A Pilot Histologic Comparison of Bone-to-Implant Contact Between Phosphate-Coated and Control Titanium Implants in the Canine Model

Purpose: This study tested the null hypothesis that phosphate-treated titanium implants would perform no differently on mineral apposition rates (MARs), new bone-to-implant contact (new BIC), and total bone-to-implant contact (total BIC) compared to standard titanium implants. Materials and Methods: Forty 3.3 × 8.0-mm titanium implants, either phosphate-treated or untreated, were placed in the mandibles of five foxhounds following 6 weeks of postextraction healing. The untreated implants (control) had sandblasted, acid-etched (SLA) surfaces, while the treated implants were electrolytically phosphorylated at 50 volts (T50) or 100 volts (T100). Confocal and histologic analyses were performed on all the implants after 4 weeks of healing. Results: The MARs could not be analyzed due to a lack of delineation between the three bone markers. New BIC results for control implants ranged from 6.0% to 56.0% with a mean of 23.92% and standard deviation (SD) of 13.29%; T50 implants ranged from 8.0% to 43.0% with a mean of 22.29% and SD of 10.26%; and T100 implants ranged from 0.0% to 47.0% with a mean of 17.43% and SD of 11.40%. Total BIC results for control implants ranged from 8.0% to 68.0% BIC with a mean of 41.4% and SD of 19.3%; T50 implants ranged from 21.0% to 65.0% with a mean of 43.7% and SD of 15.2%; and T100 implants ranged from 5.0% to 68.0% with a mean of 38.0% and SD of 19.5%. Conclusion: Within the limitations of this pilot study, no significant differences in new BIC or total BIC were found between the three implant groups (C, T50, and T100). Given the very large sample size required to show clinically significant differences, phosphated surfaces do not appear to provide additional advantages to SLA surfaces. Keywords: acid-etched, BIC, phosphate, titanium