Characterization of enamel surfaces prepared with commercial and experimental etchants.

Polished enamel surfaces were etched with various commercial and experimental etching solutions and evaluated for changes in surface profile and topography. Enamel surfaces that were exposed to solutions of phosphoric acid in a concentration between 37% and 50% for a minute gave the most suitable surfaces for retention of the polymer. Enamel surfaces that were roughened with a diamond stone were not etched uniformly. Enamel that was exposed to acid etching solutions was better protected by a polycarboxylate cement than by either calcium hydroxide or zinc phosphate.