Effects of a Calcium Phosphate-Coated and Anodized Titanium Surface on Early Bone Response

Purpose: The aim of this study was to evaluate the effectiveness of a calcium phosphate (CaPO4)-coated and anodized titanium surface in vitro and in vivo. Materials and Methods: A turned surface was employed as a negative control. A sandblasted/acid-etched surface and an anodized surface were used as positive controls, and a CaPO4-coated and anodized (CPA) surface was investigated as the experimental group. Surface characteristics were analyzed with field emission scanning electron microscopy, energy dispersive spectroscopy, and confocal laser scanning microscopy. In vitro osteoblastic differentiation was evaluated by alkaline phosphatase assay. In vivo bone response was analyzed using bone-to-implant contact (BIC) ratios and bone area (BA) of 2- and 4-week specimens obtained from six rabbits. Results: The means and standard deviations for average height deviation (Sa) and developed surface area ratio (Sdr) were 0.32 ± 0.03 µm and 3.6% ± 1.5% for the turned group, 1.36 ± 0.11 µm and 56.7% ± 16.1% for the sandblasted/acid-etched group, 0.68 ± 0.02 µm and 50.9% ± 2.9% for the anodized group, and 0.67 ± 0.11 µm and 50.0% ± 16.9% for the CPA group. There were no significant differences in alkaline phosphatase activity among the groups at 7 and 14 days. In the in vivo experiment, the CPA group exhibited a significantly higher BIC ratio than the turned group, and the anodized and CPA groups showed significantly higher BA values than the others after 2 weeks. At 4 weeks, there was no significance in either BIC ratios or BA values among the groups. Conclusion: A CaPO4 coating on an anodized surface may induce rapid osseointegration at the bone-implant interface and more bone formation near the implant surface.