pH changes in dental tissues after root canal filling with calcium hydroxide

The pH changes in dental tissues of monkeys were studied by means of pH indicators after endodontic treatment with calcium hydroxide. Untreated teeth with pulpal necrosis showed a pH of 6.0 to 7.4 in pulp, dentin, cementum, and periodontal ligament. Replanted and nonreplanted teeth with completed root formation and treated with calcium hydroxide showed pH values in the circumpulpal dentin of 8.0 to 11.1, and in the more peripheral dentin of 7.4 to 9.6. In teeth with incomplete root formation, the entire dentin showed a pH of 8 to 10. The pH of the cementum was not influenced by the calcium hydroxide. However, in resorption areas, an alkaline pH was also observed at the exposed dentinal surfaces.