Acid-etched enamel surfaces after 24 h exposure to calcifying media in vitro and in vivo.

The remineralization of acid-etched enamel lesions is investigated in this study both in vitro and in vivo over periods of 24 h. In an initial study, samples of etched bovine enamel were subjected in vitro to treatment with synthetic calcifying solutions, or were exposed to saliva by means of an intraoral appliance. Alterations in hardness of the enamel surface were measured by indentation techniques. In a second study the suitability of an impression technique for investigating the surface relief induced by an acid-etch procedure was investigated. Extracted human incisors were used to make SEM observations of eteched areas and corresponding sections of impressions. Subsequently, six subjects were selected for a clinical evaluation of the impression technique. Although a significant decrease in indentation length (increase in hardness) was observed for etched enamel lesions treated with calcifying solutions in vitro, no evidence for any such change was observed in samples exposed to the influence of saliva when investigated by the indentation and impression techniques.