Variation in the Pattern of Acid Etching of Human Dental Enamel Examined by Scanning Electron Microscopy

Abstract

This study has shown that the exposure of human dental enamel to acid solutions in vitro produces three basic etching patterns. In the most common, called type 1 etching pattern, prism core material was preferentially removed leaving the prism peripheres relatively intact. In the second, type 2 etching pattern, the reverse pattern was observed. The peripheral regions of prisms were removed preferentially, leaving prism cores remaining relatively unaffected. In the type 3 etching pattern, there was a more random pattern, areas of which corresponded to types 1 and 2 damage together with regions in which the pattern of etching could not be related to prism morphology. These findings differ from previous studies in which the type 1 pattern was ascribed to acid action and type 2 etching pattern to attack by chelators. The results therefore suggest that there is no one specific etching pattern produced in human dental enamel by the action of acid solutions. Such differences produced by acids are difficult to explain on the basis of variation in chemical composition, and crystallite orientation. This further highlights the variation in structure that can occur in enamel not only from tooth to tooth, or surface to surface, but also from site to site on a single tooth surface.