In vitro analysis of the pH alteration of the dentine after using different calcium hydroxide-based pastes

Introduction and Objective: To analyze the pH increase at the external root surface after the use of different calcium hydroxide pastes (Calen, calcium hydroxide associated with 2% chlorhexidine gel, calcium hydroxide associated with saline) with and without EDTA as chelating agent before the topical application of the intracanal medication. Material and methods: One-hundred single-rooted extracted teeth were cleaned and shaped. They were randomly divided into six experimental groups (n = 15) and one control group (n = 10), according to the medication to be used. The teeth were kept immersed in saline solution and the pH measurements were weekly verified with the aid of a pH meter. Results: It was verified the pH increasing at the first week in almost all groups. Only the groups in which Ca(OH)2 was associated with 2% chlorhexidine gel exhibited a significant evolution in the pH increasing over time (p = 0.0116). The use of EDTA did not result in higher pH values (p = 0.2278). Conclusion: i) the pH increased in all associations used; ii) 2% chlorhexidine gel allowed the gradual pH increasing over time; iii) the smear layer removal did not influence on the pH increasing.