U.S. patent application number 11/745211 was filed with the patent office on 2007-09-06 for methods and systems for concurrent tooth repositioning and substance delivery.
This patent application is currently assigned to Align Technology, Inc.. Invention is credited to Eric Kuo, Loc X. Phan.
Application Number | 20070207434 11/745211 |
Document ID | / |
Family ID | 27734934 |
Filed Date | 2007-09-06 |
United States Patent
Application |
20070207434 |
Kind Code |
A1 |
Kuo; Eric ; et al. |
September 6, 2007 |
METHODS AND SYSTEMS FOR CONCURRENT TOOTH REPOSITIONING AND
SUBSTANCE DELIVERY
Abstract
The present invention provides devices, systems and methods for
orthodontic treatment using elastic repositioning appliances while
concurrently providing dental and periodontal therapies. Such
therapies are traditionally provided with the use of a variety of
accessories and devices which are applied when the repositioning
appliance is removed from the patient's mouth. The present
invention eliminates the need for such removal and additional
devices by incorporating these therapies into the repositioning
appliance.
Inventors: |
Kuo; Eric; (San Francisco,
CA) ; Phan; Loc X.; (Milpitas, CA) |
Correspondence
Address: |
TOWNSEND AND TOWNSEND AND CREW, LLP (018563)
TWO EMBARCADERO CENTER, EIGHTH FLOOR
SAN FRANCISCO
CA
94111-3834
US
|
Assignee: |
Align Technology, Inc.
Santa Clara
CA
|
Family ID: |
27734934 |
Appl. No.: |
11/745211 |
Filed: |
May 7, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10426157 |
Apr 28, 2003 |
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11745211 |
May 7, 2007 |
|
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09666783 |
Sep 21, 2000 |
6607382 |
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10426157 |
Apr 28, 2003 |
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Current U.S.
Class: |
433/6 |
Current CPC
Class: |
A61P 1/02 20180101; A61C
7/08 20130101; A61C 19/063 20130101 |
Class at
Publication: |
433/006 |
International
Class: |
A61C 7/08 20060101
A61C007/08 |
Claims
1. An oral appliance comprising: a polymeric shell having cavities
shaped to fit a patient's teeth; and a pocket on the shell, wherein
the pocket is configured to carry an agent to the oral environment
when the shell is in place over the patient's teeth and to release
the agent into the oral environment over time.
2. An appliance as in claim 1, wherein the pocket is accessible for
replenishing with agent.
3. An appliance as in claim 1, wherein the agent comprises a
material selected from the group consisting of fluoride, an
antibiotic, a bleaching material, a flavor and a scent.
4. An appliance as in claim 3, wherein the agent comprises at least
two materials selected from the group.
5. An appliance as in claim 1, wherein said pocket is configured to
release the agent through a portion thereof.
6. An appliance as in claim 5, wherein at least a portion of the
pocket is perforated or a mesh.
7. An appliance as in claim 1, further comprising a tablet which is
insertable into the pocket.
8. An appliance as in claim 7, wherein the tablet comprises a
controlled release tablet.
9. A method for releasing an agent into an oral environment, said
method comprising: positioning a polymeric shell appliance over a
patient's teeth; placing the agent into a pocket on the appliance
such that the agent will be released from the pocket into an oral
environment of the patient over time.
10. A method as in claim 9, wherein the agent comprises a material
selected from the group consisting of fluoride, antibiotics,
bleaching materials, flavoring, and scents.
11. A method as in claim 9, wherein the polymeric shell is a thin
shell appliance with cavities configured to be received over the
patient's teeth.
12. A method as in claim 9, wherein placing the agent comprises
inserting a tablet into the pocket on the appliance.
13. A method as in claim 12, wherein the tablet is a controlled
release tablet.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] The present application is a divisional of U.S. patent
application Ser. No. 10/426,157 (Attorney Docket No.:
018563-002020US-9033.ALG.D1), filed Apr. 28, 2003 which was a
divisional of U.S. patent application Ser. No. 09/666,783 (Attorney
Docket No. 018563-002000US/9033.ALG.P), filed Sep. 21, 2000, (now
U.S. Pat. No. 6,607,382), the full disclosures of which are
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention is related generally to the field of
medical methods and devices. More particularly, the present
invention is related to the oral delivery of substances
concurrently with the realignment of teeth.
[0003] Orthodontic treatments involve repositioning misaligned
teeth and improving bite configurations for improved cosmetic
appearance and dental function. Repositioning is accomplished by
applying gentle controlled forces to the teeth over an extended
period of time. Due to the limited space within the oral cavity and
extensive movements that some teeth must undergo, the teeth will
often be moved throughout a series of intermediate patterns to
properly arrange the teeth. For example, molars may be temporarily
moved backwards (distalized) to create adequate space for movement
of the incisors. Thus, a single patient may experience an average
of 25-30 stages or alignment patterns before achieving the final
desired configuration.
[0004] Recently, it has been found that such repositioning may be
accomplished with the use of a series of removable elastic
positioning appliances. Such appliances comprise a thin shell of
elastic material that generally conforms to a patient's teeth but
is slightly out of alignment with an initial or immediately prior
tooth configuration. Placement of the elastic positioner 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 move the teeth through a series of intermediate
configurations or alignment patterns to a final desired
configuration. 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
application. Both these documents are incorporated by reference for
all purposes.
[0005] In addition to their ease of use, polymeric positioning
appliances are generally transparent and impart substantial force
on the teeth, due to stiffness of the appliance. The stiffness of
an elastic positioning appliance is a result of the modulus of the
thermoformable polymer materials from which it is made. The higher
the modulus of the materials, the higher the stiffness of the
appliance. When a patient positions such an appliance over a
prescribed group of teeth, one or more of the teeth will provide a
base or anchor region for holding the positioning appliance in
place while the stiffness of the polymeric material will impart a
resilient repositioning force against one or a portion of the
remaining teeth. By designing the appliance to cover the teeth, a
much larger contact surface area is afforded compared to
traditional spring retainers and wire-based appliances.
[0006] As described, the appliances are only effective in
repositioning teeth when the appliance is placed over the patient's
teeth. Removal of the appliance for any reason interrupts the
treatment plan and lengthens the overall period of treatment.
Therefore, removal of the appliance should be minimized for
effective and timely treatment. However, a number of dental and
periodontal therapies which may be desired or required by the
patient may not be effectively utilized while the appliance is in
place. Such therapies may be prescribed by a practitioner to
improve oral health or they may be requested by the patient for
cosmetic purposes.
[0007] Oral health concerns often include tooth decay, gingivitis,
and periodontitis, to name a few. Tooth decay may be largely
prevented or arrested with fluoride treatment. Treatments include
toothpastes, gels, rinses and varnishes. Gum disease, such as
gingivitis or periodontitis, is caused by bacterial growth
associated with dental plaque and calculus deposits. The most
common recommendation for preventing such bacterial growth is to
mechanically remove the plaque from the tooth surfaces. However,
chronic gingivitis and tooth decay have plagued many individuals
who in fact comply with good oral hygiene methods and plaque
removal. This may be due to a variety of factors including genetic
predispositions, illnesses, mouth breathing, and medical treatment
programs.
[0008] In such cases, bacterial control may be accomplished with
the use of antibacterial drugs. A common antibacterial agent shown
to be effective in reducing the activity of many common strains of
oral flora is chlorhexidine. Chlorhexidine is a cationic biguanide
microbicide with a broad spectrum of activity against many forms of
bacteria and fungi. Therefore, it has been a popular agent in many
studies of gingivitis reversal. Chlorhexidine has traditionally
been delivered to the oral environment through the use of rinses,
such as Peridex.RTM. (Proctor and Gamble). Sustained delivery to
the gingiva has also been attempted with the use of chlorhexidine
impregnated dental floss and dental appliances, such as trays or
mouthguards.
[0009] Another frequently prescribed antibacterial agent is
tetracycline. Tetracycline is a broad spectrum antibiotic which is
effective against virtually all common groups of pathogenic
bacteria, both gram positive and negative. Tetracycline may be
combined with an antifungal agent, such as amphotericin, to provide
activity against fungi. Tetracycline has traditionally been
delivered to the oral environment through systemic administration,
although localized delivery has been attempted with the insertion
of tetracycline-filled hollow fiber devices into periodontal
pockets and the use of tetracycline laden dental appliances, such
as trays and mouthguards. In addition, a number of other
antibacterial drugs are available for dental and periodontal
therapy.
[0010] Cosmetic treatments often include tooth bleaching or
whitening and breath freshening products. Discolorations of enamel
and dentin may occur due to aging, consumption of staining
substances (coffee, tea, colas, tobacco), trauma, staining due to
systemic tetracycline (antibiotic) therapy, excessive fluoride,
nerve degeneration and old dental restorations. Bleaching lightens
these discolorations for a whiter or brighter appearance.
Typically, a bleaching gel is placed in a thin custom-fitted tray
that fits over the teeth. The tray is worn at night for usually 10
to 14 days and may require periodic re-bleaching treatments for
approximately one or two nights every six months. Breath freshening
products are often used by patients to treat halitosis or for
enjoyment of the taste. These include a variety of sprays, rinses,
mints, gums, or candies, to name a few.
[0011] Many of these therapies require access to the teeth and
gingival margin which are typically covered by the elastic
repositioning appliance when in use. In addition, some of these
therapies may best be administered by localized delivery over
extended periods of time which would create substantial
interruption of the treatment plan. For example, low level delivery
of antibiotics by sustained release methods is often desired to
treat periodontal disease. Likewise, treatments such as bleaching
and whitening may require interruption of the treatment plan for up
to two weeks. Removal of the appliance during these periods would
lengthen the overall treatment period. In addition, many of these
therapies require the usage of specific devices, gels, rinses,
applicators and instructions for each administration of therapy.
These accessories may be costly, bulky and difficult to use.
[0012] Although removal of the appliance should be minimized, it is
necessary to remove the appliance during daily oral hygiene
routines, such as brushing and flossing of the teeth. Likewise, the
appliance may be removed from time to time for participation in
athletic activities or for comfort, such as when eating. The
ability to temporarily remove such appliances allows the patient to
pursue conventional oral hygiene, but teeth which are covered by
the appliances a majority of the time may still be at an increased
risk of dental and periodontal disease.
[0013] It would be desirable to provide improved devices, systems
and methods utilizing elastic repositioning appliances which permit
and/or enhance concurrent dental and periodontal therapies.
Likewise, it would be desirable to provide such devices, systems
and methods which would reduce or eliminate the need for additional
accessories and/or protocols to apply such therapies. Further, the
devices, systems and methods should be economical and easy to use.
At least some of these objectives will be met by the designs and
methods of the present invention described hereinafter.
SUMMARY OF THE INVENTION
[0014] The present invention provides devices, systems and methods
for orthodontic treatment using repositioning appliances, typically
elastic polymeric shells, while concurrently delivering substances
to the teeth or gums, for example, to provide dental and
periodontal and/or cosmetic therapies. Such therapies are
traditionally provided with the use of a variety of accessories and
devices which are applied using separate appliances, materials,
etc. The present invention eliminates the need for such additional
devices by incorporating these therapies into the repositioning
appliance. Moreover, the ability to deliver therapeutic and other
agents is concurrent with the course of a repositioning
procedure.
[0015] By "concurrent" or "concurrently," it is meant that the
substance or agent delivery to the teeth occurs during at least a
portion of the duration of the repositioning of the teeth. Thus,
the substance may be delivered continuously during the entire
duration of the repositioning process, i.e. the substance may be
present in or on each repositioning appliance in an amount or
amounts sufficient to assure that it is released to the oral
environment at all times the appliance is placed over the teeth.
Alternatively, the substance may be present in or on the
repositioning appliance(s) at only selected times or over selected
time intervals so that the substances are delivered at spaced-apart
times during the repositioning process. For example, each
successive repositioning appliance may be preloaded with a bolus of
the substance so that the bolus is delivered to the patient at the
outset of use of each new appliance. After the initial bolus is
depleted, the substance will not be delivered again until the next
successive appliance is used. As an alternative example, the
patient could apply an amount of a substance at a time each day,
where the substance is then released over a relatively short time
interval and no more substance delivered until the next day. A
multitude of other particular patterns are also possible.
[0016] While the appliances will be particularly intended for
repositioning teeth, most often when used in systems of multiple
aligners, t hey may in some instances be useful as drug or
substance delivery devices without the concurrent repositioning of
teeth. In particular, many of the specific device constructions
described below are themselves novel and useful for substance
delivery, and the present invention encompasses such devices.
[0017] In a first aspect of the present invention, an oral delivery
appliance comprises an elastic repositioning appliance providing
one or more substances or agents for oral delivery. As previously
described, elastic repositioning appliances comprise a thin shell
of elastic polymeric material having cavities shaped to receive and
resiliently reposition teeth from one arrangement to a successive
arrangement. This is possible because the cavities are shaped to
fit a mold of digitally arranged teeth in the successive
arrangement. A full description of an exemplary elastic
repositioning appliance shaped in this manner is described in U.S.
Pat. No. 5,975,893, and in published PCT application WO 98/58596.
Placement of the elastic positioner over the teeth applies
controlled forces in specific locations to gradually move the teeth
into the new configuration. In order to apply sufficient force, the
appliance generally covers the tooth surfaces and portions of the
gingival margin. Thus, both individual repositioning appliances and
systems of such elastic repositioning devices may be used to
deliver agents to the underlying tooth surfaces and gingiva
comprising the oral environment while repositioning teeth.
[0018] In a first embodiment, the oral delivery appliance delivers
fluoride to the oral environment to prevent or treat tooth decay.
Traditionally, fluoride has been delivered to the oral environment
through the use of toothpastes, gels, rinses and varnishes, to name
a few. The present invention provides fluoride delivery which may
be used in conjunction with traditional applications or may replace
certain applications. Such fluoride may be provided in a number of
forms, such as neutral sodium fluoride, stannous fluoride, hydrogen
fluoride, or acidulated phosphate fluoride (APF) gel, for example.
Fluoride may be releasably attached to the elastic repositioning
appliance in a number of forms, as will be described in more detail
in later sections, to provide delivery to the oral environment.
[0019] In a second embodiment, the oral delivery appliance delivers
an antibiotic or drug to the oral environment. In the case of
antibiotics, delivery of such an agent may inhibit or kill various
microorganisms. Antibiotics often used to treat gingivitis and
periodontitis include chlorhexidine and tetracycline. Such
antibiotics may be releasably attached to the elastic repositioning
appliance in a number of forms, as will be described in more detail
in later sections, to provide delivery to the oral environment.
[0020] In a third embodiment, the oral delivery appliance delivers
a bleaching material to the oral environment. Bleaching of the
teeth is a common cosmetic procedure requested of dental
practitioners by their patients. The active ingredient in standard
bleaching gels is carbamide peroxide and is typically present in an
18-37% suspension. Bleaching materials, such as carbamide peroxide,
may be releasably attached to the elastic repositioning appliance
in a number of forms, as will be described in more detail in later
sections, to provide delivery to the oral environment.
[0021] In a fourth embodiment, the oral delivery appliance delivers
a breath freshener to the oral environment. Breath fresheners are
commonly available in a number of flavors and scents, including
mint and fruit flavors, derived from essential oils and/or natural
or artificial flavorings, to name a few. Such breath fresheners may
be releasably attached to the elastic repositioning appliance in a
number of forms, as will be described in more detail in later
sections, to provide delivery to the oral environment.
[0022] In a second aspect of the present invention, at least some
of the elastic repositioning appliances in a system for
repositioning teeth are coupled to means for releasing the agent to
the oral environment when the appliance is placed over the teeth.
Such means may comprise a layer which includes the agent. The layer
may be formed over at least a portion of the surfaces of the
repositioning appliance. These surfaces include both the cavity
surfaces, the surfaces within the cavities which contact the teeth
when in place, and the external surfaces, the surfaces of the
appliance which contact the cheeks and lips when in place. The
layer may be comprised of various materials and may take a variety
of forms. For example, the layer may consist essentially of the
agent. In other words, the agent may be attached directly to a
surface of the polymer shell of an elastic repositioning appliance.
This may be achieved by applying the agent (optionally in an inert
carrier or diluent) itself to the surface utilizing a number of
methods, such as spraying, painting and/or dipping. When the
repositioning appliance is placed over the patient's teeth, the
agent may then be released to the oral environment.
[0023] Alternatively, the layer may comprise the agent present in
or on a carrier or binder which promotes adhesion or attachment to
the appliance and/or which creates a matrix from which the agent
can be released by diffusion or dissolution. In one embodiment, the
agent is dissolved in the carrier or binder. In this case, the
agent may be provided in powder or similar form and dissolved in a
liquid solvent. The result may be a solution which may be applied
to a surface of the shell, typically by spraying, painting and/or
dipping, to form a coating or film. When the repositioning
appliance is placed over the patient's teeth, the agent may then be
released from the coating to the oral environment. Release may be
due to activation or deactivation of the carrier or any other
releasing mechanism, such as by enzymes or proteins in saliva. Or
release may be due to degradation of the carrier by contact with,
for example, saliva. In some cases, the binder or carrier may
evaporate upon application to the layer to the surface leaving the
agent behind. In these cases, the agent may be released in a
similar fashion as when the agent is directly attached to the
surface, as described above. It may be appreciated that any agent,
particularly fluoride materials, antibiotics, bleaching materials
and breath fresheners, may be delivered to the oral environment in
this manner.
[0024] In another embodiment, the agent is encapsulated or
suspended in the layer. A common material for suspension of an
agent is a semisolid material, such as a gel, jelly or putty. Such
a material may be applied to a surface of the shell by spraying,
painting and/or dipping to form a coating or film. Here, as in all
cases, suspension is not limited to a scientific definition and may
refer to any situation in which a carrier holds, contains, supports
or otherwise includes an agent. Alternatively or in addition, the
semisolid material may be deposited in the cavities of the polymer
shell which are shaped to receive the teeth. The cavities may be
filled to any desired level. When the repositioning appliance is
positioned over the teeth, the teeth will directly contact the
semisolid material in the cavities and displace any extra material
as the teeth are inserted into the cavities. Therefore, it is
desired to fill the cavities to a level which will avoid excess
overflow of the material from the appliance. Delivery of an agent
by use of a semisolid suspension material is common in bleaching
treatments and fluoride treatments, for example. However, such
treatments apply the material with the use of a tray or generic
appliance which does not apply repositioning forces to the teeth.
By modifying a repositioning appliance, as described above,
orthodontic treatment may continue throughout the delivery of such
agents. It may be appreciated that any agent, particularly fluoride
materials, antibiotics, bleaching materials and breath fresheners,
may be delivered to the oral environment in this manner.
[0025] Another common material for encapsulation or suspension of
an agent is a controlled-release material. Thus, the layer may be
comprised of a rate-controlling material wherein the rate
controlling material controls the rate at which the agent is
released from the layer. Controlled-release or rate-controlled
materials deliver a predetermined amount of an agent at a
predetermined rate. Often such delivery maintains a steady-state
concentration of an agent in an environment within a desired
therapeutic range for a prolonged period of time. Thus, a
prescribed dosage may be delivered. In addition, the ability to
sustain delivery eliminates the need for repeated applications of
the agent for dosed delivery to the oral environment.
[0026] Although such controlled release materials may be provided
as a semisolid material, such as a gel, jelly or putty, as
described above, these materials may also be provided as a solid
material which is attached to the polymeric shell of the
repositioning appliance. One type of controlled-release material
comprises a polymer matrix membrane within which finely dispersed
particles of an agent are suspended. The agent may diffuse through
the matrix membrane according to a concentration gradient.
Alternatively or in addition, the agent may be released by
degradation of the polymer matrix membrane material. In either
case, the controlled-release material may be provided as a sheet
which may be laminated to a surface of the shell. The
controlled-release sheet may be layered with the elastomeric
polymer and vacuum formed over a mold to form the repositioning
appliance. The controlled-release material may be arranged so that
it is present on the inside or outside surfaces of the appliance
depending on the material and desired application. Or, the
controlled-release sheet may be laminated or bonded to a surface of
the polymeric shell after forming to supply agent delivery in
desired areas. Alternatively, the controlled-release material may
be provided as a tablet or similar mass which may be inserted into
the polymeric shell of the repositioning appliance. The agent may
then elute from the tablet into the oral environment over time.
[0027] In another embodiment, the agent may be held within pores of
a material and may elute out at a controlled rate from the pores.
The agent itself may be absorbed into the pores of the material, or
the agent may be suspended in a carrier which is absorbed into the
pores of the material. In the latter case, the agent may be
released from the carrier by diffusion and/or by controlled
degradation of the carrier material. This may incorporate a
rate-controlling mechanism in addition to the controlled-release of
the agent from the pores. As mentioned, in some cases, enzymes in
the patient's saliva will activate the release or degrade the
carrier material to release the agent. It may be appreciated that
the agent may be released by a combination of any of the release
methods.
[0028] In a further embodiment, the polymeric shell of the
repositioning appliance itself comprises a controlled-release
material containing the agent. In this case, at least a portion of
at least some of the polymeric shells in a system for repositioning
teeth are formed from a controlled release material wherein the
rate controlling material controls the rate at which the agent is
released from the shell. As previously described, the
controlled-release material may be a provided in the form of a
sheet. Thus, the sheet of controlled-release material may be vacuum
formed over a mold of the patient's teeth to form a repositioning
appliance itself. In this manner, no additional elastomeric
materials may be needed to form the appliance. The
controlled-release material may be a polymer matrix membrane, a
porous material or any suitable material. Controlled-release may be
designed so that the elution rate of the agent corresponds to the
repositioning rate of the teeth. The agent may elute throughout the
repositioning process, concluding as the teeth reach the desired
arrangement prescribed by the appliance.
[0029] In a still further embodiment, the releasing means coupled
to at least some of the repositioning appliances comprises a
reservoir formed in the shell of the appliance in addition to the
cavity which receives the teeth. Typically, a rate controlling
membrane is disposed over the reservoir wherein the rate
controlling membrane controls the rate at which the substance is
released from the reservoir. The reservoir may be pre-filled or
pre-loaded with an agent or substance for delivery. In this case,
the appliance may be ready for insertion or use upon removal from
any packaging without the need of loading the appliance with the
agent for delivery. If the releasing means is designed for a single
delivery period, the appliance may be worn throughout the
prescribed repositioning period and then disposed of. If the
releasing means is designed for multiple delivery periods, the
reservoir may be replenished with the agent to be released any
number of times throughout the prescribed repositioning period. It
may be appreciated that any agent, particularly fluoride materials,
antibiotics, bleaching materials and breath fresheners, may be
delivered to the oral environment in this manner.
[0030] In some instances, it may be desirable to change a visual
characteristic of the polymeric shell of an oral appliance. Such
appliances comprise a polymeric shell having a cavity shaped to be
removably placeable over the teeth and a material on or within the
shell that changes a visual characteristic of the shell. Such a
change is typically in response to a change in the environment. In
some cases, the visual characteristic is a color, such as green,
red or blue. Thus, the appliance may appear colored or a particular
color under certain environmental conditions, either in the oral
environment or when removed. The described material may be a dye
which changes color in response to a change in temperature. For
example, the dye may change color when the appliance is removed
from the mouth and changes temperature from body temperature
(37.degree. C.) to room temperature (25.degree. C.). Similarly, the
dye may change color when the appliance is rinsed with cool
water.
[0031] In a fourth aspect of the present invention, methods for
concurrently repositioning teeth and delivering agents to the oral
environment of a patient are provided. For example, one method
comprises placing a first tooth position adjustment appliance over
the patient's teeth, wherein the teeth move to a first tooth
arrangement. After removal of the first appliance, a second tooth
position adjustment appliance is placed over the patient's teeth
wherein the teeth move to a second tooth arrangement. Concurrently
with the repositioning of the teeth, an agent or substance is
released from at least one of the first and second tooth position
adjustment appliances to the oral environment while the appliance
is in place of the patient's teeth.
[0032] Although the appliance may be pre-loaded with the agent and
ready for use upon removal from any packaging, appliances that are
not pre-filled or pre-loaded may require loading prior or
immediately prior to placing the appliance over the teeth. Loading
may comprise placing the agent in a teeth-receiving cavity. As
described previously, the cavities may be filled to any desired
level. When the appliance is positioned over the teeth, the teeth
will directly contact the agent in the cavities as the teeth are
inserted into the cavities. Alternatively, loading may comprise
placing the agent into an agent release reservoir in the appliance
immediately prior to placing the appliance over the teeth. The
agent will then elute from the reservoir into the oral environment
when the appliance is in place over the teeth. The elution rate may
be controlled by a controlled release membrane which separates the
reservoir from the surrounding environment. Loading may also
comprise adhering a rate controlling material containing the agent
to a surface of the appliance prior to placing the appliance over
the teeth. Such a material may comprise a polymer matrix membrane
which may be removably or permanently adhered to the polymeric
shell of the appliance in desired areas for delivery of the agent.
And finally, loading may comprise absorbing the agent into a porous
material on or within the appliance immediately prior to placing
the appliance over the teeth.
[0033] Repositioning of the teeth with the use of a position
adjustment appliance involves placing the appliance over the teeth.
However, the appliance is periodically removed for daily dental
hygiene practices and other events throughout the repositioning
protocol until the teeth are moved to at least near the desired
tooth arrangement. While the appliance is removed from the teeth,
the appliance may be replenished with the agent or substance for
delivery. Replenishment may be performed immediately prior to each
time the appliance is replaced over the teeth or it may be
performed according to any prescribed protocol.
[0034] In a fifth aspect of the present invention, methods for
introducing agent delivery to a prescribed tooth repositioning
treatment plan are provided. A treatment plans is determined by an
orthodontist or practitioner at the outset of orthodontic
treatment. The plan involves moving the teeth through a series of
intermediate configurations or arrangements to a final desired
arrangement with the use of a system of tooth positioning
appliances. Each appliance comprises a polymeric shell having
cavities which is removably placeable over the teeth and wherein
the cavities of successive shells are shaped to reposition teeth
from one arrangement to a successive arrangement according to the
treatment plan. The entire series of appliances may be provided at
the outset of treatment, or a subset of appliances. In any case,
the need or desire for delivery of an agent to the oral environment
may occur at any point during the course of treatment. In such a
case, an agent and/or means for releasing an agent to the oral
environment may be coupled to an appliance at any time during
treatment.
[0035] Means for releasing the agent may include a number of
embodiments, including any such means previously described.
Typically, means for releasing the agent comprises a layer
including the agent, as previously described, and coupling
comprises adhering the layer to at least a portion of a surface of
the appliance. When the layer consists essentially of the agent,
adhering may involve coating, spraying, dipping or painting the
agent on the surface of the appliance. Thus, a pre-formed appliance
may simply be coated with the agent prior to insertion in the
patient's mouth. When the layer comprises an agent present in or on
a carrier or binder, adhering may involve attaching the carrier or
binder a surface of the appliance. Similarly, when the agent is
encapsulated in the layer, the layer may be attached to the surface
of the appliance. The layer may comprise a sheet of rate
controlling material wherein the rate controlling material controls
the rate at which the agent is released from the layer. In this
case, the sheet may be bonded to the surface of the appliance with
an adhesive. Alternatively, the sheet may be attached to the
surface by press fitting. The sheet and the surface may each be
shaped so that they snap or fit together by pressing them together.
For example, the sheet may have a formed protrusion and the surface
a formed inset, wherein the protrusion fits into the inset when
pressed upon the inset and holds the sheet in place. In many
instances, the appliance may be porous or have a reservoir which
can be loaded with a desired agent at any time the treating
professional and/or the patient decide that it is appropriate. For
example, an appliance can be immersed in a solution f the agent,
allowing the appliance to absorb or adsorb the agent at a
particular time.
[0036] In addition, the sheet may be pre-formed to a shape adapted
for fitting against the surface of the appliance or a surface of
the teeth or gingiva. For example, the sheet may be pre-formed to
reflect the shape of the surface of one or more teeth or the
gingiva, particularly along the gingival margin. The preformed
sheet may then be held against that surface when the sheet is
coupled to the appliance and the appliance is placed over the
teeth. Coupling may involve any means of attaching the sheet to the
appliance. In particular, the pre-formed sheet may further comprise
an adhesive layer which may provide bonding of the sheet to the
surface of the appliance.
[0037] Other objects and advantages of the present invention will
become apparent from the detailed description to follow, together
with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0038] FIG. 1 is a schematic illustration of an exemplary elastic
repositioning appliance.
[0039] FIG. 2 is a cross-sectional view along line 2-2 of the
repositioning appliance of FIG. 1 with a layer comprising an agent
on its surface.
[0040] FIG. 3 is a cross-sectional view of an appliance having a
semisolid material containing an agent applied to its surface.
[0041] FIG. 4 is a cross-sectional view of an appliance having a
cavity filled with a semisolid material containing an agent.
[0042] FIG. 5 illustrates the layering of a sheet of
controlled-release material containing an agent with a polymeric
sheet for use in the formation of an oral delivery appliance.
[0043] FIG. 6 illustrates the attachment of a controlled-release
material to the polymeric shell of an appliance and the insertion
of a controlled-release tablet into a portion of the polymeric
shell.
[0044] FIG. 7 illustrates a reservoir type releasing means having
sealed ends.
[0045] FIG. 8 illustrates a reservoir type releasing means that is
accessible to the user so that the reservoir may be replenished
with an agent.
[0046] FIG. 9 is a cross-sectional view of an appliance having a
binding material and releasably bound agent applied to its
surface.
[0047] FIG. 10 is a cross-sectional view of an appliance comprised
of a controlled-release material containing an agent.
[0048] FIG. 11 illustrates a gradual color change of an appliance
from transparent to colored as the appliance changes in
temperature.
[0049] FIG. 12 depicts the use of a color or dye localized in a
specific area; examples of a stripe formed in the appliance and a
portion of colored material affixed to a surface are shown.
[0050] FIG. 13 illustrates the positioning of an appliance of the
present invention over the teeth of the patient.
[0051] FIG. 14 is a perspective view of a pre-formed sheet 60 of
material containing an agent may have a shape contoured to fit
against a surface of an appliance.
[0052] FIG. 15 is a perspective view of the pre-formed sheet of
FIG. 14 fit over an outside surface of an appliance.
[0053] FIG. 16 is a side view of a pre-formed sheet of material
containing an agent, contoured to fit against a surface of the
teeth and gingiva, together with a side view of an appliance to
which it may be joined.
[0054] FIG. 17 is a side view of the pre-formed sheet and appliance
of FIG. 16 joined with an adhesive layer.
DESCRIPTION OF THE SPECIFIC EMBODIMENTS
[0055] An oral delivery appliance of the present invention
comprises an elastic repositioning appliance which concurrently
provides orthodontic repositioning forces and dental therapies.
FIG. 1 depicts an exemplary elastic repositioning appliance 10 used
for orthodontic treatment. The appliance 10 comprises a polymeric
shell 12 having cavities 14 shaped to receive and resiliently
reposition teeth from one tooth arrangement to a successive tooth
arrangement. The appliance 10 is preferably formed from a thin
sheet of a suitable elastomeric polymer, such as Tru-Tain 0.03 in.
thermal forming dental material (Tru-Tain Plastics, Rochester,
Minn.), or Essix A-Type or Essix B-Type thermal forming material
(Raintree-Essix, New Orleans, La.). The overall method for
producing incremental position adjustment is provided in U.S. Pat.
No. 5,975,893, previously incorporated by reference. But, in
general, the shell 10 is typically produced by heating a
thermoformable polymer sheet and vacuum or pressure forming the
sheet over tooth members of a mold. Thus, the shell 12 is a direct
representation of the characteristics of the mold. If this
appliance 10 is worn by a patient as a stage in orthodontic
repositioning, the shell 12 will preferably, but not necessarily,
fit over all teeth or dental features supported by the patient's
dental arch. Those teeth which are to be repositioned will be
slightly misfit by the appliance to allow force and movement into
the desired positions.
[0056] Dental and periodontal therapies may be simultaneously
delivered by such an elastic repositioning appliance to provide
uninterrupted orthodontic treatment while treating other
conditions. Such therapies include fluoride treatment to prevent or
treat tooth decay, antibiotic or drug therapy to treat gingivitis
and periodontitis, bleaching to improve the cosmetic appearance of
the teeth, and/or breath freshening to treat halitosis. In
addition, such an elastic repositioning appliance may also comprise
a material which changes a visual characteristic of the shell in
response to a change in the environment, as stated previously.
[0057] Each of the above identified therapies involves one or more
therapeutic agents which are delivered to the oral environment. The
present invention provides a tooth positioning appliance coupled to
means for releasing one or more of these agents to the oral
environment. Agents for the above identified therapies include, but
are not limited to, various forms of fluoride, such as neutral
sodium fluoride and stannous fluoride, various antibiotics, such as
chlorhexidine and tetracycline, bleaching ingredients, such as
carbamide peroxide, and breath fresheners or flavors. Means for
releasing the agent may include a number of embodiments.
[0058] In one embodiment, means for releasing the agent to the oral
environment comprises a layer including the agent formed over at
least a portion of the surfaces of the polymer shell. Such a layer
may comprise the agent 15 itself. This is illustrated in FIG. 2,
which depicts a cross-sectional view (along line 2-2 of FIG. 1) of
a polymer shell 12 having cavities 14, shaped to receive and
resiliently reposition teeth, and an agent 15 attached to its
surface. It may be appreciated that the depictions of the agent is
for illustration purposes and does not necessarily reflect the
actual shape, size relationship or distribution of the agent
particles. This applies to all depictions of agents hereinafter.
Such attachment or formation of the layer may be achieved by
applying the agent 15 to the surface of the shell 12 by a number of
methods, including spraying, painting and/or dipping. Thus, when
the oral delivery appliance 20 is placed over the patient's teeth,
the agent may then be released to the oral environment. When the
agent 15 is attached to the inside surface of the appliance 20, as
shown in FIG. 2, the agent may directly contact the teeth and/or
gingiva. This may be best suited for treatments such as fluoride or
antibiotic therapy which benefit from direct contact with the teeth
and/or gingiva. However, other treatments, such as breath
freshening, may most benefit from attachment to the outer surface
of the appliance 20. Therefore, agents 15 may be attached to any or
all surfaces of the appliance 20.
[0059] In another embodiment, the layer comprises the agent 15
present in a carrier or binder. A common carrier for suspension of
an agent is a semisolid material, such as a gel, jelly or putty. As
depicted in FIG. 3, such semisolid material 22 may be applied to
the surface of the shell 12 by spraying, painting and/or dipping to
form a coating or film. Alternatively, as depicted in FIG. 4, the
semisolid material 22 may be deposited in the cavities 14 of the
polymer shell 12 which are shaped to receive the teeth. The
cavities 14 may be filled to any desired level such that when the
appliance 20 is positioned over the teeth, the teeth will directly
contact the material 22 and displace any extra material 22.
Delivery of an agent 15 by the use of such a material 22 is most
common in bleaching and fluoride treatments, however any type of
agent 15 may be used.
[0060] Another type of layer is a controlled-release material
impregnated with the agent, wherein the rate controlling material
controls the rate at which the agent is released from the layer.
Controlled-release or rate-controlled materials deliver an agent at
a predetermined rate. As previously described, such delivery may be
achieved by a number of methods. First, the agent may be released
by diffusion through the controlled-release material. In this case,
the agent is typically present as finely dispersed particles in a
polymer matrix membrane. This is often termed a monolithic
dispersed type system, monolithic device, or matrix diffusion
system. As the concentration of agent is reduced in the matrix due
to diffusion delivery to the oral environment, the slope of the
drug diffusion curve is also reduced. The agent delivery rate
decreases over time as the material is depleted. Hence, the
characteristic release profile of a monolithic system follows an
asymptotic curve; after an initial burst of rapid release, the
elution approaches a constant rate. Second, the agent may be
released by degradation of the controlled-release material.
Degradation may be achieved by a number of mechanisms, including
enzymatic degradation by enzymes in the saliva. The agent may be
encapsulated or contained in a biodegradable material, such as a
polymer matrix. Any number of degradation rates may be achieved by
manipulating the molar ratio of the monomers in the matrix.
Further, the agent may be released by a combination of diffusion
and degradation of the releasing layer. Alternatively or in
addition, the agent may be released by elution from pores within
the releasing layer. Depending on the structure of the layer,
elution from the pores may be achieved by a number of methods. If
the agent is contained in a controlled-release material which fills
the pores, the agent may be released from the controlled-release
material by diffusion and/or degradation and then elution from the
pores themselves.
[0061] One attribute of controlled-release materials is that they
may be provided in a solid form, such as a thin film or sheet,
which may be attached to the polymeric shell of an elastic
repositioning appliance. Referring to FIG. 5, a controlled-release
material 24 containing the agent 15 may be provided as a sheet 25
and used in the formation of an appliance of the present invention.
Here, the sheet 25 may be layered with an elastomeric polymer sheet
28 over a mold 30 of the patient's dentition. Together the sheets
25, 28 may be vacuum formed over the mold 30 to form the
repositioning appliance. By placing the controlled-release material
sheet 25 between the mold 30 and the polymer sheet 28, as shown,
the controlled-release material 24 will cover the inside surfaces
of the appliance and will be positioned against the patient's teeth
and/or gums when the appliance is in place. This may be most
beneficial for elution of agents 15 such as fluoride, antibiotics
or bleaching materials.
[0062] Alternatively, the controlled-release material 24 may be
attached to the polymeric shell 12 of the oral delivery appliance
20 after forming the appliance. As shown in FIG. 6, the
controlled-release material 24 containing the agent 15 may be
laminated, bonded or otherwise attached to a surface of the polymer
shell 12 in a desired area. Such attachment may be removable, so
that the material 24 may be removed when the agent 15 has
substantially eluted or the therapy is to be discontinued, or it
may be non-removable, so that the material 24 is present throughout
the life of the appliance. Also shown in FIG. 6 is the use of a
controlled-release tablet 34 which may be inserted into a pocket 36
or portion of the polymeric shell 12 of the appliance 20. Portions
of the pocket may be perforated or meshed to facilitate delivery of
the agent. The agent may then elute from the tablet 34 into the
oral environment over time. This design may be most applicable to
elution by degradation of the tablet 34, wherein the tablet 34 may
be replaced periodically for renewed delivery.
[0063] In a further embodiment, the releasing means comprises a
reservoir formed in the polymer shell in addition to the cavity
which receives the teeth. Reservoir devices or membrane diffusion
systems can supply an agent or substance at a constant rate under
sink conditions. These systems consist of three elements: a
reservoir containing the agent, a low concentration sink, such as
the oral environment, and a rate-controlling membrane separating
the reservoir from the sink. The system obeys Fick's Law of
Diffusion for the mass flux across the membrane. Thus, the system
is held at a constant delivery rate based on the diffusion
coefficient through the membrane.
[0064] Referring to FIG. 7, the releasing means is shown to
comprise a reservoir 60 formed in the polymer shell 12, in addition
to the cavity 14 which receives the teeth. The reservoir holds the
agent 15 and is covered by a rate controlling membrane 62 which
controls the rate at which the agent 15 is released from the
reservoir 60. The reservoirs 60 are depicted as being located
substantially within the wall of the polymer shell 12 for elution
to the cavity 14. However, it may be appreciated that reservoirs 60
may be located anywhere in the shell 12, may be external to the
wall of the shell 12 and may elute in any direction. The reservoirs
60 may be pre-filled with the agent 15 to be released. That is, the
appliance 20 is provided with the reservoirs 60 filled with the
agent 15. In this case, the reservoirs 60 may be sealed by the
membrane 62 as depicted in FIG. 7. However, the reservoirs 60 may
also be accessible to the user so that the reservoir may be
replenished with agent 15 as desired. In this case, the reservoir
60 may be not be sealed by the membrane 62 as depicted in FIG.
8.
[0065] In another embodiment, the agent 15 is supported by a
carrier. As depicted in FIG. 9, the carrier comprises a binding
material 40 which releasably binds the agent 15 to a surface of the
polymeric shell 12. The binding material 40 may release the agent
15 by a number of mechanisms, including dissolution of the binding
material 40, activation or deactivation of the binding material 40
or any other release mechanism.
[0066] In a further embodiment, as depicted in FIG. 10, the
polymeric shell 12 of the oral delivery appliance 20 is comprised
of a controlled-release material 42 containing an agent 15. In this
case, the controlled-release material 42 itself is formed to
function as a repositioning appliance. This may be achieved by
vacuum forming a sheet of controlled-release material over a mold
of the patient's teeth. The agent 15 may then elute from the
appliance 20 by means of diffusion or other release mechanisms.
[0067] Means for releasing the agent to the oral environment have
been described in a number of embodiments, above, in regards to the
agent itself. However, in each embodiment, the agent may first be
encapsulated or microencapsulated in a material, typically a
polymer. Such encapsulation may be desired or necessary to protect
the agent from the effects of processing. For example, some agents
may be hydrolyzed or denatured by processes such as extrusion or
thermoforming which may be involved in the production of the
appliance. Encapsulation may also protect the agent from
environmental factors throughout the shelf-life of the appliance.
Therefore, in the above descriptions and throughout, "agent" may
identify the agent itself or an encapsulated agent.
[0068] Agents may be encapsulated or entrapped by a number of
materials. Such materials may include polylactic acids, polycapric
lactones, polyvinyl alcohols, polyacrylic acids, polyethylene
oxides, polylactide glycolic biodegradable polymer capsules and
side-chain crystalizable polymers, to name a few. Encapsulation may
be achieved by a variety of processes. Particularly, the agent may
be encapsulated by spray-drying. For example, the agent may be
mixed or combined with a solvent, such as polyvinyl alcohol, and
then combined with a polymer resin. After the solvent evaporates,
polymer microcapsules, each containing the agent dispersed
throughout its matrix, are retained.
[0069] The encapsulating or entrapping material may or may not
provide controlled-release of the agent from the microsphere. If
the encapsulating material does provide controlled-release
capabilities, such a layer would be in addition to any
controlled-release means for releasing the agent previously
described. For example, the encapsulated agent may be dispersed
throughout a sheet of controlled-release material which is later
attached to the polymeric shell of an elastic repositioning
appliance. When the appliance is positioned in the patient's mouth,
the agent may elute at a controlled rate based on the release of
the agent from the encapsulating material and from the sheet of
controlled-release material.
[0070] Similiarly, the encapsulating material may be an ion
exchange resin. Such resins have a very high surface area and are
able to absorb a large quantity of an agent for
controlled-delivery. An exemplary resin is sold under the trademark
MICROSPONGE (Advanced Polymer Systems), and described, for example,
in U.S. Pat. No. 5,145,675, the full disclosure of which is
incorporated herein by reference. In addition to serving as an
encapsulating material, ion exchange resins may be used for as a
controlled-delivery material in any of the above described
embodiments.
[0071] In some instances it may be desirable to change a visual
characteristic of the polymeric shell of an oral appliance. Such
appliances comprise a polymeric shell 12 having a cavity 14 shaped
to be removably placeable over the teeth and a material on or
within the shell that changes a visual characteristic of the shell.
Such a change is typically in response to a change in the
environment. For example, the material may be a dye which changes
color when the appliance is removed from the patient's mouth and
changes temperature due to the change in environment. This gradual
color change is illustrated in FIG. 11. For example, as shown, a
transparent oral delivery appliance 40 will remain transparent when
it is in the mouth and maintained at body temperature. Upon removal
from the mouth, the appliance will cool to room temperature. As the
appliance begins to cool, the colorant will gradually become
visible, as illustrated in the tinted oral delivery appliance 42.
As the appliance equilibrates to room temperature, the colorant
will become more visible, as illustrated in the colored oral
delivery appliance 44.
[0072] The color may be dispersed throughout the appliance, as in
FIG. 11, or the color may be localized in a specific area within or
on a surface of the appliance. As shown in FIG. 12, the appliance
20 may contain, for example, a stripe 46 of color or dye in a
specific location. Such a stripe 46 may be visible at all times or
it may only appear when removed from the oral environment. In
either case, the stripe 46 may be positioned so that it is hidden
from view, i.e. along the lingual surfaces or along the molars, or
it may be placed anywhere along the appliance. 20. Likewise, a
portion of material 48 which changes a visual characteristic may be
attached, bonded or laminated to a surface of the polymer shell 12,
either removably or permanently.
[0073] Methods for concurrently repositioning teeth and delivering
agents to the oral environment of a patient involve the utilization
of at least one tooth position adjustment appliance having a means
for releasing an agent as described above. Typically, repositioning
of the teeth involves placing a first repositioning appliance over
the patient's teeth wherein the teeth move to a first tooth
arrangement. After the teeth have moved to this arrangement, the
appliance is replaced with a second repositioning appliance which
is placed over the patient's teeth to move the teeth to a second
tooth arrangement. This is continued with a succession of
appliances until the teeth are moved to a desired arrangement.
Concurrent delivery of an agent is accomplished by releasing the
agent from at least one of the repositioning appliances while the
appliance is in place over the patient's teeth. Means for releasing
the agent may include any of the means described previously.
[0074] Referring to FIG. 13, simply positioning the appliance 20
over the patient's teeth 50 may deliver the agent 15 to the oral
environment. It may be appreciated that the agent 15 is enlarged in
FIG. 13 to illustrate the presence of the agent 15 in the appliance
20. In many cases, the dispersed agent 15 is so fine that the
appliance 20 appears transparent. In other cases, the agent 15 may
be present at a density high enough to be visible. When the
appliance 20 is pre-loaded or pre-filled with agent 15, the
appliance 20 may be removed from the packaging and immediately
inserted in the patient's mouth, as shown in FIG. 13. However,
appliances that are not pre-filled may require loading prior to
placing over the teeth. Loading may comprise placing the agent 15
in a teeth-receiving cavity 14, as previously shown in FIG. 4.
Alternatively, loading may comprise placing the agent 15 into an
agent release reservoir 60, as shown in FIG. 8. Loading may also
comprise adhering a rate-controlling or controlled-release material
24 containing the agent 15 to a surface of the appliance 20, as
shown in FIG. 6.
[0075] Although some of these loading methods may require specially
designed appliances, a number of these methods may be applied to
any position adjustment appliance. For example, a series of
repositioning appliances may be generated according to a treatment
plan and provided to a patient. At any point during the treatment
plan, delivery of an agent to the oral environment may be necessary
or desired. The practitioner or the patient may then load the
appliance with the agent or agent delivery means and continue with
the treatment plan. This may be easily accomplished with the use of
a strip of controlled-release material containing the agent. The
strip may be adhered to any surface of the appliance with adhesive
or any suitable means of attachment. Similarly, any type of agent
delivery layer may be attached to the appliance for this purpose.
For example, a pre-formed sheet of material encapsulating the agent
may be used wherein the form comprises a shape wherein at least a
portion of the shape is contoured to fit against the surface of an
appliance or a surface of the teeth or gingiva. As shown in FIG.
14, the pre-formed sheet 60 of material containing the agent 15 may
have a shape contoured to fit against an outside surface of the
appliance 10. Shown in FIG. 15, the material 60 may be adhered to
the surface with adhesive or may be press-fit to the surface and
therefore held in place by compressive forces or friction.
Similarly, the pre-formed sheet of material may have a shape
contoured to fit against a surface of the teeth or gingiva. As
shown in FIG. 16, the pre-formed sheet 62 containing the agent 15
may be shaped to fit against the gingival margin, thus having
contours reflecting the gumline. The sheet 62 may then be joined
with the appliance 10, as illustrated by the joining arrows in FIG.
16. Referring to FIG. 17, the sheet 62 and the appliance 10 may be
bonded together by an adhesive layer 64 to form an appliance which
provides agent delivery the sheet 62 may be flexible to accommodate
easy attachment of the sheet 62 to the appliance 10 and positioning
and removal of the appliance over the patient's teeth.
[0076] The repositioning appliances may be periodically removed for
daily dental hygiene practices and other events throughout the
repositioning protocol or treatment plan until the teeth are moved
to at least near the desired tooth arrangement. While the appliance
is removed from the teeth, the appliance may be replenished with
the agent or substance for delivery. Replenishment may be performed
immediately prior to each time the appliance is replaced over the
teeth or it may be performed according to any prescribed
protocol.
* * * * *