STUDIES ON THE PHYSICAL PROPERTIES OF RODENT ENAMEL

II. DENSITY DISTRIBUTION AND X-RAY DIFFRACTION PATTERN

¹ Division of Dental Research and the Department of Biochemistry, the University of Rochester, School of Medicine and Dentistry, Rochester, N. Y.

A method was devised for the determination of density distribution of small amounts (80 mg.) of powdered calcified tissues. It employed a modified Manly-Hodge separation tube in which successive fractionation of the same sample was performed at different densities. Albino rat enamel had a density between 2.720 and 2.920 Gm. per c.c. with a single maximum in the region of 2.90. The distribution was somewhat different from that reported for human deciduous and permanent enamel.

X-ray powder diffraction analysis demonstrated that the mineral salt in rodent molar enamel closely resembles hydroxylapatite. As a consequence of this, density differences between rat and human tissues were attributed to a relatively greater amount of organic material in rat enamel.