A STUDY OF THE PHOSPHATE SOLUBILITY OF THE HUMAN ENAMEL SURFACE

¹ Tufts College Dental School, Boston, Mass.

A quantitative method for the estimation of the phosphate solubility of intact enamel surface has been developed. Windows 4 mm. in diameter were exposed to the action of 5 c.c. of a sodium acetate buffer, pH 4, for the period of ten minutes each. The buffer, containing on the average 7 to 8 micrograms of phosphate, was analyzed by the Hoffman modification of the Fiske-Subbarow method.

Variations in phosphate solubility were found from area to area on the same tooth and between various areas on different teeth. On the average, deciduous and unerupted permanent teeth were more soluble than erupted permanent teeth. Ground surfaces were more soluble than intact enamel surfaces in all cases. The first test on an intact surface averaged lower in solubility than the second test. The reverse was true for ground surfaces.