Biomimetic apatite formation and biocompatibility on chemically treated Ti-6Al-7Nb alloy

Alkali treatment of the Ti-6Al-7Nb alloys with subsequent heat treatment has been adopted as an important surface treatment procedure for apatite formation in dental implants. This study examined the effects of alkali treatment on the precipitation of apatite on a Ti-6Al-7Nb alloy. All samples were immersed in a Hanks' Balanced Salts Solution [simulated body fluid (SBF)] at pH 7.4 and 36.5 degrees C for 15 days. The surface structural changes of samples due to the alkali treatment and immersing in SBF were analyzed by XRD, SEM and XPS. The cell toxicity was evaluated based on the optical density of the surviving cells. The samples were implanted into the abdominal connective tissue of mice for 4 weeks. A sodium titanate hydrogel layerwasformed after immersion in an NaOH solution. A dense and uniform bone-like apatite layer precipitated on the alkali and heat-treated Ti-6Al-7Nb alloy in the SBF. There was a significant difference in cell toxicity between the treated and untreated Ti-6Al-7Nb (P < 0.05). The thickness of the fibrous capsule formed around the implant body was decreased significantly by the alkali and heat treatment (P < 0.05). The alkali treatment samples showed a better biocompatibility than the commercial metal samples. Copyright (c) 2008 John Wiley & Sons, Ltd.