Morphometric evaluation of gingival overgrowth and regression caused by cyclosporin in rats

Cyclosporin A is a selective immunosuppressant, used in organ transplants t o prevent graft rejection. Cyclosporin A can cause various side effects inc luding gingival overgrowth. The aim of this work was to evaluate gingival o vergrowth of rats treated daily with 10 mg/kg body weight of cyclosporin A for 60 days, as well as the regression after the interruption of treatment. All rats treated with cyclosporin A developed gingival overgrowth, with in creased thickness of the epithelium, height and width of the connective tis sue. The density of fibroblasts and collagen fibers also increased. Five to 90 days after the interruption of treatment with cyclosporin A, there was a progressive reduction of the gingival volume and of collagen fibers and f ibroblast densities. The reduction was more pronounced in the initial perio ds and after 90 days did not return to the normal values.