“…Previous studies have confirmed that HA-modified Ti surfaces can promote cell differentiation and maturation in vitro [ [50] , [51] , [52] , 62 ], and also, HA-deposited implants were able to induce bone ingrowth at the bone-implant interface without isolation by fibrous tissue layer in vivo [ 20 , [63] , [64] , [65] , [66] ]. Although the detailed mechanism is still under exploration, the superior bioactivity and osteoconductivity of HA are related to its physicochemical properties, such as composition, morphology and geometry [ 16 , 20 , 67 ]. Moreover, the release of calcium and phosphate ions from HA into the cell-material microenvironment probably enhanced the ALP activity and extracellular matrix mineralization [ 16 , 67 ].…”