BALANCE FUNCTIONING DENTURE TOOTH SYSTEMS CONTAINING TOUGHENED COMPOSITIONS

Abstract

A dental composition that includes one or more monomers, a plurality of crosslinking agents, and an initiator.

Claims

1. A denture tooth system having anterior and posterior teeth, wherein enamels of anterior teeth and enamels of posterior teeth have different material, wherein the material is obtained by forming or molding and causing to polymerize a dental composition, the dental composition comprising: (i) about 40 to about 95 wt. % one or more monomers selected from the group of methyl methacrylate; methyl acrylate; ethyl methacrylate; isobutyl methacrylate; cyclohexylmethacrylate; isobornyl methacrylate; isobornyl acrylate; allyl methacrylate; and mixtures thereof; (ii) about 0 to about 15 wt. % a first crosslinking agent selected from the group of ethylene glycol dimethacrylate, glycerol di(meth)acrylate, glycerol tri(meth)acrylate, ethyleneglycol di(meth)acrylate, diethyleneglycol di(meth)acrylate, triethyleneglycol dimethacrylate, tetraethylene glycol di(meth)acrylate, 1,3-propanediol di(meth)acrylate, 1,3-propanediol dimethacrylate, trimethylolpropane tri(meth)acrylate, 1,2,4-butanetriol trimethacrylate, 1,4-cyclohexanediol diacrylate, 1,4-cyclohexanediol dimethacrylate, 1,6-hexanediol di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, pentaerythritol tetramethacrylate, sorbitol hexacrylate and mixtures thereof; (iii) about 5 to about 20 wt. % a second crosslinking agent selected from the group consisting of 2,2-bis(4-methacryloxyphenyl)propane, 2,2-bis[4-(2-hydroxy-3-acryloyloxypropoxy)phenyl]propane, 2,2-bis[4-(2-hydroxy-3-methacryloyloxypropoxy)phenyl]propane, 2,2-bis[4-(acryloyloxy-ethoxy)phenyl]propane; 2,2-bis[4-(methacryloyloxy-ethoxy)phenyl]propane, and mixture thereof; (iv) about 5 to about 40 wt. % of a third crosslinking agent selected from the group consisting of a reaction product of 1,3-bis(isocyanatomethyl)cyclohexane, 2-hydroxyethyl methacrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-hydroxyethyl acrylate and ethylene glycol dimethacrylate; a reaction product of 1,3-bis(isocyanatomethyl)cyclohexane, 2-hydroxyethyl methacrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-hydroxyethyl acrylate; and mixtures thereof; (v) about 0 to about 20 wt. % of a fourth crosslinking agent selected from the group consisting of a reaction product of trimethyl 1,6-diisocyanatohexane and bisphenol A propoxylate and 2-hydroxyethyl methacrylate; a reaction product of 1,6 diisocyanatohexane and 2-hydroxyethyl methacrylate modified with water; a reaction product of 1,6 diisocyanatohexane and 2-hydroxyethyl acrylate modified with water; and mixtures thereof; and (vi) about 0 to about 10 wt % an initiator. wherein the material for enamels of posterior teeth have at least 10% difference in wear resistance than the material for the enamels of anterior teeth and the material for enamels of anterior teeth have at least 10% difference in fracture toughness than the material for enamels of posterior teeth.

2. The denture tooth system according to claim 1, wherein the material for enamels of anterior teeth include composition having: a) about 35 to about 60% by weight liquid component including: (i) about 60 to about 95 wt. % one or more monomers selected from the group of methyl methacrylate, methyl acrylate, ethyl methacrylate, isobutyl methacrylate, cyclohexylmethacrylate, isobornyl methacrylate, isobornyl acrylate, allyl methacrylate and mixtures thereof; (ii) about 0 to about 15 wt. % a first crosslinking agents selected from the group of ethylene glycol dimethacrylate, glycerol di(meth)acrylate, glycerol tri(meth)acrylate, ethyleneglycol di(meth)acrylate, diethyleneglycol di(meth)acrylate, triethyleneglycol dimethacrylate, tetraethylene glycol di(meth)acrylate, 1,3-propanediol di(meth)acrylate, 1,3-propanediol dimethacrylate, trimethylolpropane tri(meth)acrylate, 1,2,4-butanetriol trimethacrylate, 1,4-cyclohexanediol diacrylate, 1,4-cyclohexanediol dimethacrylate, 1,6-hexanediol di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, pentaerythritol tetramethacrylate, sorbitol hexacrylate and mixtures thereof; (iii) about 0.5 to about 20 wt. % a second crosslinking agents selected from the group consisting of 2,2-bis(4-methacryloxyphenyl)propane, 2,2-bis[4-(2-hydroxy-3-acryloyloxypropoxy)phenyl]propane, 2,2-bis[4-(2-hydroxy-3-methacryloyloxypropoxy)phenyl]propane, 2,2-bis[4-(acryloyloxy-ethoxy)phenyl]propane; 2,2-bis[4-(methacryloyloxy-ethoxy)phenyl]propane, and mixture thereof; (iv) about 0.5 to about 15 wt. % of a third crosslinking agent selected from the group consisting of a reaction product of 1,3-bis(isocyanatomethyl)cyclohexane, 2-hydroxyethyl methacrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-hydroxyethyl acrylate and ethylene glycol dimethacrylate; a reaction product of 1,3-bis(isocyanatomethyl)cyclohexane, 2-hydroxyethyl methacrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-hydroxyethyl acrylate; and mixtures thereof; (v) about 0 to about 20 wt. % of a fourth crosslinking agent selected from the group consisting of a reaction product of trimethyl 1,6-diisocyanatohexane and bisphenol A propoxylate and 2-hydroxyethyl methacrylate; a reaction product of 1,6 diisocyanatohexane and 2-hydroxyethyl methacrylate modified with water; a reaction product of 1,6 diisocyanatohexane and 2-hydroxyethyl acrylate modified with water; and mixtures thereof; (vi) about 0 to about 10 wt % an initiator that includes a peroxide; b) about 30 to about 65% by weight of particulate material.

3. The denture tooth system according to claim 1, wherein the material for enamels of posterior teeth include composition having: a) about 35 to about 60% by weight liquid component including: (i) about 40 to about 95 wt. % one or more monomers selected from the group of methyl methacrylate, methyl acrylate, ethyl methacrylate, isobutyl methacrylate, cyclohexylmethacrylate, isobornyl methacrylate, isobornyl acrylate, allyl methacrylate and mixtures thereof; (ii) about 0 to about 15 wt. % a first crosslinking agents selected from the group of ethylene glycol dimethacrylate, glycerol di(meth)acrylate, glycerol tri(meth)acrylate, ethyleneglycol di(meth)acrylate, diethyleneglycol di(meth)acrylate, triethyleneglycol dimethacrylate, tetraethylene glycol di(meth)acrylate, 1,3-propanediol di(meth)acrylate, 1,3-propanediol dimethacrylate, trimethylolpropane tri(meth)acrylate, 1,2,4-butanetriol trimethacrylate, 1,4-cyclohexanediol diacrylate, 1,4-cyclohexanediol dimethacrylate, 1,6-hexanediol di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, pentaerythritol tetramethacrylate, sorbitol hexacrylate and mixtures thereof; (iii) about 0 to about 20 wt. % a second crosslinking agents selected from the group consisting of 2,2-bis(4-methacryloxyphenyl)propane, 2,2-bis[4-(2-hydroxy-3-acryloyloxypropoxy)phenyl]propane, 2,2-bis[4-(2-hydroxy-3-methacryloyloxypropoxy)phenyl]propane, 2,2-bis[4-(acryloyloxy-ethoxy)phenyl]propane; 2,2-bis[4-(methacryloyloxy-ethoxy)phenyl]propane, and mixture thereof; (iv) about 0 to about 40 wt. % of a third crosslinking agent selected from the group consisting of a reaction product of 1,3-bis(isocyanatomethyl)cyclohexane, 2-hydroxyethyl methacrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-hydroxyethyl acrylate and ethylene glycol dimethacrylate; a reaction product of 1,3-bis(isocyanatomethyl)cyclohexane, 2-hydroxyethyl methacrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-hydroxyethyl acrylate; and mixtures thereof; (v) about 0 to about 20 wt. % of a fourth crosslinking agent selected from the group consisting of a reaction product of trimethyl 1,6-diisocyanatohexane and bisphenol A propoxylate and 2-hydroxyethyl methacrylate; a reaction product of 1,6 diisocyanatohexane and 2-hydroxyethyl methacrylate modified with water; a reaction product of 1,6 diisocyanatohexane and 2-hydroxyethyl acrylate modified with water; and mixtures thereof; (vi) about 0 to about 10 wt % an initiator that includes a peroxide; b) about 30 to about 65% by weight of particulate material including: (i) a poly(methyl methacrylate) based component, and (ii) a modified Poly(methyl methacrylate).

4. The denture tooth system according to claim 1, wherein the material for enamels of posterior teeth include composition having: a) about 1 to about 80% by weight of liquid component including: (i) about 40 to about 60 wt. % methyl methacrylate; (ii) about 0 to about 15 wt. % ethylene glycol dimethacrylate; (iii) about 10 to about 20 wt. % 2,2-bis(4-methacryloxyphenyl)propane; (iv) about 15 to about 40 wt. % of a reaction product of 1,3-bis(isocyanatomethyl)cyclohexane, 2-hydroxyethyl methacrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-hydroxyethyl acrylate and ethylene glycol dimethacrylate, (v) about 0 to about 10 wt. % of a reaction product of trimethyl 1,6-diisocyanatohexane and bisphenol A propoxylate and 2-hydroxyethyl methacrylate; and (vi) about 0 to about 10 wt % benzoyl peroxide; and b) about 30 to about 65% by weight of particulate material.

5. The denture tooth system according to claim 3, wherein the material for enamels of posterior teeth has a wear resistance ranging from about 0.035 to about 0.070 (Volume Loss: 37 C., mm.sup.3).

6. The denture tooth system according to claim 3, wherein the material for enamels of posterior teeth has a flexural strength ranging from about 135 to about 145 (MPa).

7. The denture tooth system according to claim 3, wherein the material for enamels of posterior teeth has a modulus ranging from about 3000 to about 3500 (MPa).

8. The denture tooth system according to claim 3, wherein the material for enamels of posterior teeth has a fracture toughness ranging from about 0.85 to about 1.85 (MPa m.sup.1.sup.2).

9. The denture tooth system according to claim 3, wherein the material for enamels of posterior teeth has a wear resistance ranging from about 0.035 to about 0.070 (Volume Loss: 37 C., mm.sup.3) and a flexural strength ranging from about 135 to about 145 (MPa).

10. The denture tooth system according to claim 3, wherein the material for enamels of posterior teeth has a modulus ranging from about 3000 to about 3500 and a fracture toughness ranging from about 0.85 to about 1.85 (MPa m.sup.1/2).

11. The denture tooth system according to claim 2, wherein the material for enamels of anterior teeth has a fracture toughness ranging from about 1.8 to about 2.5 (MPa m.sup.1/2).

12. The denture tooth system according to claim 2, wherein the material for enamels of anterior teeth has a wear resistance ranging from about 0.06 to about 0.125, (Volume Loss: 37 C., mm.sup.3).

13. The denture tooth system according to claim 2, wherein the material for enamels of anterior teeth has a fracture toughness ranging from about 1.8 to about 2.5 (MPa m.sup.1/2) and a wear resistance ranging from about 0.06 to about 0.125, (Volume Loss: 37 C., mm.sup.3).

Description

DETAILED DESCRIPTION OF INVENTION

[0024] In accordance with a preferred form of the present invention, polymerizable dental compositions are provided which may easily and conveniently be molded by known techniques into prosthetic denture teeth possessing chemical and physical properties which are significantly improved over those of conventional prior art acrylic prosthetic teeth produced from precursor blend compositions prepared in accordance with the invention are characterized by high wear resistance for posterior teeth and high fracture toughness for anterior teeth. Specifically, a high wear resistance composition was developed for enamels of posterior teeth, a high fracture toughness composition for dentins of anterior and posterior teeth and a high bonding strength composition for neck or dentin of all denture teeth.

[0025] Furthermore, prosthetic teeth produced from compositions of the invention have excellent stain, chemical and solvent resistances. Their excellent bonding strength to acrylic denture base is superior to many premium plastic teeth in the market.

[0026] In comparison with conventional highly crosslinked acrylic teeth, the prosthetic teeth, especially enamel surfaces of posterior teeth, produced in accordance with the invention are characterized by outstanding wear resistance to reduce any wear issues associated with posterior denture teeth, excellent monomer and solvent resistance, outstanding thermal stability, improved hardness, improved shape stability due to the enhanced modulus of enamel layer and excellent hydrolytic stability. Teeth produced from the compositions of the invention exhibit excellent gloss when molded, excellent bonding to denture base due to better bondable dentin in these denture teeth. During denture fabrication, the glosses of these teeth are maintained better than that of conventional highly crosslinked acrylic teeth and standard acrylic plastic teeth, due to the higher crosslinking density, superior chemical and wear resistances of enamel layers.

[0027] In comparison with conventional highly crosslinked acrylic teeth, the prosthetic teeth, especially dentin area of anterior teeth, produced in accordance with the invention are characterized by outstanding fracture toughness to prevent any breakage issues associated with anterior denture teeth, excellent bonding ability, where denture base can better bonding to these denture teeth and offer better durability, outstanding thermal stability, improved modulus and strength.

[0028] The precursor blend is formed in accordance with the invention by combining a monomer, crosslinking agents for said monomer, such as an urethane based crosslinking agent, especially an aromatic and/or cyclic ring structure based urethane crosslinker, crosslinked polymer and an optional uncrosslinked polymer, and/or an initiator and by allowing said combination to age or mature.

[0029] In general, artificial plastic teeth are made from PMMA and modified PMMA polymers and MMA and modified MMA liquids. More particularly, the powder material may include one or more PMMA polymers (Methyl Methacrylate Polymer), one or more crosslinked/modified PMMA polymers (e.g., Methyl Methacrylate: Ethylene Glycol Dimethacrylate Copolymer) and mixtures thereof. When both included, the PMMA polymer and the crosslinked/modified PMMA polymers may be present in a ratio ranging from about 4:1 to about 1:4, preferably about 1:1 to about 1:3, and more preferably approximately about 1:2. Furthermore, the one or more crosslinked/modified PMMA polymer may include Methyl Methacrylate to Ethylene Glycol Dimethacrylate in a ratio ranging from about 4:1 to about 1:4, preferably about 1:1 to about 1:3, and more preferably approximately about 1:2.

[0030] In general, the crosslinked polymers which are useful in the practice of the invention are formed from monomers or blends of monomers together with crosslinking agents in proper proportion. Monomer compounds that can be used in the composition of this invention, include, but are not limited to, methyl methacrylate, methyl acrylate, ethyl methacrylate, isobutyl methacrylate, cyclohexylmethacrylate, isobornyl methacrylate, isobornyl acrylate, allyl methacrylate, etc.

[0031] Crosslinking agents that can be used in the composition of this invention, include, but are not limited to, di- or poly-acrylates and methacrylates such as glycerol di(meth)acrylate, glycerol tri(meth)acrylate, ethyleneglycol di(meth)acrylate, diethyleneglycol di(meth)acrylate, triethyleneglycol dimethacrylate, tetraethylene glycol di(meth)acrylate, 1,3-propanediol di(meth)acrylate, 1,3-propanediol dimethacrylate, trimethylolpropane tri(meth)acrylate, 1,2,4-butanetriol trimethacrylate, 1,4-cyclohexanediol diacrylate, 1,4-cyclohexanediol dimethacrylate, 1,6-hexanediol di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, pentaerythritol tetramethacrylate, sorbitol hexacrylate, 2,2-bis[4-(2-hydroxy-3-acryloyloxypropoxy)phenyl]propane; 2,2-bis[4-(2-hydroxy-3-methacryloyloxypropoxy)phenyl]propane (Bis-GMA); 2,2-bis[4-(acryloyloxy-ethoxy)phenyl]propane; 2,2-bis[4-(methacryloyloxy-ethoxy)phenyl]propane (or ethoxylated bisphenol A-dimethacrylate) (EBPADMA); urethane di(meth)acrylate (UDMA), diurethane dimethacrylate (DUDMA), 4,13-dioxo-3,14 dioxa-5,12-diazahexadecane-1,16-diol diacrylate; 4,13-dioxo-3,14 dioxa-5,12-diazahexadecane-1,16-diol dimethacrylate; the reaction product of trimethyl 1,6-diisocyanatohexane and bisphenol A propoxylate and 2-hydroxyethyl methacrylate (TBDMA); the reaction product of 1,6 diisocyanatohexane and 2-hydroxyethyl methacrylate modified with water (HDIDMA); the reaction product of 1,6 diisocyanatohexane and 2-hydroxyethyl acrylate modified with water (HDIDA); polyurethane dimethacrylate (PUDMA); alkoxylated pentacrythritol tetraacrylate; polycarbonate dimethacrylate (PCDMA); the bis-acrylates and bis-methacrylates of polyethylene glycols; and copolymerizable mixtures of acrylated monomers and acrylated oligomers, etc.

[0032] Preferably, urethane based diacrylate or dimethacrylate can be used to offer improved fracture toughness, especially urethane (meth)acrylates containing cyclic backbone or aromatic structures. It is found surprisingly the use of urethane (meth)acrylates containing cyclic backbone and/or aromatic structures as crosslinker to replace a part of conventional crosslinkers, such as ethylene glycol dimethacrylate (EGDMA) or bisphenol A-dimethacrylate (BPADMA) resulted in significant improvement in the fracture toughness of formed denture tooth materials. The urethane structure formed in polymer network generated a toughened structure which resulted in improved fracture toughness and flexural strength and modulus.

[0033] It has been discovered that the relative proportions of the crosslinkers of the liquid blend used in accordance with the invention are critical to the attainment of the desired properties in the final hardened or cured product produced therefrom, notably the wear resistance, bond strength, flexural properties, impact strength, fracture toughness, resistance to MMA monomer and other solvents, stain resistance, thermal stability, and hydrolytic stability, especially the balance of fracture toughness and wear resistance. Thus, it has been discovered that liquid blends containing from about 2 to 40 weight percent of the urethane based crosslinkers, from about 0 to 30 weight percent of BPADMA, from 0 to 30 weight percent of other crosslinkers, from about 30 to about 95 weight percent of polymerizable monomer, and from about 5 to about 70 weight percent of crosslinked agents for said monomer, together with minor amounts of initiator and in some cases activator for the initiator, provide liquid blends which are particularly useful in the production of enamel layers of prosthetic teeth or prosthetic teeth with properties, especially wear resistance, far superior to those of conventional acrylic systems now used in the art while maintain excellent fracture toughness. The novel feature of this system is the introduction of unique urethane crosslinkers, which enhanced the fracture toughness of cured product surprisingly.

[0034] This invention developed a denture teeth system with different performance for anterior and posterior denture teeth since anterior and posterior teeth functioned differently in oral environment and required different material properties. It is reported that the excess wear typically occurred among posterior teeth over their lifetime while the breakage issue is often associated with anterior teeth. It is the intention of this invention to develop a set of denture teeth with tougher anterior teeth and high wear resistant posterior teeth. The compositions of this invention enabled the development of the enamels of posterior teeth with at least 10% difference in wear resistance than the enamels of anterior teeth. It is more preferable that the enamels of posterior teeth with at least 15% difference in wear resistance than the enamels of anterior teeth. It is also preferable that the enamels of anterior teeth with at least 10% difference in fracture toughness than the enamels of posterior teeth. It is more preferable that the enamels of anterior teeth with at least 15% difference in fracture toughness than the enamels of posterior teeth. In addition, it is preferable that the dentins of posterior teeth with at least 10% difference in fracture toughness than the enamels of posterior teeth. It is more preferable that the dentins of posterior teeth with at least 15% difference in fracture toughness than the enamels of posterior teeth. It is most preferable that the dentins of posterior teeth with at least 20% difference in fracture toughness than the enamels of posterior teeth. It is also desirable to provide new denture teeth with improved tooth bonding strength to denture base. The tooth bonding layer material has relatively lower crosslinking density for better bonding. The better bonding strength provides tougher denture teeth due to the much improved bonding interfaces, which offers strengthening/synergistic effect for stronger and more durable denture teeth.

TABLE-US-00001 Liquid Component Monomer(s) (35 to 95) (35 to 95) (40 to 95) (60 to 95) (40 to 60) (60 to 85) (75 to 85) (80 to 95) First (0 to 15) (0 to 20) (0 to 10) (0 to 15) Crosslinking (0.5 to 15) (0.5 to 15).sup. (0.5 to 10).sup. (0.5 to 15).sup. Agent Second (5 to 25) (0.5 to 25).sup. (0.5 to 20).sup. (0 to 10) Crosslinking Agent (10 to 20) (10 to 17.5) (5 to 15) (0.5 to 5) Third (5 to 45) (0 to 20) (0 to 25) (0 to 15) Crosslinking (15 to 40) (0.5 to 15).sup. (7.5 to 17.5) (0.5 to 10).sup. Agent Forth (0 to 20) (0 to 20) (0 to 20) (0 to 20) Crosslinking (0.5 to 10) (0.5 to 10).sup. (0.5 to 10).sup. (0.5 to 10).sup. Agent Initiator (0 to 10) (0 to 10) (0 to 10) (0 to 10) (0.5 to 7.5) (0.5 to 7.5) (0.5 to 7.5) (0.5 to 7.5) Total 100 100 100 100 Mix Ratio L:P = 50:50 L:P = 46:54 L:P = 46:54 L:P = 46:54 Liquid:Powder (L:P) ** Tooth Composition includes a liquid component mixture and a particulate/powder material mixture that may include a mixture of PMMA homepolymer and crosslinked PMMA polymer.

Example 1

[0035] The benzoyl peroxide (0.5 wt %), 2,2-bis(4-methacryloxyphenyl)propane (BPADMA) (16 wt %), the reaction product of 1,3-bis(isocyanatomethyl)cyclohexane and 2-hydroxyethyl methacrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-hydroxyethyl acrylate and ethylene glycol dimethacrylate (22.5 wt %) and ethylene glycol dimethacrylate (13 wt %) were dissolved in the methyl methacrylate (48 wt %) at ambient temperature to form a monomer solution, then mixed with polymer powders (1:1 weight ratio of liquid to powder) to form a visibly homogeneous dough. The enamel layers of prosthetic teeth were molded from the resultant precursor blend mixture after it was aged at ambient temperature. A suitable gel-like consistency for molding prosthetic teeth was obtained after aging at ambient temperature. The resulting material has excellent wear resistance and flexural properties.

Example 2

[0036] The benzoyl peroxide (0.5 wt %), 2,2-bis(4-methacryloxyphenyl)propane (BPADMA) (16 wt %), the reaction product of 1,3-bis(isocyanatomethyl)cyclohexane and 2-hydroxyethyl methacrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-hydroxyethyl acrylate and ethylene glycol dimethacrylate (22.5 wt %) and ethylene glycol dimethacrylate (7 wt %) were dissolved in the methyl methacrylate (54 wt %) at ambient temperature to form a monomer solution, then mixed with polymer powders (48:52 weight ratio of liquid to powder) to form a visibly homogeneous dough. The enamel layers of prosthetic teeth were molded from the resultant precursor blend mixture after it was aged at ambient temperature. A suitable gel-like consistency for molding prosthetic teeth was obtained after aging at ambient temperature. The resulting material has excellent wear resistance and flexural properties.

Example 3

[0037] The benzoyl peroxide (0.5 wt %), and 2,2-bis(4-methacryloxyphenyl)propane (BPADMA) (17.3 wt %) were dissolved in the methyl methacrylate (82.2 wt %) at ambient temperature to form a monomer solution, then mixed with polymer powders (46:54 weight ratio of liquid to powder) to form a visibly homogeneous dough. The dentin layers of prosthetic teeth were molded from the resultant precursor blend mixture after it was aged at ambient temperature. A suitable gel-like consistency for molding prosthetic teeth was obtained after aging at ambient temperature. The resulting material has excellent fracture toughness and good wear resistance.

Example 4

[0038] The benzoyl peroxide (0.5 wt %), 2,2-bis(4-methacryloxyphenyl)propane (BPADMA) (14.9 wt %), and the reaction product of 1,3-bis(isocyanatomethyl)cyclohexane and 2-hydroxyethyl methacrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-hydroxyethyl acrylate and ethylene glycol dimethacrylate (2.9 wt %) were dissolved in the methyl methacrylate (81.7 wt %) at ambient temperature to form a monomer solution, then mixed with polymer powders (46:54 weight ratio of liquid to powder) to form a visibly homogeneous dough. The dentin layers of prosthetic teeth were molded from the resultant precursor blend mixture after it was aged at ambient temperature. A suitable gel-like consistency for molding prosthetic teeth was obtained after aging at ambient temperature. The resulting material has excellent fracture toughness and good wear resistance.

Example 5

[0039] The benzoyl peroxide (0.5 wt %), 2,2-bis(4-methacryloxyphenyl)propane (BPADMA) (8.5 wt %), and the reaction product of 1,3-bis(isocyanatomethyl)cyclohexane and 2-hydroxyethyl methacrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-hydroxyethyl acrylate (11.6 wt %) were dissolved in the methyl methacrylate (79.4 wt %) at ambient temperature to form a monomer solution, then mixed with polymer powders (46:54 weight ratio of liquid to powder) to form a visibly homogeneous dough. The dentin layers of prosthetic teeth were molded from the resultant precursor blend mixture after it was aged at ambient temperature. A suitable gel-like consistency for molding prosthetic teeth was obtained after aging at ambient temperature. The resulting material has excellent fracture toughness and good wear resistance.

Example 6

[0040] The benzoyl peroxide (0.5 wt %), 2,2-bis(4-methacryloxyphenyl)propane (BPADMA) (4 wt %), and the reaction product of 1,3-bis(isocyanatomethyl)cyclohexane and 2-hydroxyethyl methacrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-hydroxyethyl acrylate (11.6 wt %) were dissolved in the methyl methacrylate (83.9 wt %) at ambient temperature to form a monomer solution, then mixed with polymer powders (46:54 weight ratio of liquid to powder) to form a visibly homogeneous dough. The dentin or neck layers of prosthetic teeth were molded from the resultant precursor blend mixture after it was aged at ambient temperature. A suitable gel-like consistency for molding prosthetic teeth was obtained after aging at ambient temperature. The resulting material has excellent fracture toughness and bond strength to acrylic denture base.

Example 7

[0041] The benzoyl peroxide (0.5 wt %), 2,2-bis(4-methacryloxyphenyl)propane (BPADMA) (3 wt %), and the reaction product of 1,3-bis(isocyanatomethyl)cyclohexane and 2-hydroxyethyl methacrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-hydroxyethyl acrylate (7.5 wt %) were dissolved in the methyl methacrylate (89 wt %) at ambient temperature to form a monomer solution, then mixed with polymer powders (46:54 weight ratio of liquid to powder) to form a visibly homogeneous dough. The dentin or neck layers of prosthetic teeth were molded from the resultant precursor blend mixture after it was aged at ambient temperature. A suitable gel-like consistency for molding prosthetic teeth was obtained after aging at ambient temperature. The resulting material has excellent fracture toughness and bond strength to acrylic denture base.

Wear Resistance Tests

[0042] Wear resistance was tested using a three-body cyclic abrasion wear machine (Leinfelder method) at 37 C. Localized wear was measured by determining volume loss in mm.sup.3 after 400,000 cycles at 50 RPM. The wear data for sample prepared from Examples 1 to 7 are listed in Table 1.

TABLE-US-00002 TABLE 1 Wear loss of tooth materials of this invention tested at 37 C. Material Volume loss (37 C., mm.sup.3) S.D. Example 1 0.051 0.017 Example 2 0.059 0.010 Example 3 0.075 0.015 Example 4 0.074 0.015 Example 5 0.093 0.017 Example 6 0.097 0.007 Example 7 0.111 0.014

Flexural Property Tests

[0043] Flexural Strength and Flexural Modulus of the polymerized compositions of Examples 1 to 7 were measured with crosshead speed of 1 mm/minute by using three-point bend test on Instron bending unit according to ISO. Samples (2 mm2 mm25 mm) from Examples 1 to 6 were molded in metal molds with the same curing cycles and post cure in 260 F. oven for two hours.

TABLE-US-00003 TABLE 2 Flexural strength and flexural modulus of tooth materials of this invention tested at ambient temperature. Material Flex Strength (MPa) Modulus (MPa) Example 1 140 (sd = 8) 3277 (sd = 172) Example 2 140 (sd = 7) 3268 (sd = 162) Example 3 131 (sd = 5) 2875 (sd = 185) Example 4 134 (sd = 3) 2944 (sd = 121) Example 5 129 (sd = 2) 2893 (sd = 57) Example 6 126 (sd = 7) 3038 (sd = 139) Example 7 127 (sd = 4) 2989 (sd = 82)

Fracture Toughness Tests

[0044] Fracture toughness of the polymerized compositions of Examples 1 to 7 was measured by Instron with a crosshead speed of 0.6 mm/minute. Cylindrical short rod fracture toughness test specimens were machined and tested in accordance with ASTM E1304-97 [Standard Test Method for Plane-Strain (Chevron Notch) Fracture Toughness of Met allic Materials]. Chevron-cut samples were placed into 37 C. deionized water for 24 hours, followed by 1 hour at 23 C. deionized water prior to testing.

TABLE-US-00004 TABLE 3 Fracture toughness of tooth materials of this invention tested at ambient temperature. Material K.sub.IC (MPa m.sup.1/2) Example 1 1.33 (sd = 0.23) Example 2 1.72 (sd = 0.14) Example 3 1.91 (sd = 0.15) Example 4 1.99 (sd = 0.18) Example 5 2.32 (sd = 0.13) Example 6 2.28 (sd = 0.07) Example 7 2.26 (sd = 0.06)

[0045] Example 1 and 2 have the best wear resistance (about 0.015 to about 0.080, preferably about 0.035 to about 0.070, Volume Loss: 37 C., mm.sup.3) and flexural strength (about 125 to about 155, preferably about 135 to about 145 MPa) and modulus (about 2750 to about 3750, preferably, about 3000 to about 3500 MPa) but lower fracture toughness (about 0.85 to about 1.85, preferably, about 1.1 to about 1.6 MPa m.sup.1/2), so they are better suited for enamels of posterior teeth. A posterior enamel formulation displays higher crosslinking density, better wear resistance and higher modulus, which can better maintain desirable occlusal details (better dimensional stability) than current commercially available plastic denture tooth and IPN denture tooth materials, are highly desirable, where bite load and chewing motion often can result in excess wear or squash off occlusal details. Example 4, 5, 6 and 7 have the highest fracture toughest (e.g., about 1.6 to about 2.7, preferably, about 1.8 to about 2.5 MPa m.sup.1/2), but relatively lower wear resistance (e.g., about 0.045 to about 0.14, preferably about 0.06 to about 0.125 Volume Loss: 37 C., mm.sup.3), which are best suited for dentins (including body and neck materials). Examples 6 and 7 have lowest crosslinking density, which can provide best bonding to denture base. An anterior enamel formulation is required for a stronger and tougher denture tooth to withstand the bite force from opposing dentition or denture teeth, where the wear of denture teeth is less significant compared to posterior denture teeth. It is preferable to use materials from Example 3, 4 and 5 for enamels of anterior teeth. Compared to porcelain denture teeth, polymeric denture teeth have less resistance to creep, higher fracture toughness, better resistance to thermal shock, higher water sorption, and bond to denture base. In contrast, porcelain denture teeth show better dimensional stability and have much increased wear resistance. A higher wear resistant (about 0.015 to about 0.080, preferably about 0.035 to about 0.070, Volume Loss: 37 C., mm.sup.3) and higher modulus (about 2750 to about 3750, preferably, 3000 to about 3500 MPa) enamel layer is desirable, especially for posterior teeth, where bite load is much higher than anterior teeth. It should be understand that while the present invention has been described with respect to certain specific embodiments thereof, it should not be considered limited to such embodiments but may be used in other ways without departure from the spirit of the invention and the scope of the appended claims.

[0046] The artificial teeth composition, wherein said first resin for enamel layer has greater wear resistance than said second resin for body layer and said second resin has greater wear resistance than said third resin for neck layer.

[0047] The artificial teeth composition wherein said second and third resins for dentin layer or body and neck layers have greater fracture toughness than said first resin for enamel layer.

[0048] The artificial teeth composition, wherein said first resin for enamel layer of posterior denture teeth has greater wear resistance than said first resin for enamel layer of anterior denture teeth.

[0049] The artificial teeth composition, wherein said first resin for enamel layer of anterior denture teeth has at least 10% difference in wear resistance than said first resin for enamel layer of posterior denture teeth.

[0050] The artificial teeth composition, wherein said first resin for enamel layer of anterior denture teeth has greater fracture toughness than said first resin for enamel layer of posterior denture teeth.

[0051] The artificial teeth composition, wherein said first resin for enamel layer of anterior denture teeth has at least 10% difference in fracture toughness than said first resin for enamel layer of posterior denture teeth.

[0052] The artificial teeth composition, wherein said first resin for enamel layer of posterior denture teeth has at least 10% difference in wear resistance than said second or third resin for dentin layer of anterior and posterior denture teeth.

[0053] The artificial teeth composition, wherein said first resin for enamel layer of posterior denture teeth has at least 10% difference in fracture toughness than said second and third resins for dentin layer or body and neck layers of anterior and posterior denture teeth.

[0054] The artificial teeth composition, wherein the liquid component further includes at least one of urethane (meth)acrylate based crosslinking agent.

[0055] The artificial teeth composition, wherein the at least one of urethane (meth)acrylate based crosslinking agent includes an aromatic or cyclic backbone structure.