Acid-Reacting Stains, Softening, and Bacterial Invasion in Human Carious Dentin

Abstract

This study investigated the relationships of acid-reaction, softening, and bacterial invasion in carious dentin. Softened carious dentin took up methyl red but not lackmoid. The use of methyl red as pH indicator to show acid-reaction in dentin was questioned. Destructive changes before softening were demonstrated with ninhydrin; these changes preceded bacterial invasion.