Skeletal-unit growth in the mandible of rats given diphenylhydantoin.

With the purpose of studying the effect of diphenylhydantoin on mandibular skeletal-unit growth, 28 male Wistar rats weighing 60.0 +/- 0.8 g were assigned to five different groups. One group received saline serving as normal controls; three others were injected intra peritoneally once daily with either 25, 50 or 100 mg/kg body wt diphenylhydantoin for 30 days; the fifth group was put on a restricted diet (20% below normal intake) for the same time. On day 31, the rats were killed by ether overdose and their mandibles were evaluated for differential skeletal-unit growth. Body-weight gain of diphenylhydantoin-injected rats was up to 24% less than controls, regardless of drug dose. Diet-restricted rats showed a similar difference. The amount of food consumed by diphenylhydantoin-injected rats was 21% less than that consumed by controls, regardless of drug doses. The concentration of alkaline phosphatase and haemoglobin in rats treated with 50 or 100 mg/kg diphenylhydantoin was lower than in controls and diet-restricted rats. However, plasma urea and total calcium were similar in diphenylhydantoin-treated rats and controls. Mean appetite quotient, and the efficiency of protein and energy utilization, did not appear to change in response to the particular diphenylhydantoin dose or to the restricted diet. Mandibular dimensions of rats injected with 25 or 50 mg/kg diphenylhydantoin were not statistically different from those of the control and diet-restricted groups. With using 100 mg/kg diphenylhydantoin for 30 days, the growth of symphysial and basal heights, condylar and angular lengths and condylar width was significantly less than in the control and diet-restricted groups. The remaining mandibular skeletal units did not exhibit significant differences from those of control and diet-restricted rats. The disharmonious growth of the mandible does not appear to depend on suboptimal energy intake, efficiency of protein-energy utilization, renal failure and anaemia, but would suggest a differential toxicological effect of diphenylhydantoin on the osseous component and/or its associated non-skeletal tissues.