Effect of contact load upon attrition-corrosion of human dental enamel

Abstract

Attrition-corrosion is a dental wear process containing both mechanical (attrition) and chemical (corrosion) effects. As contact load is a critical parameter for wear, its effects on enamel wear were investigated in vitro in the present study. Enamel cusp-on-flat configuration reciprocating wear tests were performed with acetic acid (at pH 3.2 and 5.5) and distilled water, at 37 °C for 2250 cycles. Contact loads considered were from 5 N to 13 N. Following testing, the enamel loss was measured and the wear scar and its subsurface were analysed using focused ion beam (FIB) sectioning, SEM and TEM to elucidate the dominant wear mechanisms.For the acidic lubricants, the increase in enamel loss with increasing load was insignificant. However, for the distilled water lubricant, there was a significant increase in the wear loss with load. The associated wear mechanisms were shaving of the softened layer with acidic lubricants and delamination with distilled water. The greater friction and wear associated with the delamination mechanism resulted in a significantly higher wear loss with distilled water than with acidic lubricants.