OR31 - From Pulpal Calcification to Apatite Formation: Evaluating Bioactivity and Cytotoxicity in Fast- and Regular-Set EndoSequence Root Repair Materials

Introduction: An unexpected finding of our animal study showed pulpal calcification following the application of fast-set EndoSequence Root Repair Material (ESF). This observation prompted a deeper investigation into the material characteristics that may influence such biological reactions. The objective of this study is to assess the Ca ion release, pH shift, bioactivity and cytotoxicity of both forms of EndoSequence Root Repair Material, regular (ES) and fast (ESF) sets.

Methods: ES (n=10) and ESF (n=10) forms were tested for their biocompatibility. Elemental analysis of the fresh material immersed in Phosphate Buffered Saline (PBS) for 30 days was done. The surface crystal formation was studied. Cytotoxicity was evaluated at different material concentration using Human hepatocellular cancer cell line.

Results: Both materials contain Ca, P, Ta, Zr, and Si as major elements. The Ca ion concentration and distribution on the surface was higher and more homogenous in ES than in ESF. However, ESF released noticeably more Ca ions and had a higher pH over the 7 days course. Ca/P ratio in ESF was 2.95 and was significantly higher than Ca/P ratio in ES of 2.16 (p < 0.05). The ESF had a greater capacity to precipitate and grow hydroxyapatite (HA) than ES, resulting in more mature crystals formed on the surface. SE and ESF demonstrated significant low cytotoxicity against Huh-7 cells.

Conclusion: ESF demonstrated higher bioactivity than ES, with prolonged high pH and Ca release. This elevated bioactivity in ESF, however, may pose clinical challenges if persistent tissue stimulation continues.