Osseointegration of titanium implants anodized with and without fluoride in the electrolyte. A study in rats

Abstract

Based on the hypothesis that fluoride acts as a bone anabolic agent, the aim of this study was to measure in rats the osseointegration of implants (grade II titanium wire, 1 mm diameter, 4 mm long) submitted to anodic oxidation in 2 M phosphoric acid solution (control implants) or b) in 2M phosphoric acid solution plus 0.2 M NaF (F-modified implants). Chemical composition of the implants surface was assessed by energy-dispersive X-ray spectroscopy: F-modified implants exhibited a 2.57% in weight. Adult male Sprague Dawley rats (300-350 g body weight) received two implants (in the femur and in the tibia, close to the knee) in each hind limb. Control and F-modified implants were inserted in the left and right hind limbs, respectively. Three weeks after surgery, the animals were sacrificed. The undecalcified bones were embedded in methylmetacrylate. Sections were obtained to measure two histomorphometric magnitudes: bone-to-implant contact (BIC) and bone volume in a defined volume of tissue around the implant (BV/TV). BIC was significantly increased on F-modified implants with respect to their controls (57.2%±3.3%, vs. 47.9±3.4, p<0.05). BV/TV did not differ significantly between F-modified and control implants (24.5±2.2% vs. 22.9±1.4, p=0.3007). Profiles of the average gray pixel levels of pseudo3D images showed a greater roughness of F-modified implants respect to their controls (p<0.05). The relative contributions of surface roughness and its fluorine content to the osseointegration process requires further research.