An in vitro comparison of pH changes in root dentine following canal dressing with calcium hydroxide points and a conventional calcium hydroxide paste

Abstract

Aim: This study aimed to measure and compare pH changes at apical and cervical sites on the external root surface of extracted teeth dressed with calcium hydroxide in two different formulations. Methodology: Root canals of 45 single-rooted extracted human teeth were accessed and shaped using a step-down technique with rotary instrumentation. Standard cavities were prepared on the external root surface at specific apical and cervical sites. The teeth were randomly allocated to three groups. Teeth in group A were dressed with calcium hydroxide points, those in group B were dressed with an aqueous calcium hydroxide paste and teeth in group C were left unfilled. Following storage in humid conditions, the pH of the dentine at apical and cervical sites was measured at baseline and then at 24 h, 72 h, 1 week, 10 days, 2 weeks and 3 weeks. Results: The pH of the root dentine at both apical and cervical sites was significantly greater (P < 0.001) in teeth dressed with aqueous calcium hydroxide paste compared with those dressed with calcium hydroxide points, when averaged out across all time periods. For all groups, there was a significant difference between the mean apical and cervical pH values for each tooth with lower values for the apical sites (P < 0.001). Conclusion: The results of this study indicate that an aqueous calcium hydroxide paste was more effective than calcium hydroxide points at raising the pH on the external root surface of extracted teeth.