U.S. patent application number 17/721478 was filed with the patent office on 2022-07-28 for dental products and procedures.
The applicant listed for this patent is Bay Materials, LLC. Invention is credited to Ray F. Stewart.
Application Number | 20220233289 17/721478 |
Document ID | / |
Family ID | |
Filed Date | 2022-07-28 |
United States Patent
Application |
20220233289 |
Kind Code |
A1 |
Stewart; Ray F. |
July 28, 2022 |
DENTAL PRODUCTS AND PROCEDURES
Abstract
Polymeric shells which fit over one or more natural teeth to
change the perceived color of the teeth, and optionally to provide
orthodontic support. The shells can be prepared by thermoforming
selected polymeric sheets which contain optical additives over a
physical image of the teeth, or by depositing polymeric
compositions containing optical additives over a physical image of
the teeth, or by additive manufacturing based upon a digital image
of the teeth. The optical additives cause the combination of the
shell and the teeth to have a desired appearance. At least part of
the shell preferably has transparency greater than 75%,
particularly greater than 85%.
Inventors: |
Stewart; Ray F.; (Redwood
City, CA) |
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Applicant: |
Name |
City |
State |
Country |
Type |
Bay Materials, LLC |
Fremont |
CA |
US |
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Appl. No.: |
17/721478 |
Filed: |
April 15, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15849678 |
Dec 21, 2017 |
11318001 |
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17721478 |
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14381202 |
Aug 26, 2014 |
9918813 |
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PCT/US2013/027950 |
Aug 26, 2014 |
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15849678 |
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61634370 |
Feb 27, 2012 |
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International
Class: |
A61C 13/08 20060101
A61C013/08; A61C 7/08 20060101 A61C007/08; A61K 6/16 20060101
A61K006/16; B32B 27/20 20060101 B32B027/20; C08L 67/02 20060101
C08L067/02; C09K 11/06 20060101 C09K011/06 |
Claims
1. A self-supporting shell which (a) can be fitted over one or more
teeth to change the perceived color of the one or more teeth, and
(b) comprises two or more levels, at least one of the levels being
a first level comprising a polymeric composition comprising a
polymer and a first concentration of one or more optical additives,
and at least one other second level comprising a polymeric
composition comprising a polymer, the second layer (i) comprising
one or more optical additives in a second concentration which is
different from the first concentration or (ii) being free from
optical additives.
2. A self-supporting shell according to claim 1 which comprises two
or more layers, at least one of the layers being a first layer
comprising a polymeric composition comprising a polymer and a first
concentration of one or more optical additives, and at least one
other second layer comprising a polymeric composition comprising a
polymer, the second layer (i) comprising one or more optical
additives in a second concentration which is different from the
first concentration or (ii) being free from optical additives.
3. A self-supporting shell according to claim 2 which comprises (1)
a first layer which is not on the outside of the shell when the
shell is fitted over the one or more teeth and which contains a
first concentration of the one or more optically active additives,
and (2) a second layer which (i) is on the outside of the shell
when the shell is fitted over the one or more teeth and (ii)
contains a second concentration of the one or more optically active
additives, the second concentration being less than the first
concentration.
4. A self-supporting shell according to claim 1 wherein the shell
comprises a laminate comprising a layer which (i) contains an
optical brightener and (ii) is not part of the exterior surface of
the shell.
5. A self-supporting shell according to claim 1 which is for use in
an orthodontic procedure and which has a flexural modulus of more
than 1500 MPa.
6. A self-supporting shell according to claim 5 which has a
thickness of 0.5 to 0.8 mm.
7. A self-supporting shell according to claim 1 which is for use in
changing the appearance of the tooth or teeth and which has a
flexural modulus of less than 800 MPa.
8. A self-supporting shell according to claim 7 which has a
thickness of 0.2 to 0.6 mm.
9. A self-supporting shell according to claim 1 which has an
innermost level having a total visible light transmission greater
than about 75%.
10. A self-supporting shell according to claim 9 which has been
applied over the tooth or teeth, and the innermost level of the
shell extends over a gum line beyond the upper edge of the teeth
and/or the lower edge of the teeth.
11. A method of making a self-supporting shell according to claim 1
which comprises depositing a succession of polymeric compositions
onto a physical image of the tooth or teeth.
12. A method of making a self-supporting shell according to claim 1
by three-dimensional printing based on a digital image of the
teeth.
13. A sheet which can be thermoformed over a model of one or more
teeth to provide a self-supporting shell which can be fitted over
one or more teeth to change the perceived color of the one or more
teeth, the sheet comprising two or more levels, at least one of the
levels being a first level comprising a polymeric composition
comprising a polymer and a first concentration of one or more
optical additives and at least one second level comprising a
polymeric composition which (a) has a second concentration of one
or more optical additives, the second concentration being different
from the first concentration, or (b) is free from optical
additives.
14. A sheet according to claim 13, wherein there is no additive at
one or more levels in the sheet.
15. A sheet according to claim 13 wherein the polymeric composition
is based on a polymer selected from the group consisting of
elastomers, polyesters, polyurethanes, polyolefins, acrylic resins,
methacrylic resins, polyamides, polycarbonates, polyethers, ionomer
resins, cellulose esters, cellulose ethers and fluoropolymers.
16. A sheet according to claim 13 wherein the one or more optical
additives comprises light-scattering particles selected from the
group consisting of one or more of titanium dioxide, barium
sulfate, calcium carbonate, boron nitride, silica, mica and zinc
oxide, and the concentration of at least one of the optical
additives is different at different levels going through the
thickness of the sheet.
17. A sheet according to claim 13 wherein the sheet is a laminate
having two or more layers of different polymeric compositions, and
the laminate contains an optical brightener in a layer which, when
the sheet is thermoformed, is not an exterior surface of the
shell.
18. A sheet according to claim 13 wherein the sheet is a laminate
having two or more layers of different polymeric compositions and
the laminate comprises (i) a first layer which has a first
concentration of an optical additive, and (ii) a second layer which
provides an exterior surface of the laminate and is free from the
optical additive or which contains a second concentration of the
optical additive, the second concentration being substantially less
than the first concentration.
19. A polymeric sheet according to claim 13 which has a uniform
thickness of 0.10-2 mm and which comprises a polymer and one or
more optical additives, wherein the concentration of the one or
more optical additives is different at different levels going
through the thickness of the sheet, and the one or more optical
additives comprise one or more light-scattering particles selected
from the group consisting of titanium dioxide, barium sulfate,
calcium carbonate, boron nitride, silica, mica and zinc oxide.
20. A polymeric sheet according to claim 13 which has a uniform
thickness of 0.10-2 mm and which has an exterior level having a
transparency of greater than 85%.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 15/849,678, filed Dec. 21, 2017, which is a continuation of
U.S. application Ser. No. 14/381,202, filed Aug. 26, 2014 (now U.S.
Pat. No. 9,918,813 issued Mar. 20, 2018), which is an application
under the 35 USC 371 based on International Application No. PCT/US
2013/027950, which claims priority from U.S. Provisional
Application No. 61/634,370, filed Feb. 27, 2012. This application
claims priority from U.S. application Ser. No. 14/381,202, filed
Aug. 26, 2014, International Application No. PCT/US 2013/027950,
filed Aug. 26, 2014, and U.S. Provisional Application No.
61/634,370, filed Feb. 27, 2012. The entire disclosure of each of
the afore-mentioned applications is incorporated herein by
reference for all purposes.
FIELD OF THE INVENTION
[0002] The present disclosure relates to products and procedures
for changing the appearance of teeth.
BACKGROUND
[0003] Many products and procedures have been used, or proposed for
use, in order to change or modify teeth in the human mouth. In
orthodontic procedures, the objective is to change the relative
positions of two or more teeth. In some cosmetic procedures, the
objective is to change the perceived color of teeth so that the
teeth appear whiter.
[0004] One orthodontic procedure makes use of one or more rigid
polymeric shells each of which fits over the teeth and, when in
place, does not fit precisely to one or more of the teeth and,
therefore, imparts a displacing force to the teeth and over the
course of time changes the relative positions of two or more teeth.
Reference may be made for example to U.S. Pat. No. 5,975,893
(Chishti) and U.S. Pat. No. 7,220,122 (Chishti), the entire
disclosure of each of which is incorporated herein by reference.
Many polymers, including some of those used in dental and
orthodontic applications, have a slightly yellow color which is
produced during manufacturing or processing such as extrusion,
injection molding and/or thermoforming. Consequently, although the
primary objective of the rigid polymeric shell is functional, it
often contains a small quantity of additives to change the yellow
color. This is referred to as "color compensation" or "color
correction".
[0005] Much effort and expense has been expended in order to whiten
teeth. However, the known cosmetic procedures have substantial
disadvantages. Many cosmetic procedures make use of bleaching
agents which are applied directly to the teeth; bleaching agents
can damage the natural tooth structure itself and/or can produce
different cosmetic effects on the natural tooth structure and/or
stains and/or fillings and/or crowns. Other cosmetic procedures
make use of compositions which form a coating on top of the teeth;
those compositions are difficult to apply uniformly and accurately,
and degrade relatively rapidly and/or are difficult to remove. For
information about known cosmetic procedures, reference may be made
for example to U.S. Pat. Nos. 3,986,261, 4,032,627, 5,716,208,
6,343,933, 6,368,576, 6,503,485, 6,986,883 and 7,214,262, and US
Patent Publications 2005/0175552 and 2007/0086960, the entire
disclosure of each of those patents and patent publications is
incorporated herein by reference for all purposes
SUMMARY
[0006] I have discovered, in accordance with the present invention,
new products and procedures for changing the perceived color of
teeth. In some embodiments of the invention, the products and
procedures also change the relative positions of two or more teeth.
Throughout this specification, the terms tooth and teeth includes
natural teeth, including natural teeth which have been modified by
fillings or by crowns, implanted teeth, artificial teeth that are
part of a bridge or other fitting secured to one or more natural or
implanted teeth, and artificial teeth that are part of a removable
fitting.
[0007] In a first aspect, this invention provides a self-supporting
shell which fits over one or more teeth and which is composed of a
polymeric composition comprising a polymer and one or more optical
additives which cause the combination of the shell and the teeth to
have a desired appearance. The term "optical additive" is used
herein to mean an additive which substantially changes the color or
light transmission properties of the polymeric composition.
[0008] In a second aspect, this invention provides a method of
providing a desired change in the appearance of teeth which
comprises placing a self-supporting shell according to the first
aspect of the invention over one or more teeth.
[0009] In a third aspect, this invention provides a method of
making a self-supporting shell according to the first aspect of the
invention, the method comprising forming a selected polymeric
composition into a shape which will fit over the teeth over which
the shell is to be placed, the selected polymeric composition
preferably having been selected by assessing the color of the teeth
over which the shell is to be fitted and, based on that assessment,
selecting the polymeric composition from a range of polymeric
compositions of different colors.
[0010] In a fourth aspect, this invention provides a method which
comprises [0011] (A) assessing the color of teeth over which a
self-supporting shell according to the first aspect of the
invention is to be placed, [0012] (B) selecting from a range of
compositions having different colors, a composition which will
provide a desired change in the appearance of teeth when formed
into a self-supporting shell according to the first aspect of the
invention, and [0013] (C) forming the selected composition into a
self-supporting shell.
[0014] In a fifth aspect, this invention provides a method which
comprises [0015] (A) selecting, from a set of colored samples, a
sample which matches the color of teeth to be treated, and [0016]
(B) correlating the selected sample with a polymeric composition
which, when formed into a self-supporting shell and placed over the
teeth will give the teeth a desired appearance.
[0017] In a sixth aspect, this invention provides a sheet of a
polymeric composition for use in the method of the third or fifth
aspect of the invention, for example by thermoforming the sheet
around a physical model of the teeth over which the shell is to be
fitted.
[0018] In a seventh aspect, this invention provides a set of sheets
of a polymeric composition, the sheets being (i) composed of
different compositions containing different amounts of optical
additives, and (ii) being such that they can be formed into a
self-supporting shell according to the first aspect of the
invention. There can be, for example, at least 2, at least 3, at
least 4, preferably at least 5, e.g. 5-20 identical samples of each
of the different sheets.
[0019] In an eighth aspect, this invention provides a novel
polymeric composition for use in the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The invention is illustrated in the accompanying drawings.
The FIGURE shows the color ranges which are often observed for
discolored teeth (area A), normal teeth (area B) whitened teeth
(area C), orthodontic appliances (area D), and a preferred color
range for tooth shells of this invention (area E). In the FIGURE,
on the horizontal axis, the negative values relate to green colors
and the positive values relate to red colors, and on the vertical
axis, the negative values relate to blue colors and the positive
values relate to yellow colors.
DETAILED DESCRIPTION
[0021] In the Summary of the Invention above and in the Detailed
Description of the Invention below, including the Examples and
illustrations, reference is made to particular features of the
invention. It is to be understood that the disclosure of the
invention in this specification includes all possible combinations
of such particular features. For example, where a particular
feature is disclosed in the context of a particular aspect or a
particular embodiment, that feature can also be used in combination
with other particular aspects and embodiments, and in the invention
generally, except where the context excludes that possibility. The
invention disclosed herein include embodiments not specifically
described herein and can for example make use of features which are
not specifically described herein, but which provide functions
which are the same, equivalent or similar to, features specifically
disclosed herein.
[0022] The term "comprises" and grammatical equivalents thereof are
used herein to mean that, in addition to the features specifically
identified, other features are optionally present. For example, a
composition or device "comprising" (or "which comprises")
components A, B and C can contain only components A, B and C, or
can contain not only components A, B and C but also one or more
other components. The terms "consisting essentially of" and
grammatical equivalents thereof are used herein to mean that, in
addition to the features specifically identified, other features
may be present which do not materially alter the claimed invention.
The term "at least" followed by a number is used herein to denote
the start of a range beginning with that number (which may be a
range having an upper limit or no upper limit, depending on the
variable being defined). The term "at most" followed by a number is
used herein to denote the end of a range ending with that number
(which may be a range having 1 or 0 as its lower limit, or a range
having no lower limit, depending upon the variable being defined).
When a range is given as "(a first number) to (a second number)" or
"(a first number)-(a second number)", this means a range whose
lower limit is the first number and whose upper limit is the second
number. The terms "plural", "multiple", "plurality" and
"multiplicity" are used herein to denote two or more than two
features.
[0023] Where reference is made herein to "a" or "an" feature, this
includes the possibility that there are two or more such features
(except where the context excludes that possibility). Where
reference is made herein to two or more features, this includes the
possibility that the two or more features are replaced by a lesser
number or greater number of features providing the same function,
except where the context excludes that possibility. The numbers
given herein should be construed with the latitude appropriate to
their context and expression; for example, each number is subject
to variation which depends on the accuracy with which it can be
measured by methods conventionally used by those skilled in the
art.
[0024] This specification incorporates by reference all documents
referred to herein and all documents filed concurrently with this
specification or filed previously in connection with this
application, including but not limited to such documents which are
open to public inspection with this specification.
[0025] Parts, percentages and ratios given in this specification
are by weight unless otherwise noted.
[0026] Unless otherwise noted, the term color measurement is used
herein to refer to measurements made using the LAB CIE color scale
wherein L refers to total reflected light, A refers to the Red
(+)-Green (-) color Axis and B refers the Yellow (+)-Blue (-) color
axis measured using a D65 light source (daylight). However, color
can also be measured using the CYMK scale which makes use of
digital images. Other color measurement systems are known and any
suitable method may be used in evaluating products of this
invention.
[0027] The term pigment is used herein to denote a solid
particulate coloring agent which can be mixed with a polymer.
[0028] The term dye is used herein to denote a coloring agent that
is soluble or molecularly dispersed in a polymer.
[0029] The term fluorescent agent is used herein to denote a
material that absorbs light in one region of the spectrum and emits
light in the same or different region of the spectrum. The emission
may be almost immediate or may be delayed.
[0030] The term light transmission is used herein to denote the
amount of light passing through a sample. Unless otherwise stated,
transmission refers to visible light as measured by a method
similar to ASTM D1003-11 Standard Test Method for Haze and Luminous
Transmittance of Transparent Plastics. Light transmission may also
be measured using a colorimeter and a white reference sample, in
which case the measurement includes two passages of light through
the sample.
[0031] The term incident light is used herein to denote light which
shines onto an object and which may be reflected, scattered or
least partially absorbed by the object.
[0032] The term reflected light is used herein to denote incident
light which reflects off the surface of an object after impinging
on the object.
[0033] The term scattered light is used herein to denote light
which diverges from a straight path after it has impinged on an
object.
[0034] The term light scattering particles is used herein to denote
particles having a size from about 0.2 to about 20.mu. and which
are transparent or substantially white. By white is meant that the
particles do not absorb significant amounts of light in the range
from about 400 nm to about 700 nm.
[0035] The term thermoplastic polymer is used herein to denote a
polymer which is relatively hard at a lower temperature, which
becomes relatively soft when subjected to heat and pressure, and
again becomes relatively hard when cooled, provided that the heat
and pressure do not chemically decompose the polymer.
[0036] The term thermosetting polymer is used herein to denote a
polymeric composition which is a solid or viscous material at a
relatively low temperature and which, when subjected to heat and/or
suitable radiation, and/or when the material undergoes one or more
chemical reactions, changes irreversibly into an infusible polymer
network. The term thermoset polymer is used to denote a cured
thermosetting polymer.
The Polymer in the Polymeric Composition.
[0037] The polymer in the polymeric composition in the
self-supporting shell used in the present invention can be a
homopolymer, or a random, block or a graft copolymer. The
composition can contain a single polymer or a mixture of two or
more polymers. Generally, the polymer is substantially transparent,
so that the optical characteristics of the self-supporting shell
are dominated by the optical additives which are mixed with the
polymer, but the invention includes the possibility that the
polymer is a semicrystalline polymer which scatters light.
[0038] The polymer can optionally have one or more of the following
characteristics (i.e. a single one of the following characteristics
or any possible combination of two or more of the following
characteristics). [0039] (1) The polymer comprises a thermoplastic
polymer. [0040] (2) The polymer comprises a thermoset polymer.
[0041] (3) The polymer is an elastomer, preferably an elastomer
having elongation to break greater than 200% and a 100% modulus of
less than 3000 PSI (value for D50 or less TPU) [0042] (4) The
polymer is a polyester, for example a polyethylene terephthalate
glycol polymer (PETG), e.g. one of the polyesters sold by Eastman
Chemical under the trade names Eastar and Durastar, or one of the
polyesters sold by DuPont under the trade name Hytrel. [0043] (5)
The polymer is a polyurethane, for example a rigid polyurethane
such as that sold by Lubrizol Corporation under the trade name
Isoplast, or a thermoplastic polyurethane (TPU) such as one of
those sold by Lubrizol Corporation under the trade name Pellethane,
by Merquinsa under the trade name Pearlthane, by BASF under the
trade name Elastollan, and by Bayer under the trade name Texin.
[0044] (6) The polymer is a polyolefin, including high-density
polyethylene, low density polyethylene, medium density
polyethylene, linear low density polyethylene; a copolymer of
ethylene and one or more comonomers, e.g. comonomers selected from
the group consisting of other .alpha.-olefins, vinyl acetate,
acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate and
butyl acrylate; polypropylene, e.g. clarified polypropylene; a
propylene copolymer, e.g. a clarified propylene copolymer;
polystyrene; a copolymer of styrene and one or more comonomers,
e.g. comonomers selected from the group consisting of acrylic
comonomers, acrylonitrile, acrylonitrile and butadiene, including
block copolymers of styrene with ethylene, ethylene and propylene,
isoprene and butadiene; polymers of cyclic olefins; and polymethyl
pentene. [0045] (7) The polymer is an acrylic or methacrylic resin,
including polyacrylonitrile and copolymers of acrylonitrile. [0046]
(8) The polymer is an aliphatic or aromatic or mixed aliphatic
aromatic polyamide, a polycarbonate, a polyether, an ionomer resin
or a cellulose ester or ether. [0047] (9) The polymer is a
fluoropolymer, e.g. polyvinylidene fluoride, fluorinated ethylene
propylene, polyvinyl chloride, or the product sold under the
tradename Kynarflex.
The Additives in the Polymeric Compositions.
[0048] The polymeric composition can contain a single optical
additive or a mixture of two or more optical additives. The
polymeric composition can contain other additives which are not
optical additives. The optical additives may be one or more optical
additives selected from the group consisting of pigments, dyes,
light scattering particles and fluorescent materials.
[0049] The optical additive can optionally have any one of the
following characteristics, or any possible combination of one or
more of the following characteristics. [0050] (1) The optical
additive, when dispersed in a sample of the polymeric composition
having a thickness of 0.76 mm, preferentially absorbs light within
the range from about 550 to about 700 nm, such that, when measured
against a reference white sample (e.g. a white color tile) using
conditions D65, the LAB color values for the combination of the
white color tile and the polymer sheet have an L value of between
about 18 and 95, an A value from about -2 to +2 and a B value from
about -1 to -10. [0051] (2) The optical additive comprises a
pigment or dye having a color which ranges from blue to violet, for
example ultramarine blue, ultramarine violet, manganese oxides,
phthalocyanine, violet 92, violet 11C, blue 385, blue 214, blue
30C591, blue 30C588, FDC blue #1, blue 214. Other blue and violet
pigments which can be used include the following (which are listed
by their CI name) PB 1, PB 1:2; PB 9, PB 15; PB 15:1, PB 15:2, PB
15:3, PB 15:4, PB 15:6, PB 15:34; PB 16, PB 17, PB 24, PB 25, PB
27, PB 28, PB 29, PB 30, PB 31, PB 34, PB 35; PB 36; PB 36:1, PB
60, PB 61, PB 61:1, PB 62, PB 63, PB 66, PB 68, PB 71, PB 72, PB
73, PB 74, PB 75, PB 76, PB 79, PB 80, PB 81, PB 82, PB 84, PB 128,
PV 1, PV 1:1,PV 1:2, PV 2, PV 2:2, PV 3, PV 3:1, PV 3:3 PV 5, PV
5:1, PV 7, PV 13, PV 14, PV 15, PV 16, PV 18, PV 19, PV 23, PV 25,
PV 27, PV 29, PV 31, PV 32, PV 36, PV 37, PV 39, PV 42, PV 44, PV
47, PV 48, PV 49, PV 50, PV55, PV 58, and PV 17. [0052] (3) The
optical additive comprises a red pigment or die, for example NR 1.
NR 2, NR 3, NR 4, NR 6, NR 8, NR 9, NR 10, NR 11, NR 12, NR 16, NR
20, NR 22, NR 23, NR 24, NR 25, NR 26, NR 28, NR 31, PR 1, PR 2, PR
3, PR 4, PR 5, PR 6, PR 7, PR 8, PR 9, PR 12, ;PR 13, ;PR 14, PR
15, PR 17, PR 19, PR 21, PR 22, PR 23, PR 31, PR 32, PR 38, PR 39,
PR 47, PR 48, tPR 48:1, PR 48:2, PR 48:3, PR 48:4, PR 49, PR 49:1,
PR 49:2, PR 52:1, PR 52:2, PR 53, PR 53:1, PR 57, PR 57:1, PR 57:2,
PR 58:4, PR 60, PR 60:1, PR 61, PR 62, PR 63, PR 63:1, PR 69, PR
81, PR 81:1, PR 81:2, PR 81:3, PR 81:4, PR 83, PR 83:1, PR 83:3, PR
85, PR 88, PR 89, PR 90, PR 90:1, PR 101, PR 101:1, PR 102, PR 103,
PR 104, PR 105, PR 106, PR 107, PR 108, PR 108:1, PR 109, PR 112,
PR 113, PR 113:1, PR 114, PR 119, PR 120, PR 121, PR 122, PR 123,
PR 139, PR 144, PR 146, PR 147, PR 148, PR 149, PR 150, PR 160,
PR166, PR 168, PR 169, PR 170, PR 170:1, PR 171, PR 172, PR 173, PR
174, PR 175, PR 176, PR 177, PR 178, PR 179, PR 180, PR 181, PR
183, PR 184, PR 185, PR 187, PR 188, PR 190, PR 192, PR 193, PR
194, PR 200, PR 202, PR 204, PR 206, PR 207, PR 208, PR 209, PR
210, PR 211, PR 212, PR 213, PR214, PR 216, PR 221, PR 223, PR 224,
PR 226, PR 230, PR 231, PR 232, PR 233, PR 235, PR 236, PR 238, PR
239, PR 242, PR 243, PR 245, PR 251, PR 252, PR 253, PR 254, PR
255, tPR 256, PR 257, PR 258, PR 259, PR 260, PR 262, PR 264, PR
265, PR 266, PR 268, PR 269, PR 270, PR 271, PR 272, PR 273, PR
274, PR 275, PR 276, PR 279, PR 282, PR 286, PR 287, PR 288, and PR
571. [0053] (3) The optical additive comprises light scattering
(reflecting) particles, preferably light scattering particles
which, when a sample of the polymeric composition having a
thickness of 0.76 mm is exposed to natural light, from about 5% to
about 50%, preferably 5 to 25%, of the incident light is reflected.
Suitable light scattering particles include titanium dioxide,
barium sulfate, calcium carbonate, boron nitride, silica, mica, and
spherical glass particles. The presence of such an additive in the
shell tends to mask the natural color of the teeth (which usually
has a yellowish and/whole yellowish red tint) because a portion of
the incident light is reflected before it is absorbed by the teeth.
If the amount of reflected incident light is less than about 5%,
the improvement is slight, whereas if the amount of reflected
incident light is greater than about 50%, the perception of the
underlying tooth structure may be reduced to a level such that the
teeth are not perceived as natural.
[0054] Light scattering occurs when there is a difference between
the refractive index of the particles and the polymer in which they
are dispersed. The greater the difference in refractive index, the
greater the degree of scattering. If the particles are transparent
to the incident light in the wavelengths of interest, then
essentially all of the light will be reflected or will pass
through. If the particles absorb light in one or more ranges of
wavelength, then the polymeric composition will be perceived as
having a color which contains a reduced amount of those
wavelengths. If the proportion of light reflecting particles is
high and substantially all the incident light is scattered, the
composition will appear white. At lower levels, the composition may
appear translucent and light going through it will be "diffuse".
For use in this application it is generally desired that any light
scattering particles added do not absorb light, so they do not
contribute to off color or increase of the gray value of the teeth.
In some cases it is desirable to utilize particles that are
sufficient to cause light scattering, while maintaining a high
degree of total light transmission.
[0055] It has been found that appropriate use of light-scattering
particles can not only result in teeth which look whiter, but can
also mask areas of teeth having different colors, for example
stained regions or darker areas near the base of the teeth,
resulting in a more uniform and cosmetically desirable appearance.
[0056] (4) The optical additive comprises a fluorescent material
which absorbs ultraviolet light having a wavelength of less than
about 400 nm and which emits light in the range from about 400 to
about 600 nm. These fluorescent materials are also referred to as
brightening agents. Optionally the fluorescent material can also
absorb light having a wavelength in the range from about 550 to
about 700 nm. Dyes and/or pigments cause selective absorption of
light such that the reflected light is more equally balanced across
the visible spectrum (more equal amounts of each primary color); as
a result, the presence of dyes and/or pigments in the shell make
the perceived tooth color closer to white, but also reduces the
total amount of light reflected, so that the teeth do not appear as
bright. Fluorescent materials, by absorbing light outside the
visible spectrum and emitting light in the purple-blue-green region
of the visible spectrum, can make the teeth appear both whiter and
brighter. Many fluorescent materials are known and have a wide
range of chemical structures. They include for example
triazine-stilbenes, coumarins, imidazolines, diazoles, triazoles,
benzooxazolines and biphenyl-stilbenes. Specific optical
brighteners include the materials designated by the CAS number
7128-64-5, 1533-45-5, 2397-00-4, 5089-22-5, 40470-68-6, 13001-38-2,
13001-39-3, 58449-88-0, 13001-40-6, 16470-24-9, 2226-96-2,
4193-55-9, 27344-41-8 and 16090-02-1.
Polymeric Compositions.
[0057] The polymeric composition in the self-supporting shells used
in the present invention comprises a polymer, for example a polymer
as disclosed above, and an optical additive, for example an
additive as disclosed above. In some cases, it is preferable that
the composition, when in the form of a uniform sheet having a
thickness of 0.5 mm, has a total transmission of greater than about
80% and a diffuse transmission greater than about 50%, when
measured by ASTM D 1003.
[0058] For the best results, which in most cases means teeth which
are natural looking and as white as is desired by the individual
whose teeth are being treated, the selection of the optical
additives will be made in conjunction with inspection of the teeth
onto which the shell it is to be placed. It is not at present
practical to formulate a special composition for each individual.
But it is practical to formulate a relatively limited number of
"standard" compositions from which those skilled in the art, having
regard to their own knowledge and the disclosure in this
specification, will be able to select a composition which is likely
to give excellent results.
[0059] Those skilled in dentistry are familiar with the ways in
which the color of teeth can be assessed, and the selection of a
material for a filling or a crown to match the natural color of
teeth. Common tooth colors are often designated by a combination of
a letter (usually A-D) and a number (usually 1-4), with A, B, C and
D designating different hues (A red yellow, B yellow, C gray, and D
red yellow gray), and 1-4 designating the color intensity. The
designations M1, M2 and M3 are typically used to denote highly
bleached teeth. Alternatively, the color of teeth can be measured
by a colorimeter. Having determined the color of the teeth to be
covered by the self-supporting shell, one skilled in the art will
select a shell material which, when converted into a shell and
placed over the teeth, will result in covered teeth which are
perceived to have the desired color (which will normally be
substantially whiter than the natural color of teeth), and which
will preferably completely or partially disguise any staining of
the teeth. For example, if a tooth having (on the VITA scale) a B 4
color is covered with a shell having (on the LAB scale) A and B
values of 2.5 and -5, the tooth will appear from about 1 to about 4
shades lighter. It should be noted that the color of the shell
material will not be the perceived color of the covered teeth,
since the perceived color will depend on both the underlying
natural color of the tooth, the color of the shell material and the
type of incident illumination. Preferably the color of the natural
teeth is at least one shade lighter is according to the VITA scale
than the color of the same teeth without the shell.
Preparation of the Polymeric Compositions and of Polymeric Sheets
Comprising Those Compositions.
[0060] The polymeric compositions used in this invention, and
polymeric sheets comprising those compositions, can be prepared by
conventional methods which are well-known to those skilled in the
art of polymer technology.
Polymeric Sheets for Conversion into Self-Supporting Polymeric
Shells
[0061] It will often be convenient for the self-supporting
polymeric shells to be produced by shaping a polymeric sheet of a
desired composition. The polymeric sheet can optionally have any
one of the following characteristics, or any possible combination
of one or more of the following characteristics. [0062] 1. It is a
flat sheet having a uniform thickness of 0.10-2 mm, preferably
0.15-1.5 mm. [0063] 2. It is a flat sheet whose outer periphery is
circular, oval or rectangular (including square), for example with
an area of 10-100 in..sup.2 [0064] 3. It is a flat sheet having
dimensions such that it will completely cover a model of the teeth
in the upper jaw or the lower jaw of an adult, or of a child, for
example a flat sheet which is a circular disk, a flat sheet which
is part (for example half) of a circular disk. [0065] 4. The
polymeric composition is the same throughout the sheet. [0066] 5.
The polymeric composition varies from top to bottom of the sheet.
For example, the concentration of the additive (or one or more of
the additives) is different at different levels going through the
thickness of the sheet, including the possibility that there is no
additive (or none of one or more of the additives) at one or more
levels. [0067] 6. The sheet is a laminate having two or more layers
of different polymeric compositions, for example (1) a laminate
which contains an optical brightener in a layer which, when the
sheet is formed into a self-supporting shell, is not part of the
exterior surface of the shell, for example in a layer which is the
central layer of a three layer laminate, or (2) a laminate which
comprises (i) a first layer which, when the sheet is formed into a
self-supporting shell, is in contact with the teeth, and which
contains a first concentration of an optical additive, and (ii) a
second layer which, when the sheet is formed into a self-supporting
shell, is exposed, and which is free from the optical additive or
which contains a second concentration of the optical additive, the
second concentration being substantially less than the first
concentration, for example not more than 0.2 times the first
concentration. The polymers in the different layers are generally
the same but can be different. [0068] 7. The sheet has a variable
thickness such that when the sheet is thermoformed over a model of
the teeth, each part of the thermoformed sheet has a thickness of
at least 0.1 mm, at least 0.15 mm, at least 0.2 mm or at least 0.3
mm, and a thickness of at most 1.5 mm, preferably at most 1 mm.,
preferably a thickness in the range of 0.2 to 1.0 mm. [0069] 8. The
sheet has a color within the area E as shown in the FIGURE. [0070]
9. The sheet contains substantially no fluorescent agent and has
values of L, A and B on the LAB scale when the sheet is measured on
a white color tile, as shown in the following table.
TABLE-US-00001 [0070] L A B Preferred 75 to 99 -3 to 6 -10 to -1
More preferred 80 to 99 -2 to 5 -7 to -1 Particularly preferred 85
to 99 -1 to 5 .sup. -5 to -1.5
Since the value of L is the total light (L being 100), the added
coloring agents will always reduce L to less than 100 if the sheet
contains no fluorescent agent. In some embodiments, the sheet has a
value of L greater than about 85, a value of A greater than about
-0.5 and less than about 6.0, and a value of B from about -1.0 to
-15.0. [0071] 10. The sheet contains a fluorescent agent and
optionally other optical agents, and has values of L, A and B on
the LAB scale when the sheet is measured on a white color tile,
using a light source that includes light with a frequency of about
300 to about 400 nm (UV) and is filtered to D65, as shown in the
following table.
TABLE-US-00002 [0071] L A B Preferred 75 to 110 -3 to 6 -10 to -1
More preferred 80 to 110 -2 to 5 -7 to -1 Particularly preferred 85
to 110 -1 to 4 .sup. -5 to -1.5
In some embodiments, L is greater than about 85, A is -1.0 to 6.0,
and B is -1.0 to -10.0, preferably -1.0 to -5.0. [0072] 11. The
sheet has a transparency of greater than 75%, preferably greater
than 85%. [0073] 12. The sheet is in the form of a roll, 5-6 inches
(127-152 mm) wide, and 50-100 feet (15-30 m) long [0074] 13. A
plurality of sheets, e.g. 20, 50, 100 or 500 sheets, are packaged
together. [0075] 14. The sheet has a moisture content of less than
1%, preferably less than 0.5%. [0076] 15. The sheet is prepared by
a process which comprises drying under control conditions which
prevent discoloration of the sheet.
The Self-Supporting Polymeric Shells
[0077] The self-supporting shells can be prepared in any
appropriate way. In one embodiment, the shell is prepared by
shaping a sheet comprising the polymeric composition, for example
by thermoforming the sheet over a model of the teeth to which the
shell is to be fitted.
The First and Second Aspects
[0078] The self-supporting shell must fit closely to at least a
major part of the front of the teeth over which it is placed, and
preferably fits closely to a substantially the entire surface of
the teeth over which it is placed. Generally, the shell will be one
which can be removed by the wearer simply by pulling the shell off
the teeth (which may be desirable for example when eating or for
conventional tooth cleaning). However, the invention includes the
possibility that the shell is secured to the teeth in some more
permanent fashion.
[0079] The shell optionally has one of the following
characteristics, or any possible combination of one or more of the
following characteristics. [0080] (1) The average thickness of the
shell is at least 0.1 mm, preferably at least 0.15 mm, and at most
1.5 mm. When the only purpose of the shell is to change the
appearance of the teeth, the average thickness is preferably at
most 0.5 mm or at most 0.4 mm. When the shell is also used as part
of an orthodontic procedure, for example a retainer or other dental
appliance, the average thickness of the shell is greater, for
example at least 0.5 mm or at least 0.6 mm. [0081] (2) When the
shell is prepared by thermoforming a polymeric sheet of uniform
thickness, the thickness of the shell will vary from place to
place, depending upon the amount of deformation of the sheet during
the thermoforming process. When the only purpose of the
thermoformed shell is to change the appearance of the teeth, it
generally has a thickness which is at least 0.06 mm, at least 0.08
mm, at least 0.1 mm or, at least 0.2 mm, at least 0.3 mm, at least
0.4 mm at least 0.5 mm, at least 0.6 mm, or at least 0.7 mm, and a
thickness of at most 1.0 mm or most 0.8 mm. When the thermoformed
shell is also used as part of an orthodontic procedure, it
generally has a thickness which is at least 0.5 mm, at least 0.6
mm, and the 0.7 mm, at least 0.8 mm, at least 0.9 mm, at least 1.0
mm, at least 1.1 mm, at least 1.2 mm, at least 1.3 mm, or at least
1.4 mm, and a thickness of at most 1.5 mm. When the only purpose of
the shell is to change the appearance of the teeth, it preferably
has a thickness in the range of 0.2 to 0.06 mm, particularly in the
range of 0.3 to 0.5 mm. When the thermoformed shell is also used as
part of an orthodontic procedure, it preferably has a thickness of
the range of 0.3 to 1.0 mm, particularly in the range of 0.5 to 0.8
mm.
[0082] The shell can be prepared by thermoforming a polymeric sheet
which is not of uniform thickness, for example a polymeric sheet
which has a greater thickness in the areas which will be deformed
by the thermoforming.
[0083] When the only purpose of the shell is to change the
appearance of the teeth, the polymeric composition can have a
flexural modulus of less than 1000 MPa or less than 800 MPa. When
the shell is also used as part of an orthodontic procedure, the
polymeric composition preferably has a flexural modulus of more
than 1000 MPa, preferably more than 1500 MPa, e.g. 1000-3000 MPa.
[0084] (2) The polymeric shell comprises one or more optical
additives. The concentration of the additives which modify the
optical properties of the shell can be greater near the surface of
the tooth than it is further from the surface of the tooth. For
example, the polymer at the surface of the shell remote from the
surface of the tooth can be substantially free of the optical
additives. When the optical additive is uniformly dispersed in the
shell, there is often a "fattening" effect which tends to make the
teeth appear to extend to the outer surface of the shell. In an
extreme case, where the outer surface of the shell is white and
opaque, only the relatively flat outer surface of the shell is
perceived, and the surface of the actual teeth is not perceived. In
a preferred embodiment, the colored part of the shell (or she)
would be no more than about 0.5 mm thick, preferably no more than
about 0.25 mm thick, and in some cases less than 0.1 mm. [0085] (3)
At least a portion of the shell has a total visible light
transmission greater than about 75% and a LAB transmission value,
when measured on a white tile, of L greater than or equal to 85, A
from about -1.0 to about 6, preferably about -1 to about 3, and B
from about -1.0 to about -15, preferably about -1.0 to -5.0. [0086]
(4) At least a portion of the thermoformed shell extends over the
gum line (beyond the upper or lower edge of the teeth). When the
portion of the thermoformed shell which extends over the gum line
has a total visible light transmission greater than about 75%, the
portion of the shell that extends over the gum line is essentially
not visible.
The Third Aspect
[0087] The third aspect of the invention preferably makes use of a
polymeric composition which is selected by assessing the color of
teeth over which the shell is to be fitted, the selection being
made from a range of polymeric compositions of different colors.
However, the invention includes the possibility that the
composition is one of a number of "standard" colors. The assessment
of the color of the teeth can be carried out by a dentist and the
selection of the appropriate polymeric composition can be carried
out by the dentist or by another party at a different location.
[0088] Any method can be used to make the selected polymeric
composition into a shape which will fit over the teeth whose
appearance is to be changed. Since the compositions cannot be
shaped over the teeth themselves, the first step is to make a
digital or physical image which corresponds to the teeth. A
physical image can be made by forming an impression of the teeth,
for example using an alginate composition, and then forming the
physical image in the mold provided by the impression. A physical
image can also be made from a digital image.
[0089] One method of making the self-supporting shell is to
thermoform a sheet of the polymeric composition over a physical
image of the teeth. Another method of making the self-supporting
shell is to form the polymeric composition on the physical image of
the teeth, for example by spraying, painting or deposition. The
polymer can be a thermoplastic polymer or a thermosetting polymer
which is cured, for example with ultraviolet light, after it has
been formed into the desired shape.
[0090] Another method of making the self-supporting shell is to
create it by a stereolithographic process (three dimensional
printing) based upon a digital image of the teeth.
The Fourth Aspect
[0091] The fourth aspect of the invention includes the steps of (A)
assessing the color of teeth over which the shell is to be placed,
and (B) based on the assessment in step (A), selecting a
composition from a range of compositions having different colors.
The method can also include, as a preferred step, (C) forming the
selected composition into a self-supporting shell. These steps can
be carried out by the same person (usually a dentist); or each of
the steps can be carried out by a different person; or steps A and
B can be carried out by the same person (usually a dentist) and
step C carried out by a different person; or step A can be carried
out by one person (usually a dentist) and steps B and C carried out
by a different person.
The Fifth Aspect
[0092] The fifth aspect of the invention is a method which
comprises [0093] (A) selecting, from a set of colored samples, a
sample which matches the color of teeth to be treated, and [0094]
(B) correlating the selected sample with a polymeric composition
which, when formed into a self-supporting shell and placed over the
teeth will give the teeth a desired appearance.
[0095] In a first embodiment of the fifth aspect of the invention,
the samples are (i) sized so that they can be placed against teeth
within a human being's mouth, (ii) have a range of colors which
correspond to the natural colors of teeth, and (iii) are correlated
with different compositions containing different amounts of optical
additives such that polymeric compositions correlated with the
samples, when formed into self-supporting shells according to the
first aspect of the invention, will give the teeth a desired
appearance. The set of samples can be a known set of samples except
that the samples are correlated with different compositions which
when formed into a self-supporting shells, will give teeth a
desired appearance. The set of samples can for example contain at
least 2, at least 3, at least 4, at least 5, at least 6, at least
7, at least 8, at least 9, or at least 10, for example at least 20,
e.g. 20-50 different samples. The set of samples can be
supplemented by photographs or digital images which will show how
the teeth will appear after they have been fitted with a shell made
of the correlated polymeric composition.
[0096] In a second embodiment of the fifth aspect of the invention,
the samples are thin colored polymeric strips which have a similar
thickness to a self-supporting shell and a range of colors which
are the same as the available colors for the self-supporting
shells. These strips will show the human being a good simulation of
the tooth color that will be obtained when a self-supporting shell
made of the selected colored strip is placed over the teeth.
The Sixth Aspect
[0097] The sixth aspect of the invention provides a sheet of a
polymeric composition for use in the method of the third or fifth
aspect of the invention, for example by thermoforming the sheet
around a physical model of the teeth over which the shell is to be
fitted.
The Seventh Aspect
[0098] The seventh aspect of the invention provides a set of sheets
of a polymeric composition, the sheets (i) being composed of
different compositions containing different amounts of optical
additives, usually compositions which are identical except for the
content of the optical additives, and (ii) being such that they can
be formed into a self-supporting shell according to the first
aspect of the invention. There can be, for example, at least 2, at
least 3, at least 4, preferably at least 5, e.g. 5-20 identical
samples of each of the different sheets.
The Eighth Aspect
[0099] The eighth aspect of the invention provides novel polymeric
compositions for use in the invention. The compositions can have
some or all of the characteristics set out above.
Use of the Invention When a Tooth is Missing.
[0100] When a tooth is missing, the absence of the tooth is
conventionally disguised by making a bridge which contains an
artificial tooth (a so-called "pontic"). This invention provides an
alternative way of compensating for the absence of a tooth. The
shell can be formed with a section corresponding to the missing
tooth, and the interior of that section of the shell can be
partially or completely coated and/or filled with a filling
material having substantially the same color as the natural teeth.
It has been found that it is significantly easier to match the
color of the filling material to the natural teeth when using a
shell of this invention than it is to match the color of a pontic
to the color of the natural teeth.
Use of the Invention to Provide Orthodontic as well as Cosmetic
Improvements.
[0101] If desired, one or more parts of the self-supporting shell
can be offset from the natural position of one or more teeth, so
that when the shell is in place, it exerts a force on one or more
teeth which moves the teeth in a desired direction, for orthodontic
purposes. In this use, the shell needs to be more rigid than is
necessary, or even desirable, for a shell which has only a cosmetic
purpose. For example, for orthodontic appliance, it is desirable to
use a polymeric sheet which, before being thermoformed, is 0.5 to
0.8 mm thick and for the polymeric composition to have a flexural
modulus between 1000 and 3000 MPa.
EXAMPLES
Example 1
[0102] The compositions A-F of Table 1 were prepared from tinted
and non-tinted rigid polyurethane. CPU 664 and Zendura A are
tinted. Isoplast 2530 is not tinted.
TABLE-US-00003 Thickness Composition (millimeters) L color A color
B color A- CPU 664 0.82 74.85 9.92 -20.7 B- CPU 664 0.28 88.4 4.46
-9.01 C- CPU 664 0.16 92.39 2.72 -5.15 D- Zendura A 0.77 95.9 0.45
-0.18 E- Isoplast 2530 0.81 97.47 -0.07 1.44 F - Isoplast 2530 0.8
94.5 -0.24 6.22 Normal Tooth Range 68 0.5 15
Reference tooth colors for "normal range teeth" are taken from the
literature
[0103] An impression was made of an individual's upper teeth using
alginate and converted into a positive model using dental plaster.
A sheet of polyurethane (composition C) having a thickness of 0.16
mm was thermoformed over the positive plaster model, trimmed and
cleaned. A second shell was prepared using a longer heating cycle
resulting in a slightly thinner shell. These shells are designated
UB-1 and UB-2 respectfully.
[0104] The natural teeth of individual A were examined in sunlight
and were found to have the same color. The shell UB-1 was then
applied only to the upper teeth, and the upper and lower teeth
photographed in sunlight. When the upper shell of Example 1 was
placed on the upper teeth, it was observed that the upper teeth
were significantly whiter than the lower teeth.
[0105] The shell UB-2 was applied only to the upper teeth of
individual A, and the upper and lower teeth photographed in
sunlight.
[0106] Color analysis of the right incisor in the upper teeth of
the shell UB-2 and the natural color of the right incisor was
conducted using a computer drawing program and is reported in Table
2.
TABLE-US-00004 TABLE 2 Color of Right Incisor with and Without
Shell Color of Right Incisor Cyan Magenta Yellow Black No shell 0
11 24 8 Shell 0 14 16 16
It can be noted that the yellow value was reduced from 24 to 16. In
this example the UB-1 shell slightly over-corrected the original
tooth color. It is estimated that a preferable initial value for
the tinted plastics sheet would have a LAB color value of
approximately; L=97, A=1.0, B=-2.0
Example 2
[0107] Samples A-G as shown in Table 3 below were prepared by
mixing Styrene co-polymer K Resin BK10 (Chevron Phillips, LLC) with
the ingredients and amounts thereof shown in Table 3. The
ingredient OB-1 in Table 3 is the optical brightener
2,2-(1,2-ethenediyldi-4, 1-phenylene) bisbenzoxazole (Keystone
Aniline Corporation). The ingredients were mixed in an internal
mixer and pressed into sheets approximately 0.65 mm thick. The
sheets were subsequently formed into shells as in Example 1 and
applied to the upper teeth of Individual A.
TABLE-US-00005 TABLE 3 Composition of K-Resin Formulations. Ultra-
Ultra- marine marine OB-1 Blue Violet Barium Titanium Sample
Designation (%) (%) (%) Sulfate Dioxide A BM79-38-A 0.01% B
BM79-38-B 0.01% 0.01% 0.05% C BM79-38-C 0.02% D BM79-39-A 0.015% 1%
E BM79-39-B 0.015% 1% 0.2% F BM79-39-C .005% 0.03% G BM79-39-D
.006% 0.05%
The color values of Individual A's right incisor when covered with
Shells A, B and C, UB-1 and UB-2 and two controls (two separate
measures of the color value of the Individual A's right incisor
with no cover over it) were measured, and the results are shown in
Table 4 below.
TABLE-US-00006 TABLE 4 Measured Color Values Con- Con- Con- Shell
Shell Shell Shell Shell trol-1 trol 2 trol Av UB-1 UB-2 A B C Cyan
0 0 0 0 0 0 0 0 Magenta 12 11 11.5 14 8 11 10 12 Yellow 28 25 26.5
16 12 19 15 17 Gray 11 15 13 16 7 12 12 12 Total 51 51 51 46 27 42
37 41 CYMK
The shell prepared from composition E was opaque (<50% light
transmission) and judged to be less desirable as a tooth whitening
shell as the opacity of the shell masks the spaces between the
teeth such that individual teeth are not as apparent as desired.
However, the shell of composition E has value when it is desired to
mask the absence of a tooth, such as when a pontic is used.
[0108] The shell prepared from composition G (BM 79-39-D) was
evaluated in bright daylight and in diffuse light, and the results
are shown in Table 5. As would be expected, the specific colors
values vary with type and amount of light. Table 5 shows the color
values of Individual A's right incisor when covered with shell
prepared from composition G, and the control (the color value of
the Individual A's right incisor with no cover over it).
TABLE-US-00007 TABLE 5 Evaluation of Shell From Composition
BM79-39-D Control- Bm79-39-D Control BM79-39-D Sun Sun Shade Shade
Cyan 0 0 0 0 Magenta 15 7 24 18 Yellow 23 14 49 28 Gray 19 12 28
34
The color data in both types of lighting show a dramatic reduction
in yellowing and improvement in tooth color.
Example 3
[0109] PETG resin (Eastar 6763) is combined with ultramarine blue
and ultramarine violet pigment master batch and extruded into a
sheet of thickness 0.07 mm the amount of the pigment being such
that the sheet has LAB color values measured on a white color tile
of L=94, A=1.3, B=-2.5. A dental impression is made from an
individual's upper and lower teeth using a plastic dental tray and
alginate resin. Dental stone is prepared by mixing 100 grams of
plaster with 24 grams of water and poured into the alginate mold
and allowed to set. The plaster model is removed and cleaned. Disks
are prepared from the extruded sheet by die cutting samples 125 mm
in diameter and dried at 80 C for 2 hours. The dried discs are
pressure-formed over the plaster models using a Biostar
thermoformer manufactured by distributed by Great Lakes Dental. The
thermoformed parts are removed from the plaster models, trimmed to
the gum line and cleaned. Color measurements are made on the
individual's teeth before and after the shells are placed over the
teeth.
[0110] The following statements define particular aspects of the
invention. [0111] Statement 1. A shell which is composed of a
polymeric composition containing an optical additive and which
contains cavities shaped to cover a plurality of teeth, the shell
having an average thickness of from 0. 1 mm to 1.5 mm, preferably
0.2 to 1.5 mm, and a transparency of greater than 75%, preferably
greater than 85%, the observed color of the teeth when they are
covered by the shell (i) being substantially less yellow than the
color of the teeth without the shell, and/or (ii) the observed
color of teeth when they are covered by the shell being at least
one shade lighter, according to a tooth color classification
system, than the color of the same teeth without the shell, and/or
(iii) the observed color of the teeth when they are covered by the
shell being brighter than the color of the same teeth without the
shell. [0112] Statement 2. A shell according to Statement 1 wherein
the polymeric composition is based on a polymer selected from the
group consisting of polyolefins, e.g. polyethylene, polyesters,
including for example copolymers such as polyethylene terephthalate
glycol resins (PETG), polyurethanes including rigid polyurethanes,
thermoplastic polyurethanes (TPU), polypropylene and propylene
copolymers, acrylic and methacrylic resins and co-polymers,
polystyrene and co-polymers including random and block co-polymer
and elastomers and fluoropolymers. [0113] Statement 3. A shell
according to Statement 1 or Statement 2 wherein the optical
additive comprises one or more of a pigment, a dye, light
scattering particles and a fluorescent material with optical
properties. [0114] Statement 4. A shell according to Statement 1 or
Statement 2 wherein the optical additive is selected from the group
consisting of ultramarine pigments, ultramarine blue, ultramarine
violet, cobalt-based pigments and resin soluble dyes. [0115]
Statement 5. A shell according to Statement 1 or Statement 2
wherein the optical additive comprises a material selected from the
group consisting of titanium dioxide, barium sulfate, calcium
carbonate, silica, mica and zinc oxide. [0116] Statement 6. A shell
according to Statement 1 or Statement 2 wherein the optical
additive comprises a fluorescent material which absorbs light with
a wavelength of less than 390 nm and emits light with a wavelength
of from 400 nm to 600 nm. [0117] Statement 7. A shell according to
Statement 1 or Statement 2 wherein the optical additive comprises a
fluorescent material and a pigment or dye that absorbs light in the
range of from about 550 nm to about 700 nm. [0118] Statement 8. A
shell according to any one of Statements 1 to 5 which does not
contain a fluorescent agent and which, when not fitted over teeth,
and measured on the LAB scale on a white color tile, has an L value
from 50 to 99, preferably 75 to 99, more preferably 80 to 99,
particularly preferably 85 to 99, an A value of -1 to 10,
preferably -3 to 6, more preferably -2 to 5, particularly
preferably -1 to 5 e.g. 0.5 to 5, and a B value of -1 to -14,
preferably -10 to -1, e.g. -10 to -2, more preferably -7 to -1,
particularly preferably -5 to -1.5. [0119] Statement 9. A shell
according to any one of Statements 1-7 wherein the optical additive
comprises a fluorescent agent and which, when not fitted over the
teeth, and measured on the LAB scale on a white color tile and
using a light source that includes light with a frequency of about
300-400 nm filtered to D65 has an L value from 75 to 110,
preferably 80 to 110, more preferably 85 to 110, particularly
preferably 85 to 99, an A value of -3 to 6, more preferably -2 to
5, particularly preferably -1 to 4, and a B value of -10 to -1,
more preferably -7 to -1, particularly preferably -5 to -1.5.
[0120] Statement 10. A shell according to any one of Statements 1-9
wherein from about 10% to about 50% of the incident light is
reflected from the shell rather than the underlying tooth. [0121]
Statement 11. A shell according to any one of Statements 1-10
wherein the shell provides orthodontic treatment to the teeth.
[0122] Statement 12. A shell according to any one of Statements
1-11 wherein the shell comprises two or more layers, and the
outermost layer contains a lower concentration of optically active
materials than another layer. [0123] Statement 13. A shell
according to Statement 12 wherein the outermost layer is 0.2 to 0.7
mm thick. [0124] Statement 14. A sheet of a polymeric composition
which can be thermoformed into a shell according to any one of
Statements 1-13.
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