Sclerotic Age Changes in Root Dentin of Human Teeth as Observed by Optical, Electron, and X-Ray Microscopy

Abstract

A preliminary survey of age changes in human teeth by Nalbandian,1 2 utilizing the multifactorial point system proposed by Gustafson,3 suggested that the relative transparency of root dentin-generally known as sclerosis-might be among the more reliable dental aging characteristics, presumably least affected by the superimposed pathology to which the crown portion of teeth is prone. It seemed worthwhile, therefore, to examine the nature of the age changes in the root dentin more closely. In the present study structural alterations associated with sclerotic root dentin have been observed by means of optical and electron microscopy as well as by high-resolution microradiography. While similar techniques have been employed individually as applied to studies on crown dentin, there does not appear to be any previous study comparing the combined results of these several approaches in the study of typical sclerotic age changes in the root dentin of human teeth. The classical studies of W. D. Miller,4 Beust,5-7 and Bodecker and Lefkowitz,8 9 demonstrated alterations in the optical appearance of ground sections of dentin as well as a decrease in permeability to dyes coincident with aging. These changes could be the result of intratubular calcification, which would inhibit the diffusion of dyes and cause the refractive index of the tubules to approach that of the intertubular dentin, thus modifying the relative transparency. Recently a number of microradiographic investigations of crown dentin'0-'6 have revealed areas of considerably greater X-ray absorption in relation to the dentinal tubules than in the general dentin matrix, suggesting deposition of highly concentrated minerals. For example, J. Miller'0 demonstrated a highly mineralized zone around the odontoblastic processes in microradiographs of dentin from unerupted teeth. Similar observations were made by Blake in sound teeth from elevento thirteen-year-olds. Bergmann and Engfeldt12 studied by microradiography the transparent dentin under superficial caries. Their material showed, in addition to hypercalcified zones around many tubules, other tubules which appeared to be completely obliterated by highdensity material. The following year Rbckert13 reported complete tubular obliteration in the crown dentin of young and old non-carious teeth, stating that there was a greater tendency toward tubular obliteration with increasing age.