Abstract
The Manly-Hodge flotation method was used to separate enamel and dentin in small, pooled samples of rodent molar teeth. A single separation under conditions customarily employed for human teeth resulted in considerable contamination of both enamel and dentin fractions. Avg. percentage of junction particles (fragments composed of both enamel and dentin) for enamel samples from 4 or more rats was increased 9-fold over reported values for human enamel fractions. Dentin fractions contained 16 times more enamel than previously reported as a contaminant of human dentin fractions. Two simple refractionation procedures were devised which increased the purity and completeness of the yield. The conclusion was drawn that the Manly-Hodge method should not be applied empirically to the teeth of exptl. animals. Detn. of purity is always indicated especially where analyses are made for substances which vary widely in concentration in the component parts of the tooth.