The investigation of enamel subjected to early erosive and abrasive challenges

Abstract

Tooth surface loss is an increasingly recognised clinical problem and so there are an increasing number of in vitro studies investigating factors that modify effects at the tooth surface. A literature review found that erosion and abrasion studies often quantify the amount of tooth loss; this means that conditions used to simulate acidic and abrasive challenges are relatively aggressive. There are few attempts to describe or qualify early effects of these challenges. This is necessary in order to gain a greater understanding of the initial mechanisms of tooth surface loss. A literature review also identified inconsistent reports of surface changes both between human and bovine enamel, and across treatments for erosive and abrasive challenges. No data are reported for ovine enamel. Therefore a simple in vitro model was developed in order to measure early surface changes in human, bovine and ovine enamel using profilometry, SEM and microhardness testing. Using these methods the study aimed to investigate the surface effects on enamel of early erosive and abrasive challenges, and to compare the enamel surfaces of human, bovine and ovine enamel. Results indicated that there were significant differences between the enamel surfaces of each tissue at baseline, and different characteristics were recorded for different methods of polishing. Bovine enamel was often the hardest and the smoothest, demonstrating the least surface loss after the abrasive challenge; ovine enamel was often the softest and the roughest. Recording of bearing area parameters yielded significant differences for a number of surfaces that were not identified through the roughness average alone. Bovine enamel may be able to substitute for human enamel for the in vitro testing of early erosive and abrasive challenges, showing similar surface effects to human enamel. After an erosive challenge, abrasive tooth surface loss could be predicted from a linear combination of the surface microhardness and the maximum height change within the eroded profile.