first threshold size, a first
size of plate, sheet of plastic, and/or pallet are selected. In
some embodiments, multiple (e.g., three, such as small, medium, and
larger) sizes of plate, sheet of plastic, and/or pallet are
available from which to select. Selecting a correctly sized plate,
sheet of plastic, and/or pallet can minimize the amount of plastic
discarded and the amount of defective aligners.
[0093] At block 544, the first mold and the second mold are secured
to the first plate. Block 544 is similar to block 508 of method
500A of FIG. 5A. The first sheet of plastic is secured to the first
pallet and the first pallet securing the first sheet of plastic is
transferred to a heating station.
[0094] At block 546, the first sheet of plastic is heated (e.g., at
a heating station) to generate a first heated sheet. Block 546 is
similar to block 514 of method 500A of FIG. 5A. A mask may be
placed on the first sheet of plastic to minimize heat transfer from
the heater to other sheets of plastic. The first heated sheet may
be transferred to a thermoforming station.
[0095] At block 548, the first heated sheet is simultaneously
thermoformed (e.g., at a thermoforming station) over the first mold
of the first dental arch and the second mold of the second dental
arch to form a first aligner and a second aligner. To unload the
thermoformed sheet from the pallet and form the aligners, the
thermoformed sheet may be transferred to an unloading station.
Block 548 is similar to blocks 516-518 of method 500A of FIG.
5A.
[0096] In some embodiments, the transferring of the first plate
securing the first sheet of plastic is via a conveyor system (e.g.,
via lateral movement, via conveyor system 140 of FIG. 1A). In some
embodiments, the transferring of the first plate securing the first
sheet of plastic is via a dial system (e.g., via rotational
movement, via dial system 190A of FIG. 1B).
[0097] In some embodiments, the first mold and the second mold are
transferred to be located below the thermoforming station and are
lifted to have the heated sheet thermoformed over the first mold
and the second mold. In some embodiments, the transferring of the
first mold and the second mold to be located below the
thermoforming station is via lateral movement. In some embodiments,
the transferring of the first mold and the second mold to be
located below the thermoforming station is via rotational movement
(e.g., via dial system 190A of FIG. 1B).
[0098] FIG. 6 illustrates a diagrammatic representation of a
machine in the example form of a computing device 600 within which
a set of instructions, for causing the machine to perform any one
or more of the methodologies discussed with reference to the method
of FIG. 5. In alternative embodiments, the machine may be connected
(e.g., networked) to other machines in a Local Area Network (LAN),
an intranet, an extranet, or the Internet. For example, the machine
may be networked to a rapid prototyping apparatus such as a 3D
printer or SLA apparatus. The machine may operate in the capacity
of a server or a client machine in a client-server network
environment, or as a peer machine in a peer-to-peer (or
distributed) network environment. The machine may be a personal
computer (PC), a tablet computer, a set-top box (STB), a Personal
Digital Assistant (PDA), a cellular telephone, a web appliance, a
server, a network router, switch or bridge, or any machine capable
of executing a set of instructions (sequential or otherwise) that
specify actions to be taken by that machine. Further, while only a
single machine is illustrated, the term "machine" shall also be
taken to include any collection of machines (e.g., computers) that
individually or jointly execute a set (or multiple sets) of
instructions to perform any one or more of the methodologies
discussed herein.
[0099] The example computing device 600 includes a processing
device 602, a main memory 604 (e.g., read-only memory (ROM), flash
memory, dynamic random access memory (DRAM) such as synchronous
DRAM (SDRAM), etc.), a static memory 606 (e.g., flash memory,
static random access memory (SRAM), etc.), and a secondary memory
(e.g., a data storage device 628), which communicate with each
other via a bus 608.
[0100] Processing device 602 represents one or more general-purpose
processors such as a microprocessor, central processing unit, or
the like. More particularly, the processing device 602 may be a
complex instruction set computing (CISC) microprocessor, reduced
instruction set computing (RISC) microprocessor, very long
instruction word (VLIW) microprocessor, processor implementing
other instruction sets, or processors implementing a combination of
instruction sets. Processing device 602 may also be one or more
special-purpose processing devices such as an application specific
integrated circuit (ASIC), a field programmable gate array (FPGA),
a digital signal processor (DSP), network processor, or the like.
Processing device 602 is configured to execute the processing logic
(instructions 626) for performing operations and steps discussed
herein.
[0101] The computing device 600 may further include a network
interface device 622 for communicating with a network 664. The
computing device 600 also may include a video display unit 610
(e.g., a liquid crystal display (LCD) or a cathode ray tube (CRT)),
an alphanumeric input device 612 (e.g., a keyboard), a cursor
control device 614 (e.g., a mouse), and a signal generation device
620 (e.g., a speaker).
[0102] The data storage device 628 may include a machine-readable
storage medium (or more specifically a non-transitory
computer-readable storage medium) 624 on which is stored one or
more sets of instructions 626 embodying any one or more of the
methodologies or functions described herein. A non-transitory
storage medium refers to a storage medium other than a carrier
wave. The instructions 626 may also reside, completely or at least
partially, within the main memory 604 and/or within the processing
device 602 during execution thereof by the computing device 600,
the main memory 604 and the processing device 602 also constituting
computer-readable storage media.
[0103] The computer-readable storage medium 624 may also be used to
store one or more instructions for aligner production and/or an
aligner generator 650, which may perform one or more of the
operations of methods 500A-B described with reference to FIGS.
5A-B. The computer-readable storage medium 624 may also store a
software library containing methods that call an aligner generator
650. While the computer-readable storage medium 624 is shown in an
example embodiment to be a single medium, the term "non-transitory
computer-readable storage medium" should be taken to include a
single medium or multiple media (e.g., a centralized or distributed
database, and/or associated caches and servers) that store the one
or more sets of instructions. The term "non-transitory
computer-readable storage medium" shall also be taken to include
any medium that is capable of storing or encoding a set of
instructions for execution by the machine and that cause the
machine to perform any one or more of the methodologies of the
present disclosure. The term "non-transitory computer-readable
storage medium" shall accordingly be taken to include, but not be
limited to, solid-state memories, and optical and magnetic
media.
[0104] FIG. 7A illustrates an exemplary tooth repositioning
appliance or aligner 700 that can be worn by a patient in order to
achieve an incremental repositioning of individual teeth 702 in the
jaw. The aligner 700 may be trimmed from a thermoformed sheet of
plastic 154 (e.g., of FIG. 1A or FIG. 1B) that was formed by
simultaneous thermoforming of multiple aligners, as described
herein. The appliance can include a shell (e.g., a continuous
polymeric shell or a segmented shell) having teeth-receiving
cavities that receive and resiliently reposition the teeth. An
appliance or portion(s) thereof may be indirectly fabricated using
a physical model of teeth. For example, an appliance (e.g.,
polymeric appliance) can be formed using a physical model of teeth
and a sheet of suitable layers of polymeric material. A "polymeric
material," as used herein, may include any material formed from a
polymer. A "polymer," as used herein, may refer to a molecule
composed of repeating structural units connected by covalent
chemical bonds often characterized by a substantial number of
repeating units (e.g., equal to or greater than 3 repeating units,
optionally, in some embodiments equal to or greater than 10
repeating units, in some embodiments greater or equal to 30
repeating units) and a high molecular weight (e.g. greater than or
equal to 10,000 Da, in some embodiments greater than or equal to
50,000 Da or greater than or equal to 100,000 Da). Polymers are
commonly the polymerization product of one or more monomer
precursors. The term polymer includes homopolymers, or polymers
consisting essentially of a single repeating monomer subunit. The
term polymer also includes copolymers which are formed when two or
more different types of monomers are linked in the same polymer.
Useful polymers include organic polymers or inorganic polymers that
may be in amorphous, semi-amorphous, crystalline or
semi-crystalline states. Polymers may include polyolefins,
polyesters, polyacrylates, polymethacrylates, polystyrenes,
Polypropylenes, polyethylenes, Polyethylene terephthalates, poly
lactic acid, polyurethanes, epoxide polymers, polyethers,
poly(vinyl chlorides), polysiloxanes, polycarbonates, polyamides,
poly acrylonitriles, polybutadienes, poly(cycloolefins), and
copolymers. The systems and/or methods provided herein are
compatible with a range of plastics and/or polymers. Accordingly,
this list is not all inclusive, but rather is exemplary. The
plastics can be thermosets or thermoplastics. The plastic may be a
thermoplastic.
[0105] Examples of materials applicable to the embodiments
disclosed herein include, but are not limited to, those materials
described in the following patent applications filed by Align
Technology: "MULTILAYER DENTAL APPLIANCES AND RELATED METHODS AND
SYSTEMS," U.S. Pat. No. 9,655,691 to Li, et al., filed May 14,
2012; "SYSTEMS AND METHODS FOR VARYING ELASTIC MODULUS APPLIANCES,"
U.S. Pat. No. 6,964,564 to Phan, et al., filed Jul. 26, 2002;
"METHODS OF MAKING ORTHODONTIC APPLIANCES," U.S. Pat. No. 7,641,828
to DeSimone, et al., filed Oct. 12, 2004; "TREATMENT OF TEETH BY
ALIGNERS," U.S. Pat. No. 8,740,614 to Wen et al., filed Jul. 29,
2009; and any applications claiming benefit therefrom or providing
benefit thereto (including publications and issued patents),
including any divisional, continuation, or continuation-in-part
thereof, the content of which are incorporated by reference
herein.
[0106] Examples of materials applicable to the embodiments
disclosed herein include a hard polymer layer disposed between two
soft polymer layers. In some embodiments, the hard inner polymer
layer includes a co-polyester and has a polymer layer elastic
modulus. In some embodiments, a first soft outer polymer layer and
a second soft outer polymer layer each include a thermoplastic
polyurethane elastomer and each have a soft polymer elastic modulus
less than the hard polymer layer elastic modulus, a flexural
modulus of greater than about 35,000 psi, a hardness of about 60A
to about 85D, and a thickness in a range from 25 microns to 100
microns. In some embodiments, the hard inner polymer layer is
disposed between the first soft outer polymer layer and the second
soft outer polymer layer so as to reduce degradation of the
resilient position force applied to the teeth when the appliance is
worn. The hard polymer layer can include a polyester, a
co-polyester, a polycarbonate, a thermoplastic polyurethane, a
polypropylene, a polyethylene, a polypropylene and polyethylene
copolymer, an acrylic, a cyclic block copolymer, a
polyetheretherketone, a polyamide, a polyethylene terephthalate, a
polybutylene terephthalate, a polyetherimide, a polyethersulfone, a
polytrimethylene terephthalate or a combination thereof (e.g., a
blend of at least two of the listed hard polymeric materials). In
some embodiments, the hard polymer layer includes two or more hard
polymer layers. The soft outer polymer material may include a
styrenic block copolymer (SBC), a silicone rubber, an elastomeric
alloy, a thermoplastic elastomer (TPE), a thermoplastic vulcanizate
(TPV) elastomer, a polyurethane elastomer, a block copolymer
elastomer, a polyolefin blend elastomer, a thermoplastic
co-polyester elastomer, a thermoplastic polyamide elastomer, or a
combination thereof (e.g., a blend of at least two of the listed
soft polymeric materials). The soft polymer layers can be the same
material or a different material.
[0107] Examples of materials applicable to the embodiments
disclosed herein include a middle layer disposed between two
layers. The two layers individually include a thermoplastic polymer
having a flexural modulus of from about 1,000 MPa to 2,500 MPa and
a glass transition temperature and/or melting point of from about
80.degree. C. to 180.degree. C. The middle layer includes a
polyurethane elastomer having a flexural modulus of from about 50
MPa to about 500 MPa and one or more of a glass transition
temperature and/or melting point of from about 90.degree. C. to
about 220.degree. C. The polymeric sheet composition has a combined
thickness of the middle layer and the outer layers of from 250
microns to 2000 microns and a flexural modulus of from 500 MPa to
1,500 MPa. In some embodiments, the outer layers include one or
more of a co-polyester, a polycarbonate, a polyester polycarbonate
blend, a polyurethane, a polyamide, or a polyolefin. The middle
layer may have a Shore hardness of from A90 to D55 and a
compression set of less than 35% after 22 hours at 25.degree. C. In
some embodiments, the outer layers have a lateral restoring force
of less than 100 Newtons (N) per square centimeter when displayed
by 0.05 mm to 0.1 mm relative to each other. In some embodiments,
the interplay peel strength between the outer layers and the middle
layer is greater than 50 N per 2.5 cm. In some embodiments, the
combined thickness of the outer layers is from 50 microns to 1,000
microns. In some embodiments one or more of the outer layers
include a microcrystalline polyamide including of from 50 to 100
mole % of C6 to C14 aliphatic diacid moieties and about 50 to 100
mole % of 4,4'-methylene-bis(cyclohexylamine), having a glass
transition of between about 100.degree. C. and 180.degree. C., a
heat of fusion of less than 20 J/g and a light transmission of
greater than 80%. In some embodiments, one or more of the outer
layers includes a co-polyester including: a dicarboxylic acid
component including 70 mole % to 100 mole % of terephthalic acid
residues; and a diol component including (i) 0 to 90 mole %
ethylene glycol, (ii) 5 mole % to 50 mole % of
2,2,4,4-tetramethyl-1,3-cyclobutanediol residues, (iii) 50 mole %
to 95 mole % 1,4-cyclohexanedimethanol residues, and (iv) 0 to 1
mole % of a polyol having three or more hydroxyl groups, where the
sum of the mole % of diol residues (i), (ii), (iii), and (iv)
amounts to 100 mole % and the co-polyester exhibits a glass
transition temperature Tg from 80.degree. C. to 150.degree. C. In
some embodiments, the middle layer includes an aromatic polyether
polyurethane having a Shore hardness of from A90 to D55 and a
compression set of less than 35%, where the interlayer peel
strength between the outer layers and the middle layer is greater
than 50 N per 2.5 cm. In some embodiments, one or more of the outer
layers includes a polyurethane that includes: a di-isocyanate
including 80 mole % to 100 mole % of methylene diphenyl
diisocyanate residues and/or hydrogenated methylene diphenyl
diisocyanate; and a diol component including: (i) 0 to 100 mole %
hexamethylene diol; and (ii) 0 to 50 mole %
1,4-cyclohexanedimethanol, where the sum of (i) and (ii) amounts to
greater than 90 mole % and the polyurethane has a glass transition
temperature Tg from about 85.degree. C. to about 150.degree. C.
[0108] Although polymeric aligners are discussed herein, the
techniques disclosed may also be applied to aligners having
different materials. Some embodiments are discussed herein with
reference to orthodontic aligners (also referred to simply as
aligners). However, embodiments also extend to other types of
shells formed over molds, such as orthodontic retainers,
orthodontic splints, sleep appliances for mouth insertion (e.g.,
for minimizing snoring, sleep apnea, etc.) and/or shells for
non-dental applications. Accordingly, it should be understood that
embodiments herein that refer to aligners also apply to other types
of shells. For example, the principles, features and methods
discussed may be applied to any application or process in which it
is useful to perform simultaneous forming multiple shells which are
any suitable type of shells that are form fitting devices such as
eye glass frames, contact or glass lenses, hearing aids or plugs,
artificial knee caps, prosthetic limbs and devices, orthopedic
inserts, as well as protective equipment such as knee guards,
athletic cups, or elbow, chin, and shin guards and other like
athletic/protective devices.
[0109] The aligner 700 can fit over all teeth present in an upper
or lower jaw, or less than all of the teeth. The appliance can be
designed specifically to accommodate the teeth of the patient
(e.g., the topography of the tooth-receiving cavities matches the
topography of the patient's teeth), and may be fabricated based on
positive or negative models of the patient's teeth generated by
impression, scanning, and the like. Alternatively, the appliance
can be a generic appliance configured to receive the teeth, but not
necessarily shaped to match the topography of the patient's teeth.
In some cases, only certain teeth received by an appliance will be
repositioned by the appliance while other teeth can provide a base
or anchor region for holding the appliance in place as it applies
force against the tooth or teeth targeted for repositioning. In
some cases, some, most, or even all of the teeth will be
repositioned at some point during treatment. Teeth that are moved
can also serve as a base or anchor for holding the appliance as it
is worn by the patient. Typically, no wires or other means will be
provided for holding an appliance in place over the teeth. In some
cases, however, it may be desirable or necessary to provide
individual attachments or other anchoring elements 704 on teeth 702
with corresponding receptacles or apertures 706 in the appliance
700 so that the appliance can apply a selected force on the tooth.
Exemplary appliances, including those utilized in the
Invisalign.RTM. System, are described in numerous patents and
patent applications assigned to Align Technology, Inc. including,
for example, in U.S. Pat. Nos. 6,450,807, and 5,975,893, as well as
on the company's website, which is accessible on the World Wide Web
(see, e.g., the url "invisalign.com"). Examples of tooth-mounted
attachments suitable for use with orthodontic appliances are also
described in patents and patent applications assigned to Align
Technology, Inc., including, for example, U.S. Pat. Nos. 6,309,215
and 6,830,450.
[0110] FIG. 7B illustrates a tooth repositioning system 710
including a plurality of appliances 712, 714, 716. The appliances
712, 714, 716 may be trimmed from a thermoformed sheet of plastic
that was formed via simultaneous thermoforming of multiple
aligners, as described herein. Any of the appliances described
herein can be designed and/or provided as part of a set of a
plurality of appliances used in a tooth repositioning system. Each
appliance may be configured so a tooth-receiving cavity has a
geometry corresponding to an intermediate or final tooth
arrangement intended for the appliance. The patient's teeth can be
progressively repositioned from an initial tooth arrangement to a
target tooth arrangement by placing a series of incremental
position adjustment appliances over the patient's teeth. For
example, the tooth repositioning system 710 can include a first
appliance 712 corresponding to an initial tooth arrangement, one or
more intermediate appliances 714 corresponding to one or more
intermediate arrangements, and a final appliance 716 corresponding
to a target arrangement. A target tooth arrangement can be a
planned final tooth arrangement selected for the patient's teeth at
the end of all planned orthodontic treatment. Alternatively, a
target arrangement can be one of some intermediate arrangements for
the patient's teeth during the course of orthodontic treatment,
which may include various different treatment scenarios, including,
but not limited to, instances where surgery is recommended, where
interproximal reduction (IPR) is appropriate, where a progress
check is scheduled, where anchor placement is best, where palatal
expansion is desirable, where restorative dentistry is involved
(e.g., inlays, onlays, crowns, bridges, implants, veneers, and the
like), etc. As such, it is understood that a target tooth
arrangement can be any planned resulting arrangement for the
patient's teeth that follows one or more incremental repositioning
stages. Likewise, an initial tooth arrangement can be any initial
arrangement for the patient's teeth that is followed by one or more
incremental repositioning stages.
[0111] In some embodiments, the appliances 712, 714, 716 (or
portions thereof) can be produced using indirect fabrication
techniques, such as by thermoforming over a positive or negative
mold. Indirect fabrication of an orthodontic appliance can involve
producing a positive or negative mold of the patient's dentition in
a target arrangement (e.g., by rapid prototyping, milling, etc.)
and thermoforming one or more sheets of material over the mold in
order to generate an appliance shell.
[0112] In an example of indirect fabrication, a mold of a patient's
dental arch may be fabricated from a digital model of the dental
arch, and a shell may be formed over the mold (e.g., by
thermoforming a polymeric sheet over the mold of the dental arch
and then trimming the thermoformed polymeric sheet). The
fabrication of the mold may be performed by a rapid prototyping
machine (e.g., a stereolithography (SLA) 3D printer). The rapid
prototyping machine may receive digital models of molds of dental
arches and/or digital models of the appliances 712, 714, 716 after
the digital models of the appliances 712, 714, 716 have been
processed by processing logic of a computing device, such as the
computing device in FIG. 6. The processing logic may include
hardware (e.g., circuitry, dedicated logic, programmable logic,
microcode, etc.), software (e.g., instructions executed by a
processing device), firmware, or a combination thereof. For
example, one or more operations may be performed by a processing
device executing an aligner generator 650.
[0113] To manufacture the molds, a shape of a dental arch for a
patient at a treatment stage is determined based on a treatment
plan. In the example of orthodontics, the treatment plan may be
generated based on an intraoral scan of a dental arch to be
modeled. The intraoral scan of the patient's dental arch may be
performed to generate a three dimensional (3D) virtual model of the
patient's dental arch (mold). For example, a full scan of the
mandibular and/or maxillary arches of a patient may be performed to
generate 3D virtual models thereof. The intraoral scan may be
performed by creating multiple overlapping intraoral images from
different scanning stations and then stitching together the
intraoral images to provide a composite 3D virtual model. In other
applications, virtual 3D models may also be generated based on
scans of an object to be modeled or based on use of computer aided
drafting techniques (e.g., to design the virtual 3D mold).
Alternatively, an initial negative mold may be generated from an
actual object to be modeled (e.g., a dental impression or the
like). The negative mold may then be scanned to determine a shape
of a positive mold that will be produced.
[0114] Once the virtual 3D model of the patient's dental arch is
generated, a dental practitioner may determine a desired treatment
outcome, which includes final positions and orientations for the
patient's teeth. Processing logic may then determine a number of
treatment stages to cause the teeth to progress from starting
positions and orientations to the target final positions and
orientations. The shape of the final virtual 3D model and each
intermediate virtual 3D model may be determined by computing the
progression of tooth movement throughout orthodontic treatment from
initial tooth placement and orientation to final corrected tooth
placement and orientation. For each treatment stage, a separate
virtual 3D model of the patient's dental arch at that treatment
stage may be generated. The shape of each virtual 3D model will be
different. The original virtual 3D model, the final virtual 3D
model and each intermediate virtual 3D model is unique and
customized to the patient.
[0115] Accordingly, multiple different virtual 3D models (digital
designs) of a dental arch may be generated for a single patient. A
first virtual 3D model may be a unique model of a patient's dental
arch and/or teeth as they presently exist, and a final virtual 3D
model may be a model of the patient's dental arch and/or teeth
after correction of one or more teeth and/or a jaw. Multiple
intermediate virtual 3D models may be modeled, each of which may be
incrementally different from previous virtual 3D models.
[0116] Each virtual 3D model of a patient's dental arch may be used
to generate a unique customized physical mold of the dental arch at
a particular stage of treatment. The shape of the mold may be at
least in part based on the shape of the virtual 3D model for that
treatment stage. The virtual 3D model may be represented in a file
such as a computer aided drafting (CAD) file or a 3D printable file
such as a stereolithography (STL) file. The virtual 3D model for
the mold may be sent to a third party (e.g., clinician office,
laboratory, manufacturing facility or other entity). The virtual 3D
model may include instructions that will control a fabrication
system or device in order to produce the mold with specified
geometries.
[0117] A clinician office, laboratory, manufacturing facility or
other entity may receive the virtual 3D model of the mold, the
digital model having been created as set forth above. The entity
may input the digital model into a rapid prototyping machine. The
rapid prototyping machine then manufactures the mold using the
digital model. One example of a rapid prototyping manufacturing
machine is a 3D printer. 3D printing includes any layer-based
additive manufacturing processes. 3D printing may be achieved using
an additive process, where successive layers of material are formed
in proscribed shapes. 3D printing may be performed using extrusion
deposition, granular materials binding, lamination,
photopolymerization, continuous liquid interface production (CLIP),
or other techniques. 3D printing may also be achieved using a
subtractive process, such as milling.
[0118] In some instances, stereolithography (SLA), also known as
optical fabrication solid imaging, is used to fabricate an SLA
mold. In SLA, the mold is fabricated by successively printing thin
layers of a photo-curable material (e.g., a polymeric resin) on top
of one another. A platform rests in a bath of a liquid photopolymer
or resin just below a surface of the bath. A light source (e.g., an
ultraviolet laser) traces a pattern over the platform, curing the
photopolymer where the light source is directed, to form a first
layer of the mold. The platform is lowered incrementally, and the
light source traces a new pattern over the platform to form another
layer of the mold at each increment. This process repeats until the
mold is completely fabricated. Once all of the layers of the mold
are formed, the mold may be cleaned and cured.
[0119] Materials such as a polyester, a co-polyester, a
polycarbonate, a polycarbonate, a thermopolymeric polyurethane, a
polypropylene, a polyethylene, a polypropylene and polyethylene
copolymer, an acrylic, a cyclic block copolymer, a
polyetheretherketone, a polyamide, a polyethylene terephthalate, a
polybutylene terephthalate, a polyetherimide, a polyethersulfone, a
polytrimethylene terephthalate, a styrenic block copolymer (SBC), a
silicone rubber, an elastomeric alloy, a thermopolymeric elastomer
(TPE), a thermopolymeric vulcanizate (TPV) elastomer, a
polyurethane elastomer, a block copolymer elastomer, a polyolefin
blend elastomer, a thermopolymeric co-polyester elastomer, a
thermopolymeric polyamide elastomer, or combinations thereof, may
be used to directly form the mold. The materials used for
fabrication of the mold can be provided in an uncured form (e.g.,
as a liquid, resin, powder, etc.) and can be cured (e.g., by
photopolymerization, light curing, gas curing, laser curing,
crosslinking, etc.). The properties of the material before curing
may differ from the properties of the material after curing.
[0120] Appliances may be formed from each mold and when applied to
the teeth of the patient, may provide forces to move the patient's
teeth as dictated by the treatment plan. The shape of each
appliance is unique and customized for a particular patient and a
particular treatment stage. In an example, the appliances 712, 714,
716 can be pressure formed or thermoformed over the molds. Each
mold may be used to fabricate an appliance that will apply forces
to the patient's teeth at a particular stage of the orthodontic
treatment. The appliances 712, 714, 716 each have teeth-receiving
cavities that receive and resiliently reposition the teeth in
accordance with a particular treatment stage.
[0121] In one embodiment, a sheet of material is pressure formed or
thermoformed over the mold. The sheet may be, for example, a sheet
of polymeric (e.g., an elastic thermopolymeric, a sheet of
polymeric material, etc.). To thermoform the shell over the mold,
the sheet of material may be heated to a temperature at which the
sheet becomes pliable. Pressure may concurrently be applied to the
sheet to form the now pliable sheet around the mold. Once the sheet
cools, it will have a shape that conforms to the mold. In one
embodiment, a release agent (e.g., a non-stick material) is applied
to the mold before forming the shell. This may facilitate later
removal of the mold from the shell. Forces may be applied to lift
the appliance from the mold. In some instances, a breakage,
warpage, or deformation may result from the removal forces.
Accordingly, embodiments disclosed herein may determine where the
probable point or points of damage may occur in a digital design of
the appliance prior to manufacturing and may perform a corrective
action.
[0122] Additional information may be added to the appliance. The
additional information may be any information that pertains to the
appliance. Examples of such additional information includes a part
number identifier, patient name, a patient identifier, a case
number, a sequence identifier (e.g., indicating which appliance a
particular liner is in a treatment sequence), a date of
manufacture, a clinician name, a logo and so forth. For example,
after determining there is a probable point of damage in a digital
design of an appliance, an indicator may be inserted into the
digital design of the appliance. The indicator may represent a
recommended place to begin removing the polymeric appliance to
prevent the point of damage from manifesting during removal in some
embodiments.
[0123] In some embodiments, a library of removal methods/patterns
may be established and this library may be referenced when
simulating the removal of the aligner in the numerical simulation.
Different patients or production technicians may tend to remove
aligners differently, and there might be a few typical patterns.
For example: 1) some patients lift from the lingual side of
posteriors first (first left and then right, or vice versa), and
then go around the arch from left/right posterior section to the
right/left posterior section; 2) similar to #1, but some other
patients lift only one side of the posterior and then go around the
arch; 3) similar to #1, but some patients lift from the buccal side
rather than the lingual side of the posterior; 4) some patients
lift from the anterior incisors and pull hard to remove the
aligner; 5) some other patients grab both lingual and buccal side
of a posterior location and pull out both sides at the same time;
6) some other patients grab a random tooth in the middle. The
library can also include a removal guideline provided by the
manufacturer of the aligner. Removal approach may also depend on
presence or absence of attachments on teeth as some of the above
method may result in more comfortable way of removal. Based on the
attachment situation on each tooth, it can be determined how each
patient would probably remove an aligner and adapt that removal
procedure for that patient in that specific simulation.
[0124] After an appliance is formed over a mold for a treatment
stage, the appliance is removed from the mold (e.g., automated
removal of the appliance from the mold), and the appliance is
subsequently trimmed along a cutline (also referred to as a trim
line). The processing logic may determine a cutline for the
appliance. The determination of the cutline(s) may be made based on
the virtual 3D model of the dental arch at a particular treatment
stage, based on a virtual 3D model of the appliance to be formed
over the dental arch, or a combination of a virtual 3D model of the
dental arch and a virtual 3D model of the appliance. The location
and shape of the cutline can be important to the functionality of
the appliance (e.g., an ability of the appliance to apply desired
forces to a patient's teeth) as well as the fit and comfort of the
appliance. For shells such as orthodontic appliances, orthodontic
retainers and orthodontic splints, the trimming of the shell may
play a role in the efficacy of the shell for its intended purpose
(e.g., aligning, retaining or positioning one or more teeth of a
patient) as well as the fit of the shell on a patient's dental
arch. For example, if too much of the shell is trimmed, then the
shell may lose rigidity and an ability of the shell to exert force
on a patient's teeth may be compromised. When too much of the shell
is trimmed, the shell may become weaker at that location and may be
a point of damage when a patient removes the shell from their teeth
or when the shell is removed from the mold. In some embodiments,
the cut line may be modified in the digital design of the appliance
as one of the corrective actions taken when a probable point of
damage is determined to exist in the digital design of the
appliance.
[0125] On the other hand, if too little of the shell is trimmed,
then portions of the shell may impinge on a patient's gums and
cause discomfort, swelling, and/or other dental issues.
Additionally, if too little of the shell is trimmed at a location,
then the shell may be too rigid at that location. In some
embodiments, the cutline may be a straight line across the
appliance at the gingival line, below the gingival line, or above
the gingival line. In some embodiments, the cutline may be a
gingival cutline that represents an interface between an appliance
and a patient's gingiva. In such embodiments, the cutline controls
a distance between an edge of the appliance and a gum line or
gingival surface of a patient.
[0126] Each patient has a unique dental arch with unique gingiva.
Accordingly, the shape and position of the cutline may be unique
and customized for each patient and for each stage of treatment.
For instance, the cutline is customized to follow along the gum
line (also referred to as the gingival line). In some embodiments,
the cutline may be away from the gum line in some regions and on
the gum line in other regions. For example, it may be desirable in
some instances for the cutline to be away from the gum line (e.g.,
not touching the gum) where the shell will touch a tooth and on the
gum line (e.g., touching the gum) in the interproximal regions
between teeth. Accordingly, it is important that the shell be
trimmed along a predetermined cutline.
[0127] FIG. 7C illustrates a method 750 of orthodontic treatment
using a plurality of appliances, in accordance with embodiments.
One or more of the plurality of appliances may be generated from
simultaneous thermoforming of multiple aligners (e.g., two or more
of the plurality of appliances may be simultaneously thermoformed
using an aligner manufacturing system, as described herein). The
method 750 can be practiced using any of the appliances or
appliance sets described herein. In block 760, a first orthodontic
appliance is applied to a patient's teeth in order to reposition
the teeth from a first tooth arrangement to a second tooth
arrangement. In block 770, a second orthodontic appliance is
applied to the patient's teeth in order to reposition the teeth
from the second tooth arrangement to a third tooth arrangement. The
method 750 can be repeated as necessary using any suitable number
and combination of sequential appliances in order to incrementally
reposition the patient's teeth from an initial arrangement to a
target arrangement. The appliances can be generated all at the same
stage or in sets or batches (e.g., at the beginning of a stage of
the treatment), or the appliances can be fabricated one at a time,
and the patient can wear each appliance until the pressure of each
appliance on the teeth can no longer be felt or until the maximum
amount of expressed tooth movement for that given stage has been
achieved. A plurality of different appliances (e.g., a set) can be
designed and even fabricated prior to the patient wearing any
appliance of the plurality. After wearing an appliance for an
appropriate period of time, the patient can replace the current
appliance with the next appliance in the series until no more
appliances remain. The appliances are generally not affixed to the
teeth and the patient may place and replace the appliances at any
time during the procedure (e.g., patient-removable appliances). The
final appliance or several appliances in the series may have a
geometry or geometries selected to overcorrect the tooth
arrangement. For instance, one or more appliances may have a
geometry that would (if fully achieved) move individual teeth
beyond the tooth arrangement that has been selected as the "final."
Such over-correction may be desirable in order to offset potential
relapse after the repositioning method has been terminated (e.g.,
permit movement of individual teeth back toward their pre-corrected
positions). Over-correction may also be beneficial to speed the
rate of correction (e.g., an appliance with a geometry that is
positioned beyond a desired intermediate or final position may
shift the individual teeth 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. Furthermore,
over-correction may be deliberately applied in order to compensate
for any inaccuracies or limitations of the appliance.
[0128] FIG. 8 illustrates a method 800 for designing an orthodontic
appliance to be produced by direct fabrication, in accordance with
embodiments. The method 800 can be applied to any embodiment of the
orthodontic appliances described herein. Some or all of the blocks
of the method 800 can be performed by any suitable data processing
system or device, e.g., one or more processors configured with
suitable instructions.
[0129] In block 810, a movement path to move one or more teeth from
an initial arrangement to a target arrangement is determined. The
initial arrangement can be determined from a mold or a scan of the
patient's teeth or mouth tissue, e.g., using wax bites, direct
contact scanning, x-ray imaging, tomographic imaging, sonographic
imaging, and other techniques for obtaining information about the
position and structure of the teeth, jaws, gums and other
orthodontically relevant tissue. From the obtained data, a digital
data set can be derived that represents the initial (e.g.,
pretreatment) arrangement of the patient's teeth and other tissues.
Optionally, the initial digital data set is processed to segment
the tissue constituents from each other. For example, data
structures that digitally represent individual tooth crowns can be
produced. Advantageously, digital models of entire teeth can be
produced, including measured or extrapolated hidden surfaces and
root structures, as well as surrounding bone and soft tissue.
[0130] The target arrangement of the teeth (e.g., a desired and
intended end result of orthodontic treatment) can be received from
a clinician in the form of a prescription, can be calculated from
basic orthodontic principles, and/or can be extrapolated
computationally from a clinical prescription. With a specification
of the desired final positions of the teeth and a digital
representation of the teeth themselves, the final position and
surface geometry of each tooth can be specified to form a complete
model of the tooth arrangement at the desired end of treatment.
[0131] Having both an initial position and a target position for
each tooth, a movement path can be defined for the motion of each
tooth. In some embodiments, the movement paths are configured to
move the teeth in the quickest fashion with the least amount of
round-tripping to bring the teeth from their initial positions to
their desired target positions. The tooth paths can optionally be
segmented, and the segments can be calculated so that each tooth's
motion within a segment stays within threshold limits of linear and
rotational translation. In this way, the end points of each path
segment can constitute a clinically viable repositioning, and the
aggregate of segment end points can constitute a clinically viable
sequence of tooth positions, so that moving from one point to the
next in the sequence does not result in a collision of teeth.
[0132] In block 820, a force system to produce movement of the one
or more teeth along the movement path is determined. A force system
can include one or more forces and/or one or more torques.
Different force systems can result in different types of tooth
movement, such as tipping, translation, rotation, extrusion,
intrusion, root movement, etc. Biomechanical principles, modeling
techniques, force calculation/measurement techniques, and the like,
including knowledge and approaches commonly used in orthodontia,
may be used to determine the appropriate force system to be applied
to the tooth to accomplish the tooth movement. In determining the
force system to be applied, sources may be considered including
literature, force systems determined by experimentation or virtual
modeling, computer-based modeling, clinical experience,
minimization of unwanted forces, etc.
[0133] The determination of the force system can include
constraints on the allowable forces, such as allowable directions
and magnitudes, as well as desired motions to be brought about by
the applied forces. For example, in fabricating palatal expanders,
different movement strategies may be desired for different
patients. For example, the amount of force needed to separate the
palate can depend on the age of the patient, as very young patients
may not have a fully-formed suture. Thus, in juvenile patients and
others without fully-closed palatal sutures, palatal expansion can
be accomplished with lower force magnitudes. Slower palatal
movement can also aid in growing bone to fill the expanding suture.
For other patients, a more rapid expansion may be desired, which
can be achieved by applying larger forces. These requirements can
be incorporated as needed to choose the structure and materials of
appliances; for example, by choosing palatal expanders capable of
applying large forces for rupturing the palatal suture and/or
causing rapid expansion of the palate. Subsequent appliance stages
can be designed to apply different amounts of force, such as first
applying a large force to break the suture, and then applying
smaller forces to keep the suture separated or gradually expand the
palate and/or arch.
[0134] The determination of the force system can also include
modeling of the facial structure of the patient, such as the
skeletal structure of the jaw and palate. Scan data of the palate
and arch, such as X-ray data or 3D optical scanning data, for
example, can be used to determine parameters of the skeletal and
muscular system of the patient's mouth, so as to determine forces
sufficient to provide a desired expansion of the palate and/or
arch. In some embodiments, the thickness and/or density of the
mid-palatal suture may be measured, or input by a treating
professional. In other embodiments, the treating professional can
select an appropriate treatment based on physiological
characteristics of the patient. For example, the properties of the
palate may also be estimated based on factors such as the patient's
age--for example, young juvenile patients will typically require
lower forces to expand the suture than older patients, as the
suture has not yet fully formed.
[0135] In block 830, appliance design for an orthodontic appliance
configured to produce the force system is determined. Determination
of the orthodontic appliance, appliance geometry, material
composition, and/or properties can be performed using a treatment
or force application simulation environment. A simulation
environment can include, e.g., computer modeling systems,
biomechanical systems or apparatus, and the like. Optionally,
digital models of the appliance and/or teeth can be produced, such
as finite element models. The finite element models can be created
using computer program application software available from a
variety of vendors. For creating solid geometry models, computer
aided engineering (CAE) or computer aided design (CAD) programs can
be used, such as the AutoCAD.RTM. software products available from
Autodesk, Inc., of San Rafael, Calif. For creating finite element
models and analyzing them, program products from a number of
vendors can be used, including finite element analysis packages
from ANSYS, Inc., of Canonsburg, Pa., and SIMULIA(Abaqus) software
products from Dassault Systemes of Waltham, Mass.
[0136] Optionally, one or more orthodontic appliances can be
selected for testing or force modeling. As noted above, a desired
tooth movement, as well as a force system required or desired for
eliciting the desired tooth movement, can be identified. Using the
simulation environment, a candidate orthodontic appliance can be
analyzed or modeled for determination of an actual force system
resulting from use of the candidate appliance. One or more
modifications can optionally be made to a candidate appliance, and
force modeling can be further analyzed as described, e.g., in order
to iteratively determine an appliance design that produces the
desired force system.
[0137] In block 840, instructions for fabrication of the
orthodontic appliance incorporating the appliance design are
generated. The instructions can be configured to control a
fabrication system or device in order to produce the orthodontic
appliance with the specified orthodontic appliance. In some
embodiments, the instructions are configured for manufacturing the
orthodontic appliance using direct fabrication (e.g.,
stereolithography, selective laser sintering, fused deposition
modeling, 3D printing, continuous direct fabrication,
multi-material direct fabrication, etc.), in accordance with the
various methods presented herein. In alternative embodiments, the
instructions can be configured for indirect fabrication of the
appliance, e.g., by thermoforming. In some embodiments, the
instructions for fabrication of the orthodontic appliance include
instructions for simultaneous thermoforming of multiple orthodontic
appliances (e.g., simultaneous thermoforming of multiple aligners
using an aligner manufacturing system, as described herein).
[0138] Method 800 may comprise additional blocks: 1) The upper arch
and palate of the patient is scanned intraorally to generate three
dimensional data of the palate and upper arch; and/or 2) The three
dimensional shape profile of the appliance is determined to provide
a gap and teeth engagement structures as described herein.
[0139] Although the above blocks show a method 800 of designing an
orthodontic appliance in accordance with some embodiments, a person
of ordinary skill in the art will recognize some variations based
on the teaching described herein. Some of the blocks may comprise
sub-blocks. Some of the blocks may be repeated as often as desired.
One or more blocks of the method 800 may be performed with any
suitable fabrication system or device, such as the embodiments
described herein. Some of the blocks may be optional, and the order
of the blocks can be varied as desired.
[0140] FIG. 9 illustrates a method 900 for digitally planning an
orthodontic treatment and/or design or fabrication of an appliance,
in accordance with embodiments. The method 900 can be applied to
any of the treatment procedures described herein and can be
performed by any suitable data processing system.
[0141] In block 910, a digital representation of a patient's teeth
is received. The digital representation can include surface
topography data for the patient's intraoral cavity (including
teeth, gingival tissues, etc.). The surface topography data can be
generated by directly scanning the intraoral cavity, a physical
model (positive or negative) of the intraoral cavity, or an
impression of the intraoral cavity, using a suitable scanning
device (e.g., a handheld scanner, desktop scanner, etc.).
[0142] In block 920, one or more treatment stages are generated
based on the digital representation of the teeth. The treatment
stages can be incremental repositioning stages of an orthodontic
treatment procedure designed to move one or more of the patient's
teeth from an initial tooth arrangement to a target arrangement.
For example, the treatment stages can be generated by determining
the initial tooth arrangement indicated by the digital
representation, determining a target tooth arrangement, and
determining movement paths of one or more teeth in the initial
arrangement necessary to achieve the target tooth arrangement. The
movement path can be optimized based on minimizing the total
distance moved, preventing collisions between teeth, avoiding tooth
movements that are more difficult to achieve, or any other suitable
criteria.
[0143] In block 930, at least one orthodontic appliance is
fabricated based on the generated treatment stages. For example, a
set of appliances can be fabricated, each shaped according a tooth
arrangement specified by one of the treatment stages, such that the
appliances can be sequentially worn by the patient to incrementally
reposition the teeth from the initial arrangement to the target
arrangement. The appliance set may include one or more of the
orthodontic appliances described herein. The fabrication of the
appliance may involve creating a digital model of the appliance to
be used as input to a computer-controlled fabrication system. The
appliance can be formed using direct fabrication methods, indirect
fabrication methods, or combinations thereof, as desired. The
fabrication of the appliance may include simultaneous thermoforming
of multiple appliances (e.g., simultaneous thermoforming of
multiple aligners via aligner manufacturing system 100, as
described herein).
[0144] In some instances, staging of various arrangements or
treatment stages may not be necessary for design and/or fabrication
of an appliance. As illustrated by the dashed line in FIG. 9,
design and/or fabrication of an orthodontic appliance, and perhaps
a particular orthodontic treatment, may include use of a
representation of the patient's teeth (e.g., receive a digital
representation of the patient's teeth at block 910), followed by
design and/or fabrication of an orthodontic appliance based on a
representation of the patient's teeth in the arrangement
represented by the received representation.
[0145] It is to be understood that the above description is
intended to be illustrative, and not restrictive. Many other
embodiments will be apparent upon reading and understanding the
above description. Although embodiments of the present disclosure
have been described with reference to specific example embodiments,
it will be recognized that the invention is not limited to the
embodiments described, but can be practiced with modification and
alteration within the spirit and scope of the appended claims.
Accordingly, the specification and drawings are to be regarded in
an illustrative sense rather than a restrictive sense. The scope of
the invention should, therefore, be determined with reference to
the appended claims, along with the full scope of equivalents to
which such claims are entitled.
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