Dentinal diffusion of hydroxyl ions of various calcium hydroxide pastes / Difusão para a dentina de íons hidroxila de várias pastas de hidróxido de cálcio

ABSTRACT

The aim of this study was to analyze in vitro the dentinal diffusion of hydroxyl ions of calcium hidroxide pastes, prepared with different acid-base vehicles, in an inert nitrogen atmosphere. Sixty maxillary central incisors with mature apexes were selected and after and 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 2mm from the apical vertex and the teeth mounted in the center of a round platform, filled with saline solution up to 2mm 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 36.5ºC. 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 6-7 to 7-8 after 30 days, remaining at this level at 60 days. In the polythylene glycol 400 group, the same alteration occurred at 45 days, and continued at 60 days