pH changes in root dentin after root canal dressing with gutta-percha points containing calcium hydroxide

Alkalinizing action on root dentin was investigated by treating the enlarged root canals of a total of 120 extracted teeth for 24 h, 3 days, or 7 days with either gutta-percha points (size 40) containing calcium hydroxide or an equivalent quantity of aqueous calcium hydroxide suspension. After splitting the teeth longitudinally the pH of the dentin was determined using a pH microelectrode in small cavities at each of four set measuring points. The gutta-percha points were unable to alkalinize the root dentin over a period of 7 days. Clear, rapid, and prolonged alkalinization of the dentin extending through to the root surface was achieved, however, with the aqueous calcium hydroxide suspension.