Two-body in vitro wear study of some current dental composites and amalgams

Statement of problem. Wear resistance of restorative materials is a major c oncern in clinical practice for restorations involving occlusion. The relat ively poor wear resistance of dental composites in stress-bearing posterior situations has restricted even wider clinical application of this type of restorative material. Purpose. This in vitro study compared the relative wear resistance of a sel ection of current dental composites and amalgams under cyclic loading to ex plore the wear mechanisms operating on these materials and to assess their relative potential clinical wear resistance under variable masticatory load s. Material and methods. A 2-body in vitro wear test was undertaken on a selec tion of 2 Ultrafine Compact-Filled composites, 1 microfilled composite, and 3 dental amalgams. An alternating sine curve load (0.5 to 15 N)! was appli ed to the wear surface through a rotating countersample with a purpose-buil t system to simulate the variable loading pattern that occurs during mastic ation. Results. Under conditions simulating the repetitive cyclic loading pattern that may occur intraorally in high stress occlusal contact situations, the Ultrafine Compact-Filled composites exhibited a delamination wear pattern a nd had a significantly lower wear resistance than the amalgams. By comparis on, the microfilled composite (Silux Plus) displayed an improved wear resis tance that was superior to some amalgams. Dispersalloy had the best wear re sistance among the materials selected. Conclusion. The wear of Ultrafine Compact-Filled composite and microfilled composite differed and reflect different operative wear mechanisms. For ama lgams, the size, shape, and composition of the particles had an effect on t he wear resistance of the materials.