Long-term pH Alterations in the Periradicular Area Following the Application of Calcium Hydroxide and MTA

A rise in pH and the presence of calcium ions play an important role in prevention or management of external root resorption.

This study assessed the long-term pH alterations in the periradicular area following the application of calcium hydroxide (CH) and mineral trioxide aggregate (MTA) intracanal medicaments.

This in vitro, experimental study evaluated 45 single-canal extracted human teeth. After decoronation and root canal instrumentation, defects (3×3×1mm) were created in the middle third of the roots. Following smear layer removal, the root surface (except for the defect) was sealed with nail varnish. Five teeth served as negative controls and were filled with distilled water. The remaining 40 teeth were randomly divided into two groups (n=20) for application of MTA and CH as intr-acanal medicaments. Periapical radiographs were obtained to ensure optimal quality of obturation. After coronal sealing with glass ionomer, the teeth were incubated at 37°C, and their pH was measured at 1 and 2 weeks, and 1 and 3 months, using a pH-meter. Data were analyzed using one-way ANOVA, Tukey's test and Bonferroni adjustment.

The mean pH was significantly higher in CH group at 1 and 2 weeks (p< 0.01) but no difference was noted at 1 and 3 months (p= 0.52). The mean pH in both groups was significantly higher at 2 weeks compared with other time points (p< 0.05).

CH may be preferred for use in the first weeks following the initiation of root resorption to provide a high pH. MTA can be later applied to maintain the high pH for a longer period of time without the need for medicament exchange.