(12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)
`(19) World Intellectual Property
`Organization
`International Bureau
`
`(OQ UTAA ATTAN
`
`\a
`
`(43) International Publication Date
`6 September 2013 (06.09.2013)
`
`WIPO!IPCT
`
`GD)
`
`International Patent Classification:
`AGIC 7/08 (2006.01)
`A61K 6/083 (2006.01)
`A61IC 8/00 (2006.01)
`CO08J 5/18 (2006.01)
`AGIC 13/00 (2006.01)
`B29C 35/02 (2006.01)
`
`(81)
`
`(21)
`
`International Application Number:
`
`PCT/US2013/027950
`
`(10) International Publication Number
`WO 2013/130552 Al
`
`Designated States (unless otherwise indicated, for every
`kind of national protection available): AE, AG, AL, AM,
`AO, AT, AU, AZ, BA, BB, BG, BH, BN, BR, BW, BY,
`BZ, CA, CH, CL, CN, CO, CR, CU, CZ, DE, DK, DM,
`DO, DZ, EC, EE, EG, ES, FI, GB, GD, GE, GH, GM, GT,
`HIN, HR, HU, ID,IL, IN, IS, JP, KE, KG, KM, KN, KP,
`KR, KZ, LA, LC, LK, LR, LS, LT, LU, LY, MA, MD,
`ME, MG, MK, MN, MW, MX, MY, MZ, NA, NG, NL
`NO, NZ, OM, PA, PE, PG, PH, PL, PT, QA, RO, RS, RU,
`RW, SC, SD, SE, SG, SK, SL, SM, ST, SV, SY, TH, TJ,
`T™,, TN, TR, TT, TZ, UA, UG, US, UZ, VC, VN, ZA,
`ZM, ZW.
`
`(84)
`
`Designated States (unless otherwise indicated, for every
`kind of regional protection available): ARIPO (BW, GH,
`GM, KE, LR, LS, MW, MZ, NA, RW, SD, SL, SZ, TZ,
`UG, ZM, ZW), Eurasian (AM, AZ, BY, KG, KZ, RU,TJ,
`TM), European (AL, AT, BE, BG, CH, CY, CZ, DE, DK,
`EE, ES, FI, FR, GB, GR, HR, HU,IE,IS, IT, LT, LU, LV,
`MC, MK, MT, NL, NO,PL, PT, RO, RS, SE, SI, SK, SM,
`TR), OAPI (BF, BJ, CF, CG, CI, CM, GA, GN, GQ, GW,
`ML, MR,NE, SN, TD, TG).
`Published:
`
`with international search report (Art. 21(3))
`
`/ Continued on next page|
`
`(57) Abstract: Polymeric shells which fit over natural teeth
`to change the perceived color of the teeth, and optionally to
`provide orthodontic support. The shells are prepared by ther-
`moforning selected polymeric sheets which contain optical
`additives; the optical additives cause the combination ofthe
`shell and the teeth to have a desired appearance. The shell
`preferably has transparency ofgreater than 75%, particularly
`greater than 85%.
`
`(22)
`
`International Filing Date:
`
`27 February 2013 (27.02.2013)
`
`(25)
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`(26)
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`(30)
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`(7)
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`(72)
`(7D)
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`(74)
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`Filing Language:
`
`Publication Language:
`
`English
`
`English
`
`Priority Data:
`61/634,370
`
`27 February 2012 (27.02.2012)
`
`US
`
`Applicant: BAY MATERIALS LLC; 3700 Haven Court,
`Menlo Park, CA 94025 (US).
`
`Inventor; and
`Applicant (for US only): STEWART, Ray, F. [US/US];
`3700 Haven Court, Menlo Park, CA 94025 (US).
`
`Agent: RICHARDSON T.H.P.; 1055 TRINITY DRIVE,
`MENLOPARK,CA 94025 (US).
`
`(54)
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`‘Title: DENTAL PRODUCTS AND PROCEDURES
`
`FIGURE 7
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`wo2013/130552A1TIMINTANTIYTNTIMTINATATUTITA
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`WO 2013/130552 A1 IMMIMUTINITN ACN IE TETAAO AAAATA
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`— before the expiration of the time limit for amending the
`claims and to be republished in the event of receipt of
`amendments (Rule 48.2(h))
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`WO 2013/130552
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`PCT/US2013/027950
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`FIELD OF THE INVENTION.
`
`This invention relates to products and procedures for changing the appearance
`
`of teeth.
`
`BACKGROUND OFTHE INVENTION.
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`10
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`15
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`20
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`25
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`30
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`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 changetherelative 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.
`Oneorthodontic procedure makes useof one or more rigid polymeric shells each
`of whichfits over the teeth and, whenin place, does notfit precisely to one or more of
`the teeth and, therefore, imparts a displacing force to the teeth and over the course of
`time changesthe relative positions of two or more teeth. Reference may be madefor
`example to US 5,975,893(Chishti) and US 7,220, 122(Chishti), the entire disclosure of
`each of whichis 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’.
`Mucheffort and expense has been expendedin 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 damagethe natural tooth structure itself and/or can produce
`different cosmetic effects on the natural tooth structure and/or stains and/orfillings
`and/or crowns. Other cosmetic procedures make use of compositions which form a
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`WO 2013/130552
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`PCT/US2013/027950
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`coating on top of the teeth; those compositions are difficult to apply uniformly and
`accurately, and degraderelatively rapidly and/orare difficult to remove. For information
`about known cosmetic procedures, reference may be made for example to US Patents
`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 which is Incorporated herein by reference for all purposes
`
`SUMMARYOF THE INVENTION.
`
`| 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 changethe 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 byfillings or by crowns,
`
`implanted teeth, artificial teeth that are part of a bridge or otherfitting secured to one or
`
`more natural or implanted teeth, and artificial teeth that are part of a removablefitting.
`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 orlight transmission properties of the
`polymeric composition.
`
`In a second aspect, this invention provides a methodof providing a desired
`changein the appearance of teeth which comprises placing a self-supporting shell
`accordingto the first aspect of the invention over one or more teeth.
`in a third aspect, this invention provides a method of making a self-supporting
`shell accordingto the first aspect of the invention, the method comprising forming a
`selected polymeric composition into a shape whichwill 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.
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`In a fourth aspect, this invention provides a method which comprises
`(A)
`assessing the color of teeth over which a self-supporting shell according to
`the first aspect of the invention is to be placed,
`(B)—selecting from a range of compositions having different colors, a
`composition which will provide a desired changein the appearance of teeth when
`formed into a self-supporting shell according to the first aspect of the invention,
`
`and
`
`forming the selected composition into a self-supporting shell.
`(C)
`In a fifth aspect, this invention provides a method which comprises
`(A)
`selecting, from a set of colored samples, a sample which matchesthe
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`color of teeth to be treated, and
`
`(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.
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`15
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`In a sixth aspect, this invention provides a sheet of a polymeric composition for
`
`use in the method of the third orfifth aspect of the invention, for example by
`
`thermoforming the sheet around a physical mode! of the teeth over which the shell is to
`
`befitted.
`
`In a seventh aspect, this invention provides a set of sheets of a polymeric
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`composition, the sheets being (i) composedof 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.
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`25
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`In an eighth aspect, this invention provides a novel polymeric composition for use
`
`in the invention.
`
`Brief Description of the Drawings
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`30
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`The invention is illustrated in the accompanying drawings. Figures 1A, 1B, 2, 3,
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`4, 5 and 6 are grayscale versions of color photographs (the color photographswill be
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`addedto the application in the jurisdictions where this is possible). Figure 7 shows the
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`color ranges which are often observed for discolored teeth (area A), normal teeth (area
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`B), whitened teeth (area C), orthodontic appliances (area D), and a preferred color
`
`range for tooth shells of this invention (area E). In Figure 7, on the horizontal axis, the
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`negative values relate to green colors and the positive values relate to red colors, and
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`on the vertical axis, the negative values relate to blue colors and the positive values
`
`relate to yellow colors.
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`10
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`Detailed Description of the Invention
`In the Summary of the Invention above andin the Detailed Description of the
`Invention below,including the Examplesandillustrations, 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
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`15
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`particular aspect or a particular embodiment, that feature can also be used in
`
`combination with other particular aspects and embodiments,andin 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, equivalentor similar to, features specifically disclosed
`herein.
`
`The term "comprises" and grammatical equivalents thereof are used herein to
`meanthat, 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
`numberis used herein to denote the start of a range beginning with that number (which
`may be a range having an upperlimit or no upperlimit, depending on the variable being
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`defined). The term “at most" followed by a numberis used herein to denote the end ofa
`
`range ending with that number (which may be a range having 1 or 0 asits lower limit, or
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`a range having no lowerlimit, depending upon the variable being defined). Whena
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`range is given as "(a first number) to (a second number)”or "(a first number) - (a
`
`second number)", this means a range whose lowerlimit is the first number and whose
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`upperlimit is the second number. The terms “plural”, “multiple”, “plurality” and
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`“multiplicity” are used herein to denote two or more than two features.
`
`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 excludesthat
`
`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 numberor greater
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`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 numberis subject to variation which
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`15
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`dependson the accuracy with which it can be measured by methods conventionally
`
`used by those skilled in the art.
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`This specification incorporates by reference all documents referred to herein and
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`all documentsfiled concurrently with this specification or filed previously in connection
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`with this application, including but not limited to such documents which are open to
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`public inspection with this specification.
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`Parts, percentages andratios given in this specification are by weight unless
`
`otherwise noted.
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`Unless otherwise noted, the term color measurementis used herein to refer to
`
`measurements made_using the LAB CIE color scale wherein L refers to total reflected
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`25
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`light, A refers to the Red (+) — Green (-) color Axis and B refers the Yellow (+) — Blue (-)
`
`color axis measured using a D65light source (daylight). However, color can also be
`
`measured using the CYMK scale which makesuseofdigital images. Other color
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`measurement systems are known and any suitable method may be usedin evaluating
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`products of this invention.
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`The term pigment is used herein to denote a solid particulate coloring agent
`which can be mixed with a polymer.
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`The term dye is used herein to denote a coloring agent that is soluble or
`
`molecularly dispersed in a polymer.
`The term fluorescent agent is used herein to denote a_material that absorbslight
`in one region of the spectrum and emitslight in the same ordifferent region of the
`spectrum. The emission may be almost immediate or may be delayed.
`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 TransparentPlastics. Light transmission may also be
`
`measured using a colorimeter and a white reference sample, in which case the
`
`measurementincludes two passagesoflight through the sample.
`The term incidentlight is used herein to denote light which shines onto an object
`and which maybereflected, scattered or least partially absorbed by the object.
`The term reflected light is used herein to denote incident light which reflects off
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`the surface of an object after impinging on the object.
`
`The term scattered light is used herein to denote light which diverges from_a
`
`straight path after it has impinged on an object.
`
`The term light scattering particles is used herein to denote particles having a size
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`from about 0.2 to about 20 pp and which are transparent or substantially white. By white
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`20
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`is meant that the particles do not absorb significant amounts oflight in the range from
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`about 400 nm to about 700 nm.
`
`The term thermoplastic polymer is used herein to denote a polymerwhich is
`relatively hard at a lower temperature, which becomesrelatively soft when subjected to
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`heat and pressure, and again becomesrelatively hard when cooled, provided that the
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`heat and pressure do not chemically decompose the polymer.
`
`The term thermosetting polymer is used herein to denote a polymeric
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`composition whichis a solid or viscous material at a relatively low temperature and
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`which, when subjected to heat and/or suitable radiation, and/or when the material
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`undergoes one or more chemical reactions, changesirreversibly into an infusible
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`30
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`polymer network. The term thermoset polymeris used to denote a cured thermosetting
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`polymer.
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`The Polymerin the Polymeric Composition.
`
`The polymerin 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
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`composition can contain a single polymeror a mixture of two or more polymers.
`
`Generally, the polymeris substantially transparent, so that the optical characteristics of
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`the self-supporting shell are dominated by the optical additives which are mixed with the
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`polymer, but the invention includes the possibility that the polymer is a semicrystalline
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`polymerwhich scatterslight.
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`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
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`of the following characteristics).
`
`(1)
`
`(2)
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`(3)
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`The polymer comprises a thermoplastic polymer.
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`The polymer comprises a thermoset polymer.
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`The polymeris an elastomer, preferably an elastomer having elongation to
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`break greater than 200% and a 100% modulusof less than 3000 PS! (value for
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`D50 or less TPU)
`
`The polymeris a polyester, for example a polyethylene terephthalate
`(4)
`glycol polymer (PETG), e.g. one of the polyesters sold by Eastman Chemical
`underthe trade names Eastar and Durastar, or one of the polyesters sold by
`DuPont underthe trade name Hytrel.
`
`The polymeris a polyurethane, for example a rigid polyurethane such as
`(5)
`that sold by Lubrizol Corporation underthe trade nameIsoplast, or a
`thermoplastic polyurethane (TPU) such as one of those sold by Lubrizol
`Corporation under the trade name Pellethane, by Merquinsa underthe trade
`name Pearlthane, by BASF underthe trade name Elastollan, and by Bayer under
`the trade name Texin.
`
`The polymeris a polyolefin, including high-density polyethylene, low
`(6)
`density polyethylene, medium density polyethylene,linear low density
`polyethylene; a copolymerof ethylene and one or more comonomers,e.g.
`comonomers selected from the group consisting of other a-olefins, vinyl acetate,
`
`i)
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`acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate and butyl acrylate;
`polypropylene, e.g. clarified polypropylene; a propylene copolymer,e.g. a
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`clarified propylene copolymer; polystyrene; a copolymerof styrene and one or
`
`more comonomers, e.g. comonomers selected from the group consisting of
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`acrylic comonomers,acrylonitrile, acrylonitrile and butadiene, including block
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`copolymers of styrene with ethylene, ethylene and propylene, isoprene and
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`butadiene; polymers of cyclic olefins; and polymethyl pentene.
`
`(7)
`
`The polymeris an acrylic or methacrylic resin, including polyacrylonitrile
`
`and copolymers of acrylonitrile.
`
`(8)|The polymeris an aliphatic or aromatic or mixed aliphatic aromatic
`10
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`polyamide, a polycarbonate, a polyether, an ionomerresin or a cellulose ester or
`
`ether.
`
`(9)
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`|The polymeris 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.
`
`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.
`
`The optical additive can optionally have any one of the following characteristics,
`or any possible combination of one or moreof the following characteristics.
`(1)
`The optical additive, when dispersed in a sample of the polymeric composition
`having a thickness of 0.76 mm, preferentially absorbslight within the range from about
`550 to about 700 nm, such that, when measured against a reference white sample (e.g.
`a white colortile) using conditions D 65, the LAB color values for the combination of the
`white colortile 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.
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`(2)
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`The optical additive comprises a pigment or dye having a color which ranges
`
`from blue to violet, for example ultramarine blue, ultramarine violet, manganeseoxides,
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`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 usedinclude the
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`following (which are listed by their Cl 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,
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`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, PV39, PV 42, PV 44, PV 47, PV 48, PV 49, PV 50,
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`PV55, PV 58, and PV 17.
`
`(3)
`
`The optical additive comprises a red pigmentor 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,
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`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,
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`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,
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`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
`
`20
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`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,
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`PR 112, PR 113, PR 113:1, PR 114, PR 119, PR 120, PR 121, PR 122, PR 123, PR
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`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,
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`25
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`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, PR221, 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,
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`30
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`PR 260, PR 262, PR 264, PR 265, PR 266, PR 268, PR 269, PR 270, PR 271, PR 272,
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`PR 273, PR 274, PR 275, PR 276, PR 279, PR 282, PR 286, PR 287, PR 288, and PR
`
`571.
`
`The optical additive compriseslight scattering (reflecting) particles, preferably
`(3)
`light scattering particles which, when a sample of the polymeric composition having a
`thickness of 0.76 mm is exposedto naturallight, from about 5% to about 50%,
`preferably 5 to 25%,ofthe incidentlight 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
`maskthe natural color of the teeth (which usually has a yellowish and/whole yellowish
`red tint) because a portion of the incidentlight is reflected before it is absorbed by the
`teeth. If the amount of reflected incidentlight is less than about 5%, the improvementis
`slight, whereas if the amount of reflected incidentlight is greater than about 50%,the
`perception of the underlying tooth structure may be reducedto a level such that the
`teeth are not perceived as natural.
`Light scattering occurs whenthereis a difference between the refractive index of
`the particles and the polymerin which they are dispersed. The greater the difference in
`refractive index, the greater the degree of scattering.
`If the particles are transparent to
`the incidentlight 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 amountof those wavelengths.
`If the proportion oflight reflecting
`particles is high and substantially all the incidentlight is scattered, the composition will
`appearwhite. At lower levels, the composition may appeartranslucent and light going
`throughit will be “diffuse”. For use in this application it is generally desired that anylight
`scattering particles added do not absorblight, so they do not contribute to off color or
`increase of the grey value of the teeth.
`In some casesit is desirable to utilize particles
`
`that are sufficient to cause light scattering, while maintaining a high degreeoftotal light
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`transmission.
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`It has been found that appropriate useof light-scattering particles can not only
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`result in teeth which look whiter, but can also mask areas of teeth having different
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`colors, for example stained regions or darker areas near the base of the teeth, resulting
`in a more uniform and cosmetically desirable appearance.
`
`(4)
`
`The optical additive comprises a fluorescent material which absorbsultraviolet
`
`light having a wavelength of less than about 400 nm and which emitslight in the range
`from about 400 to about 600 nm. Thesefluorescent 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 pigmentsin the shell make the perceived tooth color closer to
`white, but also reduces the total amountoflight reflected, so that the teeth do not
`appearas 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-
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`02-1.
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`Polymeric Compositions.
`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 somecases,it is
`preferable that the composition, when in the form of a uniform sheet having a thickness
`of 0.5 mm,hasa total transmission of greater than about 80% and a diffuse
`transmission greater than about 50%, when measured by ASTM D 1003.
`For the best results, which in most cases meansteeth 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
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`whichthe 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 andthe disclosurein this specification, will be able to select a
`
`composition whichis likely to give excellent results.
`
`Thoseskilled in dentistry are familiar with the ways in which the color of teeth can
`
`be assessed, andthe selection of a materialfora filling or a crown to match the natural
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`color of teeth. Commontooth colors are often designated by a combination of a letter
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`(usually A-D) and a number(usually 1-4), with A, B, C and D designating different hues
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`(A red yellow, B yellow, C gray, and D red yellow gray), and 1-4 designating the color
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`intensity. The designations M1, M2 and M3aretypically used to denote highly bleached
`
`teeth. Alternatively, the color of teeth can be measured by a colorimeter. Having
`
`determinedthe 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
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`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
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`shadeslighter. 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
`incidentillumination. Preferably the color of the natural teeth is at least one shade
`
`lighter is according to the VITA scale thanthe color of the same teeth without the shell
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`Preparation of the Polymeric Compositions and of Polymeric Sheets Comprising
`Those Compositions.
`
`The polymeric compositions used in this invention, and polymeric sheets
`comprising those compositions, can be prepared by conventional methods which are
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`well-known to those skilled in the art of polymer technology.
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`Polymeric Sheets for Conversion into Self-Supporting Polymeric Shells
`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.
`
`It is a flat sheet having a uniform thickness of 0.10-2 mm, preferably 0.15-1.5
`
`1.
`
`mm.
`
`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.?
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`3.
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`it is a flat sheet having dimensions suchthatit will completely cover a modelof
`
`the teeth in the upperjaw or the lowerjaw of an adult, or of a child, for exampleaflat
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`sheet whichis a circular disk, a flat sheet which is part (for example half) of a circular
`
`disk.
`
`4.
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`5.
`
`The polymeric composition is the same throughout the sheet.
`
`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 thicknessof the sheet, including the possibility that there is no
`additive (or none of one or more of the additives) at one or morelevels.
`
`The sheetis a laminate having two or more layers of different polymeric
`6.
`compositions, for example (1) a laminate which contains an optical brightener in a iayer
`which, when the sheetis 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 sheetis
`formedinto a self-supporting shell, is in contact with the teeth, and which containsa first
`
`concentration of an optical additive, and (ii) a second layer which, when the sheetis
`formed into a self-supporting shell, is exposed, and whichis 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 polymersin the different layers are generally
`the same but can bedifferent
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`7.
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`The sheet has a variable thickness such that when the sheetis thermoformed
`
`over a model of the teeth,