Eggshell sourced hydroxyapatite as a bone regenerative material in dentistry - a narrative review

Although bone is a dynamic connective tissue with inherent regenerating potential, grafting materials are frequently needed to recuperate shape and function in cases of bone defects. Eggshell-derived hydroxyapatite (EHA) and its nano-form (EnHA) have become viable alternatives because of their availability, affordability, osteoconductivity, biocompatibility, and environmental friendliness. Human studies evaluating the clinical potential of EHA/EnHA in bone regeneration that were published between 2014 and 2024 were reviewed. A total of seven trials with 112 patients and 88 intervention locations were included in this narrative review. EHA showed promising results in improving bone density, volume, and healing time across a variety of motives including socket preservation, intrabony defects, apicoectomy, and cystic lesions. When paired with platelet-rich fibrin, EnHA consistently demonstrated better healing than ungrafted areas and equivalent outcomes to conventional grafts, such as demineralised freeze-dried bone allograft and synthetic hydroxyapatite. Significant improvements in bone density and the production of new trabecular bone were confirmed by radiographic and histomorphometric investigations. The therapeutic viability of materials generated from eggshells is further supported by their high calcium content, non-cytotoxic profile, and efficient high-temperature sterilising. However, there are drawbacks, such as inconsistent resorption rates, a dearth of long-term randomised controlled studies, and a lack of established preparation procedures. Large multi-centre studies, long-term result validation, and manufacturing process optimisation should be the main areas of future study. However, with the existing literature, EHA and EnHA are found to be affordable, biocompatible, and sustainable substitutes for conventional graft materials in bone repair and regeneration in dentistry.