Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2002-07-08
2004-05-04
Sanders, Kriellion A. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C523S116000, C523S118000, C524S430000, C524S433000, C524S442000, C524S443000, C524S495000, C524S701000, C524S706000, C524S710000, C524S712000, C524S800000, C524S804000, C526S323100
Reexamination Certificate
active
06730715
ABSTRACT:
BACKGROUND
This invention relates to composite materials for restorative dentistry, and more particularly to composites useful as reconstructive materials and restorative materials for tooth cavity filling, lining or basing, cementation, orthodontic bracket bonding, laminate veneers, dental adhesives, cements, sealants, and the like.
In recent years, materials used for dental restorations have comprised principally acrylic resin systems, that is, acrylate or methacrylate polymers. Typical acrylic resin systems are disclosed in U.S. Pat. No. 3,066,112 to Bowen, U.S. Pat. No. 3,179,623 to Bowen, U.S. Pat. No. 3,194,784 to Bowen, U.S. Pat. No. 3,751,399 to Lee et al. and U.S. Pat. No. 3,926,906 to Lee et al. An especially important methacrylate monomer is the condensation product of bisphenol A and glycidyl methacrylate, 2,2′-bis [4-(3-methacryloxy-2-hydroxy propoxy)-phenyl]-propane (“Bis-GMA”). Urethane dimethacrylate (“UDMA”), polyurethane dimethacrylate (“PUDMA”) are also commonly used as a principal polymer in dental restoratives of this type.
Since Bis-GMA, PUDMA, and other resins are highly viscous at room temperature, they are generally diluted with an acrylate or methacrylate monomer having a lower viscosity, such as trimethylol propyl trimethacrylate, 1,6-hexanediol dimethacrylate, 1,3-butanediol dimethacrylate, and the like. Other dimethacrylate monomers, such as ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate (PEGDMA) and tetraethylene glycol dimethacrylate, are also in general use as diluents.
Because acrylic resin systems exhibit high coefficients of thermal expansion relative to the coefficient of thermal expansion of the tooth structure, these substances by themselves are less than satisfactory. The disparity in thermal expansion coupled with high shrinkage upon polymerization, results in poor marginal adaptability, and ultimately leads to secondary decay. Furthermore, the wear and abrasion characteristics and the overall physical, mechanical, and optical properties of these unfilled acrylic resinous materials is poor. “Composite acrylic dental restorative materials” containing acrylate or methacrylate resins and fillers were thus developed, the fillers generally comprising inorganic materials based on silica, silicate based glasses, or quartz.
Another type of dental restorative is a “glass ionomer”, wherein a poly(carboxylic acid) (such as a homo- or co-polymer of acrylic acid) is reacted with a fluoride ion leachable species (such as a fluoroaluminosilicate glass) in the presence of water to yield a crosslinked network structure. Because of the incorporation of the fluoride ion leachable species, glass ionomers are capable of providing long-term fluoride release.
Combinations of the various components of composite acrylic dental restoratives and glass ionomers have also been described. These hybrid materials generally fall into two classes, one referred to as “resin modified glass ionomers” (hereinafter “RMGIs”) and the other as “compomers”.
RMGIs retain most of the characteristics of conventional glass ionomers in that water is an essential ingredient. RMGI accordingly comprise a water-miscible acidic polymer, a curing system, and finely divided acid-reactive fillers. Three cure mechanisms are available: an acid-base setting reaction of the conventional glass ionomer type, photo curing using photo initiators, and chemical curing using redox initiators via free-radical polymerization of the polymerizable vinyl groups. The three-way curing mechanism facilitates thorough, uniform cure and retention of good clinical properties. RMGI materials can be clinically applied using conventional techniques and possess improved mechanical properties compared to conventional glass ionomers. However, their application is still limited to use in low stress bearing areas of the mouth due to their inadequate mechanical strength and wear resistance. Another drawback is that RMGI restoratives, once placed in a restoration, tend to absorb excessive and uncontrolled amounts of water, causing crowns cemented with RMGIs to fracture due to excessive hygroscopic expansion.
The second type of hybrid material, compomers, comprise an acrylate or methacrylate monomer containing acid functional groups, a reactive fluoroaluminosilicate glass, and a curing system. They may also contain other copolymerizable acrylate and methacrylate monomers that do not contain acid functional groups. Water is absent from the composition; it is in an anhydrous (non-aqueous) form. The primary setting reaction of a compomer is free radical photo polymerization involving the vinyl functional groups. This provides the immediate strength and resistance needed in the oral cavity. In addition to long-term fluoride release, another desirable characteristic of compomers is the ability to absorb a small amount of water and, as a result, expand slightly to alleviate the shrinkage stress caused by the polymerization of the acrylate or methacrylate resin, thus contributing to good marginal integrity. However, improvements in mechanical strength and wear resistance are still desirable in order to provide satisfactory use, particularly as anterior/posterior restoratives.
SUMMARY OF THE INVENTION
The above-described drawbacks and disadvantages are alleviated by a curable dental restorative composition comprising about 1 to about 90 wt %, based on the total weight of the dental restorative composition, of a filler component, the filler component comprising about 10 to 100 wt %, based on the total weight of the filler component, of a surface reactive glass component, and up to about 90 wt %, based on the total weight of the filler component, of other organic or inorganic filler; about 1 to about 50 wt %, based on the total weight of the composition, of water; and about 10 to about 97 wt %, based on the total weight of the composition, of a curable organic component, comprising about 50 to about 99 wt %, based on the total weight of the curable organic component, of an ethylenically unsaturated resin component, about 1 to about 50 wt %, based on the total weight of the curable organic component, of an ethylenically unsaturated phosphoric acid ester; and about 0.01 to about 5 wt %, based on the total weight of the curable organic component, of a curing system.
A method of using the dental restorative composition and a dental restoration are also disclosed. Such compositions are useful for a variety of dental treatments and restorative functions including cavity fillings, adhesives, sealants, luting agents or cements, orthodontic bonding materials and sealants, and other dental restoratives and dental restorations. The above described and other features are exemplified by the following detailed description.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
An improved dental restorative is formed from a composition that comprises a curable organic component, a catalyst system, a surface reactive glass, and water. The curable organic component comprises an ethylenically unsaturated monomer or oligomer, wherein the unsaturation is preferably derived from acrylate or methacrylate groups. The curable component also comprises a curable, ethylenically unsaturated phosphoric acid ester component, for example, an acrylate terminated phosphoric acid ester or methacrylate terminated phosphoric acid ester. The dental restorative composition may be provided as a single admixture of components to the practitioner, even more preferably in the form of uniform, mixed phase. Alternatively, the curing system and/or other components may be provided to the practitioner separately as part of a multi-component system.
Acrylate and methacrylate monomers and oligomers for use as the ethylenically unsaturated resin component are known in the art, and may include the viscous acrylate or methacrylate monomers such as those disclosed in U.S. Pat. No. 3,066,112 to Bowen, U.S. Pat. No. 3,179,623 to Bowen, U.S. Pat. No. 3,194,784 to Bowen, U.S. Pat. No. 3,751,
Cantor & Colburn LLP
Pentron Clinical Technologies LLC
Sanders Kriellion A.
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