EP2217104A2

EP2217104A2 - Decorated pieces with gem materials

Info

Publication number: EP2217104A2
Application number: EP08856625A
Authority: EP
Inventors: Laurent Grenier De Cardenal
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-12-07
Filing date: 2008-12-08
Publication date: 2010-08-18
Also published as: WO2009071704A3; WO2009071704A2; WO2009071966A1

Abstract

The invention relates to a method of sealing gem materials on pieces to produce pieces decorated with stones. The invention relates more specifically to the use of a dental bonding resin or adhesive as a sealing agent for fixing gem materials on any piece. It further deals with pieces presenting sealed gem materials on the surface thereof.

Description

DECORATED PIECES WITH GEM MATERIALS

FIELD OF THE INVENTION

The invention relates to a method of sealing gem materials on pieces to produce decorated pieces. The invention relates more specifically to the use of a dental bonding resin or adhesive as a sealing agent for fixing gem materials on any piece. It further deals with pieces presenting sealed gem materials on the surface thereof.

BACKGROUND OF THE INVENTION

Gem materials are generally fixed on pieces, including jewelry, such as rings, neckwear, or any ornamental object, such as plates, glasses, service settings (knifes, forks, spoons, etc.), by mounting gems on holders or by setting them by claws.

However, it is well known that methods of fixing gem materials are complex and quiet long to carry out as to obtain a satisfactory and reliable attachment of the gem materials in or on the pieces. Moreover, such methods may give rise to decorative objects where the attachment of gem materials is readily breakable and cannot support any mechanical, chemical or heat stress, such as washing, in a dishwasher for instance, or any other washing or sterilization process.

Moreover, although there are a variety of processes for setting gem materials, there is still a need for a piece presenting on a face thereof gem materials which are sealed, wherein the piece and gem materials keep their physical, optical and chemical properties respectively, while ensuring a good attachment between each other.

Moreover, there is still a need to have such a piece which can support any mechanical, chemical or heat stress, such as washing, in a dishwasher for instance, or any other washing or sterilization process. These are objects of the invention. Another object of the invention is to provide a piece presenting on a face thereof gem materials sealed thereto through a bonding resin or adhesive and optionally coated with a transparent glaze, which fulfils the sanitary and biological requirements of USP class VI. Accordingly, the piece of the invention may be a plate, glass, or any service setting. Another object of the invention is to provide a new way of presenting gem materials on a piece, without necessarily setting them by claws. It is also an object of the invention to provide a method of fixing gem materials on a piece wherein the piece on the side of the decorated face is not deformed in order to secure the gem materials. SUMMARY OF THE INVENTION

In a totally unexpected and surprising manner, it has been observed that gem materials can be sealed efficiently on a piece by using a dental bonding resin or adhesive as a sealing agent. The invention therefore relates to a method of sealing gem materials on at least one face of a piece to produce decorated pieces, wherein the sealing method comprises (i) contacting at least one gem material and at least one face of the piece with a dental bonding resin or adhesive and (ii), optionally coating the gem materials with a transparent glaze. The invention also relates to the use of a dental bonding resin or adhesive as a sealing agent for fixing gem materials on any support element or piece.

It further deals with a decorated piece presenting sealed gem materials on at least one face of the piece, wherein said decorated piece is prepared by the method of the invention. BRIEF DESCRIPTION OF THE FIGURES

Figure 1 is a longitudinal section of one embodiment of a decorated piece according to the invention, where three layers of adhesive composition (Cl, C2, and C3) were applied and fraize was used on the surface of the piece before applying an adhesive composition (holes on the surface of the piece represent the porosities obtained by using fraize). Figure 2 is a longitudinal section of another embodiment of a decorated piece according to the invention, where one layer of adhesive composition was applied on the piece or the gem material and fraize was used on the surface of the gem material before applying an adhesive composition (holes on the surface of the gem material represent the porosities obtained by using fraize). Figure 3 is a longitudinal section of one embodiment of a decorated piece according to the invention, where one layer of adhesive composition was applied on the piece or the gem material and fraize was used on surfaces of the gem material and piece before applying an adhesive composition (holes on the surfaces represent the porosities obtained by using fraize). Figure 4 is the same as figure 3, with an enamel coating.

Figures 5, 6, 7 and 8 are the same as figures 1, 2, 3 and 4, respectively, with a glaze coating. Figure 9 is a longitudinal section of one embodiment of a decorated piece according to the invention, where one layer of adhesive composition was applied on the piece or the gem material and fraize was used on the surface of the piece before applying an adhesive composition (holes on the surfaces represent the porosities obtained by using fraize). The piece is fraized to obtain a shape that accommodates to the shape of the gem material. The gem material is further coated with a glaze. Figure 10 is the same as figure 9, with an enamel coating.

In the figures, P stands for gem material; C, Cl, C2, and C3 stand for several layers of adhesive composition; S for piece; E for enamel; and R for glaze. In the figures, scales and shapes of gem materials and pieces are not respected.

DETAILED DESCRIPTION OF THE INVENTION

A piece, according to the invention, can be any object to be decorated with a gem material. It can be for instance a jewelry, clock or accessory article to form a ring, earrings, a necklace, a bracelet, a watch, a pendant, a belt or a brooch, or any other decorative objects. The other decorative objects include, but are not limited to, a plate, a glass, knife, forks, spoons, or any other service setting.

Material of the piece can be made of any kind of organic or inorganic components, including silica, kaolin, clay, metal, porcelain, wood and/or leather. Any metal can be used, including iron, gold, aluminium, copper, silicon, and alloy thereof. The piece of the invention is more particularly an inorganic piece made of silica, kaolin, clay, metal, or porcelain.

The piece can be of different shapes depending essentially on its final utility. The face of the piece to be decorated with gem materials can be prepared before sealing the gem materials. For instance, a hole can be made by one skilled in the art and preferably adapted to the size of the gem material, as to present the gem material properly on said face.

According to the invention, the term gem material includes any natural material or artificial product, as described in the blue books of the CIBJO (Confederation Internationale de Ia Bijouterie, Joaillerie, Orfevrerie), it also includes any pearl or diamond material, as defined in the diamond and pearls CIBJO books respectively.

According to the invention, a natural material is any material which has been formed completely by nature without human interference and subsequently modified only by means of cutting and polishing. Natural materials include precious stones, gemstones, ornamental stones, organic substances and modified gemstones. Precious stones, gemstones, ornamental stones and organic substances are often modified by various processes, before and/or after cutting, to improve their color or clarity. Of course, said treatments or modifications should not prevent the use of said treated or modified gem materials according to the invention.

According to the invention, an artificial product is any product which partially or completely made by man. Artificial products include reconstructed stones (manufactured by melting or fusing natural material to form a coherent whole), composite stones (composed of two or more, previously separate, parts or layers assembled by bonding or other artificial methods, their components may be natural and/or artificial), synthetic stones (products having essentially the same chemical composition, physical properties and structure as that of their naturally occurring counterparts), artificial stones (crystalline products with no known natural couterparts), and imitations (products that imitate the appearance of precious stones, gemstones, ornamental stones or organic substances without having their chemical composition and/or their physical properties and/or ther structure.

Preferably, gem materials are natural materials as defined above. They are more particularly selected from the beryl material, such as emerald or aquamarine, the coral material, the corundom material, such as ruby, sapphire, the quartz material, such as amethyst or citrine, the garnet group, such as pyrope, grossular or tsavorite, the lapis lazuli material, the turquoise material, the opal material, the spinel group, such as orange spinel or red spinel, pearls, diamonds, and all varieties therefrom. Pearls may be natural or cultured pearls. The size of the gem materials may depend on several aspects. In particular, the size of the gem material may depend on the support to be decorated.The dental bonding resin or adhesive used according to the invention can be any dental polymerizable composition, usually comprising at least a polymerizable monomer and preferably a polymerization initiator. This has been widely clinically used at present in the dentistry area. The dental polymerizable composition has been used, for example, in a dental restorative material which is so-called a composite resin usable in filling or repairing fracture of teeth or cavities of dental caries, a dental adhesive agent for adhering a crowning prosthetic such as a composite resin or inlay and crown to teeth, or cement, further artificial teeth or a denture base material, a coating agent, or the like. The dental bonding resin or adhesive used in the invention is preferably food safe, i.e. it is not toxic and may be swallowed without side effects.

As mentioned above, the dental polymerizable composition generally comprises: (a) a polymerizable monomer; (b) preferably, a polymerization initiator; (c) and optionally, a solvent.

The kinds of polymerizable monomers (a) and polymerization initiators (b) that are usable in the present invention are not particularly limited, and those that are generally employed can be used. In general, the kinds of these monomers and the polymerization initiator include preferably a combination of a radical polymerizable monomer and a radical polymerization initiator (radical polymerizable composition); optionally a combination of a cationic polymerizable monomer and a cationic polymerization initiator (cationic polymerizable composition); and the like.

Specific examples of the radical polymerizable monomer in the polymerizable monomer (a) include esters derived from unsaturated carboxylic acids, such as -cyanoacrylic acid, (meth)acrylic acid, -halogenated acrylic acid, crotonic acid, cinnamic acid, sorbic acid, maleic acid, and itaconic acid; (meth)acrylamide, (meth)acrylamide derivatives, vinyl esters, vinyl ethers, mono-N-vinyl derivatives, and styrene derivatives; and the like. Among them, (meth)acrylic esters are preferred. The term "(meth)acrylate" as used herein means both of "acrylate" and "methacrylate." The same applies to the term "(meth)acryl-" as used herein, it generally means both of "acryl-" and "methacryl-."

Examples of (meth)acrylic ester-based polymerizable monomers are given hereinbelow. (l)The mono functional (meth)acrylates includes:

Methyl (meth)acrylate, isobutyl (meth)acrylate, benzyl (meth)acrylate, lauryl (meth)acrylate, 2-(N,N-dimethylamino)ethyl (meth)acrylate, 2,3-dibromopropyl (meth)acrylate, 3-methacryloyloxypropyl trimethoxysilane, 2-hydroxyethyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, propylene glycol mono(meth)acrylate, glycerol mono(meth)acrylate, erythritol mono(meth)acrylate, N-methylol (meth)acrylamide, N-hydroxyethyl(meth)acrylamide, N,N-bis(hydroxyethyl) (meth)acrylamide, (meth)acryloyloxydodecylpyridinium bromide, (meth)acryloyloxydodecylpyridinium chloride,

(meth)acryloyloxydodecylpyridinium bromide, (meth)acryloyloxyhexadecylpyridinium chloride, and the like. (2) The bifunctional (meth)acrylates include: Ethylene glycol di(meth)acrylate, Methylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, bisphenol A diglycidyl (meth)acrylates (so-called BisGMA), 2,2-bis[4-(meth)acryloyloxyethoxyphenyl]propane, 2,2-bis[4- (meth)acryloyloxypolyethoxyphenyl]propane, 2,2-bis[4-[3-(meth)acryloyloxy-2- hydroxypropoxy]phenyl]propane, 1 ,2-bis[3-(meth)acryloyloxy-2- hydroxypropoxy] ethane, pentaerythritol di(meth)acrylate, l,2-bis(3-methacryloyloxy-2- hydroxypropoxy)ethane, [N,N'-(2,2,4-trimethylhexamethylene)bis(2- carbamoyloxyethyl)] dimethacrylate, and the like. (3) The trifunctional or higher polyfunctional (meth)acrylates include:

Trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, [N,N'-(2,2,4-trimethylhexamethylene)bis[2- (aminocarbonyloxy)propane- 1 ,3-diol]]tetramethacrylate, 1 ,7-diacryloyloxy-2,2,6,6- tetraacryloyloxymethyl-4-oxaheptane, and the like.

According to a preferred embodiment, (meth)acrylates are selected from methyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate (also called HEMA) and bisphenol A diglycidyl (meth)acrylates. Any one of the above-mentioned polymerizable monomers can be used alone or in a mixture of two or more kinds.

When the adhesion is to be improved, in some cases it is a preferred embodiment that a functional monomer that gives the adhesion to the substrates may be contained in the polymerizable composition of the present invention as a part of the polymerizable monomer (a). As functional monomers, for example, monomers having a phosphoric acid group, such as 2-(meth)acryloyloxyethyl dihydrogenphosphate, 10-(meth)acryloyloxydecyl dihydrogenphosphate (so-called MDP), and 2-(meth)acryloyloxyethyl phenyl hydrogenphosphate, and monomers having a carboxylic acid group, such as 11- (meth)acryloyloxy-l,l-undecanedicarboxylic acid and 4- (meth)acryloyloxyethoxycarbonyl phthalic acid are preferred because the monomers show excellent adhesion to gem materials and the piece to be decorated. MDP is particularly preferred. It is preferable that the amount of the functional monomer is from 0.1 to 80 parts by weight, based on 100 parts by weight of the entire polymerizable monomer (a), from the viewpoint of adhesive strength and adhesive durability.

In the polymerizable composition of the present invention, it is preferable that a polymerization initiator (b) is previously added so as to facilitate the polymerization curing.

As polymerization initiator (b) used in combination with the above-mentioned radical polymerizable monomer, any known suitable radical polymerization initiator, such as a hot polymerization initiator, an ambient-temperature polymerization initiator, a photopolymerization initiator, can be used.

The hot polymerization initiator includes polymerization initiators such as peroxides and azo compounds, of which operable temperature range is generally from 40 to 100 ⁰C. Specific examples of the hot polymerization initiator include organic peroxides, such as diacyl peroxides, peroxyesters, dialkyl peroxides, peroxyketals, ketone peroxides, and hydroperoxides.

The diacyl peroxides include, for example, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, m-toluoyl peroxide, and the like. The peroxyesters include, for example, t-butyl peroxybenzoate, bis-t-butyl peroxyisophthalate, 2,5-dimethyl-2,5- bis(benzoylperoxy)hexane, t-butylperoxy-2-ethyl hexanoate, t-butyl peroxyisopropylcarbonate, and the like. The dialkyl peroxides include, for example, dicumyl peroxide, di-t-butyl peroxide, lauroyl peroxide, and the like. The peroxyketals include, for example, l,l-bis(t-butylperoxy) 3,3,5-trimethylcyclohexane, and the like. The ketone peroxides include, for example, methyl ethyl ketone peroxide, and the like. The hydroperoxides include, for example, t-butyl hydroperoxide, and the like. As the ambient-temperature polymerization initiator, for example, a redox polymerization initiator system composed of an oxidizing agent (polymerization initiator) and a reducing agent (accelerating agent) can be favorably used. In this case, for example, benzoyl peroxide can be used as a polymerization initiator, and an aromatic tertiary amine, such as diethanol toluidine, or an aromatic sulfmate can be used as an accelerating agent.

When a redox polymerization initiator is used, it is preferable that the polymerizable composition of the present invention takes the form in which two or more divided portions are wrapped. As the oxidizing agent in the redox polymerization initiator system, for example, the organic peroxides, such as diacyl peroxides, peroxy esters, dialkyl peroxides, peroxyketals, ketone peroxides, and hydroperoxides, mentioned above are preferred.

As the reducing agent, for example, an aromatic tertiary amine, an aliphatic tertiary amine, and sulfuric acid or a salt thereof, or the like, are preferred.

The aromatic tertiary amines include, for example, N,N-dimethylaniline, N,N-dimethyl- p-toluidine, N,N-dimethyl-m-toluidine, N,N-diethyl-p-toluidine, N,N-dimethyl-3,5- dimethylaniline, N,N-dimethyl-3,4-dimethylaniline, N,N-dimethyl-4-ethylaniline, N ,N- dimethyl-4-isopropylaniline, N,N-dimethyl-4-t-butylaniline, N,N-dimethyl-3,5- di-t- butylaniline, N,N-bis(2-hydroxyethyl)-3,5-dimethylaniline, N,N-di(2-hydroxyethyl)-p- toluidine, N,N-bis(2-hydroxyethyl)-3 ,4-dimethylaniline, N,N-bis(2-hydroxyethyl)-4- ethylaniline, N,N-bis(2-hydroxyethyl)-4-isopropylaniline, N,N-bis(2-hydroxyethyl)-4-t- butylaniline, N,N-bis(2-hydroxyethyl)-3,5-diisopropylaniline, N,N-bis(2- hydroxyethyl)- 3,5-di-t-butylaniline, 2-butoxyethyl 4-dimethylaminobenzoate, 2-methacryloyloxyethyl 4-dimethylaminobenzoate, and the like. Each of these aromatic tertiary amines can be used alone or in a mixture of two or more kinds. The aliphatic tertiary amines include, for example, trimethylamine, triethylamine, N-methyldiethanolamine, N- ethyldiethanolamine, N-n-butyldiethanolamine, N-lauryldiethanolamine, triethanolamine, 2-(dimethylamino)ethyl methacrylate, N-methyldiethanolamine dimethacrylate, N- ethyldiethanolamine dimethacrylate, triethanolamine monomethacrylate, triethanolamine dimethacrylate, triethanolamine trimethacrylate, and the like. Each of these aliphatic tertiary amines can be used alone or in a mixture of two or more kinds. The sulfmic acids or salts thereof include, for example, benzenesulfmic acid, sodium benzenesulfinate, potassium benzenesulfinate, calcium benzenesulfinate, lithium benzenesulfinate, toluenesulfinic acid, sodium toluenesulfinate, potassium toluenesulfinate, calcium toluenesulfinate, lithium toluenesulfinate, 2,4,6-trimethylbenzenesulfmic acid, sodium 2,4,6-trimethylbenzenesulfmate, potassium 2,4,6-trimethylbenzenesulfmate, calcium 2,4,6-trimethylbenzenesulfmate, lithium 2,4,6-trimethylbenzenesulfmate, 2,4,6- triethylbenzenesulfmic acid, sodium 2,4,6-triethylbenzenesulfmate, potassium 2,4,6- triethylbenzenesulfinate, calcium 2,4,6-triethylbenzenesulfmate, 2,4,6- isopropylbenzenesulfinic acid, sodium 2,4,6-triisopropylbenzenesulfmate, potassium 2,4,6-triisopropylbenzenesulfinate, calcium 2,4,6-triisopropylbenzenesulfmate, and the like. Each of these sulfuric acids or salts thereof can be used alone or in a mixture of two or more kinds.

As the photopolymerization initiator, a photopolymerization initiator which is excited with light having a wavelength of from 350 to 700 nm can be preferable because a photoirradiation device in a visible light range, which has been conventionally widely used, can be used without necessitating a specialized photoirradiation device (for example, an ultraviolet ray irradiation device).

The photopolymerization initiator which is excited with light having a wavelength of from 350 to 700 nm includes, for example, -diketones, ketals, thioxanthones, acyl phosphine oxides, coumarins, halomethyl group-substituted s-triazine derivatives, and the like.

Examples of the above-mentioned -diketones include camphor quinone, naphtoquinone, 2,3-pentanedione, and the like. Examples of the above-mentioned ketals include benzyl dimethyl ketal, benzyl diethyl ketal, and the like. Examples of the above-mentioned thioxanthones include 2-chlorothioxanthone, 2,4-diethylthioxanthone, and the like. Examples of the above-mentioned acyl phosphine oxides include 2,4,6-trimethylbenzoyl diphenylphosphine oxide, 2,6-dimethoxybenzoyl diphenylphosphine oxide, 2,6- dichlorobenzoyl diphenylphosphine oxide, 2,3,5,6-tetramethylbenzoyl diphenylphosphine oxide, benzoylbis(2,6-dimethylphenyl) phosphonate, 2,4,6- trimethylbenzoyl ethoxyphenylphosphine oxide, and water-soluble acyl phosphine oxide compounds. Examples of the above-mentioned coumarins include 3,3'-carbonylbis(7- diethylamino)coumarin, 3-(4-methoxybenzoyl)coumarin, and 3-thienoyl coumarin. Examples of the above-mentioned halomethyl group-substituted s-triazine derivatives include 2,4,6-tris(trichloromethyl)-s-triazine, 2,4,6-tris(tribromomethyl)-s-triazine, and 2- methyl-4,6-bis(trichloromethyl)-s-triazine, and the like. Camphor quinone is particularly preferred.

In the case where the adhesive composition used according to the invention is cured by using an irradiator using a blue LED, the [alpha] -diketones such as camphorquinone are preferably used as the photopolymerization initiator because they provide a high curing property to the adhesive composition.

Any one of the photopolymerization initiators may be used alone or in a mixture of two or more kinds. It is desired that the amount of the above-mentioned radical polymerization initiator is usually from 0.01 to 10 parts by weight, preferably from 0.05 to 5 parts by weight, and even more preferably from 0.1 to 3 parts by weight, based on 100 parts by weight of the polymerizable monomer (a). Incidentally, when a photopolymerization initiator is used, it can be preferred that the photopolymerization initiator and a reducing agent are used together in order to accelerate the photo-curing property.

The reducing agent primarily includes tertiary amines, aldehydes, compounds having a thiol group, and the like. Each of these reducing agents can be used alone or in a mixture of two or more kinds. Examples of the tertiary amines include 2-dimethylaminoethyl (meth)acrylate, N,N-bis[(meth)acryloyloxyethyl]-N-methylamine, ethyl A- dimethylaminobenzoate, butyl 4-dimethylaminobenzoate, butoxyethyl A- dimethylaminobenzoate, N-methyldiethanolamine, 4-dimethylaminobenzophenone, and the like. Examples of the aldehydes include dimethylaminobenzaldehyde, terephthalaldehyde, and the like. Examples of the compounds having a thiol group include 2-mercaptobenzoxazole, decanethiol, 3-mercaptopropyltrimethoxysilane, thiobenzoic acid, and the like.

It is desired that the amount of the reducing agent is usually from 0.01 to 10 parts by weight, preferably from 0.05 to 5 parts by weight, and more preferably from 0.1 to 3 parts by weight, based on 100 parts by weight of the polymerizable monomer (a).

As the polymerizable composition of the present invention, besides the radical polymerizable composition containing a radical polymerizable monomer and a radical polymerization initiator as mentioned above, a cationic polymerizable composition containing a cationic polymerizable monomer as the polymerizable monomer (a), and a cationic polymerization initiator as the polymerization initiator (b) can be also used. The cationic polymerizable monomer includes, for example, cationic polymerizable vinyl compounds, lactones, cyclic ethers, and the like.

The cationic polymerizable vinyl compound includes, for example, vinyl ethers and styrene derivatives, such as ethylene glycol divinyl ether, glycerol trivinyl ether, trimethylolpropane trivinyl ether, 4-vinyl ether styrene, and allyl vinyl ether. The lactones include cyclic lactones such as -propiolactone and -caprolactone. The cyclic ethers include, for example, alicyclic epoxy compounds, oxetane compounds, spiro orthoesters, bicyclo-orthoesters, cyclic carbonates, and the like. Among them, the alicyclic epoxy compounds and the oxetane compounds are preferable. Examples of the alicyclic epoxy compounds include 3,4-epoxycyclohexyl methyl-3',4'- epoxycyclohexane carboxylate [products manufactured by Union Carbide Corporation under the trade name of UVR6105 (low- viscosity product) and UVR6110 (low- viscosity product), a product manufactured by DAICEL CHEMICAL INDUSTRIES, LTD. under the trade name of CELLOXIDE 2021, and the like], bis(3,4-epoxycyclohexylmethyl) adipate [a product manufactured by Union Carbide Corporation under the trade name of UVR 6128], vinylcyclohexene monoepoxide [a product manufactured by DAICEL CHEMICAL INDUSTRIES, LTD. under the trade name of CELOXIDE 2000], - caprolactone-modifϊed 3,4-epoxycyclohexylmethyl 3', 4'-epoxycyclohexanecarboxylate [a product manufactured by DAICEL CHEMICAL INDUSTRIES, LTD. under the trade name of CELOXIDE 2081], l-methyl-4-(2-methyloxiranyl)-7-oxabicyclo[4.1.0]heptane [a product manufactured by DAICEL CHEMICAL INDUSTRIES, LTD. under the trade name of CELOXIDE 3000], and the like.

Examples of the oxetane compound include oxetanes such as 3-ethyl-3- hydroxymethyloxetane, l,4-bis{[(3-ethyl-3-oxetanyl)methoxy]methyl}benzene, 3-ethyl- 3-(phenoxymethyl)oxetane, 3-ethyl-3-(2-ethylhexyloxymethyl)oxetane, and di[l-ethyl(3- oxetanyl)]methyl ether. These compounds can be easily made available, for example, from TOAGOSEI CO., LTD. Incidentally, when the oxetane compound is used together with the above-mentioned alicyclic epoxy compound, the curing property can be further improved in some cases. As the cationic polymerization initiator a photo-cationic polymerization initiator is preferable. Examples of the photo-cationic polymerization initiator include known sulfonium salts, ammonium salts, and the like, and diaryl iodonium salts, triaryl sulfonium salts, and the like.

In addition, as the photo-cationic polymerization initiator, commercially available products can be directly used. Representative examples of the commercially available product include products manufactured by Nippon Soda Co., Ltd under the trade names of CI-1370, CI-2064, CI-2397, CI-2624, CI-2639, CI-2734, CI-2758, CI-2823, CI-2855, CI-5102, and the like; products manufactured by Rhodia under the trade names of PHOTOINITIATOR 2047, and the like; products manufactured by Union Carbide Corporation under the trade names of UVI-6974, UVI-6990, and the like, and the present invention is not limited to those exemplified.

The amount of the cationic polymerization initiator used may differ depending upon its kind, the kind of the cationic polymerizable compound used, and compositional ratio therebetween, operating conditions, and the like. It is desired that the amount of the cationic polymerization initiator used is usually from 0.1 to 20 parts by weight, preferably from 1 to 10 parts by weight, and more preferably from 1 to 5 parts by weight, based on 100 parts by weight of the cationic polymerizable compound, from the viewpoint of improving the curing property and enhancing the storage stability. In addition, a composition comprising an epoxy compound and a hydroxyl group- containing compound, and the like, can be applied as a polymerizable monomer in the present invention to a system in which the polymerizable monomer is cured in the presence of a photopolymerization catalyst comprising a iodonium salt (polymerization initiator) and a visible light ray sensitizing agent (accelerator). In the present invention, a more preferred embodiment of the polymerizable composition is a composition in which a solvent (c) is further added to a polymerizable monomer (a), and a polymerization initiator (b).

The solvent (c) as referred to herein is a liquid which has a boiling point at a normal pressure within the range of from 40 to 180 ⁰C, and includes, for example, water, alcohols such as methanol, ethanol, isopropanol, n-propanol, butanol, and cyclohexanol; halogenated compounds such as chloroform, methylene chloride, and chlorobenzene; hydrocarbons such as hexane, cyclohexane, toluene, and xylene; ketones such as acetone, methyl ethyl ketone, cyclohexanone; esters such as ethyl acetate and butyl acetate; ethers; and the like, and the present invention is not limited only to those exemplified. Water, methanol, ethanol, propanol, butanol, acetone, or the like is preferred.

It is preferred that the amount of the solvent (c) is from 30 to 1000 parts by weight, preferably from 50 to 500 parts by weight, and more preferably from 100 to 300 parts by weight, based on 100 parts by weight of the polymerizable monomer (b). Amount of the solvent can vary as to get a more or less liquid composition. Such dental polymerizable compositions may also include thickening agents, fillers, coloring agents, antioxidants, stabilizers or other additives commonly used in dental polymerizable compositions. The dental bonding resins or adhesives as described above are usually presented in a single or dual pack system. There are various dental adhesive systems commercially available. One can cite Clearfϊl SE Bond™ (manufactured and sold by Kuraray), Clearfil S Bond™ (manufactured and sold by Kuraray), G-Bond™ (manufactured and sold by Kuraray), Scotch Bond 2™ (manufactured and sold by Bayer), Excite™ (manufactured and sold by Ivoclar Vivadent). According to the invention, the booklet instructions of such dental adhesive systems will be followed and optionally (and/or slightly) adapted by one of ordinary skill in the art as to comply with the requirements of the used materials. For instance, one skilled in the art may, in the dual pack system, only use the called Bond composition and not the Primer composition.

The conventional form of dental adhesives generally requires three steps with successive applications of 1) an acid etchant, 2) an adhesion promoting agent or primer, and 3) a bonding resin or adhesive, as described above. Between the first and second steps, water rinsing and drying are generally required. Between the second and third steps, drying can be required.

According to the present invention, the first and second steps 1) and 2) are not necessary, each one, preferably step 1), or both (steps 1) and 2)) can however be optionally implemented. Steps 1) and/or 2) allow adhesion to be improved. According to specific embodiments, the invention therefore relates to a method of sealing a gem material on at least one face of a piece, wherein the sealing method further comprises 1) carrying out an etching step on a part of the gem material and/or a face of the piece, 2) optionally applying an adhesion promoting agent (also called primer) on said part and/or face, before applying the dental polymerizable composition to the face of the piece and/or a part of the gem material (also named step 3) below). According to another embodiment, the method of the invention can also comprise a preparative step 0), before step 3), wherein said preparative step comprises a mechanical treatment of the face of the piece and/or the part of the gem material to be contacted with the face of the piece by using a fraize. This embodiment allows, if necessary, to prepare the part of the gem material and/or the face of the piece by creating porosities (preferably from 0.01 to 20 μm and more preferably from 0.01 to 10 μm) on said part and/or face as to improve attachment thereafter. Part and/or face to be sealed is treated accordingly, then preferably rinsed off by water, and excess water is removed by drying, such as air jet. According to the invention, and unless otherwise stated, rinsing and drying are contemplated by preparative step 0).

According to a specific embodiment, steps 0), and 1), and optionally 2), are carried out before step 3). According to another specific embodiment, step 0) and optionally step 2) are carried out before step 3). According to a further specific embodiment, only step 0) is carried out before step 3).

More specifically, the etching step 1) comprises applying an acid-containing aqueous solution. The acid-containing aqueous solution is generally an aqueous solution containing phosphoric acid, citric acid, maleic acid, fluorhydric acid, or the like acid. The acid-containing aqueous solution comprises preferably phosphoric acid or fluorhydric acid. Part and/or face to be sealed is thus etched with phosphoric acid, fluorhydric acid, or the like acid, which is preferably then rinsed off, and excess water is removed by drying, such as air jet. According to the invention, and unless otherwise stated, rinsing and drying are contemplated by etching step 1). Primers are generally surface-active compounds that exhibit an affinity for the face to be sealed and adhesive resin systems and participate in the polymerization process, thereby promoting adhesion. The primer generally comprises a light curable resin including acrylate and/or methacrylate monomers e.g. di-, tri- or polymethacrylate monomers, as described above and, optionally, polymerization initiators and/or activators and a volatile solvent. Primers are applied to one or both surface to be sealed in solution form, such commonly used solvents including acetone, ethanol, water, and various mixed solvent systems. Such primer compositions may also include thickening agents, fillers, coloring agents, antioxidants, stabilizers and other additives commonly used for improving or altering the characteristics of the light curable materials. In one embodiment of the present invention, a substantial part of the solvent of the primer composition is allowed to evaporate prior to bringing into contact the gem material and the face of the piece with a bonding resin or adhesive.

The method of sealing gem materials on at least one face of a piece to produce decorated pieces, is preferably characterized in that step (i) of the method comprises applying the dental polymerizable composition as defined above to the face of the piece and/or a part of the gem material, optionally allowing a solvent contained in the dental polymerizable composition to evaporate, and bringing into contact the face of the piece and the part of the gem material to be sealed, wherein either one or both said face and/or part is coated by at least one layer of the dental polymerizable composition, and then curing said polymerizable composition.

Applying the dental polymerizable composition, for instance with a brush, to a face of the piece and/or a part of the gem material forms thereby a layer of the dental polymerizable composition on said face of the piece and/or the gem material. Accordingly, the polymerizable composition can be applied only either on the gem material or the piece, or both. For instance, the polymerizable composition may be coated onto the area of the part of the gem material; and the surface of the piece to be brought into contact with said coated area of the gem material can be coated or not with the polymerizable composition. After such coating, the coated area of the gem material is positioned on and slightly pressed against the surface of the piece, coated or not.

Several layers comprising dental polymerizable compositions can be applied to the face of the piece and/or part of the gem material. In a particular embodiment, one layer is first applied to the face of the piece and part of the gem material, then another layer is applied to the face of the piece or part of the gem material, already coated by the first layer (as illustrated by figure 1), wherein the polymerizable composition used for the first layer is preferably more liquid than the composition of the second layer. In a more specific embodiment, the polymerizable compositions used for the first and second layers are the same qualitatively, but the amount of the used solvent in the first composition is greater than in the second composition. This particular embodiment allows increasing penetration of the first composition on the surface where it is applied and increasing adhesion and therefore attachment of the gem material on the piece. The amount of the polymerizable composition to be applied is such that it allows to obtaining a satisfactory attachment of the gem material on the piece. More specifically, the amount is such that the applied polymerizable composition covers entirely the face of the piece and/or part of the gem material to be sealed.

After these steps, curing is generally required to polymerize and harden the adhesive. The curing treatment depends on the used bonding resin or adhesive, and in particular the polymerizable monomer and polymerization initiator comprised therein. Curing is preferably a light-curing step, using UV, visible light, halogen light, or an irradiator using a blue LED to induce polymerisation. This procedure is easy to handle and appears to be very useful to seal gem materials on the face of piece to be decorated. According to a specific embodiment, the method of the invention can further comprise, after curing, a step of depositing enamel at the location where the attachment of the gem materials and the piece is located. Enamel can be cold enamel or enamel to be fired after deposition. It can also be coloured or not. This particular embodiment is illustrated by figures 4, 8 and 10. In the case where enamel to be fired is used, glass frit is applied and then fired to form an enamelled layer. Depositing enamel is preferably implemented in order to improve strength of the attachment, in particular fill small grooves and/or attenuate asperities optionally present between the gem material and the piece. The grooves and/or asperities may be due for instance to the thickness of the adhesive composition.

In a preferred embodiment, the method of the invention comprises step (ii) which comprises coating the gem materials with a transparent glaze. The use of a transparent glaze (which can also be called varnish or resin) for completing the sealing of the gem material has several advantages. First, the glaze further fastens the gem material on the piece and thus allows maintaining a more reliable contact between said gem and said piece. Furthermore, the glaze protects the gem materials. In a particular embodiment, suitable glazes have protective effects against the drastic conditions of dishwashing, specifically relative to the temperature and the detergent compositions used in dishwashers. This kind of glazes is thereafter called a dishwasher resistant glaze. Accordingly, implementation of both steps (i) and (ii) in the method of the invention leads to the production of pieces decorated with gem materials that may be washed in a dishwasher with a decreased risk of unsealing the gem materials. The method according to the present invention is of particular interest since it may allow producing permanent and dishwasher resistant pieces decorated by gem materials. The transparent glaze used according to the invention may be a polymerizable composition.

In a preferred embodiment of the invention, the transparent glaze is a photopolymerizable composition that polymerizes upon irradiation with visible light or UV light. In this case, referring to US 4,854,666 and EP 1,591,502, it is possible to use UV curable coating material such as epoxy acrylate, urethane acrylate, polyurethane, polybutadiene acrylate and others, as long as this material is transparent. More specifically, one can cite light- cure composite glaze products. For instance, light-cure composite glaze products are sold under the trademark Surface Coat™ by the company Kuraray or under the trademark DuraFinish™ by the company Parkell.

Alternatively, the transparent glaze may also be a hot polymerizable composition that polymerizes upon exposure to elevated temperature from ambient temperature to 250 ⁰C, preferably from 50 ⁰C to 150 ⁰C, and even more preferably from 40 to 100⁰C. For example, hot polymerizable compositions that may be used in step (ii) of the method of the invention for coating the gem materials comprise allylic resins, epoxy resins, phenolic resins, polyester resins, polyimides resins, polyurethanes resins, silicones resins and others, as long as these compositions form a transparent glaze after polymerisation. More specifically, one can cite, as transparent glaze, transparent paintings, such as the ones sold by the company PEBEO : Pebeo porcelain 150™, or polymeric paste, such as the ones sold under the trademarks Fimo Classic and Soft, or Fimo liquid, Sculpey liquid, or Kato liquid. In a preferred embodiment, the transparent glaze used in step (ii) is a food-safe glaze. It should be noted that certain gem materials such as coral, arzamite, ruby, ivory, pearl and lapis-lazuli are not food-safe materials. This point should be taken into consideration if the piece to be decorated with non food-safe gem materials is a piece that may enter into contact, either directly or indirectly, with a mucosa of an animal or human subject, for example the mouth of a user of said piece. For example, if the piece to be decorated is a glass, it is essential to implement step (ii) for coating the non food-safe materials with a food-safe glaze for safety reasons. Gem materials such as diamonds are food-safe and do not require a coating according to step (ii). However, coating of diamonds with a transparent glaze, may said glaze be food-safe or not, can be implemented for its protective role as described above. In a more preferred embodiment, the glaze according to the invention is a dishwasher resistant glaze; typically the glaze is suitable to be used at a temperature ranging between 60 ⁰C to 90 ⁰C and to withstand dishwasher detergents.

In a particular embodiment of the method of the invention, the dental bonding resin or adhesive used in step (i) and the transparent glaze used in step (ii) are both polymerizable compositions. When both the glaze and the dental bonding resin or adhesive are polymerizable compositions, they may either contain the same kind of polymerization initiators or different kinds of polymerization initiators. For example: both the transparent glaze and the dental polymerizable composition are photopolymerizable compositions; the transparent glaze is a photopolymerizable composition and the dental polymerizable composition is a hot polymerizable composition; the transparent glaze is a hot polymerizable composition and the dental polymerizable composition is a photo polymerizable composition; or both the transparent glaze and the dental polymerizable composition are hot polymerizable compositions.

In a particular embodiment of the, the dental bonding resin or adhesive and/or the transparent glaze, preferably all of them, is(are) photopolymerizable and the method of the invention further comprises a light-curing step. In another particular embodiment of the invention, the dental bonding resin or adhesive and/or the transparent glaze, preferably all of them, is(are) hot polymerizable and the method of the invention further comprises heating the piece decorated with gem materials at a temperature suitable for polymerization, for example at a temperature ranging between 50 and 150⁰C. In a further embodiment of the invention, step (i) comprises applying the dental polymerizable composition to the face of the piece and/or a part of the gem material, optionally allowing a solvent contained in the dental polymerizable composition to evaporate, and bringing into contact said face of the piece and said part of the gem material to be sealed. In this way, either one or both of said face of the piece and/or part of the gem material is coated by at least one layer of the dental polymerizable composition. In addition, in this embodiment, the method further comprises curing said dental polymerizable composition.

In yet another embodiment of the invention, step (ii) comprises coating the gem material contacted to the face of the piece in step (i) with the transparent glaze and then curing said transparent glaze. The transparent glaze and the dental polymerizable resin or adhesive may be cured simultaneously. Otherwise, it is possible to first implement step (i) and cure the dental polymerizable composition, and then implement step (ii) to coat the gem materials with the transparent glaze, and to cure independently said glaze. In a preferred embodiment, the method of the invention comprises: - step (i) comprising applying the dental polymerizable composition to the face of the piece and/or a part of the gem material, optionally allowing a solvent contained in the dental polymerizable composition to evaporate, and bringing into contact said face of the piece and said part of the gem material to be sealed; - step (ii) comprising coating the gem material brought into contact with the face of the piece in step (a) with said transparent glaze ; and then

- step (iii) comprising curing said dental polymerizable composition and transparent glaze simultaneously. In another particular embodiment of the invention, the transparent glaze applied to the gem material is the dental polymerizable composition. In a particular aspect of this embodiment, the method of the invention comprises:

- applying the dental polymerizable composition onto the entire gem material and optionally to the face of the piece, optionally allowing a solvent contained in the dental polymerizable composition to evaporate, and bringing into contact said face of the piece and the part of the gem material to be contacted to the face of the piece, and then

- curing said dental polymerizable composition.

Thereby, contacting the gem material with the piece and coating said gem material occurs simultaneously. In a particular embodiment, if the method of the invention comprises a step of depositing enamel at the location where the attachment of the gem materials and the piece is located, said deposition step is implemented after step (i) and a step of curing the dental polymerizable composition, and before implementation of step (ii).

The curing treatment for the glaze depends on the used glaze, and in particular the polymerizable monomer and polymerization initiator comprised therein. Curing is preferably a light-curing step, using UV, visible light, halogen light, or an irradiator using a blue LED to induce polymerisation.

The following examples are intended to particularly point out and more clearly illustrate the invention and are not intended to be limiting. Examples

Example 1

A cushion cabochon-cut natural ruby of 4.45 ct and a porcelain plate (IKEA® Type) are used.

Preparation of the gem material: A ruby (A) whose basis was fraized at +/- 1 μm (the fraized surface was slightly smaller than the total surface of the basis - such treatment was made under a head loupe X7) with a dentist fraize (N⁰ISO 534), then treated with an etching agent (fluorhydric acid) for 60 seconds, and finally washed with water for more than one minute and dried with air flow.

Preparation of the plate:

The same preparation step was carried out with the porcelain plate (B), except the fraizing was more important: +/- 2 μm.

Sealing step:

The used dental bonding system was Clearfϊl SE Bond presented in a dual pack system, including a Primer and Bond. In this example, one used only the Bond system (C), which comprises as basic components MDP, HEMA, dimethacrylate monomer, microfϊller and catalyst. The Bond system (C) composition was applied onto the surface of the plate as prepared above. Ruby was then placed on and pressed against the plate thus covered with the dental bond system.

An irradiator (blue LED) to induce curing was applied just after contact with plate and ruby. Direct light was applied from 2 to 3 cm of the bonding composition for about 20 seconds at four different positions all around the ruby to be sealed.

The adhesive strength was first assessed by trying to unseal the ruby from the plate with the thumb strength for 10 seconds.

The decorated plate was allowed to stand for 30 minutes. Then, said plate was put in a dishwasher at a temperature of 60 ⁰C for a long cycle. At the end of the cycle, the decorated plate showed no damage, even when observed with a head loupe.

Other types of gem materials, such as blue topaz, almandine garnet, and lapis lazuli, were used instead of a ruby and the same conclusive results were obtained.

Example 2 An oval cabochon-cut natural orange sapphire of 2.25 ct and a glass are used.

Preparation of the gem material:

An orange sapphire (A) whose basis was fraized at +/- 1 μm (the fraized surface was slightly smaller than the total surface of the basis - such treatment was made under a head loupe X7) with a dentist fraize (N⁰ISO 534), then treated with an etching agent (fluorhydric acid) for 40 seconds, and finally washed with water for more than one minute and dried with air flow.

Preparation of the glass: The same preparative step was carried out with the glass (B), except the fraizing was more important: +/- 2 μm, and the treatment with the etching agent lasted 60 seconds.

Sealing step:

The used dental bonding system was G-Bond presented in a single pack system. The Bond system (C) composition was applied, according to the provided instructions, onto the surface of the glass as prepared above. Orange sapphire was then placed on and pressed against the glass thus covered with the bond system.

An irradiator (blue LED) to induce curing was applied just after contact with glass and ruby. Direct light was applied at 2 to 3 cm from the bonding composition for about 20 seconds at four different positions all around the orange sapphire to be sealed.

The adhesive strength was first assessed by trying to unseal the orange sapphire from the glass with the thumb strength for 10 seconds.

The decorated glass was allowed to stand for 30 minutes. Then, said glass was put in a dishwasher at a temperature of 60⁰C for a long cycle. At the end of the cycle, the decorated glass showed no damage, even when observed with a head loupe.

Other types of gem materials, such as blue topaz, almandine garnet, and lapis lazuli, were used instead of an orange sapphire and the same conclusive results were obtained.

Example 3 A squared cabochon-cut amethyst of 2.15 ct and a porcelain plate (IKEA® Type) are used.

Preparation of the gem material:

An amethyst (A) whose basis was fraized at +/- 1 μm (the fraized surface was slightly smaller than the total surface of the basis - such treatment was made under a head loupe X7) with a dentist fraize (N⁰ISO 534), then treated with an etching agent (fluorhydric acid) for 60 seconds, and finally washed with water for more than one minute and dried with air flow.

Preparation of the plate:

The same preparation step is applied to the porcelain plate (B), except the fraize is more important: +/- 2 μm.

Contacting step:

The used dental bonding system is Clearfϊl SE Bond presented in a dual pack system, including a Primer and Bond. In this example, one uses only the Bond system (C), which comprises as basic components MDP, HEMA, dimethacrylate monomer, microfiller and catalyst. The Bond system (C) composition is applied onto the surface of the plate as prepared above. Amethyst is then placed on and pressed against the plate thus covered with the dental bond system. Glazing step (or coating step):

After placing the amethyst (contacting Step) on the plate, the complete surface of the ruby is covered by a thin layer of light cured photopolymerizable dental acrylic resin layer, which is processed under head loupe in order to control the process. More specifically, drops of Surface Coat™ were deposited on top of the amethyst and a head loupe was used to verify the homogenous display/repartition of the resin (3 drops were enough to cover the complete surface of the amethyst).

Photo polymerization step:

The resin is brushed on to assist its repartition over the whole surface of the amethyst.

Polymerizable compositions layers are thus present both below (C) and above (R) the amethyst. Irradiation with a blue LED is applied to induce curing. Direct light is applied from 2 to 3 cm of both bonding compositions for about 2 minutes at four different positions all around the amethyst to be sealed.

The adhesive strength is first assessed by trying to unseal the amethyst from the plate with the thumb strength for 10 seconds. The decorated plate is allowed to stand for 30 minutes. The polymerization process step is checked using by pressing a nail on the glaze. No marking were observed with a head loupe. Then, the plate was put in a dishwasher at a temperature of 60 ⁰C for a long cycle.

At the end of the cycle, the decorated plate shows no damage, even when observed with a head loupe. Other types of gem materials, such as rubelite, pyrope, and rhodochrosite, were used instead of an amethyst and the same conclusive results were obtained.

Claims

1 - A method of sealing gem materials on at least one face of a piece to produce a piece decorated with gem materials, wherein the sealing method comprises the following steps: (i) contacting at least one gem material and at least one face of the piece with a dental bonding resin or adhesive ;

(ii) optionally, coating the gem materials with a transparent glaze, preferably with a transparent food-safe glaze, and more preferably with a transparent food-safe glaze which is dishwasher resistant. 2 - The method according to claim 1, wherein the dental bonding resin or adhesive and/or the transparent glaze, preferably all of them, is(are) photopolymerizable and said method further comprises a light-curing step.

3 - The method according to claim 1 or 2, wherein the dental bonding resin or adhesive and/or the transparent glaze, preferably all of them, is(are) hot polymerizable glaze and said method further comprises heating the piece decorated with gem materials at a temperature ranging between 50 and 150 ⁰C.

4 - The method according to claim 2 or 3, wherein step (i) comprises applying the dental polymerizable composition to the face of the piece and/or a part of the gem material, optionally allowing a solvent contained in the dental polymerizable composition to evaporate, and bringing into contact said face of the piece and said part of the gem material to be sealed.

5 - The method according to claim 4, said method further comprising curing said dental polymerizable composition.

6 - The method according to anyone of claims 2 to 5, wherein step (ii) comprises coating the gem material contacted to the face of the piece in step (i) with said transparent glaze and then curing said transparent glaze.

7 - The method according to any one of claims 2 to 6, wherein said method comprises

- step (i) comprising applying the dental polymerizable composition to the face of the piece and/or a part of the gem material, optionally allowing a solvent contained in the dental polymerizable composition to evaporate, and bringing into contact said face of the piece and said part of the gem material to be sealed ;

- step (ii) comprising coating the gem material brought into contact with the face of the piece in step (a) with said transparent glaze ; and then - step (iii) comprising curing said dental polymerizable composition and transparent glaze simultaneously.

8 - The method according to any one of claims 2 to 7, wherein the transparent glaze applied to the gem material is the same polymerizable composition as the dental polymerizable composition.

9 - The method according to claim 8, said method comprises

- applying the dental polymerizable composition onto the entire gem material and optionally to the face of the piece, optionally allowing a solvent contained in the dental polymerizable composition to evaporate, and bringing into contact said face of the piece and said part of the gem material to be contacted to the face of the piece; and then

- curing said dental polymerizable composition.

10 - The method according to any one of claims 1, 2, and 4 to 10 when depending on claim 2, wherein the transparent glaze is a light-cure composite glaze product or an UV curable coating material such as epoxy acrylate, urethane acrylate, polyurethane or polybutadiene acrylate.

11 - The method according to any one of the preceding claims, wherein it further comprises 1) carrying out an etching step on a part of the gem material and/or a face of the piece, 2) optionally applying an adhesion promoting agent on said part and/or face, before applying the dental polymerizable composition to the face of the piece and/or a part of the gem material (also named step 3).

12 - The method according to any one of the preceding claims, wherein it further comprises a preparative step 0), before step 3), comprising a mechanical treatment of the part of the gem material and/or the face of the piece by using a fraize. 13 - The method according to claim 12, wherein steps 0), and 1), and optionally 2), are carried out before step 3).

14 - The method according to claim 12, wherein step 0) and optionally step 2) are carried out before step 3).

15 - The method according to claim 12, wherein only step 0) is carried out before step 3). 16 - The method according to anyone of claims 11-15, wherein etching step 1) comprises applying an acid-containing aqueous solution.

17 - The method according to claim 16, wherein the acid-containing solution comprises phosphoric acid, citric acid, maleic acid, fluorhydric acid, or the like acid. 18 - The method according to any one of claims 5 to 17, wherein curing is a light-curing step, using UV, visible light or an irradiator using a blue LED.

19 - The method according to any one of claims 5-18, wherein it further comprises, after curing, a step of depositing enamel at the location where the attachment of the gem material and the piece is located. 20 - The method according to any one of claims 2 to 19, wherein the dental polymerizable composition generally comprises:

(a) a polymerizable monomer; (b) preferably, a polymerization initiator; (c) and optionally, a solvent.

21 - The method according to claim 20, wherein the polymerizable monomer is selected from (meth)acrylic esters.

22 - The method according to claim 20 or 21, wherein the polymerizable monomer a) further includes functional monomers, more particularly monomers having a phosphoric acid group or a carboxylic acid group.

23 - The method according to any one of claims 20-22, wherein the polymerization initiator (b) is a hot polymerization initiator, an ambient-temperature polymerization initiator, a photopolymerization initiator.

24 - The method according to anyone of the preceding claims, wherein the piece is a plate, a glass, knifes, forks, spoons, or any other service setting.

25 - The method according to anyone of the preceding claims, wherein the piece is made of silica, kaolin, clay, metal, porcelain, wood and/or leather.

26 - The method according to anyone of the preceding claims, wherein the gem material includes any natural material or artificial product, pearl or diamond material.

27 - The method according to anyone of the preceding claims, wherein the gem material is a natural materials, more particularly it is selected from beryl material, such as emerald or aquamarine, the coral material, the corundom material, such as ruby, sapphire, the quartz material, such as amethyst or citrine, the garnet group, such as pyrope, grossular or tsavorite, the lapis lazuli material, the turquoise material, the opal material, the spinel group, such as orange spinel or red spinel, pearls, diamonds, and all varieties therefrom. 28 - A use of a dental bonding resin or adhesive as a sealing agent for fixing and/or coating gem materials on any face of a piece.

29 - A decorated piece presenting sealed gem materials on at least one face of the piece, wherein said decorated piece is prepared by the method according to anyone of claims 1- 27.