Release of hydroxyl ions from calcium hydroxide preparations used in endodontic treatment

The purpose of our study was to compare the in vitro release of hydroxyl ions from several calcium hydroxide preparations used in endodontic treatment.

Equal quantities of the materials--nonsetting (pure calcium hydroxide, Biopulp, Calcicure), setting--canal sealers (Sealapex, Apexit) and points were placed in dialysis tubes which were then immersed in deionized water. The release of hydroxyl ions from the preparations was measured by the median pH of the deionized water used for dialysis, by means of a pH-meter. The results of our study were analyzed by means of Tukey's reasonable correlation. Significance difference (one-way variance analysis ANOVA) and Pearson's linear correlation coefficient (r2).

Nonsetting preparations of calcium hydroxide have a significantly higher capability of hydroxyl ions release in comparison with sealers and points, irrespective of time (p < 0.05). Sealapex and "plus" points released hydroxyl ions to a much greater extent than both Apexit and "regular" points at most periods of the experiment (p < 0.05). Apexit released significantly more of hydroxyl ions than "regular" points, and Sealapex more than "plus" points in the later periods of the experiment (p < 0.05). The pH values of dialysis samples of all materials correlated positively with time and the pH. Almost all materials reached a maximum on the 8-th day of the experiment.

To achieve maximum concentration of hydroxyl ions in tissues: for temporary root fillings nonsetting preparations of calcium hydroxide should be chosen rather than points and they should be placed for at least one week, for permanent root fillings it is more recommended to use Sealapex than Apexit as a sealer.