An in vitro study of the pH of three calcium hydroxide dressing materials

Abstract

Calcium hydroxide is widely used as a root canal dressing material because of its favorable alkalinizing effect. It has been suggested that the action comes from diffusion of hydroxyl ions through the apical foramen. The purpose of this in vitro study was to test the pH changes that occurred over a period of 30 days using a mixture of calcium hydroxide and distilled water and two commercial calcium hydroxide products in a simulated periapical environment. The materials were inserted in glass tubes closed at one end, which were placed in individual vials containing distilled water at a pH 7.4. Unfilled glass tubes were used as controls. Alkalinity changes of the medium were measured at 1 and 24 h and 15 and 30 days. The alkalinizing properties of all materials showed a rapid increase at 1 and 24 h followed by a continuous but more gradual increase from 15 to 30 days. The control tubes did not cause a change in pH of the medium, which remained at pH 7.4. At the end of the observation period, the alkalinizing properties of Calasept and Ultracal XS were significantly higher (P < 0.05) than the calcium hydroxide/distilled water paste.

Assessment of ion diffusion from a calcium hydroxide-propolis paste through dentin

“…Other authors have also reported the greater effectiveness of aqueous and viscous vehicles. 1,4,[6][7][8] Similarly to previous reports, 1,4,[6][7][8] this study evidenced that saline-and propylene glycol-containing pastes diffuse well through dentin, as can be seen in Tables 1, 2 and 4. Similar levels of ion diffusion in dentin were observed for both groups, at different experimental times, confirming the indication of these substances as vehicles for calcium hydroxide pastes.…”

“…4 Such vehicles include olive oil, propylene glycol, saline, distilled water, and others. 1,4,[6][7][8] Lage-Marques et al 8 conducted a study to evaluate the rate of ionic dissociation of calcium hydroxide associated to different vehicles-aqueous, viscous, and oily-and concluded that aqueous and viscous vehicles are better suited for paste use.…”

Efficacy of NiTi rotary instruments in removing calcium hydroxide dressing residues from root canal walls

“…4 To be effective, it has to be adequately placed and condensed in the root canal space. 5 However, before the root canal can be filled, the dressing on the canal must first be removed. 6 Calcium hydroxide residues on the canal walls interfere negatively in endodontic treatment prognosis, 7 influence dentine bond strength, 8 affect the adhesion of the endodontic filling material to the root canal walls 9 and the penetration of sealers into dentinal tubules, 10 and react chemically with the sealer, interfering with its physical properties.…”

Biocompatibility of a Calcium Hydroxide-Propolis Experimental Paste in Rat Subcutaneous Tissue

“…Different substances, like distilled water, saline and propylene glycol have been combined with CH powder to prepare pastes (1,2,4,7) to obtain a material with adequate consistency and enhanced antimicrobial capacity.…”