Cyclosporine-induced gingival overgrowth in beagle dogs.

Development of gingival overgrowth during daily long-term cyclosporine A treatment was studied in 2-yr-old beagles. Gingival enlargement developed in five of 12 dogs (42%), primarily in the mandibular anterior area. The earliest gingival changes occurred by 3 wk as an increase in the size of the interdental papillae. The lesions progressively became more severe, in some cases obscuring portions of teeth by wk 6. The redundant tissue exhibited an increase in connective tissue components and an inflammatory infiltrate primarily of plasma cells. Severity of the overgrowth varied in responding animals; both incidence and severity were related to the CSA concentration in blood. The mean CSA blood levels of responders were significantly greater than nonresponders at wk 3, 6 and 10. Since beagles develop gingival overgrowth similar to humans, they provide an excellent model to investigate the roles of local and systemic factors in the induction of gingival overgrowth.