Tissue-response to calcium-bonded titanium surface

Our previous study demonstrated that calcium-bonded titanium surface (Ca-Ti) can be obtained by hydrothermal reaction between titanium(Ti) and CaCl₂ and that bone-apatite like formation was observed after immersion in simulated body fluid. The purpose of the study was to determine the in vivo response to Ca-Ti surface using a rodent tibia model. Cylinders of commercially pure Ti were divided into three groups: (1) untreated group; (2) NaOH+hTi group: soaked in 5 mol/L NaOH solution at 60°C then heated at 400°C for 1 h; and (3) Ca-Ti group: hydrothermally treated in the presence of 10 mmol/L CaCl₂ at 200°C for 24 h. The cylinders implanted in surgically created defects in tibias of 8-week old male Wistar rats were retrieved after 1, 2, and 4 weeks. Histomorphometric evaluations were made on stained decalcified thin sections. Results showed that at 1, 2, and 4 week after implantation, respectively, bone contact was 55.2 ± 16.4%, 88.1 ± 9.9%, and 96.1 ± 4.8% for Ca-Ti implants, 5.7 ± 5.3%, 19.9 ± 1.2%, 57.4 ± 4.8% for untreated; and 27.2 ± 0.7%, 70.9 ± 7.7%, and 96.0 ± 5.1% for NaOH+hTi implants. These results suggest that hydrothermal treatment with CaCl₂ provides a bioactive Ca-Ti bonded surface that allows bone formation greater than that obtained with NaOH+heat treated Ti surfaces.