Density and Refractive Index Studies of Dental Hard Tissues

Abstract

A rapid, quantitative method for the separation of the enamel, dentin, and cementum of a single tooth to obtain samples of known purity will permit the following investigations: 1) Normal values and ranges of variation in the composition of enamel and dentin. 2) Changes in composition associated with caries (5), pyorrhea or disturbances in nutrition, metabolism or endocrine balance. 3) Proportion of enamel to dentin in normal, hyperand hypoplastic teeth and changes due to attrition, erosion or caries. Methods for obtaining pure dentin or enamel by heating or grinding are unsatisfactory because of the time required and the incomplete recovery. The method described by Brekhus and Armstrong (3), based on the use of heavy liquids with density intermediate between dentin and enamel, offers a distinct improvement over previous methods, but leaves a few things to be desired. For instance, it would be advantageou§ to have (a) a more rapid method, (b) a check on the purity of the enamel and dentin fractions, and (c) an avoidance of filtration. According to the literature, a centrifugal separation method would seem to be desirable, especially when working with fine powders. Bernal and Crowfoot (2) found centrifugation to give a more accurate