Scanning electron microscopic observations of the enamel surface before and after etching by orthophosphoric acid

ABSTRACT

Ten unerupted human third molars were examined under the scanning electron microscope. In the fractured surfaces can be observed an external "prismless" layer at the buccal and lingual faces. The specimens treated by phosphoric acid "in vitro" showed three basic etching patterns. The type I etching pattern showed a rough enamel surface with the prism core removed. The type II etching pattern showed that the prism cores are left projecting towards the enamel surface, and the type III, showed the loss of prism with irregular arranged structures. The effects of acid-etching on the enamel surface depend on the variation of tooth morphology, selected surface and changes in enamel structure