[Essential and iatrogenic gingival hyperplasia. Its morphology and significance]

11 specimens were carried out in patients with idiopathic gingival hyperplasia (3 cases), gravidic hyperplasia (1 case), iatrogenic hyperplasia (5 cases after cyclosporin A administrated in patients with cardiac grafts, 2 cases after treatment by Adalat). By optic microscopy, the deep collagen base is thickened, associated sometimes to an inflammatory process. By histoenzymology, the fibroblasts have high activities of their oxidative enzymes and also of the enzymes of protein synthesis. The electron microscopy corroborates the numerous globular fibroblasts with well-developed rough endoplasmic reticulum. These results prove the main role of fibroblasts in these lesions and the etiopathogenesis of this hyperplasia is discussed.