The effects of diphenylhydantoin and vitamin D deficiency on developing teeth in the rat.

The effects of short-term (21 days) and long-term (116 days) treatment with oral diphenylhydantoin (DPH, 6 g/kg diet) on the development of rat teeth was investigated. Long-term DPH reduced the size of the incisors and of all the molars except the upper first. There was also a reduction in tooth weight and both changes were shown to be independent of body weight. Short-term DPH reduced the size of the incisors and upper third and second molars only.The relationship of these lesions to the shortened tooth roots found in epileptics on chronic anticonvulsant therapy and the stunted root development seen in hypoparathyroidism is discussed. It is suggested that DPH may induce a state of “pseudohypoparathyroidism” by inhibiting the action of parathyroid hormone on bone and tooth. This complication would appear to be additional to the so-called “anticonvulsant-induced osteomalacia”.