New insights into tooth wear based on in vitro studies

Abstract

In vitro experimental systems for the study of tooth wear have the potential to overcome the long time frames and ethical complexities involved in undertaking clinical studies. The aim of this article is to review in vitro studies undertaken by the authors and highlight areas in which significant progress has been made. Investigations of enamel, dentine, and restorative material wear and potential wear-prevention strategies were conducted using a purpose-built wear simulation machine with loads between 32 and 160 N and with specimens lubricated by solutions at pH = 6–7 (simulating a serous oral environment), pH = 3 (resembling an acidic diet), pH = 1.2 (resembling regurgitated acid), or with pooled natural saliva (pH = 7). These studies have demonstrated a linear relationship between load and the rate of dentine wear and very low wear rates for enamel except at the highest loads (when enamel and dentine wear at similar rates) and at the lowest pHs (when both enamel and dentine wear rapidly). Comparisons of wear rates for enamel and common restorative materials have shown that at low pH, the enamel tends to wear more rapidly than any of the materials considered: resin composites are more resistant to acid and high loads than glass-ionomer cements (GICs); resin-modified GICs have intermediate properties; and, most modern dental porcelains wear at about the same rate as opposing enamel. Recent studies of preventive strategies have provided evidence of the wear-reducing potential of both lubricants and remineralizing agents. Considered together, these studies have given a clearer understanding of the factors that influence the wear of enamel, dentine, and restorations under various conditions.