Histologic evaluation of early human bone response to different implant surfaces

Background: Studies have demonstrated that roughened dental implant surfaces show firmer bone fixation and an increased percentage of bone-to-implant contact (BIC%) compared to commercially pure titanium-surface (machined) implants. Therefore, the purpose of this study was to evaluate the influence of implant-surface topography on human bone tissue after 2 months of unloaded healing. Methods: Fourteen subjects with a mean age of 46.87 +/- 9.45 years received two microimplants each (2.5 mm in diameter and 6 mm in length), one test (sandblasted acid-etched surface) and one control (machined surface), either in the mandible or in the maxilla. After a healing period of 2 months, the microimplants and surrounding tissues were removed with a trephine bur and prepared for histologic analysis. Results: All microimplants, except for one of the controls, were clinically stable after the healing period. Histometric evaluation indicated that the mean BIC% was 23.08% +/- 11.95% and 42.83% +/- 9.80% for machined and rough microimplant surfaces, respectively (P = 0.0005). The bone area within the threads was also higher for sandblasted-surface implants (P = 0.0005). The mean percentage of bone density did not differ between the two groups (P = 0.578). Conclusion: Data from the present histological study suggest that the sandblasted acid-etched implant provides a better human bone tissue response than machined implants under unloaded conditions after a healing period of 2 months.