An in vitro study of the wear mechanism of a leucite glass dental ceramic

Ceramics and glass-ceramics are materials of choice for dental crowns due to their attractive hardness, biocompatibility, etc. However, a major problem with their usage is the observed high wear of either the opposing dental enamel or both the enamel and ceramic itself. Although these issues have been known for some time, the responsible wear mechanism(s) are not clearly identified. Accordingly, an in vitro investigation was undertaken to identify the mechanism(s) responsible for the wear of a popular leucite glass-ceramic (LGC) dental prosthesis material when opposing both itself and human dental enamel. Reciprocating sliding wear tests were carried out with LGC or enamel cusp sliding on LGC flat-surface samples with varying surface roughness. The wear loss was quantified using profilometry and the wear scar surface and subsurface were analysed using electron microscopy techniques to reveal the underlying wear mechanism. The present results revealed that the dominant wear mechanism for LGC, when opposed by LGC or enamel, was micro-abrasion due to lateral crack formation/extension. Leucite crystals in the ceramic׳s microstructure appear to act as hard asperities and their loading/unloading during sliding contact caused the formation and extension of lateral cracks and, consequently, wear of the LGC dental material. For human enamel, the dominant wear mechanism was delamination