title: Quantitative histopathologic assessment of developing phenytoin-induced gingival overgrowth in the cat.
abstract: Phenytoin (Dilantin) induces gingival overgrowth characterized by an accumulation of connective tissue The cell-to-matrix ratio in the mature lesion is normal, yet there must be more fibroblasts per oral cavity if there is excessive tissue mass. Using a mongrel cat model system, we studied the early, developing phenytoin-induced lesion by quantitating fibroblasts per unit of tissue in papilla biopsies collected over a 3-month period of daily drug administration. At 6 and 8 weeks, the number of fibroblasts per unit of tissue increased dramatically. By 3 months, as the lesions matured, the fibroblast-to-matrix ratio returned to normal. We suggest that the drug interacts with resident gingival fibroblasts, causes them to proliferate and thus induces a true, but transient, hypercellularity. Cell division then appears to slow or cease, and rapid production of connective tissue matrix ensues, returning the cell-to-matrix ratio to normal.
mesh_terms: D000818:Animals; D002415:Cats; D003238:Connective Tissue / Q000187:drug effects; D004195:Disease Models, Animal; D005260:Female; D005347:Fibroblasts / Q000187:drug effects; D005881:Gingiva / Q000473:pathology; D005885:Gingival Hyperplasia / Q000139:chemically induced / Q000473:pathology* / Q000503:physiopathology; D008297:Male; D010672:Phenytoin / Q000009:adverse effects* / Q000031:analogs & derivatives* / Q000494:pharmacology; D013997:Time Factors
chemical_list: C001419:hydroxyphenytoin; D010672:Phenytoin