Reactions of Tin (II) and Fluoride Ions with Etched Enamel

Abstract

For many years the occurrence and distribution of fluoride in human teeth have been compelling subjects of dental research. Realization of the benefits of fluoridated water supplies gave new impetus to the study of fluoride in teeth. More recently there has been much attention focused on topical treatment of teeth with solutions or pastes containing fluoride as sodium fluoride or tin (II) fluoride. Topical fluoride treatments have considerable biologic and practical dental significance. In addition, the reactions occurring between the treating agents and the enamel raise chemical questions of fun-damental importance. This article describes studies of the rates of the topical reactions on uniform, etched enamel surfaces. The distribution of fluoride in human enamel has been examined and discussed by Brudevold, Gardner, and Smith. ' These authors, in agreement with others, pointed out that enrichment of fluoride in a thin outer layer of enamel is a general phenomenon. The concentration of fluoride at the very surface seems to approach a limit of about 1 per cent of the enamel by weight, a value that may be the "physiological saturation" point.