Composite resins bisGMA

Compomers contain no water, but rather are mainly formulated from the same components as conventional composite resins. Typically this means macromonomers, such as bis-glycidyl ether dimethacrylate (bisGMA) or its derivatives and/or urethane dimethacrylate, blended with viscosity-reducing diluents, such as triethylene glycol dimethacrylate (TEGDMA). These polymer systems are filled with non-reactive inorganic powders, for example, quartz or a silicate glass [271]. 

The phenomenon of polymerization shrinkage in composite resins based on either bisGMA or UDMA is considered to be their most important deficiency... 

As well as conventional composites of the type based on bisGMA and/or UDMA and filled with silicate-based filler, there are now materials available that are essentially composites in that they comprise a polymeric matrix reinforced with finely divided filler. However, either the polymer system or the filler phase is of a different chemical composition from that of conventional composite resins. Three such materials are currently available, and these are the ormocers, the siloranes and the giomers. Their details are given in Table 3.3, and their characteristics are described in the following subsections. 

PMMA and other methacrylate and acrylate polymers are widely used in dentistry. PMMA is used for dentures and root canal sealants. Polymers of 2,2-bis[4-(2-hydroxy-3-methacry-loyolxypropoxy)phenyl]propane (BisGMA), triethyleneglycol dimethacrylate (TEGDMA), and urethane dimethacrylate (UDMA) are used in dental composite resins, most commonly with a silica filler. Such composite resins are used for filling cavities, reshaping, and restoring teeth and for full and partial crowns. 

Composite Restoration Seaiants. Systems nsed in this case consist essentially of dimethacrylate mononers, such as BisGMA, homologues of BisGMA, urethane dimethacrylate, and silanated inorganic fillers, as discnssed in the section on Composite Resins. The sealants used for restorations (called bonding agents) are applied onto the cavity walls prior to the placement of composites and bond the two substances tightly. 

Modern resin-based restorative materials used in stomatology originated with the invention of the so-called Bowen s monomer and the introduction of composites [142]. This monomer is known as BisGMA, a label easier to use than chemical name of 2,2-bis[4-(2-hydroxy-3-methacryloyloxypropoxy)-phenyl]propane.Today, both unfilled and composite resins are widely employed in dentistry—as binding agents, pit and fissure sealants, direct filling materials, orthodontic adhesives, and resin cements [143]. 

Dental Composite Restoratives. Polymeric restoratives have three major components an organic resin matrix, an inorganic filler modified with a coupling agent, and a suitable polymerization initiator system. The formulation used to produce the organic matrix, or continuous phase, is made up of free-radical polymerizable monomers. The monomer mostly used in the formulations for both anterior and posterior resins is BisGMA (Fig. 7), or alternatively formulated with... 

Guo, X., Wang, Y, Spencer, R, Ye, Q., Yao, X. Effects of water content and initiator composition on photopolymerization of a model BisGMA/HEMA resin. Dent. Mater. 24, 824-831 (2008)... 

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