A Method for Study of Penetration of Enamel by Acid Buffers

¹ Research Department, Tufts University School of Dental Medicine, Boston, Massachusetts

A procedure was developed for imbedding tooth sections between glass slides in a manner to leave 3-5 mm. of outer enamel surface exposed. These sections were studied for rate of penetration of pH 6 lactate buffers into the enamel, as recorded by photomicrography of the sections under polarized light. Epoxy resin was used to cement the section between the slide, and a rubber-base impression material was used to maintain an opening to the area under observation. A series of experiments was carried out with various molarities and degrees of saturations of lactate buffer and acetate buffer, to study certain variables associated with the imbedding technique.

Agitation was observed to be generally effective in increasing the rate of penetration of enamel. The influence of depth of slot on rate of penetration was studied, and it was found, contrary to expectation, that the rate was greatest at the bottom of a 3-mm. slot. The use of wax to prevent coverage of enamel by epoxy resin was found to be unsuitable because the wax frequently left an impermeable coating on the enamel surface.

Strong solutions of buffer (1 molar) generally caused more cavitation and penetration than did weaker solutions. High degree of saturation caused less cavitation and penetration than did less saturated solutions.