Idiopathic gingival hypertrophy--a morphological study and a review of literature

Gingival overgrowth occurs as a response to several drugs, in some systemic diseases, as a consequence of a genetic predisposition or could be idiopathic, the last being less studied. Independently of the etiological factor involved, histological changes are maintained and intensified by the presence of the bacterial plaque.

Fibrotic mucosa clinically diagnosed with idiopathic hypertrophy was included in paraffin and studied using usual histological stains and immunohistochemical techniques for vimentin, MMP-3 and TIMP-2.

Evaluation of histological changes revealed an unspecific pattern like the thickening of the epithelium, with acanthosis and acantholysis and massive deposition of connective tissue in the lamina propria. Keratinocytes from the areas with acantholysis express MMP-3. In the fibrous areas we noted few fibroblasts and a discrete expression of MMP-3. Extended areas of inflammatory tissue with numerous de novo capillaries were observed among the collagen bundles. Proinflammatory and endothelial cells expressed both MMP-3 and TIMP-2. The last antibody had an intense expression deeper in the epithelium. Our results were discussed in accordance with reference data.

We conclude that the histological changes observed were not specific for the idiopathic gingival hypertrophy and the imbalance of tissue homeostasis was due to the interaction between keratinocytes and connective cells in the milieu of specific changes induced by the inflammatory conditions.