Dental composite materials and method of manufacture thereof

Details Dental composite materials and method of manufacture thereof Dental composite materials and method of manufacture thereof

2002-04-30

2003-11-25

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...

C524S413000, C524S417000, C524S430000, C524S439000, C524S442000, C524S443000, C524S730000, C433S202100, C433S204000, C528S012000, C424S078170, C424S078310

Reexamination Certificate

active

06653365

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to composite materials and to the methods for the manufacture of such composite materials for restorative dentistry, and more particularly to composites which are useful as crown and bridge materials, either with or without an alloy substrate, as reconstructive materials, restorative materials, filling materials, inlays, onlays, laminate veneers, dental adhesives, cements, sealants and the like.
2. Brief Description of the Related Art
In recent years, materials used for dental restorations have comprised principally acrylate or methacrylate resins. Typical acrylic resinous materials are disclosed in U.S. Pat. No. 3,066,112 to Bowen, No. 3,179,623 to Bowen, No. 3,194,784 to Bowen, No. 3,751,399 to Lee et al. and No. 3,926,906 to Lee et al. Acrylic resinous materials, however, exhibit high coefficients of thermal expansion relative to the coefficient of thermal expansion for the tooth structure, and therefore these substances by themselves proved to be 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 was quite poor. Composite dental restorative materials containing acrylate or methacrylate resins and fillers were thus developed, the fillers generally comprising inorganic materials based on silica, silicate glass, or quartz. Particularly suitable improved inorganic filler materials include those disclosed in commonly assigned U.S. Pat. No. 4,547,531 to Waknine, and U.S. Pat. No. 4,544,359 to Waknine. These filled compositions are useful for a variety of dental treatments and restorative functions including crown and bridge materials, fillings, adhesives, sealants, luting agents or cements, denture base materials, orthodontic materials and sealants, and other dental restorative materials. Despite their suitability for their intended purposes, however, there nonetheless remains a need in the art for dental resin materials with even more advantageous physical properties.
SUMMARY OF THE INVENTION
An improved dental composite material comprises an ethylenically unsaturated resin composition; a filler composition comprising a polyhedral oligomeric silsesquioxane filler; and a curing system. These dental composite materials are useful in a variety of dental materials, treatments, and restorative functions, including crown and bridge materials, fillings, adhesives, sealants, luting agents or cements, denture base materials, orthodontic materials and sealants, and other dental restorative materials.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A new dental restorative composition comprises a polymerizable resin composition and a polyhedral oligomeric silsesquioxane (POSS) filler. POSS-filled resins typically exhibit lower mass densities and greater stiffness, and are capable of withstanding higher temperatures, as well as higher levels of ionizing radiation. In addition, POSS-filled resins are capable of wetting fibers to desirably high degrees. The use of POSS with dental resin materials, particularly the acrylate/methacrylate resins, minimizes polymerization shrinkage and increases material toughness. The nanoscale dimensionality of the POSS fillers also allows for better aesthetic properties, including easier polishability and improved transparency.
Resin compositions suitable for use with dental restorations are well known in the art, and generally comprising ethylenically unsaturated groups that are polymerizable. Especially useful are the polymerizable acrylate or methacrylate resins such as those disclosed in U.S. Pat. No. 3,066,112 to Bowen, No. 3,179,623 to Bowen, No. 3,194,784 to Bowen, No. 3,751,399 to Lee et al., No. 3,926,906 to Lee et al., and commonly assigned U.S. Pat. No. 5,276,068 and No. 5,444,104 to Waknine, all of which are incorporated herein by reference. Other suitable resin materials include, but are not limited to, various polyurethane dimethacrylates (PUDMA), diurethane dimethacrylates (DUDMA), and other monomers and oligomers known in the art. A useful monomer disclosed in U.S. Pat. No. 5,276,068 and 5,444,104 to Waknine is polycarbonate dimethacrylate (PCDMA) which is the condensation product of two parts of a hydroxyalkylmethacrylate and 1 part of a bis(chloroformate). Another advantageous resin having lower water sorption characteristics is an ethoxylated bisphenol A dimethacrylate (EBPDMA) as disclosed in U.S. Pat. No. 6,013,694. An especially important methacrylate resin is the condensation product of bisphenol A and glycidyl methacrylate, 2,2′-bis [4-(3-methacryloxy-2-hydroxy propoxy)-phenyl]-propane (hereinafter abbreviated “Bis-GMA”). Included within the scope of the resin compositions herein are the resin compositions suitable for use with glass ionomer cements, including polycarboxylic acids such as homo- and copolymers of acrylic acid and/or itaconic acid.
In addition to the aforementioned resins and oligomers, the resin compositions can further include a diluent acrylate or methacrylate monomer to increase the surface wettability of the composition and/or to decrease the viscosity of the polymerization medium. Suitable diluent monomers include those known in the art such as hydroxy alkyl methacrylates, for example 2-hydroxyethyl methacrylate and 2-hydroxypropyl methacrylate; ethylene glycol methacrylates, including ethylene glycol methacrylate, diethylene glycol methacrylate, tri(ethylene glycol) dimethacrylate and tetra(ethylene glycol) dimethacrylate; and diol dimethacrylates such as 1,4-butanedioldimethacrylate, dodecanedioldimethacryalte, or 1,6-hexanedioldimethacrylate (HDDMA). Tri(ethylene glycol) dimethacrylate (TEGDMA) is particularly preferred.
The more viscous polymerizable ethylenically unsaturated resins, i.e., PUDMA, Bis-GMA, and the like are generally present in an amount greater than or equal to about 30, preferably greater than or equal to about 50 wt % of the total composition. It is generally desirable to have the polymerizable ethylenically unsaturated resins less than or equal to about 99, preferably less than or equal to about 90, more preferably less than or equal to about 80 wt % of the total composition. Diluent monomers, when present, are incorporated into the resin composition in an amount from about 1 to about 70 wt % of the total resin composition.
In addition to the above monomers and oligomers, the resin compositions also include a curing system, which typically include polymerization initiators and polymerization accelerators; ultraviolet light absorbers; antioxidants; and other additives known in the art.
Suitable polymerization initiators are those conventional initiators known in the art. For example, visible light curable compositions employ light-sensitive compounds, including but not being limited to benzil, benzoin, benzoin methyl ether, DL-camphorquinone (CQ), and benzil diketones. Either UV-activated cure or visible light-activated cure (approximately 230 to 750 nm) is acceptable. The amount of photoinitiator is selected according to the curing rate desired. A minimal catalytically effective amount is generally about 0.01 wt % of the polymerizable resin composition, and will lead to a slower cure. Faster rates of cure are achieved with amounts of catalyst in the range from greater than about 0.01 percent to about 5 wt % of the resin composition.
Alternatively, the composition may be formulated as a self-curing system. Self-curing compositions will generally contain free radical polymerization initiators such as, for example, a peroxide in amounts ranging from about 0.01 to about 1.0 wt % of the resin composition. Particularly suitable free radical initiators are lauryl peroxide, tributyl hydroperoxide and, more particularly benzoyl peroxide.
Polymerization accelerators suitable for use are the various organic tertiary ami

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