While increased biological/biomechanical results have been observed at 3 and 5 weeks for Plasma Sprayed Hidroxyapatite (PSHA) coated implants in preliminary studies, their long term survival rates have been a concern due to the weak bonding between coating and metallic substrate. Objective: Evaluate the biological/biomechanical response of PSHA-coated versus alumina-blasted/acid-etched (AB/AE) implants at 8 and 15 weeks in a canine model. Materials and Methods: Six beagle dogs received three implants per femur which remained for a period of 8 and 15 weeks in vivo. Oxytetracycline and Calcein-green were administered at 10 and 2 days prior to euthanization for mineral apposition rate (MAR) determination. After euthanization, the implants were exposed and subjected to torque testing in a universal testing machine. Torque, MAR, and % bone to implant contact (BIC) were evaluated as a function of implant surface and time in-vivo by ANOVA. Results: Time in-vivo did not have a significant effect on BIC and torque values. The torque values obtained were 34.92±9.15a N.cm for PSHA and 47.31±9.15a N.cm for AB/AE (P>0.055). BIC values were 69.13±13.88a % for PSHA and 60.76±15.35a % AB/AE (P>0.37). MAR values were 2.34±0.07a μm/day for AB/AE and 1.96±0.06b μm/day for PSHA (P<0.0001). MAR values were 2.02±0.09a μm/day for 8 weeks in-vivo and 2.28±0.07b μm/day for 15 weeks in-vivo (P<0.0001). Conclusion: Despite higher BIC values presented for PSHA-coated implants, a weak bioceramic-metallic interface was indicated by lower torque values. MAR values showed that an increase in bone kinetics occur for AB/AE implants at a later time compared to bone around PSHA implants (peaks at 3-5 weeks).

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