Histologic changes in human enamel following treatment with acidic adhesive conditioning agents

Abstract

Topographic histologic changes in human enamel following treatment with several acidic adhesive conditioning agents were correlated with changes in the depth of the tissue. Light microscopy, microradiography and scanning electron microscopy were used. Surface characteristics included preferential etching of prism cores, selective etching of prism peripheries and smooth or pitted surfaces with little clear delineation of prism structure. Etching of prism cores was by far the most common occurrence. The changes in enamel structure was subtle and involved an increase in enamel porosity. The extent of change varied with the depth of gross and obvious loss of tissue. 0.5N hydrochloric acid produced the most drastic change (excess of 25 μm) while e.g. 50 per cent citric and 85 per cent phosphoric acid produced the least alteration (approximately 5 μm). All acids were applied for two minutes. The changes produced could be related to intrinsic differences in histology and/or solubility of the enamel.