Surface observation of thin hydroxyapatite-coated implants at 80 months after insertion.

We observed surfaces and cross sections of thin hydroxyapatite (HA)-coated implants produced by the thermal decomposition method in a patient attending our clinic who underwent implant removal at 80 months due to fracture of the implants. On the implant surfaces of the removed sample, most of the HA had dissolved, and extensive osseointegration was observed where Ti had closely bonded to bone. This indicated that the HA coated on the implant surfaces had disappeared and osseointegration had been established where Ti directly bonded to the bone. In addition, calcium titanate (CaTiO(3)) and HA layers formed by the thermal decomposition method showed no desorption. The results clearly indicate the positive clinical potential of thin HA-coating by the thermal decomposition method.