Surface characteristics and biological studies of hydroxyapatite coating by a new method.

Hydroxyapatite was coated on the Ti implants by a new coating method called low temperature high speed collision (LTHSC). Higher roughness values were estimated in the formed thick coating on the implant surface. While the roughness value was lower than plasma sprayed HA coatings, LTHSC HA-coated surface showed higher hydrophilicity. The cell proliferation of oseteoblastic cells evaluated by MTT assay showed that HA-coated surface had significantly higher cell viability than the control. The HA-coated surface showed higher mean total protein production even though there was no statistical difference between two surfaces. Osteoblast differentiation, ALP activity and expression of differentiation marker genes such as osteopontin and osteocalcin were elevated in the cells cultured on HA-coated surface and this surface also showed higher collagen protein expression than titanium control. Moreover, in experimental group, BIC values were significantly increased after 12 weeks of implantation and about 30-50% cortical bone-implant contact was observed.