Mechanical properties and three-body wear of veneering composites and their matrices

Fatigue as one of the major factors affecting three-body wear of resin composites is influenced by mechanical properties of the resin matrix. The aim of this in vitro study was to determine three-body wear (ACTA methodology), fracture strength, and Young's modulus of four veneering composites (Artglass old and new formula, Vita Zeta LC Composite, Targis) and one direct restorative composite (Z 100). Furthermore, three-body wear of the pure matrices of the materials was tested. The wear results were compared to Amalgam as reference material. It should be computed whether there exists a correlation between the wear results of resin composite and matrix alone. Wear of the veneering composites was significantly higher than of Z100 (13 microm) and Amalgam (14 microm; p < 0.01, Mann-Whitney U-test). Mean fracture strengths of indirect composites ranged from 127.5 MPa (Targis) to 71.6 MPa (Vita Zeta LC). The elastic moduli of the composites were between 2.9 and 12.8 GPa. The matrix wear rates did not differ significantly. Three-body wear results of complex resin composites are highly influenced by their filler content, filler particle size distribution, kind of filler particles, shape, and their silanization to the matrix. Due to this fact, three-body wear testing is an essential testing method and cannot be replaced by testing single material components.