Behavior of ProRoot Endo Sealer After Immersion in Phosphate-containing Fluid

Objectives: To investigate the sealing quality of ProRoot Endo Sealer (Dentsply Tulsa Dental Specialties), a calcium silicate-based sealer and its morphologic characteristics after immersion in a phosphate-containing simulated body fluid (SBF). Methods: Thirty single-rooted canals were filled with gutta-percha and either the calcium silicate-based sealer or two commercially-available zinc oxide eugenol (ZOE)-based and epoxy resin-based sealers (n=10). Three teeth each were used as the positive and negative controls. The sealers were allowed to set for 6 days and the filled teeth were immersed in SBF for 24 hours before fluid leakage evaluation. A computerized Flodec device was employed to measure fluid flow through the filled canals with nitrogen applied at 69 kPa gas pressure. After initial leakage evaluation at the seventh day, each filled root was restored with Cavit (3M ESPE) and re-immersed in SBF for 28 days before the second phase of leakage evaluation at 35 days. Cryofractured specimens of ten additional teeth filled with the calcium silicate-based sealer were examined using scanning electron microscopy after immersion in SBF for the two periods (n=5). Results: One-way repeated measures ANOVA and Tukey's test revealed significant differences between the ZOE-based sealer at 35 days and the calcium silicate-based sealer at 35 days (p<0.001), and between the ZOE-based sealer at 7 days and the calcium silicate-based sealer at 35 days (p=0.001). No difference was found between the epoxy resin-based sealer and the calcium silicate-based sealer after both storage periods. Cryofractured calcium silicate-based sealer specimens demonstrated apatite-like crystalline deposits along the apical and middle-thirds of the canal walls via transformation from amorphous calcium phosphate-like precursors. Conclusion: The calcium silicate-based sealer is comparable in sealing quality to the two other sealers examined in this study. This calcium and hydroxyl ion-releasing sealer also demonstrates in vitro bioactivity when it comes into contact with phosphate ions.