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This study assessed the biocompatibility and chemical properties of two bioceramic root canal sealers, EndoSequence BC Sealer (EBC) and Nishika Canal Sealer BG (NBG), using a sealer extrusion model. Eight-week-old male Wistar rats were used. The mesial root canals of the upper first molars were pulpectomized and overfilled with EBC, NBG, or, as reference, epoxy resin-based AH Plus (AHP). After 28 days, periapical tissue reactions were assessed using microcomputed tomography and histological staining. The elemental composition and chemical composition of the extruded EBC and NBG were analyzed at Day 1 and 28 using an electron probe microanalyzer and micro-Raman spectroscopy. No periapical lesions were observed with the sealer extrusion. Additionally, inflammation around the extruded EBC and NBG was minimal to mild on Day 28, whereas moderate inflammation was found around the extruded AHP. Silicon concentration in the extruded EBC and NBG decreased significantly from Day 1 to 28, with almost no silicon present on Day 28. Furthermore, the extruded EBC and NBG became calcium- and phosphorus-rich, showing a Raman band for hydroxyapatite on Day 28. In conclusion, EBC and NBG demonstrated favorable biocompatibility and the ability to release silicon elements and produce hydroxyapatite when extruded into the periapical tissues. AHP showed moderate periapical tissue irritancy. [ABSTRACT FROM AUTHOR]

Hydroxyapatite formation on endodontic hydraulic calcium silicate cements (HCSCs) plays a significant role in sealing the root canal system and elevating the hard-tissue inductivity of the materials. This study evaluated the in vivo apatite-forming ability of 13 new-generation HCSCs using an original HCSC (white ProRoot MTA: PR) as a positive control. The HCSCs were loaded into polytetrafluoroethylene tubes and implanted in the subcutaneous tissue of 4-week-old male Wistar rats. At 28 days after implantation, hydroxyapatite formation on the HCSC implants was assessed with micro-Raman spectroscopy, surface ultrastructural and elemental characterization, and elemental mapping of the material–tissue interface. Seven new-generation HCSCs and PR had a Raman band for hydroxyapatite (v1 PO43− band at 960 cm−1) and hydroxyapatite-like calcium-phosphorus-rich spherical precipitates on the surfaces. The other six HCSCs with neither the hydroxyapatite Raman band nor hydroxyapatite-like spherical precipitates did not show calcium-phosphorus-rich hydroxyapatite-layer-like regions in the elemental mapping. These results indicated that 6 of the 13 new-generation HCSCs possessed little or no ability to produce hydroxyapatite in vivo, unlike PR. The weak in vivo apatite-forming ability of the six HCSCs may have a negative impact on their clinical performance. [ABSTRACT FROM AUTHOR]