Review article
Contemporary concepts on composite materials
Zrinka Tarle
Danijela Marović
Vlatko Pandurić
Abstract
Composite materials are a tridimensional combination of at least two different materials mutually connected with a clearly recognizable coupling agent. In the development of composite materials, an outstanding place belongs to Michael G. Buonocore, who suggested etching the enamel surface with orthophosphoric acid; Rafael L. Bowen, who created composite resin, and to Nobuo Nakabayashi, who suggested hybridization of the dentin substrate and accomplished the promotion of adhesion by the infiltration of monomer into the tooth structure. Composite material consists of three fundamental parts: an organic resin matrix with a complimentary initiator of polymerization, an inorganic filler and a coupling agent.
Composite materials were primarily developed for fillings on anterior and posterior teeth, but materials with similar composition are also used for an extremely large number of indications: pit and fissure sealants, adhesive cementation of ceramic and indirect composite restorations, for crown build-ups, temporary crowns and bridges, the bonding of brackets in orthodontics, making splints and root canal sealers.
Contemporary composite materials are being constantly upgraded and have significantly improved physical and mechanical characteristics in comparison with previous generations, especially concerning the hardness, firmness, elasticity, resistance to bending, breaking, torsion and wear. However, since cross linking in net formation during polymerization leads to volumetric shrinkage and, consequently, polymerization stress that can affect the creation of a marginal gap and also compromise the longevity of the restoration, stress compensation represents the biggest scientific and clinical challenge.
The future of composite materials is mirrored in several directions. The first one is finding low shrinking or expanding composite materials, the second one is the optimization of composite materials based on amorphous calcium phosphate which is a direct precursor of hydroxyapatite, the basic unit of tooth structure. Others include the incorporation of anti-bacterial agents into composites as well as the development of materials with self-adhesive properties.
Keywords
composites; adhesives; polymerization; shrinkage; remineralization
Hrčak ID:
91350
URI
Publication date:
22.10.2012.
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