TRANSPARENCY AND LIGHT SCATTERING OF DENTAL HARD TISSUES

¹ Department of Biochemistry and Pharmacology, the University of Rochester School of Medicine and Dentistry, Rochester, N. Y.

Measurements were made of the transparency of different areas of moist tooth sections, and the changes in transparency were observed after drying and after immersing the sections in liquids with known refractive indices. Average values and normal variations are reported for light transmission by several different areas of dental hard tissues. The transparencies of dentin areas were not correlated with the moisture or ash percentages of the areas. Transparency normal normal dentin was dependent upon the refractive index of the media filling the tubules, and was greatest when the refractive indices of tubules and matrix were the same; dentin modifications which had become transparent in the mouth were similarly affected but to a lesser degree. The findings suggest that dentin becomes transparent in vivo because of calcific deposits within the tubules, and that the deposits resemble cementum in their degree of calcification.