Bone-bonding properties of Ti metal subjected to acid and heat treatments.

The effects of surface treatment on the bone-bonding properties of Ti metal were examined by both mechanical detaching test and histological observation after implantation into rabbit tibiae for various periods ranging from 4 to 26 weeks. The bone-bonding ability of Ti metal, which is extremely low as it is abraded, was hardly increased by simple heat treatment at 600 °C or treatment with H(2)SO(4)/HCl mixed acid alone, but was markedly increased by the heat treatment after the acid treatment. Even Ti metal that had been previously subjected to NaOH treatment showed considerably high bone-bonding ability after acid and heat treatments. Such high bonding abilities were attributed to their high apatite-forming ability in the body environment. Their high apatite-forming abilities were attributed to a high positive surface charge, and not to the type of crystalline phase or specific roughness of their surfaces. The present study has demonstrated that acid and subsequent heat treatments are effective for conferring stable fixation properties on Ti metal implants.