Dentinal diffusion of hydroxyl ions of various calcium hydroxide pastes.

The aim of this study was to analyze in vitro the dentinal diffusion of hydroxyl ions of calcium hydroxide pastes, prepared with different acid-base vehicles, in an inert nitrogen atmosphere. Sixty maxillary incisors with mature apexes were selected and after access and root canal preparation each root was filled with calcium hydroxide pastes prepared with different vehicles: saline solution, anesthetic and polyethylene glycol 400. The roots were then sectioned 2 mm from the apical vertex and the teeth mounted in the center of a round platform, filled with saline solution up to 2 mm from the root tip. The platforms remained inert in an atmosphere of nitrogen, completely sealed, in the absence of light and with a constant temperature of 36.5 degrees C. Diffusion analysis of the hydroxyl ions was carried out by a colorimetric method on days 7, 15, 30, 45 and 60. Calcium hydroxide pastes prepared with saline solution and anesthetic showed a pH change of 5-7 to 7-8 after 30 days, remaining at this level at 60 days. In the polyethylene glycol 400 group, the same alteration occurred at 45 days, and continued at 60 days.

Mechanism of action of calcium and hydroxyl ions of calcium hydroxide on tissue and bacteria.

The biological and bacteriological action of calcium hydroxide confer to its current success as an intracanal dressing. For this reason the mechanism of action of calcium and hydroxyl ions on tissue and bacteria deserves further study. The objective of the present paper is to analyze and discuss the mechanism of action of calcium and hydroxyl ions on anaerobic bacteria, starting from the isolated study of the influence of pH on these bacteria , as well as the mechanism of action of calcium hydroxide on tissue.