Bone Adaptation of Fibronectin-Immobilized Titanium Implants Using a Tresyl Chloride-Activated Method

The aim of the present study was to evaluate the bone adaptation of fibronectin-immobilized titanium implants in vivo using a tresyl chloride-activated method in implantation experiments with rabbit tibiae. Cylindrical pure titanium (3.5 mm in diameter and 7 mm in height) was treated with tresyl chloride (2,2,2-trifluoroethanesulfonyl chloride, CF3CH2SO2Cl) and then coupled with fibronectin to give fibronectin-immobilized cylindrical titanium (Fn/Ti) implants. Non-treated cylindrical titanium (Ti) implants were used as a control. Ti and Fn/Ti implants were implanted into bone defects in the tibiae of rabbits. The implants were excised 12 weeks later and non-decalcified thin sections were prepared. After staining each section with methylene blue and basic fuchsin, the implant-bone interface was histologically evaluated and the bone-to-implant contact ratio (BIC) and bone mass (BM) were histomorphometrically calculated using an image analysis system. A larger amount of new bone formation was recognized for Fn/Ti implants and histomorphometrical evaluations showed that BIC and BM were significantly higher for Fn/Ti implants than for Ti implants. Fn/Ti implants also showed better bone adaptation. These results demonstrated that the immobilization of fibronectin onto cylindrical titanium implants effectively enhanced bone regeneration around implants.