Preparation and characterization of double layered coating composed of hydroxyapatite and perovskite by thermal decomposition

Abstract

A new modified thermal decomposition method is described for preparing a double layered coating on titanium plates which includes an initial perovskite (CaTiO₃) layer followed by a hydroxyapatite (HA) layer on top. The characterization of the coating was studied by X-ray diffractometry and infrared spectroscopy and indicated that the double layer consisted of carbonate HA and CaTiO₃ and the thickness of the layer was 4 μm. The coating was performed on the inner surfaces of 50-200 μtm sized pores and was also consistent in the smallest of the pores even those of 50 μm. Bone formation was examined in canines at 2-32 week intervals and was dominant on coated plates and in large-sized pores before 16 weeks. However, after 16 weeks bone ingrowth was similar in non-coated and coated plates and in all pore sizes. The results indicated that HA could only influence early bone ingrowth, though good bone ingrowth into small pores indicated that HA exhibited enhanced osteocompatibility. Our methodology ensured the stability of the HA layer consequently minimizing the problems associated with HA loss.