U.S. patent application number 10/827923 was filed with the patent office on 2004-10-14 for method and kits for forming pontics in polymeric shell aligners.
This patent application is currently assigned to ALIGN TECHNOLOGY, INC.. Invention is credited to Bruns, Craig R., Knopp, Peter G., Kuo, Eric, Tricca, Robet E., Woncheol, Choi.
Application Number | 20040202983 10/827923 |
Document ID | / |
Family ID | 36913144 |
Filed Date | 2004-10-14 |
United States Patent
Application |
20040202983 |
Kind Code |
A1 |
Tricca, Robet E. ; et
al. |
October 14, 2004 |
Method and kits for forming pontics in polymeric shell aligners
Abstract
Systems and methods are disclosed for forming a pontic in a
polymeric shell dental appliance, including providing a polymeric
shell dental appliance of the type which is removably placeable
over a patient's dentition, said shell having a concave trough
which conforms to the teeth when the appliance is placed over the
dentition and a location in the trough corresponding to a missing
tooth; and depositing a flexible, durably affixed material in the
location to form the pontic.
Inventors: |
Tricca, Robet E.; (Danville,
CA) ; Kuo, Eric; (Foster City, CA) ; Knopp,
Peter G.; (Palo Alto, CA) ; Woncheol, Choi;
(San Jose, CA) ; Bruns, Craig R.; (Danville,
CA) |
Correspondence
Address: |
TOWNSEND AND TOWNSEND AND CREW, LLP
TWO EMBARCADERO CENTER
EIGHTH FLOOR
SAN FRANCISCO
CA
94111-3834
US
|
Assignee: |
ALIGN TECHNOLOGY, INC.
Santa Clara
CA
|
Family ID: |
36913144 |
Appl. No.: |
10/827923 |
Filed: |
April 19, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10827923 |
Apr 19, 2004 |
|
|
|
09967822 |
Sep 28, 2001 |
|
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Current U.S.
Class: |
433/215 ;
433/24 |
Current CPC
Class: |
A61C 7/00 20130101 |
Class at
Publication: |
433/215 ;
433/024 |
International
Class: |
A61C 005/00; A61C
003/00 |
Claims
What is claimed is:
1. A kit comprising: a curable silicone rubber material for filling
a portion of appliance trough which has been coated with the
adhesive, and instructions for use setting forth a method
comprising: determining the location in the trough where a tooth is
missing from the dentition, coating the trough with a bonding
agent; and filling the location with the curable silicone rubber so
that the location resembles a tooth when the location is
filled.
2. A kit as in claim 1, further comprising: an adhesive for coating
an interior surface of the appliance trough at the location to be
filled; and a brush for applying the adhesive to the appliance
trough.
3. A kit as in claim 1, further comprising at least one nozzle for
use with an applicator for the curable silicone rubber.
4. A kit as in claim 3, further comprising one or more additional
nozzles or use with the applicator, wherein at least two nozzles
have different tip sizes.
5. A kit as in claim 4, wherein at least two nozzles have different
tip sizes.
6. A kit as in claim 1, wherein the curable silicone rubber is
tooth-shaded.
7. A kit as in claim 6, further comprising a second curable
silicone rubber having a different tooth-shade.
8. A kit as in claim 1, further comprising at least one spatula
tool for shaping the filler material before or after it has been
placed in the appliance trough.
9. A kit as in claim 8, comprising at least a spatula for shaping
the material before curing and a knife for shaping the material
after it has hardened.
10. A kit as in claim 1, wherein filling comprises dispensing the
curable silicone rubber from a dispenser having a nozzle.
11. A kit as in claim 10, wherein the nozzle is removable and
dispensing comprises choosing a nozzle size and connecting the
chosen nozzle to the dispenser.
12. A kit as in claim 1, wherein filling comprises shaping the
curable silicone rubber with a tool.
13. A kit as in claim 1, wherein filling comprises curing a silicon
rubber to harden said material in situ.
14. A kit as in claim 1, further comprising coating the location in
the trough prior to filling with a bonding agent.
15. A kit as in claim 14, wherein coating comprises applying a
bonding agent.
16. A kit as in claim 15, wherein the curable silicone rubber is
tooth-shaded.
17. A kit as in claim 16, further comprising selecting a curable
silicone rubber having a desired tooth-shade.
18. An improved method for repositioning teeth using polymeric
shell appliances which each have a trough to receive and
resiliently reposition teeth, wherein the appliances have different
geometries and are worn successively by a patient to reposition
teeth, wherein the improvement comprises providing a pontic at a
location in at least one of the appliance troughs to fill a gap
between teeth when the appliance is worn.
19. An improved method as in claim 18, wherein the improvement
further comprises providing a pontic at a location in at least one
additional of the appliance troughs to fill the gap between teeth
when the additional appliance is worn.
20. An improved method as in claim 19, wherein the gap is being
closed as the teeth are repositioned, wherein the size of the
pontic is reduced in successive appliances.
21. An improved method as in claim 20, wherein presence of the
pontic when the appliance is worn inhibits collapse of adjacent
teeth into the gap as the adjacent teeth are moved together to
close the gap.
22. A method for forming a pontic in a polymeric shell dental
appliance, said method comprising: determining a location where a
tooth is missing from a patient's dentition; generating a mold for
a polymeric shell dental appliance with a cavity enclosing the
location; forming a polymeric shell dental appliance of the type
which is removably placeable over the dentition; and filling the
cavity with a curable silicone rubber that resembles a tooth.
23. A method as in claim 22, wherein filling comprises dispensing a
curable silicone rubber wherein the curable silicone rubber is an
addition reaction polyvinylsiloxane.
24. A method as in claim 22, wherein filling comprises dispensing a
curable silicone rubber wherein the curable silicone rubber is a
condensation reaction polysiloxane.
25. A method as in claim 23, wherein the curable silicone rubber is
tooth-shaded.
26. A method as in claim 24, further comprising selecting a curable
silicone rubber source having a desired tooth-shade.
27. A method as in claim 22, further comprising filling in the
cavity when generating the mold.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] The present application is a division of U.S. patent
application Ser. No. 09/967,822 (Attorney Docket No.
018563-006100US/AT-00117), filed Sep. 28, 2001, the full disclosure
of which is incorporated herein by reference. This application is
also related to U.S. application Ser. No. 09/313,289 (Attorney
Docket No. 018563-005200US/AT-00110) filed May 13, 1999 (now U.S.
Pat. No. 6,318,994); U.S. application Ser. No. 09/169,036 (Attorney
Docket No. 18563-004900US/AT-00106), filed Oct. 8, 1998 (now U.S.
Pat. No. 6,450,807); and U.S. application Ser. No. 09/169,034
(Attorney Docket No. 018563-005000US/AT-00107), filed Oct. 8, 1998
(now U.S. Pat. No. 6,471,511).
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates in general to orthodontics and more
particularly to methods and kits for for providing pontics in
orthodontic appliances.
[0004] 2. Description of the Background Art
[0005] Orthodontic treatments involve repositioning misaligned
teeth and improving bite configurations for improved cosmetic
appearance and dental function. Repositioning teeth is accomplished
by applying controlled forces to the teeth over an extended period
of time. This is conventionally accomplished by wearing what are
commonly referred to as "braces." Braces comprise a variety of
appliances such as brackets, bands, archwires, ligatures, and
O-rings. After they are bonded to the teeth, periodic meetings with
the orthodontist are required to adjust the braces. This involves
installing different archwires having different force-inducing
properties or by replacing or tightening existing ligatures.
Between meetings, the patient may be required to wear supplementary
appliances, such as elastic bands or headgear, to supply additional
or extraoral forces.
[0006] Although conventional braces are effective, they are often a
tedious and time-consuming process requiring many visits to the
orthodontist's office. Moreover, from a patient's perspective, they
are unsightly and uncomfortable. Consequently, alternative
orthodontic treatments have developed. A particularly promising
approach relies on the use of elastic positioning appliances for
realigning teeth. Such an appliance may be comprised of a thin
shell of elastic material, referred to as an "aligner" that
generally conforms to a patient's teeth but is slightly out of
alignment with the initial tooth configuration. Placement of an
aligner over the teeth applies controlled forces in specific
locations to gradually move the teeth into the new configuration.
Repetition of this process with successive appliances comprising
new configurations eventually moves the teeth through a series of
intermediate arrangements to a final desired arrangement. A full
description of an exemplary elastic polymeric positioning appliance
is described in U.S. Pat. No. 5,975,893, and in published PCT
application WO 98/58596 which designates the United States and
which is assigned to the assignee of the present invention. Both
documents are incorporated by reference for all purposes.
[0007] Systems of preformed aligners employing technology described
in U.S. Pat. No. 5,975,893, are commercially available from Align
Technology, Inc., Santa Clara, Calif., under the tradename
Invisalign.RTM. System. Align Technology, Inc., is the assignee of
the present application. The Invisalign.RTM. System relies on
designing and fabricating the aligners to be worn by the patient
throughout treatment. The design of the aligners relies on computer
modeling of a series of successive tooth arrangements, and the
individual aligners are designed to be worn over the teeth and to
reposition the teeth to each of said tooth arrangements. Usually,
the set of aligners which is designed and fabricated at the outset
of the treatment is able to successfully reposition the teeth to a
final desired arrangement.
[0008] With the Invisalign.RTM. System, as well as with other
conventional orthodontic treatment systems, it is sometimes
necessary to extract one or more teeth prior to tooth
repositioning. At present, the Invisalign.RTM. System does not
provide for filling in the space or void which remains within the
aligner after the tooth is extracted with a structural component
such as an artificial tooth which is commonly referred to as a
dental pontic.
[0009] The design and fabrication of dental pontics are described
in U.S. Pat. Nos. 6,186,790; 6,050,820; 6,049,743 and 5,613,845,
the full disclosures of which are incorporated herein by
reference.Currently, dental professionals trained in the use of the
Invisalign orthodontic system are using a variety of materials and
techniques known in the art to fabricate dental pontics which can
be worn in the aligner extraction site(s). The most commonly
employed materials are tooth-shaded dental composites typically
used to repair carious lesions or fabricate provisional (temporary)
crowns and bridges. These materials consist mainly of a polymer
matrix and dispersed reinforcing inorganic filler particles.
Typical polymers used are based on dimethacrylate such as Bis-GMA
or urethane dimethacrylate (UDMA). Quartz, lithium aluminum
silicate and barium, strontium, or zinc glasses have been
commercially distributed as fillers. Typically these materials are
packaged as a two-paste (base/catalyst) system. The polymer matrix
may be visible light curable, self-curing, dual curing, and vacuum,
heat and pressure curable compositions as well as any combination
thereof. A popular method for mixing and dispensing these materials
involves the use of an automix system whereby a dispensing gun is
utilized to dispense the base and catalyst, which are in separate
cartridges, through a mixing cannula directly into the extraction
site. Commercial examples of the autopolymerizing composites are
Luxatemp Plus (DMG/Zenith), Integrity (Dentsply/Caulk), Protemp
Garant (ESPE) and Turbo Temp (Danville Engineering). Alternatively
light cured composites may be used to fabricate dental pontics.
Commercial examples of light cured composites are Revolution
(Kerr), Star-Flow (Danville Engineering), and Tetric (Vivadent).
Other useful dental composite materials are based on the methyl
methacrylate polymer. Such acrylic polymers are well known and
commercially available for example as Jet Tooth Shade self-curing
acrylic resin by Lang Dental.
[0010] Although dental composites have been used to fabricate
dental pontics for the Invisalign system there remain two important
disadvantages to using these materials. First the ability of these
materials to bond to the aligner thermoplastic is poor and second
these materials are very stiff and non-flexing. These
characteristics significantly compromise retention of the pontic in
the aligner especially if it is subjected to torsional or flexing
forces such as when the aligner is either being inserted or removed
from a patient's mouth or while the patient is cleaning their
aligner using a cleaning device such a toothbrush or denture
brush.
[0011] While it has been proposed to paint or color a portion of
the aligner which overlies the void (see co-pending application
Ser. No. 09/454,278, the full disclosure of which is incorporated
herein by reference), partial coloring of the aligner can affect
the light transmitting properties and be unaesthetic and the lack
of any underlying structure can weaken or lessen the resilience of
the aligner and limit its effectiveness.
[0012] For these reasons, it would be desirable to provide methods,
systems, and kits for modifying an aligner to accommodate patients
who have had teeth extracted prior to treatment with an aligner or
other polymeric shell orthodontic appliance. It would be
particularly desirable if the methods would permit an orthodontist
or other clinician to modify an aligner or other orthodontic
appliance in the professional office, rather than having the
modification done at the time of fabrication or at an off-site
location. It would be further desirable still if the aligner could
be modified by the treating clinician, fitted with the patient, and
further modified if necessary for patient comfort or other reasons.
The resulting modified aligners or other orthodontic appliances
should be esthetically pleasing, and preferably should mask the
absence of an underlying tooth while the aligner or other appliance
is worn. At least some of these objectives will be achieved by the
inventions described hereinafter.
[0013] U.S. Pat. No. 5,975,893, and published PCT application
W098/58596, have been described above. Co-pending application Ser.
No. 09/454,278, which has been published as W099/028,228, relates
to the fabrication of aligners which have been colored to cover a
void left where teeth have been removed. The full disclosures of
each of these patents and pending applications are incorporated
herein by reference.
SUMMARY OF THE INVENTION
[0014] The present invention provides methods and kits for forming
a pontic in a polymeric shell dental appliance, such as the
Invisalign.RTM. System aligners described above. In addition, the
present invention provides for methods of using such modified
aligners for treating patients having gaps between adjacent teeth,
where the gaps resulted from prior tooth extractions or other
causes. In addition to the esthetic improvement, i.e., the voids or
empty spaces between teeth will be generally invisible, it is
believed that the pontics may reduce the tendency of teeth to
collapse inward toward each other as the teeth are moved to close
the gaps during the orthodontic treatment. In the case of the
Invisalign.RTM. System, successive aligners which are used to treat
an individual patient can each be separately modified, with the
pontic placed in a gap between adjacent teeth being reduced in size
as the treatment progresses and the gap is gradually closed.
[0015] According to a first aspect of the present invention, a
method for forming a pontic in a polymeric shell dental appliance,
such as an Invisalign.RTM. System aligner, comprises providing a
polymeric shell dental appliance of the type which is removably
placeable over a patient's dentition. The shell will have a concave
trough or cavity which conforms to the teeth when the appliance is
placed or worn over the dentition. When the polymeric shell is
worn, the treating clinician can determine the location in the
appliance trough where a tooth is missing. The treating clinician
will usually note the location on the appliance and further
determine the width and shape of the gap between the teeth.
Optionally, in the case of the Invisalign.RTM. System aligners, the
aligner will have been shaped or otherwise modified to indicate the
location where the gap will occur. If not, the treating clinician
can simply mark the aligner or take other appropriate steps to
determine the location of the space within the trough.
[0016] After the space (or spaces ) is determined, the pontic is
formed by filling the spaces(s) within the trough with a material
that resembles a tooth. While it would be possible to shape a cured
material into the desired geometry to be placed within the
appliance trough, it will be much more convenient to fill the
location with a relatively viscous but flowable and flexible
material which can fill and conform to the interior volume of the
target location within the appliance trough. Optionally, an
adhesive or other treating material will be coated on the target
location prior to filling with the pontic material. The flowable
pontic material will then be cured to form the final pontic.
Optionally, the shape of the pontic can be modified using spatulas
(while it is still workable) and/or knives (after it has cured).
Preferably, the pontic will be shaped so that it fills
substantially the entire gap between adjacent teeth and extends
down to the gingiva, without intruding upon the gingiva when the
aligner or other appliance is worn.
[0017] In a specific embodiment of the present invention, curable
silicone compositions, especially the addition-curable silicone
rubber compositions known in the art are employed to form an
elastomeric, flexible polyvinylsiloxane (PVS) dental pontic.
Typically these polyvinylsiloxane materials are formed from a two
component curable silicone prepolymer system. A first component,
which is referred to as a "Base Paste", typically contains a
vinylorganopolysiloxane dispersion, an organo
hydrogen-polysiloxane, inorganic fillers and other additives well
known in the art. The second component of this two-part composition
is referred to as a "Catalyst Paste" and typically consists of a
second portion of the vinyl polysiloxanes, polymerization
initiators, accelerators, cross-linking agents and other additives
well known in the art. The base and catalyst may either be hand
mixed and delivered to the appliance trough using a spatula or
application syringe or a mixing device such as an auto-mix
cartridge commonly used for impression materials may be employed to
combine the proper volumes of base and catalyst. The tip size of
the nozzle can be selected to provide a desired ribbon of material
to be delivered to the appliance trough. Preferably, the tip of the
nozzle will be held beneath the surface of the PVS as it is being
dispensed within the appliance trough. By providing applicators
having different tip diameters, the size of the material ribbon and
the pontic can be selected by the treating physician.
[0018] Another class of curable silicone rubbers useful in forming
elastomeric dental pontics are the condensation reaction silicones.
Condensation silicones are supplied as either a paste and liquid or
as two pastes. Typically the base paste consists of a silicone
polymer with terminal hydroxy groups and a filler and the catalyst
paste consists of a cross-linking agent (organohydrogen siloxane)
and an activator such as dibutyl-tin dilaurate. On mixing the two
pastes react by a condensation reaction causing cross-linking.
Typically the setting reaction produces a gas such as hydrogen or
an alcohol.
[0019] Prior to delivering the curable silicone rubber, an adhesive
is applied to the aligner segment corresponding to the site of the
missing tooth to enhance the bond between the PVS pontic and
aligner thermoplastic.
[0020] After sufficient material has been dispensed to form the
pontic, the treating clinician may optionally shape or form the
pontic as desired, typically using conventional shaping tools, such
as spatulas. The material will then be cured. In the case of PVS,
curing will typically occur after five to ten minutes at room
temperature but anybody skilled in the art can vary the material
composition to allow for curing times <60 seconds or as long as
24 hours. If it is desired to expedite curing, the PVS material may
be gently warmed, e.g., held under a warm water stream. After
curing, shaping or trimming of the pontic may be performed using a
knife, abrasive instrument, or the like.
[0021] Non-toxic, inorganic iron oxide pigments may be incorporated
in the PVS polymer to provide for a tooth-colored shade for the
finished pontic.Optionally, a range of tooth-colored PVS resins may
be provided in a kit allowing the clinician to select a color that
best matches patient's teeth. In a second aspect of the present
invention, kits are provided comprising components of the system
useful for performing the methods described above. In particular,
the basic kit would include a curable, toothshaded PVS resin
material such as described above in combination with instructions
for use setting forth a method for forming the pontic within the
trough of an aligner or other thin polymeric appliance having a
trough or cavity which is removebly placed over teeth. In
particular, the instructions will set forth a first step of
determining the location in the trough where a tooth is missing
from the patient's dentition, and a second step comprising filling
the location with the filler so that the material resembles a tooth
when the location is filled.
[0022] Optionally, the kit may further include other components,
such as an adhesive for coating an interior surface of the
appliance trough at the location to be filled. When an adhesive is
supplied, the kit will typically also include a brush, sprayer, or
other applicator for applying the adhesive to the appliance trough.
The kit may still further comprise one or more nozzles for use with
a filler applicator for dispensing the curable filler material
within the appliance trough. Typically, the filler applicator will
be a dispensing gun capable of applying the PVS resin in a
controlled manner through the nozzle which is attached to the gun.
More typically, the kit will include two or more nozzles, where
each nozzle will have a different tip diameter to dispense a
different ribbon size of the filler to most efficiently fill target
locations of differing sizes. Further optionally, the kit may
include two or more cartridges or other containers of the curable
filler material, where the materials have different properties,
such as color. Still further optionally, the kit could include one
or more coloring materials to permit the clinician to mix and color
the filler material at the time of use. In addition, the kit may
include one or more shaping tools which permit precise sizing and
shaping of the pontic. For example, the kit may be provided with a
spatula for sizing and shaping the material before it is cured.
Alternatively or additionally, the kit may comprise a knife,
grinder, or other tool for shaping and removing the filler material
after it has cured. To facilitate the fabrication of dental pontics
in a manufacturing setting, the curable tooth-colored silicone
rubber catalyst- and base-paste may be supplied in foil bags and
precisely dispensed from a Pentamix system eliminating either
hand-mixing or dispensing with a hand held dispensing gun.
[0023] In a third aspect of the present invention, improved methods
for repositioning teeth after extractions or impatience with
substantial gaps between adjacent teeth are provided. The
improvements are in methods for repositioning teeth which use
polymeric shell appliances each of which have a trough for
receiving and resiliently repositioning the teeth, e.g., as in the
Invisalign.RTM. System commercially available from Align
Technology, Inc., assignee of the present application. The
polymeric shell appliances have different geometries and are worn
successively by a patient to reposition the teeth in a number of
stages. The improvement comprises providing at least some of the
polymeric shell appliances, also referred to as aligners, which
have pontics at a location within the appliance trough which will
fill a gap between teeth when the appliance is worn. Usually, each
appliance worn will have a pontic at the location of the gap, and
the size of the pontic may be decreased as the treatment progresses
and the width of the gap closes. In addition to the esthetic
benefits described above, the provision of a pontic within the gap
as the teeth are being closed is believed to provide therapeutic
benefits as well. In particular, the presence of the pontic will
reduce or eliminate the tendency of teeth which are being closed
over a gap to tilt or incline into the gap. Thus, it is expected
that teeth which are treated with the polymeric appliances to close
such gaps will remain generally more upright as they are moved,
thus reducing or eliminating the need to correct any tilt or
inclination which is induced by the treatment.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 illustrates an aligner of the type employed in the
Invisalign.RTM. System being placed over a patient's teeth.
[0025] FIGS. 2A and 2B illustrate a portion of the aligner of FIG.
1 prior to placement of a pontic (FIG. 2A) and after placement of a
pontic (FIG. 2B). For convenience, placement of the pontic is shown
in black, but it will be appreciated that in practice the pontic
will usually be a shade of white selected to match the patient's
teeth.
[0026] FIG. 3A is a cross-sectional view taken along line 3A-3A of
FIG. 2A, showing a view of the aligner prior to filling with the
pontic material.
[0027] FIG. 3B illustrates filling of the aligner with the pontic
material.
[0028] FIG. 3C is a cross-sectional view taken along line 3C-3C of
FIG. 2B, showing the aligner after the pontic has been formed
therein.
[0029] FIG. 4 illustrates a kit constructed in accordance with the
principles of the present invention.
[0030] FIG. 5 illustrates an exemplary process for generating an
aligner capable of receiving the pontic material.
[0031] FIG. 6 shows an exemplary pontic in an aligner.
[0032] FIG. 7 shows an exemplary space filler in an aligner.
DESCRIPTION OF THE SPECIFIC EMBODIMENTS
[0033] The present invention provides improved methods and kits for
the use of aligners 100 for positioning teeth in a tooth
arrangement TA, as illustrated in FIG. 1. The aligner is a thin
shell polymeric appliance of the type commercially available as
part of the Invisalign.RTM. System available from Align Technology,
Inc., Santa Clara, Calif. The planning and fabrication of such
aligners is described in detail in issued U.S. Pat. No. 5,975,893,
the full disclosure of which has previously been incorporated
herein by reference. The aligners 100 are worn by a patient over
the tooth arrangement for a sufficient time to rearrange the teeth
to a desired subsequent tooth arrangement. A plurality of
successive aligners are worn until an entire course of the
treatment is completed.
[0034] As shown in FIG. 2A, the aligner 100 will include a number
of individual tooth-shaped segments 102, 104, 106, 108, and 110.
Each of these individual segments will be designed to fit over an
individual tooth, with the particular placement of the segment
being moved slightly to effect a corresponding tooth movement while
the aligner is worn.
[0035] For the purposes of describing the present invention, it
will be assumed that the tooth corresponding to segment 108 will be
extracted, e.g., to remove over-crowding. Once the tooth is
removed, of course, there will be a void or gap left between the
teeth which are beneath segments 106 and 110. The purpose of the
present invention is to provide an artificial tooth, commonly
referred to as a pontic, within the cavity or trough of the aligner
100 which would have covered the tooth prior to extraction. The
aligner 100 having a pontic formed in the interior of segment 108
is illustrated in FIG. 2B. For ease of illustration, presence of
the pontic is shown by coloring the segment 108 black. In actual
practice, of course, the pontic will usually be colored a shade of
white to match the patient's other teeth.
[0036] Referring now to FIGS. 3A-3C, formation of a pontic 120 in
the tooth segment 108 of aligner 100 will be illustrated.
Initially, the trough 112 of the tooth segment 108 is empty, as
illustrated in FIG. 3A. A bonding agent is applied to the tooth
aligner tooth trough as illustrated in FIG. 3B. The bonding agent
may be a simple compound, more preferably a polymer which attaches
or substantively, adhesively, cohesively or otherwise bonds the
curable silicon rubber to the aligner thermoplastic. The preferred
bonding agents can be those disclosed in German Pat. DE 19934117 to
Engelbrecht et al. The pontic is preferably formed by dispensing a
curable PVS prepolymer resin (M) as shown in FIG. 3B. Typically,
the curable PVS prepolymer resin will be dispensed through a mixing
nozzle 114 from an applicator 115. The applicator can be a
conventional dispenser gun, e.g., holding a dual cartridge; one
cartridge containing the uncured PVS resin base, inorganic fillers
and other additives known in the art the other containing the
catalyst components. As the trigger of the dispensing gun is
squeezed, the PVS base and catalyst materials flow through the
mixing nozzle where they are combined initiating the curing of the
PVS rubber. The PVS rubber is dispensed through the mixing nozzle,
where the width of the bead dispensed is determined by the tip
diameter of the nozzle. Preferably, the tip diameter of the nozzle
will be selected to provide an appropriate material bead size to
fill the trough 112 at a desired rate. Useful tip diameters will be
in the range from 0.01" inches to 0.2" inches, preferably from
0.03" inches to 0.10" inches. The PVS rubber will be dispensed,
preferably while maintaining the nozzle tip beneath the surface of
the material, until the trough 112 is substantially filled, as
shown in FIG. 3C. At that point, the pontic 120 has been formed.
Immediately after dispensing the PVS rubber in the aligner trough
the user may, if necessary, sculpt and contour the material using a
spatula or similar instrument. The user may continue to do this
during the "working phase" of the resin curing process. Useful
working phase times will be in the range from 30 seconds to 5
minutes, preferably from 45 seconds to 3 minutes. Curing or
hardening of the PVS filler material will then take an additional 3
minutes to 10 minutes depending on the formulation After the pontic
material has cured, it may still be shaped using a knife, abrasive
instrument, or the like. In addition to fitting the pontic so that
it can be inserted and removed between the adjacent teeth, it is
also desirable that the exposed portion of the pontic not intrude
upon the gingiva. The treating clinician can place the aligner 100
over the patient's teeth to make sure that it fits properly before
releasing the aligner to the patient.
[0037] Referring now to FIG. 4, a kit 200 adapted for forming
pontics within aligners or other polymeric shell appliances will be
described. The kit 200 will include at least a container 202 which
holds the pontic material. Typically, the container 202 will be in
the form of a cartridge which may be dispensed through a
conventional applicator, such as a gun-type applicator used with
the preferred PVS filler material. The kit 200 will also include
instructions for use 204 which set forth the methods of the present
invention, as generally described above. Optionally, the kit may
further include one or more nozzles 114 which may be used together
with the applicator, as generally described above. In preferred
embodiments, the kits will include two or more nozzles, where the
nozzles have different tip diameters to permit dispensing of
different bead sizes of the filler material into the aligner.
Further optionally, the kit may include a bonding agent, as
described in German Patent DE 19934117 assigned to Engelbrecht et
al. for coating the interior of the aligner prior to dispensing of
the pontic material. When including the adhesive 206, a brush 208
may also be provided either separately or optionally within the cap
of the adhesive container. Other tools, such as a spatula 210 for
forming the filler material prior to hardening, a knife or other
tool for forming the pontic material after hardening, and the like,
may also be provided. Preferably, all components of the kit will be
packaged together with a box, tray, pouch, tube, or other
conventional medical device package 220.
[0038] FIG. 5 illustrates an exemplary process 500 for generating
an aligner capable of receiving the pontic material. The process of
FIG. 5 creates a pontic that is customized to each patient. The
customization is needed since shapes of teeth vary: for the same
tooth, different patients have different tooth sizes and shapes. In
order to represent a generic tooth shape that can be modified for
each patient, a standard parametric tooth model is employed, and
the process 500 customizes the parametric tooth model to each
patient.
[0039] Starting from the first tooth position that requires a
pontic, the process 500 determines a tooth identification or tooth
type (step 502). Next, the process 500 determines neighboring teeth
dimensions (step 504). The parameters are determined by the
neighboring teeth dimensions. The height of the pontic is
determined in proportion to the neighboring teeth heights. The
pontic thickness is also proportional to the neighboring teeth
thickness. Other parameters can be predefined or proportional to
the neighboring teeth.
[0040] The process 500 then determines the gap size based on the
neighboring teeth dimensions as the pontic width also depends on
the gap size (step 506). Next, the process 500 determines whether
the gap provides sufficient clearance for the pontic (step 508).
From step 508, if the gap is too small, the process exits (step
520). Alternatively, if the gap is sufficient, the process 500
determines the pontic parameters (step 510). It also determines the
pontic position (step 512). The process 500 also creates pontic
geometry for the current tooth (step 514). Step 514 completes the
processing for the current tooth, and the next tooth for the
current stage is selected (step 516) before the process loops back
to step 508. The pontic is updated in each stage, thus each stage
has a different pontic. Thus, the pontic will be updated as the
stage changes.
[0041] FIG. 6 shows an exemplary pontic 600 in an aligner. The
position of the pontic 600 is determined by the neighboring teeth
602 and 604. As shown in FIG. 6, two points 610 and 612 on the
interproximal area of the neighboring teeth are used to define an
axis 620. The pontic 600 is placed in contact with a plane that
passes the two points 610 and 612. The position can be manually
adjusted by the user.
[0042] FIG. 7 shows an exemplary space filler 700 between two teeth
702 and 704 in an aligner. The space filler 700 is used when the
missing tooth is in the posterior region of the jaw that is not
likely to be visible. In such situation, a geometric beam is formed
connecting the center of the teeth 702 and 704 and the beam width
is selected that is smaller than the diameters of the teeth 702 and
704 and a geometric filling is performed to fill in the beam. The
use of the space filler 700 provides structural strength to the
resulting aligner while avoiding the costs associated with a
pontic.
[0043] While the above is a complete description of the preferred
embodiments of the invention, various alternatives, modifications,
and equivalents may be used. Therefore, the above description
should not be taken as limiting the scope of the invention which is
defined by the appended claims.
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