Experimental studies of human dentine wear

Previous in vitro studies have described the relation between rates of enam el wear and variables such as applied load and lubricant pH. The aim here w as to extend understanding of tooth-wear processes by considering the rate of wear in human dentine. Enamel was removed from extracted third molar tee th that had been sectioned mesiodistally. Moisture fluctuation within denti ne was minimized by conducting all procedures under copious irrigation or i n sealed containers of lubricant at pH 7.0. Specimens were subjected to wea r using a purpose-built apparatus at loads of 6.2, 9.95 and 13.2 kg. All ex periments were done with a unidirectional wear stroke of 3 mm at a rate of 80 cycles/min for 75 min and repeated for 75 min. Dentine wear was assessed by specimen weight loss. At pH 7.0, wear rates ranged from 0.50 mg/10(3) c ycles at a load of 6.2 kg to 0.77 mg/10(3) cycles when a load of 13.2 kg wa s applied. At higher loads, dentine wear rates were similar to those of ena mel. Increasing load is thus associated with a progressive increase in the rate of dentine wear. This relation differs significantly from that for ena mel, reflecting fundamental differences in the composition and structure of these tissues. (C) 1999 Elsevier Science Ltd. All rights reserved.