Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
2000-10-30
2002-01-15
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C522S077000, C522S083000, C522S081000, C522S079000, C522S109000, C522S111000, C522S170000, C522S182000, C522S181000, C522S908000, C523S115000, C523S116000, C523S113000, C523S111000, C523S117000, C523S118000
Reexamination Certificate
active
06339113
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to photopolymerizable composite resin compositions for dental restoration having improved physical and mechanical properties, and biocompatibility, and long time sustainability after operation. More particularly, the invention relates to new photopolymerizable composite resin composition for dental restoration i) based on the multifunctional prepolymer mixture of 2,2-bis-(4-(2-hydroxy-3-methacryloyloxypropoxy)phenyl)propane (“Bis-GMA”) and multifunctional prepolymer formed by substituting hydrogen atoms in hydroxyl group with methacrylate groups in the Bis-GMA molecules, and ii) comprising a diluent, an inorganic filler, a photoinitiation system, and other additives.
2. Description of the Prior Art
Polymethylmethacrylate (PMMA) is one example of a dental polymer material that is used as a denture base, an impression material, an adhesive, a dental restoration material and so on, of which the latter is most frequently used.
A mercury amalgam has been generally used as dental restoration materials up to date. It is reported that mercury amalgam can be easily applied, and that it has superior mechanical physical properties such as abrasion resistance and mechanical strength. But it is also a distinctly different color from that of natural teeth, and has poor adhesion with teeth tissues. In addition, it is reported that mercury amalgam is harmful to the human body due to the long term gradual outflow of mercury.
Accordingly, many recent studies have been conducted to develop materials to complement the defects of mercury amalgam or to substitute it for something else. Acrylic resins, which were first used as polymer material resins and have superior mechanical properties in terms of strength, color stability, and water-resistant stability when compared to silicates that have been developed since mercury amalgam are defective in that they have poor abrasion resistance and high shrinkage upon curing. In order to overcome these defects, high filling composite resins using inorganic fillers as reinforcement are developed as dental restoration materials.
A photopolymerizable composition for dental restoration is conventionally composed of an inorganic filler, a prepolymer, a diluent, a photoinitiation system (a photoinitiator and a reductant), and other additives and so on. The composition should meet the requirements of mechanical strength to support the high biting pressure generated when chewing food, the coefficient of heat expansion similar to the tooth, and a polymerization shrinkage low enough to inhibit exfoliation from tooth upon polymerization-curing. Together with its physical properties, the composition should also be the same color and gloss of the natural tooth, and provide a natural tongue-touch feeling of the restored tooth.
2,2-bis-(4-(2-hydroxy-3-methacryloyloxypropoxy)phenyl)propane (Bis-GMA), which is a dimethacrylate, is most generally used as a prepolymer of a photopolymerizable composition for dental restoration. The Bis-GMA is principally low in volatility and polymerization shrinkage. A polymer prepared from the Bis-GMA has the advantages of superior strength and, thus, the Bis-GMA is used as a matrix resin. U.S. Pat. No. 4,102,856, U.S. Pat. No. 4,131,729, and U.S. Pat. No. 3,730,947 and so on describes the use of the Bis-GMA. However, the Bis-GMA has high viscosity that requires the addition of a diluent such as triethylene glycol dimethacrylate (TEGDMA) since it is advantageous that a prepolymer such as the Bis-GMA should have low viscosity in order to be efficiently mixed with an inorganic filler. Also, moisture absorption due to hydroxyl group (—OH) in the molecular structure of the Bis-GMA makes the physical property or aesthetics of the cured substances impermanent.
The dental composite material includes a dental composite filling material for dental restoration to fill a cavity caused by dental caries, a crown material, a coalescence material, a dentition correction material, and an artificial tooth material. U.S. Pat. No. 3,066,112 describes various compositions for early dental composite resin, which have not been used in practice since there were various defects on restoring posterior teeth. An amalgam formed from a silver alloy and mercury has been in use from before 1900 as a dental restoring material, but it has been gradually substituted with a material of organic polymer due to its dangerous side effects to humans and circumstances.
The first dental composite resin was prepared by mixing the PMMA powder and a methylmethacrylate (MMA) monomer by Kulzer Corp. (Germany) in 1942 and has been clinically used. The acrylic resin has been used for a long time. However, an organic polymer has such advantages as aesthetics, operation simplicity, and low toxicity, but the polymer itself lacks such physical properties as hardness, strength, and abrasion resistance to support against chewing. Thus, a composite resin compounded with an inorganic filler was developed.
Brown developed a chemical initiating type of commercial composite resin in 1962. Due to the development in the 1970s of ultraviolet-photopolymerization and, subsequently, to the development in the 1980s of visible ray-photopolymerization by ICI (England), polymer composite materials have encroached on conventional amalgams, and their use has increased dramatically.
Dental restoration material is used in anterior filling, posterior filling, cervical erosion filling, fractured porcelain repair, bracket bonding, core building, anterior interdental diastasis treatment, discoloration- and coloration-tooth treatment, and porcelain laminate bonding and so on. In addition to the restoration of dental caries, this dental restoration material is applied in various kinds of dental treatment, such as bonding and coalescense, with an increasing demands for various kinds of aesthetic treatment.
This polymer composite resin has, thus, secured itself a position as a dental restoration material as a result of the above-mentioned uses. However, it still must be improved with respect to the strength, hardness, polymerization shrinkage, water absorption, and solubility, toxicity and aesthetics of the cured substance made of the material.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a photopolymerizable composite resin composition for dental restoration having higher photocuring conversion, strength, and hardness as well as physical and mechanical properties such as low polymerization shrinkage and water absorption, and improved biocompatibility than the conventional composite resin composition for dental restoration.
Other objects and advantages of the invention will be clarified in the following detailed description of the invention.
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention is described in detail.
The object of the invention is achieved by means of a photopolymerizable composite resin composition for dental restoration that
i) has improved physical and mechanical properties and biocompatibility;
ii) is based on the multifunctional prepolymer mixture of 2,2-bis-(4-(2-hydroxy-3-methacryloyloxypropoxy)phenyl)propane (“Bis-GMA”) and at least one multifunctional prepolymer containing multimethacrylate groups formed by substituting hydrogen atoms in hydroxyl groups with methacrylate groups in the Bis-GMA molecules; and
iii) comprises an adequate amount of a diluent, an inorganic filler, a photoinitiation system and other additives.
Generally, the Bis-GMA has been most frequently used as a prepolymer for dental restoration because of its superior physical properties, such as high strength after curing. The Bis-GMA molecule has two hydroxyl groups that play a role in promoting an affinity between an organic resin and an inorganic filler, whereas said hydroxyl groups have a property to absorb water due to its high hydrophilicity. In cases where an organic resin absorbs water, the physical properties and aesthetics of a photocured substance is gradually reduced. Thus, if a polymerized
Ahn Kwang-Duk
Han Dong-Keun
Jeong Jin-Hee
Kim Jong-Man
Dentkist Co. Ltd.
McClendon Sanza L.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Seidleck James J.
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