Apical sealing ability of calcite-synthesized hydroxyapatite as a filler of epoxy resin-based root canal sealer

Background: The success of root canal treatment is influenced by hermetic root canal obturation. This study was conducted to analyze the apical sealing ability after the addition of calcite-synthesized hydroxyapatite (HA) as an epoxy resin sealer filler. Methods: Calcite-synthesized HA powder was prepared using the microwave hydrothermal process. HA resin sealer powder and epoxy resin paste (3:1) were mixed, and concentrations of 10%, 20%, 30%, 40%, and 50% were prepared. A sample of thirty maxillary incisors were prepared in the root canal and then, the crown was cut to leave 13 mm of the root and a working length of 12 mm. The root canal was prepared using the crown-down technique and irrigated using 2.5% sodium hypochlorite and 17% ethylenediaminetetraacetic acid alternately. The samples were divided into six groups, with each group consisting of five roots. Group I was obturated with gutta percha using an epoxy resin sealer without HA (HA-0%) as a control group. In each of the Groups II, III, IV, V, and VI, 10% HA resin sealer, 20% HA, 30% HA, 40% HA, and 50% HA were used. All the samples were incubated in a 10-ml simulated body fluid solution at 37°C for 4 weeks. Apical closure density measurement was done using a scanning electron microscope, and the results were analyzed using the Kruskal–Wallis and Mann–Whitney U-tests. Results: A significant increase in the apical sealing ability was observed in the HA-20% sealer group and the HA-30% and HA-40% groups compared to that in the control group. However, the HA-50% sealer group showed a decrease in the apical sealing ability, whereas the HA-10% sealer group showed no difference. The HA-30% had the highest sealing ability than other concentrations. Conclusion: The addition of calcite-synthesized HA as a filler at concentrations of 20%, 30%, and 40% increased the apical sealing ability of the epoxy resin sealer.