Influence of different vehicles on the pH of calcium hydroxide pastes

The main known benefit of calcium hydroxide as an intracanal medicament lies in the bactericidal effect conferred by its pH. The objective of this work was to determine the influence of the vehicle on the pH of calcium hydroxide pastes after usage in patients and in vitro. The incisor root canals of 180 patients were instrumented and filled with calcium hydroxide pastes containing distilled water, chlorhexidine, propylene glycol, anesthetic solution, camphorated p-monochlorophenol and camphorated p-monochlorophenol-propylene glycol. The pH of the paste in the patients' root canals was measured at 7, 14 and 21 days. Similarly, pH was measured in vitro up to 21 days. The pH of all the pastes remained constant throughout the time periods assessed. The calcium hydroxide-water combination showed significantly higher pH values than the other pastes in clinical use. Comparative analysis showed that the pH values of the anesthetic solution, camphorated p-monochlorophenol and camphorated p-monochlorophenol-propylene glycol were significantly higher in vitro. The type of vehicle was shown to influence the final pH of the pastes. However, the alkalinity of all pastes was maintained over time under the experimental conditions. (J. Oral Sci. 46, 107-111, 2004)