Collagen synthesis in idiopathic and dilantin-induced gingival fibromatosis

Gingival fibromatosis is an uncommon but benign oral disease which causes progressive and non-hemorrhagic enlargement of the gingiva. There are two types of gingival fibromatosis: idiopathic gingival fibromatosis (GF), which is of unknown cause and may be associated with hereditary factors, and drug-induced gingival fibromatosis which is caused primarily by phenytoin intake. In cases of gingival fibromatosis, either the teeth are delayed in emergence or most of the crowns are embedded in the soft tissue even after full eroption. The objective of this study was to examine the basis of excess collagen formation in the two types of gingival fibromatosis in four patients admitted to the dental clinic at Kaohsiung Medical College Hospital, Kaohsiung, Taiwan. There were two male patients, aged ten (Case 1) and sixteen (Case 2), with idiopathic gingival fibromatosis and hypertrichosis, and two female patients, aged sixteen (Case 3) and eleven (Case 4), with Dilantin-induced gingival hyperplasia (DGH). Cultures of gingival fibroblasts were established either from clinically excised hyperplastic tissues or from pre-orthodontic surgical normal gingiva. The synthesis of collagen and levels of prolyl hydroxylase, a key enzyme in collagen synthesis, were examined in the healthy and affected fibroblasts. Our studies showed that after two days in culture, fibroblasts from all four patients multiplied faster than healthy gingival fibroblasts, though the amount of DNA and protein per cell remained unchanged. In addition, all cultures (except Case 1) had a 2- to 3- fold increase of prolyl hydroxylase activity over that of the controls. As in the cases of prolyl hydroxylase activity, Case 1 did not show any change in collagen synthesis when compared to the control. However, Cases 2, 3, and 4 showed appreciable collagen increases in the cell and medium: 61% and 60% for Case 2; 16% and 36% for Case 3; and 21% and 80.7% for Case 4 respectively.