Diphenylhydantoin (dilantin) gingival hyperplasia: drug-induced abnormality of connective tissue.

Various degrees of gingival overgrowth may occur in individuals taking diphenylhydantoin, a drug used widely in the treatment of epilepsy. The tissue overgrowth is made up predominantly of collagen, and may therefore be a useful model for analysis of fibrosis and some other connective tissue abnormalities. Fibroblasts derived from the overgrown tissue exhibit a level of protein synthetic activity approximately twice that of comparable cells obtained from nonepileptic control individuals and from the gingiva of age-matched epileptics taking the drug but not exhibiting gingival enlargement. In addition, 20% of the protein synthesized by cells from the affected tissue is collagen, whereas collagen accounts for only about 11% of the total protein produced by control cells of both types. The drug appears to induce or select for fibroblasts characterized by enhanced levels of protein synthesis and collagen production. This alteration persists through several cell replications in vitro in the absence of drug.