The effects of three different food acids on the attrition-corrosion wear of human dental enamel

Abstract

With increased consumption of acidic drinks and foods, the wear of human teeth due to attrition in acidic environments is an increasingly important issue. Accordingly, the present paper investigates in vitro the wear of human enamel in three different acidic environments.Reciprocating wear tests in which an enamel cusp slides on an enamel flat surface were carried out using acetic, citric and lactic acid lubricants (at pH 3–3.5). Distilled water was also included as a lubricant for comparison. Focused ion beam milling and scanning electron microscopy imaging were then used to investigate the enamel subsurfaces following wear tests. Nanoindentation was used to ascertain the changes in enamel mechanical properties.The study reveals crack generation along the rod boundaries due to the exposure of enamel to the acidic environments. The wear mechanism changes from brittle fracture in distilled water to ploughing or shaving of the softened layer in acidic environments, generating a smooth surface with the progression of wear. Moreover, nanoindentation results of enamel samples which were exposed to the above acids up to a duration of the wear tests show decreasing hardness and Young’s modulus with exposure time.