A study of secondary caries in cast restored teeth

Abstract

The purpose of this study was to investigate the state of the natural secondary caries and in vitro artificial secondary caries, associated with cast restorations cemented with zinc phosphate cement, histopathologically. For this study, the method of making and staining ground serial sections of teeth with cemented cast restorations was established. The material consisted of 50 extracted human permanent teeth with cemented cast restorations, and 12 human premolar teeth with in vitro secondary caries produced by the acid-gelatin system (pH 4.0). These specimens were embedded in MMA resin and then they were sliced to serial thin sections. Each section was etched by 0.1 N HCl, and stained with methylene blue fuchsin, and then observed with optical microscope, microradiography, and SEM. The result were as follows: 1. When the margin of restoration was set on dentine (cementum), the typical shape of natural secondary caries was found out. 2. The rate of natural secondary caries in case of margin set on dentine was about four times as many as the rate in case of margin set on enamel. 3. The shape of artificial secondary caries was very similar to the shape of natural secondary caries. 4. The resistance to secondary caries in case of the margin set on enamel was higher than the resistance in case of the margin set on dentine.