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

Abstract

Immunosuppressive agents have been recognized as a factor affecting bone metabolism. We investigated the consequences of the administration and withdrawal of cyclosporin A/nifedipine on bone around titanium implants to observe whether these changes occur and if they are reversible. Twenty-eight New Zealand rabbits were included in the study. Following anesthesia, the tibiae surface was exposed, and 2 screw-shaped implants 7.0 mm in length and 3.75 mm in diameter were placed bilaterally. The animals were randomly assigned to 1 of 4 experimental groups and received daily subcutaneous injections for 14 days: groups A and C were injected with vehicle while groups B and D received cyclosporin A (10 mg/kg) plus nifedipine (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 measured. Intergroup analysis revealed no significant difference (P > 0.05) in the degree of bone contact with the implant surface between the control and test groups on days 14 and 42. In contrast, the treated animals demonstrated a significant (P < 0.05) decrease in the bone area within the limits of the threads of the implant in both periods. The data of the present study suggest that the use of cyclosporin A/nifedipine may influence bone healing around titanium implants. This observation may have important clinical implications.