CORRELATION OF MICROHARDNESS AND WEAR IN DIFFERENTLY ERODED BOVINE DENTAL ENAMEL

The purpose of the study was to compare the microhardness data of diff erently eroded enamel surfaces with the wear caused by toothbrushing. Sixty bovine enamel specimens were polished and prepared for microhard ness determination. The polished surfaces were covered with tape excep t for a 1.3 x 10.0 mm window. Fifteen specimens each were stored in an erosive beverage (Sprite Light(R)) for either 1, 5 or 15 min. Each sp ecimen was immersed in 10 ml of the beverage. The remaining 15 specime ns were not eroded. Interferometrical analysis revealed that substance loss after 15 min of erosion was negligibly low (about 75 nm). In all specimens Vickers microhardness determinations were conducted on erod ed (= final hardness) and non-eroded (= initial hardness) enamel surfa ces. The specimens were subsequently submitted to toothbrushing abrasi on using a slurry consisting of 1 g non-fluoridated dentifrice in 5 mi artificial saliva. The total amount of tooth wear due to erosion and subsequent abrasion was profilometrically evaluated. Statistical analy sis revealed a significant decrease in hardness and a significant incr ease in wear with increasing time of storage in the erosive beverage. Overall regression analysis yielded a statistically significant correl ation between both initial and final hardness and the amount of tooth wear. The correlation of abrasion and final hardness could be describe d by a quadratic mathematical function. It is concluded that the susce ptibility of eroded enamel to toothbrushing abrasion can be correlated with Vickers microhardness values, thereby suggesting an overproporti onate increase of abrasion with decreasing hardness values. (C) 1997 E lsevier Science Ltd.