U.S. patent application number 14/318283 was filed with the patent office on 2015-01-01 for method of forming a dental appliance.
The applicant listed for this patent is Align Technology, Inc.. Invention is credited to Yan Chen, Chunhua Li.
Application Number | 20150004553 14/318283 |
Document ID | / |
Family ID | 43588784 |
Filed Date | 2015-01-01 |
United States Patent
Application |
20150004553 |
Kind Code |
A1 |
Li; Chunhua ; et
al. |
January 1, 2015 |
METHOD OF FORMING A DENTAL APPLIANCE
Abstract
The present disclosure includes dental appliances and methods of
making and using such appliances. One method for forming a dental
appliance includes forming a liquid thermoset polymer material into
a semi-solid first shape, thermoforming the semi-solid first shape
of thermoset polymer material onto a dentition mold, and curing the
thermoset polymer on the dentition mold with a curative trigger to
complete a molecular cross-linking reaction.
Inventors: |
Li; Chunhua; (Cupertino,
CA) ; Chen; Yan; (Cupertino, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Align Technology, Inc. |
San Jose |
CA |
US |
|
|
Family ID: |
43588784 |
Appl. No.: |
14/318283 |
Filed: |
June 27, 2014 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
12583062 |
Aug 13, 2009 |
8765031 |
|
|
14318283 |
|
|
|
|
Current U.S.
Class: |
433/6 ;
264/16 |
Current CPC
Class: |
B29L 2031/7532 20130101;
B29K 2075/00 20130101; B29C 45/0001 20130101; B29B 11/14 20130101;
B29C 39/006 20130101; B29B 13/023 20130101; B29L 2031/753 20130101;
B29K 2101/10 20130101; A61C 7/08 20130101; B29C 51/002 20130101;
B29C 39/026 20130101; B29C 35/02 20130101; B29C 51/02 20130101 |
Class at
Publication: |
433/6 ;
264/16 |
International
Class: |
A61C 7/08 20060101
A61C007/08; B29C 45/00 20060101 B29C045/00 |
Claims
1. A method for forming a dental appliance for a patient,
comprising: forming a semi-solid formable first shape of thermoset
polymer material, wherein the semi-solid first shape of thermoset
polymer material is a different shape than the patient dentition;
and curing the thermoset polymer material to induce a molecular
cross-linking reaction to form the dental appliance, wherein the
dental appliance is a shell having a number of cavities to receive
one or more teeth.
2. The method of claim 1, wherein curing the thermoset polymer
includes adding a curative trigger to complete the molecular
cross-linking reaction.
3. The method of claim 2, wherein the curative trigger is
energy.
4. The method of claim 1, wherein the forming of the dental
appliance is accomplished by a process selected from the group
including: molding, extrusion, and rolling.
5. The method of claim 1, wherein the forming of the dental
appliance is accomplished by a process selected from the group
including: compression molding, liquid injection molding, or
reaction injection molding.
6. The method of claim 1, wherein the semi-solid formable first
shape is substantially horseshoe-shaped in at least one
dimension.
7. The method of claim 1, wherein the semi-solid formable first
shape is substantially horseshoe-shaped in at least two
dimensions.
8. A dental appliance comprising: a number of cavities to receive
one or more teeth, the cavities shaped to receive and resiliently
reposition teeth from a first arrangement to a second arrangement,
wherein: the dental appliance is fabricated from a thermoset
polymer material that is irreversibly cured to irreversibly link
molecules into a rigid three dimensional structure to form the
dental appliance, wherein the dental appliance is formed by a
process of curing a semi-solid formable shape of thermoset polymer
material to induce a molecular cross-linking reaction in the shape
of the second arrangement.
9. The dental appliance of claim 8, the dental appliance is one of
a series of dental appliances corresponding to steps of an
orthodontic treatment where the number of cavities are arranged to
reposition the one or more teeth from a first configuration to a
successive configuration.
10. The dental appliance of claim 8, wherein the dental appliance
is formed by formation of a semi-solid formable shape of thermoset
polymer material onto a dentition mold.
11. The dental appliance of claim 10, wherein the semi-solid shape
of thermoset polymer material is formed in a first mold and the
first mold is a different mold than the dentition mold.
12. The dental appliance of claim 11, wherein the dental appliance
is further formed by curing the semi-solid formable shape of
thermoset polymer material on the dentition mold to induce a
molecular cross-linking reaction.
13. A dental appliance comprising: a number of cavities to receive
one or more teeth, wherein: the dental appliance is one of a series
of dental appliances corresponding to intermediate steps of an
orthodontic treatment where the number of cavities are arranged to
reposition the one or more teeth from a first configuration to a
successive configuration, and the dental appliance is fabricated
from a thermoset polymer material that is irreversibly cured to
irreversibly link molecules into a rigid three dimensional
structure to form the dental appliance, wherein the dental
appliance is formed by a process of curing a semi-solid formable
shape of thermoset polymer material to induce a molecular
cross-linking reaction.
14. The appliance of claim 13, where the thermoset polymer material
has at least a one percent (1%) cross-linking network
structure.
15. The appliance of claim 13, where the thermoset polymer material
has a tensile strength at yield of greater than 6,000 psi.
16. The appliance of claim 13, where the thermoset polymer material
has an elongation at yield of greater than ten percent (10%).
17. The appliance of claim 13, where the thermoset polymer material
has an elongation at break of greater than eighty percent
(80%).
18. The appliance of claim 13, where the thermoset polymer material
has a tensile modulus at secant one percent (1%) greater than
100,000 psi.
19. The appliance of claim 13, where the thermoset polymer material
has a flexural modulus greater than 100,000 psi.
20. The appliance of claim 13, where the thermoset polymer material
has a stress relaxation in 37.degree. C. and 100% relative humidity
over 24 hours of more than twenty percent (20%).
Description
PRIORITY INFORMATION
[0001] This application is a Continuation of U.S. application Ser.
No. 12/583,062, filed Aug. 13, 2009, the specification of which is
incorporated herein by reference.
BACKGROUND
[0002] The present disclosure is related generally to the field of
dental treatment. More particularly, the present disclosure is
related to the fabrication of polymeric dental appliances for
orthodontic dental treatment.
[0003] Many dental treatments involve repositioning misaligned
teeth and changing bite configurations for improved cosmetic
appearance and dental function. Repositioning can be accomplished,
for example, by applying controlled forces to one or more teeth
over a period of time. Repositioning teeth for aesthetic or other
reasons has been accomplished by wearing what are commonly referred
to as "braces." Braces typically encompass a variety of hardware
such as brackets, archwires, ligatures, and O-rings.
[0004] Some dental processes use polymeric dental positioning
appliances, rather than braces, for realigning teeth. Such
appliances may, for example, utilize a thin shell of material
having resilient properties, referred to as an "aligner" that
generally conforms to a patient's teeth but is slightly out of
alignment with the present (e.g., initial) tooth configuration.
Placement of such an appliance over the teeth provides controlled
forces in specific locations to gradually move the teeth into a new
configuration. Repetition of this process with successive
appliances that provide progressive configurations eventually move
the teeth through a series of intermediate arrangements to a final
desired arrangement.
[0005] Many processes for forming such dental appliances utilize
thermoplastic material. These materials have a long period in which
the forming of the dental appliance can take place, and therefore
are desirable materials.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1A illustrates a jaw including patient's teeth and an
embodiment of a dental appliance to treat a dental condition of the
patient according to the present disclosure.
[0007] FIG. 1B illustrates a dental appliance cross section as
taken along line 1B-1B of FIG. 1A.
[0008] FIG. 1C illustrates a dental appliance cross section as
taken along line 1C-1C of FIG. 1A.
[0009] FIG. 2A is a block diagram illustrating a method for
fabricating a dental appliance according to an embodiment of the
present disclosure.
[0010] FIG. 2B is a block diagram illustrating another method
embodiment for fabricating a dental appliance according to the
present disclosure.
[0011] FIG. 3 illustrates an embodiment of a first shape with
respect to a dentition according to the present disclosure.
[0012] FIG. 4A illustrates an embodiment of a first shape
substantially horseshoe-shaped in at least one dimension according
to the present disclosure.
[0013] FIG. 4B illustrates a first shape cross section as taken
along line 4B-4B of FIG. 4A.
[0014] FIG. 5A illustrates an embodiment of a first shape
substantially horseshoe-shaped in at least two dimensions according
to the present disclosure.
[0015] FIG. 5B illustrates a first shape cross section as taken
along line 5B-5B of FIG. 5A.
[0016] FIG. 6 illustrates an embodiment of a first shape having a
variable thickness according to the present disclosure.
[0017] FIG. 7 illustrates working range curves of displacement as a
function of static force for a thermoset polymer material in
contrast to a thermoplastic material that may be used to form
dental appliances of embodiments according to the present
disclosure.
[0018] FIG. 8 illustrates stress relaxation performance curves of
percentage of load remaining as a function of time for a thermoset
polymer material in contrast to a thermoplastic material that may
be used to form dental appliances of embodiments according to the
present disclosure.
[0019] FIG. 9 illustrates a computing device embodiment to perform
a method for evaluating a dental condition according to an
embodiment of the present disclosure.
DETAILED DESCRIPTION
[0020] Embodiments of the present disclosure provide dental
appliances and methods of making and using such appliances. In
various embodiments, for example, a method embodiment for forming a
dental appliance is described that includes partially curing a
thermoset polymer material into a formable first shape. This method
embodiment further includes thermoforming the first shape of
thermoset polymer material onto a dentition mold, and fully curing
the thermoset polymer on the dentition mold to complete a molecular
cross-linking reaction.
[0021] In various embodiments, a dentition of the patient's teeth
can be formed in a number of ways. For example, an impression of
the patient's teeth can be taken to form the dentition.
[0022] In some instances, one or more digital models can be created
and used to form the dentition. For example, the patient's teeth or
the dentition created from the patient's teeth can be digitally
scanned and the data manipulated to form dentitions used for
repositioning teeth or for application of materials (e.g., chemical
treatments) to the patient's teeth.
[0023] For instance, a digital model can be used to fabricate a
dental appliance corresponding to a present, anticipated, and/or
desired configuration of the patient's dentition through analysis
and/or manipulation of the data set forming the digital model.
Additional detail on the use of digital modeling can be found in
commonly assigned U.S. patent application Ser. No. 12/283,770,
filed on Sep. 16, 2008, entitled "Dental Condition Evaluation and
Treatment", and having attorney docket number 1126.ALG.US.P.
[0024] A series of dental appliances, e.g., "aligners," generally
rely on designing and fabricating some, most, or all of the
appliances, to be worn by the patient over time, at the outset of
treatment, or while treatment is occurring. In some processes, the
design of the appliances uses computer modeling of a series of
successive tooth arrangements and the individual appliances are
designed to be worn over the teeth and to reposition the teeth by
using the appliances in a serial order, progressing from a first
appliance, through each of the intermediate appliances, to the last
appliance. An example of a dental treatment system, including a
series of dental appliances, e.g., "aligners," is described in
commonly-assigned U.S. Pat. No. 5,975,893, which is incorporated
herein in its entirety.
[0025] Dental aligners have been made of thermoplastic polymers,
since this category of polymer can be easily thermoformed into a
desired aligner configuration. For example, a sheet of
thermoplastic polymer material can be heated over a mold in order
to conform the thermoplastic polymer material to the shape of the
mold. The mold may be of an existing configuration of a patient's
teeth, or of an intended future configuration.
[0026] However, in some implementations, thermoplastic polymer
materials tend to fatigue over time, particularly under constant
loading, such as in orthodontic treatment applications.
Thermoplastic polymer materials may also tend to deform over time
due to stress relaxation of material, and/or material fatigue in
some instances.
[0027] In some applications, aligner deformation can reduce force
delivered to the teeth for some orthodontic movements, and thus,
can provide inconsistent application of force throughout a
particular course of treatment with a given aligner. In such
applications, the fatigue and/or deformation limitations associated
with thermoplastic polymer materials may limit the magnitude of
movement that can be obtained from a particular aligner, or the
time over which a particular aligner may be utilized.
[0028] In the embodiments described in the present disclosure,
aligners can be molded using a thermoset polymer material. As used
herein, a thermoset polymer material includes those polymeric
materials that once shaped by applied energy (e.g., heat, pressure,
radiation), or chemical reaction, so as to form a cross-linked
polymeric matrix, are incapable of being reprocessed into a
different form by further application of the particular energy.
[0029] That is, aligners can be molded using a category of polymers
that are irreversibly cured in the desired aligner configuration.
Examples of thermoset polymer materials include castable/casting
polyurethane, acrylate curable polymers, silicone thermoset
polymers and elastomers, and epoxy polymers, among others.
[0030] An aligner is formed to a patient's teeth, or to programmed
dentitions (e.g., intermediate teeth configurations of a proposed
orthodontic treatment plan). An aligner formed using thermoset
polymer materials is capable of capturing the details of a
particular dentition, either by intermediate thermoforming over the
dentition, or by another suitable process. Several examples of
methods for forming a dental appliance (e.g., an aligner) using
thermoset polymer materials are provided below.
[0031] FIG. 1A illustrates a jaw including patient's teeth and an
embodiment of a dental appliance to treat a dental condition of the
patient according to the present disclosure. The devices, methods,
or systems of the present disclosure can be, or employ, any manner
of positioners, trays, retainers, and/or other removable dental
appliances. The systems for use in various embodiments of the
present disclosure can utilize a single appliance, or a plurality
of such appliances that can, for example, be worn by a patient
successively in order to achieve the gradual tooth repositioning,
as described herein.
[0032] Accordingly, embodiments of the present disclosure are not
limited to an "aligner" that is intentionally fabricated slightly
out of alignment with the present tooth configuration so as to
provide force to one or more teeth. As will be appreciated, a
dental appliance according to embodiments of the present disclosure
may conform to a patient's tooth configuration. Thus, according to
at least one embodiment of the present disclosure, treatment
targeted at a particular tooth, several teeth, and/or the gingiva
can be accomplished concurrent with alignment treatment (e.g.,
tooth position adjustment), or separate and distinct from the
alignment treatment.
[0033] The present disclosure also includes one or more method
embodiments for forming (e.g., casting) a dental appliance. For
example, one such method embodiment includes delivering a fluid
(e.g., liquid, viscous mass) thermoset polymer precursor to a first
mold having an internal cavity.
[0034] The internal cavity has a surface corresponding to an
external surface of the dental appliance. The method further
includes placing a second mold in proximity to the first mold such
that a volume for the thermoset polymer precursor remains
therebetween, the second mold being a positive dentition mold
having an external surface corresponding to an internal surface of
the dental appliance, and curing the thermoset polymer precursor
with energy to complete a molecular cross-linking reaction, e.g.,
cause molecules of the thermoset polymer precursor to irreversibly
link into a rigid three dimensional structure.
[0035] In various apparatus embodiments, a tooth position
adjustment dental appliance is produced according to a method set
forth above, the dental appliance having cavities shaped to receive
and resiliently reposition teeth from a first arrangement to a
second arrangement. For example, a dental appliance can include a
shell having a number of cavities to receive one or more teeth
formed of cross-linked polymer materials. In some embodiments, the
shell is formed of thermoset polymer materials.
[0036] In one or more apparatus embodiments, the dental appliance
is an aligner (e.g., shell) having a number of cavities to receive
one or more teeth. The aligner is one of a series of aligners
corresponding to intermediate steps of an orthodontic treatment
where the number of cavities are arranged to reposition the one or
more teeth from a first configuration to a successive
configuration, and the aligner is fabricated from material that is
irreversibly cured to irreversibly link molecules into a rigid
three dimensional structure.
[0037] A dental appliance 106 (e.g., a dental positioning appliance
such as an aligner, a tray for delivery of chemicals in proximity
to the teeth or gums, etc.) can include a number of cavities for
receiving one or more corresponding teeth. In various embodiments,
the cavities can correspond to one, or multiple, teeth, implants,
and/or other features of a patient's jaw.
[0038] Embodiments of the present disclosure include dental
appliances, such as aligners for orthodontic positioning of one or
more teeth, formed from thermoset polymer materials. In contrast to
thermoplastics, thermoset polymer materials tend to fatigue less
over time when placed under constant loading, such as in
orthodontic treatment applications. Thermoset polymer materials
deform less over time due to stress relaxation of material, and
material fatigue, thereby maintaining the force delivered to the
teeth for orthodontic movements for a longer period, and providing
more consistent application of force throughout a particular course
of treatment.
[0039] Embodiments of the present disclosure are described in
relation to the accompanying drawings, which will at least assist
in illustrating the various features of the various embodiments. In
the Figures, the first digit of a reference number refers to the
Figure in which it is used, while the remaining two digits of the
reference number refer to the same or equivalent parts of
embodiment(s) of the present disclosure used throughout the several
figures of the drawing. The scaling of the figures does not
represent precise dimensions and/or dimensional ratios of the
various elements illustrated herein.
[0040] The dental appliance 106 may be designed to fit over a
number of, in many instances all teeth, present in an upper or
lower jaw. Dental appliances can be configured to apply force to
reposition one or more teeth from a first configuration of the
teeth to a successive configuration of the teeth, used in
application of medication or other beneficial materials in
proximity to one or more teeth and/or the gums, or used to hold
teeth in place, among other such uses.
[0041] In some embodiments, certain individual teeth, or small sets
of the teeth, can be repositioned while one or more other the teeth
provide a base or anchor region for holding the repositioning
appliance in place as it applies a resilient repositioning force
against the tooth or teeth to be repositioned. Some embodiments can
have repositioning portions, anchor portions, and/or portions that
cover a portion of a tooth or teeth but do not provide any force to
the covered tooth or teeth.
[0042] In various embodiments, one or more cavities of the dental
appliance are formed in an oversized manner with respect to the
teeth over which it is to be applied (e.g., by scaling-up) for
chemically treating one or more certain teeth. For example, one or
more chemicals (e.g., medications) or other materials may be
applied to the interior surface of the appliance due to the scaled
up nature of this appliance's fabrication.
[0043] FIG. 1B illustrates a dental appliance cross section 112, as
taken along line 1B-1B of FIG. 1A. FIG. 1C illustrates a dental
appliance cross section 118, as taken along line 1C-1C of FIG. 1A.
As illustrated, the dental appliance can have a U-shaped
cross-section to form one or more cavities for placement of a
patient's teeth therein. Such a shape can be formed, for example,
by placement of a partially cured thermoset polymer material over a
dentition mold (e.g., forming the inner surface).
[0044] Thermoset polymer material can be classified as uncured,
partially cured, or cured (i.e., fully cured). Uncured thermoset
polymer material describes unreacted resin (e.g., A-stage of cure).
Fully cured thermoset polymer material describes thermoset polymer
material having complete molecular cross-linking reaction, so as to
irreversibly cross-link molecules into a rigid three dimensional
structure (e.g., C-stage of cure). Partially cured thermoset
polymer material describes thermoset polymer material between
uncured and fully cured stages of cure (e.g., sometimes called the
green phase or B-stage of cure).
[0045] FIG. 2A is a block diagram illustrating a method for
fabricating a dental appliance according to an embodiment of the
present disclosure. According to one or more embodiments, a method
for forming a dental appliance includes forming and partially
curing a liquid thermoset polymer material into a semi-solid first
shape at 220. The method further includes thermoforming the
semi-solid first shape of thermoset polymer material onto a
dentition mold at 222, and curing the thermoset polymer on the
dentition mold with energy, or chemical reaction, to complete a
molecular cross-linking reaction at 224.
[0046] A wide range of processing techniques may be used for
forming, or partially curing, the liquid thermoset polymer material
into a semi-solid first shape, including molding, extrusion,
rolling, etc. Some suitable processing techniques for producing the
first shape include compression molding, such as is used to make
precision parts; liquid injection molding, for example using low
pressure in conjunction with a bottom fill mold; and reaction
injection molding with high pressure impingement mixing. Other
suitable processing techniques may also be used, including, but not
limited to: open casting; centrifugal molding, including
pipelining, making of sheet goods and use of multi-cavity molds;
ribbon flow moldless casting where the first shape is formed using
rollers rather than a mold; transfer molding, such as is used to
make multiple precision parts; rotational molding, often used to
make hollow items; vacuum casting, as may be used to make wire or
fiber inserts; pressure casting utilizing a pressure chamber;
B-staging used when the shape of particular molds create difficulty
in holding liquids; spray; solvent casting involving low pressure
for fabric penetration; and dipping for materials having a
sufficiently long working life which may be heat activated; among
others.
[0047] FIG. 2B is a block diagram illustrating another method
embodiment for fabricating a dental appliance according to the
present disclosure. According to one or more embodiments, a method
for forming a dental appliance includes delivering a fluid
thermoset polymer precursor to a first mold (e.g., to form a sheet
or shell, for example) at 226, partially curing the thermoset
polymer precursor in the first mold at 228, removing the partially
cured thermoset polymer precursor in a semi-solid state from the
first mold at 230, thermoforming the partially cured thermoset
polymer precursor onto a dentition mold at 232, and curing the
thermoset polymer precursor on the dentition mold with energy to
induce a cross-linking reaction at 234.
[0048] One example of a method embodiment such as that described in
FIG. 2B includes two or more urethane prepolymer components being
prepared and mixed with one or more curatives to initiate a
chemical reaction of the urethane prepolymer components. The
thermoset polymer precursor is cast, or molded, into a preliminary
configuration (e.g., sheet, shell), and partially cured.
[0049] As the thermoset polymer precursor begins to solidify into
thermoset polymer material, but while the sheet is still not fully
cured (e.g., a semi-solid state), it is often referred to as being
in a "green" phase. The green phase sheets may be removed from the
cast, or mold, and used to fabricate a dental appliance (e.g., an
aligner) such as by thermoforming the green phase sheet onto a
negative dentition mold of the intended configuration (e.g., 104 in
FIG. 1A). Thereafter (e.g., after forming into an aligner
configuration), the dental appliance can be further (e.g., fully)
cured.
[0050] In some embodiments, the dental appliance is formed using
green phase material that is further cured by exposure to a
curative trigger. The curative trigger can be one or more of energy
(e.g., light, heat, radiation), force (e.g., pressure), or chemical
reaction. After forming (e.g., applied to a mold), the green phase
material can be exposed to the curative trigger for some period of
time to allow the formed dental appliance to substantially cure as
a thermoset polymer material. However, embodiments of the present
disclosure are not limited to exposing the green phase material to
a curative trigger after forming in order to obtain substantial
curing.
[0051] In some embodiments, a dental appliance may be formed after
exposure of the green phase material to a curative trigger (e.g.,
at an appropriate time during curing as the thermoset polymer
precursor transitions to being substantially cured as a thermoset
polymer material). That is, curing may be initiated as a result of
a chemical reaction, and at some window of time during the curing
process, the partially cured materials are removed from a
preliminary configuration mold, thermoformed onto a dentition, and
allowed to continue curing thereon, without further exposure to a
curative trigger (e.g., energy, force, chemical, or other
trigger).
[0052] According to one or more embodiments, a method for forming a
dental appliance does not include forming green phase stock used
for further forming into a dental appliance. Rather, a dental
appliance is fabricated directly from the thermoset polymer
precursor materials.
[0053] For example, curable polymers can be mixed with the desired
components and initiators. This thermoset polymer precursor can
then be directly injected into a positive dentition mold, and
allowed to partially cure in the mold.
[0054] In this manner, a partially cured dental appliance can be
formed directly. This partially cured dental appliance aligner can
be further cured (e.g., fully), in the mold or after removal from
the mold, by application of energy such as radiation, light, heat,
pressure, or some combination thereof, to complete the
cross-linking reaction. Again, further curing is not limited by
input of additional energy, and can also occur without additional
application of additional energy or other curative trigger (e.g.,
force).
[0055] In some embodiments, the dental appliance can be molded of a
thermoset polymer material, as discussed herein. As will be
appreciated, the dental appliance can be placed within a molding
tool and the thermoset polymer precursor can be supplied to the
molding tool to form the dental appliance. Supplying the thermoset
polymer precursor can, for example, include injecting a fluid
thermoset polymer precursor, and an optional catalyst, into the
mold under low pressure to fill the mold cavity volume.
[0056] Since the thermoset polymer precursor can have a low
viscosity, the thermoset polymer precursor can substantially fill
spaces defined by various surfaces of the dental appliance. A
curative trigger (e.g., pressure, one or more chemicals, light
and/or heat that causes the thermoset polymer to finally cure) can
then be applied to cure the thermoset polymer precursor to form the
dental appliance.
[0057] In some embodiments, a method for molding a dental appliance
includes placing a mold having an internal cavity, where the
internal cavity includes a first portion and a second portion, at a
first position so that the second portion is in a higher relative
position than the first portion. Also, a thermoset polymer
precursor can be injected through the mold into the first portion
of the internal cavity to partially fill the internal cavity.
[0058] Once the thermoset polymer precursor has been injected, the
mold can be moved from a first position to a second position to
reorient the first portion and the second portion so the first
portion is in a higher relative position than the second portion.
The thermoset polymer precursor can then be injected through the
mold into the second portion of the internal cavity to at least
partially fill the internal cavity.
[0059] After partial or substantially complete curing, the dental
appliance can be removed from the mold. A post cure process can
also be used.
[0060] As will be appreciated, a variety of molding processes exist
that can be used to form the dental appliances. Examples of such
molding processes can include thermoset polymer precursor transfer
molding, compression molding, and injection molding, among
others.
[0061] In various embodiments, the dental appliance could be formed
in a casting process or stamping process. In one or more
embodiments, portions (e.g., layers, sections) of a dental
appliance can be individually formed (e.g., cast, molded) and
subsequently coupled together to form the dental appliance.
Examples of suitable techniques for coupling the individual
portions include use of natural or synthetic adhesives and/or
thermal energy to join the individual portions together.
[0062] As provided herein, thermoset polymer materials can be
formed from the cross-linking (e.g., polymerization) of one or more
thermoset polymer precursor(s). In the embodiments described
herein, the thermoset polymer precursor can be selected from an
unsaturated polyester, a polyurethane, an epoxy, an epoxy vinyl
ester, a phenolic, a silicone, an alkyd, an allylic, a vinyl ester,
a furan, a polyimide, a cyanate ester, a bismaleimide, a
polybutadiene, and a polyetheramide, among other suitable thermoset
polymer materials. In one embodiment, the thermoset polymer
precursor includes resin in an A-stage of cure (i.e., unreacted
resin).
[0063] As will be appreciated, the thermoset polymer material used
in the embodiments of the present disclosure can also include
reinforcement materials and/or additives such as one or more
fillers, wires, fibers, curing agents, inhibitors, catalysts, and
toughening agents (e.g., elastomers), among others, to achieve a
desirable combination of physical, mechanical, chemical, and/or
thermal properties. Reinforcement materials can include woven
and/or nonwoven fibrous materials, particulate materials, and/or
other high strength materials. Examples of reinforcement materials
can include, but are not limited to, synthetic fibers, natural
fibers, and ceramic fibers. Fillers include materials added to the
matrix of the thermoset polymer material to alter its physical,
mechanical, thermal, or chemical properties. Such fillers can
include, but are not limited to, organic and inorganic materials,
clays, silicates, mica, talcs, rubbers, fines, and paper, among
others.
[0064] In one or more embodiments, the classes of thermoset polymer
materials are biocompatible (e.g., thermoset polyurethanes,
silicone rubbers, and acrylics such as methyl methacrylate (MMA)
and polyethene glycol dimethacrylate (PEGDMA) copolymer).
Embodiments can use a material that is mechanically and/or
chemically stable in a saliva environment. In some embodiments, it
is beneficial for the thermoset polymer material to be chemically
resistant to teeth cleaning materials.
[0065] As will be appreciated, the thermoset polymer precursor can
be formed into the thermoset polymer material by a polymerization
reaction initiated and cured through heat, pressure, chemical
reaction with catalysts, ultraviolet light, irradiation (e.g.,
electron beam processing), and/or other types of energy. The curing
process transforms the thermoset polymer precursor into the
thermoset polymer by a cross-linking process.
[0066] Energy or catalysts may be added that cause the molecules to
react at chemically active sites, linking the molecules into a
rigid three-dimensional structure. The cross-linking process forms
a molecule with a relatively larger molecular weight, resulting in
a material having a higher melting point. The polymerization
reaction increases the molecular weight such that the material
solidifies, and will burn rather than melt at elevated
temperatures.
[0067] In one or more embodiments, the thermoset polymer material
of the present disclosure can have at least one percent (1%)
cross-linking network structure. This improves the structural
characteristics of the material for a dental appliance application
in some instances, as discussed further below.
[0068] The thermoset polymer material can have clarity
characteristics ranging from opaque to clear (e.g., transparent).
The thermoset polymer material can be non-colored or colored (e.g.,
include colored agents), which thereby may provide shading ranging
from a colored opaque to a tinted transparent, or further to a
clear transparent.
[0069] As previously discussed, polymeric dental positioning
appliances can be used for aligning teeth. Such appliances may, for
example, utilize a thin shell of material having resilient
properties that generally conforms to a patient's teeth but is
slightly out of alignment with the patient's teeth. Placement of
such an appliance over the teeth provides controlled forces in
specific locations to gradually move the teeth into a new
configuration.
[0070] Therefore, the material used to fabricate the polymeric
dental positioning appliances (e.g., an aligner) needs to have a
tensile strength such that when the material is deformed over an
initial tooth configuration, sufficient force may be transferred to
the tooth, or teeth, causing the deformation. Since deformation of
the polymeric dental positioning appliance is used to create the
forces applied to a tooth, or teeth, the material should be capable
of elongation without breakage, have sufficiently large tensile and
flexural moduli, and/or have stress relaxation characteristics that
allow for the generation of force by resilient opposition to
deformation.
[0071] In one or more embodiments, the thermoset polymer material
can have one or more of the following characteristics: a tensile
strength at yield of greater than 6,000 pounds per square inch
(psi), an elongation at yield of greater than ten percent (10%), an
elongation at break of greater than eighty percent (80%), a tensile
modulus at secant one percent (1%) greater than 100,000 psi, a
flexural modulus greater than 100,000 psi, and stress relaxation in
37.degree. C. and one hundred percent (100%) relative humidity over
24 hours of more than twenty percent (20%).
[0072] Dental appliances fabricated using thermoset polymer
material, such as those having one or more of the above-mentioned
characteristics, can be more resilient than that of thermoplastic
polymers. Due to the cross-linked structure, thermoset polymer
materials can retain their original shape better and/or longer than
thermoplastic polymers, and thereby maintain application of a
relatively more consistent force when used to achieve orthodontic
tooth movement. As will be appreciated, fabricating dental
appliances using thermoset polymer materials that retain their
original shape better and/or longer can improve dental appliance
performance, such as over a given treatment time of a particular
dental appliance (e.g., 2-3 weeks for some aligner embodiments),
since material fatigue is reduced.
[0073] Less material fatigue results, for example, in a more
constant force being delivered by a dental appliance formed with a
thermoset polymer material. Using a dental appliance fabricated of
thermoset polymer material for orthodontic treatment can also
result in more predictable outcomes (e.g., teeth movement) with
respect to original programmed movements in some instances.
Increasing predictability through better controlled force
application can reduce treating professional intervention to
correct a teeth configuration that does not match expected
results.
[0074] Improved performance can also support longer treatment
periods and/or greater tooth movement distance, and thus, fewer
intermediate aligners between an initial and final teeth position,
may be utilized in some instances. In turn, fabrication costs may
be reduced for some treatment plans, since fewer dental appliances
may be needed.
[0075] FIG. 3 illustrates an embodiment of a first shape 343 with
respect to a dentition 344 according to the present disclosure.
According to one or more embodiments, the first shape 343 can be
formed to be substantially flat, such as into a semi-solid sheet of
partially cured thermoset polymer material, for example.
[0076] The first shape 343 can be formed to have a substantially
constant thickness, or non-uniform thickness, (e.g., t as shown in
FIG. 3). The thickness of the first shape may, for example, be
based on jaw size or crown height, crown height being the dimension
of a tooth measured from the junction between the enamel of the
crown and the dentine of the roots, to the occlusal surface, as
will be understood by one having ordinary skill in the art. For
instance, a thicker first shape may provide more material, e.g.,
greater volume, to thermoform over a larger jaw size, e.g., larger
dentition molds. For example, relatively larger dental appliances
can also be provided with a thicker first shape 343, since the
first shape 343 may be stretched more in forming a larger sized
dental appliance relative to a smaller size dental appliance.
[0077] Non-uniform thickness can, for example, be utilized to
provide a more uniform final thickness to a dental appliance, as in
some instances, the thickness of the material may change as the
appliance is formed. Accordingly, sections that typically get
thinner during formation of the dental appliance, can be provided
with an extra thickness during formation of the first shape 343. In
some embodiments, extra thickness can be used to reinforce some
areas of the appliance. For example, in some areas, the extra
thickness can be used to provide extra force and/or rigidity to a
particular area of the appliance.
[0078] Non-uniform thickness can, for example, vary in the range of
10-30 mil.; however, embodiments of the present disclosure are not
limited to this range, and thickness may vary more, or less, than
the above-mentioned range. According to one or more embodiments, a
green phase first sheet is fabricated to include a non-uniform
thickness across the first sheet in the range of 20-30 mil., the
thickness at any particular point on the first sheet such that
after forming the dental appliance has a uniform thickness of 20
mil.
[0079] To achieve uniform thickness after forming and curing, areas
of the first sheet that will be subject to stretching and/or
thinning by bending during forming of the dental appliance over a
mold may be fabricated to have a greater thickness than areas of
the first sheet that will not be subject to such localized forming
forces. The reader will appreciate, that areas of the first sheet
corresponding to transitions during forming into a final dental
appliance, can be formed to have a greater thickness in the first
sheet to accommodate the change in thickness during the forming
transition.
[0080] The first sheet can be fabricated to have non-uniform
thickness, such that a dental appliance formed from the first sheet
having the non-uniform thickness, will also have non-uniform
thickness. For example, it may be desired to have an occlusal area
of a dental appliance (after forming) to have a different thickness
than a gingival area of the dental appliance. It may also be
desired, depending on the forces needed to move particular teeth,
to have one area of the dental appliance have a different thickness
than another area of the dental appliance. These areas of different
thickness in the final dental appliance may be achieved, at least
in part, by forming the dental appliance using a green phase first
sheet fabricated to have a non-uniform thickness across the first
sheet (e.g., the first sheet being thicker in areas corresponding
to areas of the dental appliance desired to have greater
thickness).
[0081] Computer analysis may be used to model such material forces
during formation from the first sheet (e.g., green phase) to the
final dental appliance, for example, by using a computer system
such as that illustrated in FIG. 9. Computer modeling and analysis
may also be used to predict forces used to achieve desired tooth
movement over a course of treatment, and how dental appliance
material thickness impacts those forces, such as uniform thickness
across the dental appliance and/or localized variations in material
thickness. A computer system may be used to simulate force,
accounting for material thickness, and in doing so determine
customized thickness characteristics for a particular first
sheet.
[0082] FIG. 4A illustrates an embodiment of a first shape 436
substantially horseshoe-shaped in at least one dimension according
to the present disclosure. As a patient's dentition, and the
polymeric dental appliances for orthodontic dental treatment, are
general horseshoe-shaped in at least one dimension, by forming the
first shape, e.g., 436, to be substantially horseshoe-shaped in at
least one dimension can save some material, compared with a
square-shaped, e.g., sheet-like, first shape.
[0083] FIG. 4B illustrates a first shape 436 cross section as taken
along line 4B-4B of FIG. 4A. The cross section of first shape 436
illustrates that the first shape can be formed to have a
non-uniform thickness. However in some embodiments, a first shape
that is substantially horseshoe-shaped in at least one dimension
can also be formed to be substantially flat, e.g., having a
constant thickness.
[0084] As one might envision first shape 436 being subsequently
thermoformed onto a dentition, the reader can appreciate the
location of side portions used to form the sides of a dental
appliance generally at lines 438 and 440 on the first shape. The
portion of the first shape 436 that will be formed into an occlusal
surface of the dental appliance is located generally between lines
439 and 441. The approximate location on the first shape 436 which
corresponds then to the transition from the occlusal surface to the
side surfaces after thermoforming onto a dentition is generally
between lines 438 and 439, and between lines 440 and 441
respectively.
[0085] The area between lines 438 and 440 on the first shape
corresponds to the location at which the occlusal surface area 442
will exist after thermoforming onto a dentition, as shown in FIGS.
4A and 4B. The thickness of the first sheet 436 need not be uniform
in cross section at lines 438 and 440 with respect to the occlusal
surface area 442. The thickness of a first shape can vary across
its cross section.
[0086] The material in some areas of the first shape may be
stretched further in forming a dental appliance; therefore, in some
instances it can be beneficial to have a greater quantity of
thermoset polymer material with which to use in stretching in
particular areas of the first shape. For a fixed area of the first
shape, and given a constant density of thermoset polymer material,
a greater quantity of thermoset polymer material corresponds to a
greater thickness in the fixed area.
[0087] One skilled in the art will appreciate then, that a thicker
first shape provides a greater quantity of thermoset polymer
material than a thinner first shape having the same planar area. It
will be further appreciated that for a larger jaw size, in order to
obtain a dental appliance with the same post-shaping thicknesses, a
greater quantity of thermoset polymer material is needed, which can
be obtained by using a thicker first shape for a given planar
area.
[0088] The thickness of the first shape can also vary such that the
thermoset polymer material has a greater thickness along the
transition lines 438 and 440 and/or along the side surfaces than
along an occlusal surface after thermoforming onto the dentition
mold. The thickness of the first shape can also vary, in one or
more dimensions, such that the thermoset polymer material has a
substantially constant thickness after thermoforming onto the
dentition mold.
[0089] In some embodiments, first shapes may be made in mass
quantities, and stored, or may be made on demand according to a
particular patient's needs. The first shape may be customized to
the shape of a patient's jaw, and with variable thickness to
accommodate different crown heights.
[0090] FIG. 5A illustrates an embodiment of a first shape 550
substantially horseshoe-shaped in at least two dimensions according
to the present disclosure, and FIG. 5B illustrates the first shape
cross section 552 as taken along line 5B-5B of FIG. 5A. FIG. 5A
shows a first shape 550 used to form a dental appliance that will
correspond to a negative dentition mold of the intended
configuration 504.
[0091] From FIGS. 5A and 5B, it can be seen that the first shape
550 is formed to be substantially horseshoe-shaped in a first
dimension, similar to first shape 436 shown in FIG. 4A. First shape
550 also has a substantially horseshoe-shaped cross section, e.g.,
be substantially horseshoe-shaped in a second dimension, as can be
appreciated from FIG. 5B. Thus, first shape 550 has a substantially
horseshoe-shaped cross section 552 along its substantially
horseshoe-shape in a first dimension. Lines 538, 539, 540 and 541
shown in FIG. 5B on cross-section 552 correspond in location
respectively to lines 438, 439, 440 and 441 shown on first shape
436 in FIGS. 4A and 4B.
[0092] FIG. 6 illustrates an embodiment of a first shape 670 having
a variable thickness according to the present disclosure. It can be
beneficial in some instances to apply force to move teeth at a
particular location close to the root. Therefore in such instances,
it can be beneficial for a polymeric dental appliance for
orthodontic dental treatment to be thicker along a gingival line,
in order to provide more material stiffness, and thus more force.
It can also be beneficial in some embodiments for a polymeric
dental appliance for orthodontic dental treatment to be thinner at
the occlusal surface, for example, to minimize the gap created in
bite between the jaws when the dental appliance is in place.
[0093] The thickness, e.g., 672, of a first shape 670 can vary
independently along one or more dimensions, e.g., width 676 and/or
length 678. First shape can have one or more flat surfaces, e.g.,
on a bottom surface 680 and or a top surface 682. Furthermore, the
first shape may be formed to have a thickness that varies such that
the thermoset polymer material has a greater thickness 672 at
locations corresponding to where the gingival lines will be formed,
than the thickness 674 corresponding to where an occlusal surface
will be formed.
[0094] For example, first shape 670 may be formed to have a
channel, or groove, within a top surface 682 (as shown) and/or a
bottom surface. The channel can, for example, substantially follow
a horse-shoe shape of the dentition onto which it may be
thermoformed, and may be any suitable cross-section (e.g.,
semi-circular as shown in FIG. 9).
[0095] FIG. 7 illustrates working range curves of displacement as a
function of static force for thermoset polymer material in contrast
to thermoplastic material. As will be appreciated, the displacement
of thermoset polymer material is generally within a narrower range
for a given magnitude of static force, than are expected for
thermoplastic material.
[0096] That is, that the range of deformation for thermoset polymer
material is generally less at a particular applied force, than the
range of deformation for thermoplastic material at the same
particular applied force, as can be seen by the narrower horizontal
width bounded by each curve at the particular applied force. A
smaller deformation range can help provide more precise, and thus
controllable, locating of teeth positioning.
[0097] FIG. 8 illustrates stress relaxation performance curves of
percentage of load remaining as a function of time for thermoset
polymer material (e.g., casting polyurethane) in contrast to
thermoplastic material (e.g., polyester, thermoplastic
polyurethane). FIG. 8 illustrates thermoset polymer material and
thermoplastic material response to relaxation of stress when tested
at five percent (5%) strain, a temperature of 37.degree. C., and
one hundred percent (100%) relative humidity. As may be observed,
the thermoset polymer material exhibits a greater percentage of
load remaining over time, indicating less susceptibility to fatigue
of the thermoset polymer material as compared to the thermoplastic
material.
[0098] FIG. 9 illustrates a computing device embodiment to perform
a method for evaluating a dental condition according to an
embodiment of the present disclosure. The computing device 984
illustrated in FIG. 9, includes a processor 985 and memory 986.
Memory 986 can include various types of information including data
987 and computing device executable instructions 988 as discussed
herein.
[0099] Memory can be used for a variety of different functions in
the various embodiments. For example, memory can be used to store
executable instructions that can be used to interact with the other
components of the computing device and/or network including other
computing devices and can be used to store information, such as
instructions for manipulating one or more files.
[0100] For instance, in some embodiments, a computing device can
include executable instructions for saving a number of program
and/or data files, such as files, for providing executable
instructions that allow for the viewing functionality for viewing
scans and/or models, and the data files for the scans and/or
digital models. Some executable instructions can, for example, be
instructions for saving local scans and/or digital models, scans
and/or digital models from another computing device on the network,
or a combination of two or more of these.
[0101] Additionally, as illustrated in the embodiment of FIG. 9, a
system can include a network interface 990. Such an interface can
allow for processing on one or more networked computing devices or
such devices can be used to transmit and/or receive scans and/or
digital models and/or executable instructions for use with various
embodiments provided herein.
[0102] The network interface 990 can connect the computing device
to a network 991. The network 991 can be connected to other
computing devices that can execute to make scans and/or digital
models of a patient's teeth.
[0103] For example, the digital model obtained from a scanner that
is interfaced with computing device 984 can be sent on the network
991 to other computing devices. In some embodiments, a number of
treatment professionals can have access to the computing devices on
the network 991 so they can view and diagnose the dental condition
of a user based on the digital model from a remote location.
[0104] In the embodiment of FIG. 9, the network 991 is connected to
a database 998. The database 998 can, for example, include a case
history database that can give access to prior patient's data or
other data resources to use in the evaluation and/or treatment
process. In such embodiments, treatment professionals that have
access to the network 991 and in turn the database 998 can use the
database to supplement their evaluation and/or treatment of a
user's dental condition.
[0105] In some embodiments, the computing device 984 can include
executable instructions for estimating the thickness of various
portions of the partially cured material. For example, executable
instructions can be provided to adjust the thickness of the
partially cured material in order to compensate for bending or
stretching that may occur during formation of the dental appliance.
The data regarding the bending and/or stretching for such analysis
can be provided, for example, in memory 986 and/or database
998.
[0106] As illustrated in the embodiment of FIG. 9, a system can
include one or more input and/or output interfaces 992. Such
interfaces can be used to connect the computing device with one or
more input and/or output devices.
[0107] Such connectivity on the network 991 can allow for the input
and/or output of manipulations (e.g., changes to the common file
embedded in executable instructions) among other types of
information. Although some embodiments may be distributed among
various computing devices within one or more networks, such systems
as illustrated in FIG. 9, can be beneficial in allowing for the
capture, calculation, and/or analysis of the various information
discussed herein. For example, the information regarding the
adjustment of the thickness of the partially cured material can be
provided to a device that is forming the partially cured material,
such as via the output interface 992.
[0108] Various embodiments include the use of executable
instructions to accomplish one or more processes. Such instructions
can, for example, be implemented on one or more computing devices
and therefore in such embodiments, the executable instructions
should be viewed as being computing device executable instructions
for implementation by one or more computing devices.
[0109] Although specific embodiments have been illustrated and
described herein, those of ordinary skill in the art will
appreciate that any arrangement calculated to achieve the same
techniques can be substituted for the specific embodiments shown.
This disclosure is intended to cover any and all adaptations or
variations of various embodiments of the disclosure.
[0110] It is to be understood that the use of the terms "a", "an",
"one or more", "a number of", or "at least one" are all to be
interpreted as meaning one or more of an item is present.
Additionally, it is to be understood that the above description has
been made in an illustrative fashion, and not a restrictive one.
Combination of the above embodiments, and other embodiments not
specifically described herein will be apparent to those of skill in
the art upon reviewing the above description.
[0111] The scope of the various embodiments of the disclosure
includes any other applications in which the above structures and
methods are used. Therefore, the scope of various embodiments of
the disclosure should be determined with reference to the appended
claims, along with the full range of equivalents to which such
claims are entitled.
[0112] In the foregoing Detailed Description, various features are
grouped together in a single embodiment for the purpose of
streamlining the disclosure. This method of disclosure is not to be
interpreted as reflecting an intention that the embodiments of the
disclosure require more features than are expressly recited in each
claim.
[0113] Rather, as the following claims reflect, inventive subject
matter lies in less than all features of a single disclosed
embodiment. Thus, the following claims are hereby incorporated into
the Detailed Description, with each claim standing on its own as a
separate embodiment.
* * * * *