Development of a Nano‐Hybrid Composite Using Bovine Hydroxyapatite and Montmorillonite for Endodontic Applications—An In Vitro Study

AIM: Hydraulic calcium silicate cements are widely employed in endodontics due to their excellent biocompatibility, bioactivity, sealing ability, and remineralisation potential. However, currently used products such as mineral trioxide aggregate (MTA) exhibit several limitations, including discolouration, cost, and poor handling properties. Therefore, this study aimed to develop and characterise a bovine-derived hydroxyapatite (BHA) and montmorillonite (MMT) nanoclay hybrid composite (BHA-MMT), incorporating zirconium oxide as a radiopacifier and calcium silicate phases as setting agents. METHODOLOGY: BHA was produced from waste bovine bones using a defatting and deproteination method. MMT clay was exfoliated into nanoclay using shear force with a planetary ball mill. The composite powders were prepared by combining BHA (20% and 25% wt), zirconium oxide (30% wt), setting agents with exfoliated MMT (15% and 20% wt) to produce three composite materials with different BHA and MMT ratios, namely B20, B25, and M20. The resulting powders were mixed with deionised water to form hydraulic cements. The composite materials were tested for chemical, mechanical, and physical properties compared with the commercially available ProRoot MTA. The biocompatibility, bioactivity, and remineralisation potential of the materials were also examined using established in vitro assays. RESULTS: The pH of the material increased above 11 after 24 h and remained constant up to 21 days. The compressive strengths of B20, B25, and M20 were 23.63, 21.2, and 23.8 MPa, respectively, after 21 days. The mean setting time of the composites ranged from 13 to 14 min, and the concentrations of heavy metals were within the permissible limits specified by ISO standards. The experimental composite materials demonstrated radiopacity values within the range, consistent with ISO recommendations. Among the variants, B20 and B25 demonstrated good cell viability, while M20, containing a higher proportion of MMT, showed enhanced apatite formation and remineralization, indicating improved bioactivity. CONCLUSION: The developed BHA-MMT composites demonstrated promising physicochemical, biological, and remineralisation properties consistent with ISO standard requirements. Overall, the product represents a bioactive composite material system; further investigations, including in vivo studies, are necessary to confirm its clinical applicability in vital pulp treatment (direct/indirect pulp capping, pulpotomy) and root-end filling procedures.