Improved biocompatibility of hydroxyapatite thin film prepared by aerosol deposition

Technical development for an efficient coating of bioactive materials improves the characteristics of a fully functional implant. The aim of this study was to investigate the osteoinductive effect of a newly developed hydroxyapatite (HA)-coating technique using aerosol deposition without post-heat treatment [room temperature (RT) group] on the titanium (Ti) dental implant in vitro and in vivo, compared with that of HA coating with post-heat treatment (HT-400 group) or machined surface (control group). Cell proliferation or attachment on the HA-coated Ti surface was assessed using tetrazolium salt, WST-8 or scanning electron microscopy (SEM). Human osteoblasts (HOB) on RT group were well attached and grew alike in the control or HT-400 group. The alkaline phosphatase activity of HOB cultured on RT and HT-400 group was significantly higher than the control group (p < 0.05). Evaluation by SEM, TEM, and XRD demonstrated that aerosol deposition facilitated HA particles to form a dense and uniform HA layer in the RT group despite no post-heating. In a rabbit tibia model (n = 3), the ratios of bone implant contact and bone area in the RT group (49.88%, 86.05%) were greater than in the HT-400 group (38.82%, 77.34%) or the control (28.31%, 73.86%). The finding of this study showed that the HA coating using aerosol deposition without post-heat treatment has a good biocompatibility, and provide a promoting strategy to enhance osseointegration in the application of the dental implant.