Synthesis of hydroxyapatite from eggshells to be used in regenerative endodontics: An in vitro study

Introduction: The use of artificial hydroxyapatite (HA) as a biomaterial for tissue regeneration has gained significant interest in endodontics. Given the need for sustainable and cost-effective HA sources, this study aimed to synthesize HA from eggshells, characterize its structural and biocompatibility properties, and evaluate its antioxidant activity for potential application in regenerative endodontics. Materials and Methods: Eggshell-derived HA was synthesized and characterized using energy-dispersive spectroscopy to determine elemental composition, field emission scanning electron microscopy (FE-SEM) to assess morphological features, and X-ray diffraction (XRD) to confirm phase composition. Hemocompatibility testing was conducted to evaluate biocompatibility. Antioxidant activity was assessed using a 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay. Samples ( n = 45) were randomly divided into three groups: Group I (control, ascorbic acid, n = 15), Group II (HA, n = 15), and Group III (eggshell-derived HA, n = 15). Statistical analysis was performed to compare antioxidant activity among groups. Results: A statistically significant difference ( P < 0.05) was observed in antioxidant activity among groups. FE-SEM analysis revealed an interconnected porous morphology with elongated spherical particles, which is suitable for biological applications. XRD confirmed HA formation through characteristic diffraction peaks. Hemocompatibility assessment demonstrated minimal hemolysis, indicating favorable biocompatibility. Conclusion: Eggshell-derived HA exhibited desirable structural, biocompatibility, and antioxidant properties, supporting its potential as a biomaterial for regenerative endodontics. Further, in vivo studies are recommended to validate its clinical efficacy.