The effect of an immunosuppressive therapy and its withdrawal on bone healing around titanium implants. A histometric study in rabbits

Background: Immunosuppressive agents have been recognized as a factor affec ting bone metabolism. We investigated the consequences of the administratio n and withdrawal of cyclosporin A/nifedipine on bone around titanium implan ts to observe whether these changes occur and if they are reversible. Methods: Twenty-eight New Zealand rabbits were included in the study. Follo wing anesthesia, the tibiae surface was exposed, and 2 screw-shaped implant s 7.0 mm in length and 3.75 mm in diameter were placed bilaterally. The ani mals were randomly assigned to 1 of 4 experimental groups and received dail y subcutaneous injections for 14 days: groups A and C were injected with ve hicle while groups B and D received cyclosporin A (10 mg/kg) plus nifedipin e (0.5 mg/kg). Groups A and B were sacrificed 14 days and groups C and D 42 days postoperatively. The degree of bone contact with the implant surface and the bone area within the limits of the threads of the implant were meas ured. Results: Intergroup analysis revealed no significant difference (P >0.05) i n the degree of bone contact with the implant surface between the control a nd test groups on days 14 and 42. In contrast, the treated animals demonstr ated a significant (P <0.05) decrease in the bone area within the limits of the threads of the implant in both periods. Conclusions: The data of the present study suggest that the use of cyclospo rin A/nifedipine may influence bone healing around titanium implants. This observation may have important clinical implications.