Dissolution Rates of Enamel and Dentin in Acid Buffers

¹ Eastman Dental Dispensary, Rochester, New York

A comparison of the rates of solution of enamel and dentin in simple pH 4 buffers of nine acids (acetic, lactic, glycolic, aspartic, glutamic, glutaric, succinic, propionic, formic) indicated that the rate of enamel dissolution was influenced by the kind of acid used. The rate of dentin solubility, on the other hand, which is approximately the same in all the buffers, appears to depend not on the kind of acid but on the pH and anion concentration of the buffer.

The solubility of enamel was lowest in the buffers of the amino acids, with the solubility in the aspartic acid buffer ranging from about 40 to 50 per cent less than in the other buffers.

It has been postulated that the multicharged ions derived from the amino acids, by forming surface-bound complexes with the enamel particles, retard dissolution rates. With dentin the presence of the organic matter may interfere with the formation of surface complexes.

Effects of this sort occurring in vivo could have significant bearing on the rate of initiation and spread of caries in enamel.