M. Bohner et al. Calcium-Deficient hydroxyapatite as a bone graft material: From hydrated-layer chemistry to clinical performance. Acta Biomaterialia

M. Bohner, N. Döbelin, C. Drouet, M.P. Ginebra, Y. Maazouz, D. Marchat. Calcium-Deficient hydroxyapatite as a bone graft material: From hydrated-layer chemistry to clinical performance. Acta Biomaterialia, Volume 218, 2026, Pages 1-37. OPEN ACCESS.

doi: doi.org/10.1016/j.actbio.2026.06.010

Abstract

Calcium-deficient hydroxyapatite (CDHA) is a widely studied calcium phosphate biomaterial due to its chemical similarity to bone mineral and its relevance as a bone graft substitute. This review presents a comprehensive analysis of CDHA's structure, composition, physico-chemical properties, synthesis methods, and biological performance. Attention is given to the material’s multiphasic nature, consisting of a crystalline core and an amorphous hydrated surface layer, and to how this structural-chemical duality governs CDHA's thermal stability, mechanical behavior, solubility, and ion exchange capacity. Various synthesis routes, including aqueous precipitation, hydrolysis, and cementitious reactions, are examined with respect to their impact on particle morphology and clinical applicability. Biological performance is assessed through in vitro and in vivo studies, highlighting CDHA's biocompatibility, osteoconductivity, osteoinductivity, and resorption mechanisms. Challenges such as precise compositional characterization and the dynamic behavior of the hydrated surface layer are addressed, underscoring the need for further research. Overall, CDHA stands out as a promising and versatile material for bone substitution, with significant potential for future developments in regenerative medicine and beyond.