Two-body wear of dental composites under different loads

Purpose: Although dental composites are excellent for restoring the appeara nce of natural tooth tissues, their relatively poor resistance to wear, esp ecially in approximal and occlusal contact areas, is still a major source o f concern. The aim of this research was to study a basic wear mechanism, un der 2-body wear conditions, that may be integrated into our understanding o f the in vitro and in vivo wear behavior of dental composites. Materials an d Methods: An in vitro 2-body wear test was conducted on 2 selected ultrafi ne compact-filled dental composites under different magnitudes of sinusoida l cyclic load. The wear surfaces and cross sections of the wear layers were assessed using scanning electron microscopy (SEM) to explore the nature of the wear pattern of the dental composites under cyclic loading conditions. Results: The wear losses of both composites increased with load. SEM analy sis of wear surfaces and subsurface sections indicated that the composites tested displayed different wear mechanisms from low to high loads. An expla nation for the wear pattern is proposed based on the observed wear behavior . Conclusion: The in vitro wear pattern of the ultrafine compact-filled den tal composites tested is closely related to the applied load. Although the wear loss increased in a roughly linear relationship with applied load, the underlying wear mechanism involved may experience a significant change fro m low to high load conditions during wear.