Bruxing-type dental wear simulator for ranking of dental restorative materials.

An instrumented dental wear test simulator was developed to simulate jaw movement in the chewing process between two molar teeth. It simulated the natural impact with sliding masticatory action, known as bruxing (defined as the gnashing, grinding, or clenching of teeth) type of wear, in order to simulate a worst-case dental wear scenario. In vitro wear testing of dental restorative materials was performed. Impact and sliding wear were simulated on the machine, with water as the lubricant, on three metal alloys (Tytin, Valiant Ph.D., Galloy) and three composite resins (Silux Plus, Z100, P50). The impact force for each machine cycle was brought closer to the maximum natural masticatory forces by the use of a shock absorbing layer. To replicate the natural masticatory action, the specimens had a surface profile with the shape of a conical depression. Ranking of the materials' performance on the wear test simulator was seen to be consistent with published clinical ranking. Metal alloys showed greater wear resistance than composite resins. Among the different metal alloys, those with lower hardness and compressive strengths exhibited greater wear. Composite resins with large filler particles wore worse than those with small filler particles. Results were compared with previous work on impact with sliding on a flat surface without a cushioning layer. It was concluded that the magnitude of the impact force and the angle of approach during impact with sliding wear are important parameters in the in vitro wear ranking of dental restorative materials.