Biocomposites Based on New Monomer Systems Reinforced with Micro / Nanoparticles and Glass Fibers

The resin composites were introduced for the first time in dentistry in the mid-1960s, for the restoration of anterior teeth, because of the necessity to eliminate the shortcomings of the restorative materials existing at that time. Because of their properties, aesthetic aspect, adhesion to hard dental tissues, high values of the physico-mechanical properties, they play an important role in dental practice (Bowen & Marjenhoff, 1992). Today, resin composite materials are frequently used for direct restoration of anterior teeth, as pit and fissure sealants for the prophylaxis of caries with children, and in prosthetic dentistry for the preparation of composite veneers, inlays and onlays by the photo-barrothermal polymerization. The composite veneers, inlays and onlays are fixed in the oral cavity using a luting agent, which is also a dual cured resin composite. The development of total polymeric restorations and the reinforcement of the resins with fibers for the obtaining of the prosthesis frameworks represent one of the actual achievements in the world. The resin composites comprise three components: a) the resin matrix which consists of the monomer system, the initiator system for free radical polymerization, antioxidants and UV stabilizers, b) the inorganic filler consisting of particulates such as glass, quartz, and/or fused silica, or glass fibers, c) the coupling agent usually an organo-silane that chemically bonds the reinforcing filler to the resin matrix. When hardening is desired the polymerization of the monomers is initiated by a chemical or photochemical system. In the cured material, the inorganic filler particles are dispersed and chemically bonded in a crosslinked threedimensional network formed by the polymerization of the di(poly)functional monomers. The properties, and hence the performances of the materials are dependent upon the nature and features of the components of the material. In spite of the progress in dental composite technology, loss of anatomic form in time, marginal leakage due to polymerization