Experimental Effects of Thiouracil and Selenium on the Teeth and Jaws of Dogs

Abstract

References are to be found in the literature pertaining to toxic effects of thiouracil when it is used clinically; similarly, Se is reported to be toxic when it occurs in the soil and vegetation, as is the case in certain western states. No published accounts of exptl. work have been found relating either of these substances to possible oral manifestations. In this study, dogs of the same litter were treated with the following doses, per kg. of body wt., respectively 25 mg. organic Se, 5 mg. organic Se, and 5 mg. thiouracil. Changes observed in the dentition and jaws were: Hypoplasia of enamel in a thiouracil-treated dog; structural defects of dentin in dog receiving large dose Se; structural changes in mandibular supporting bone in both of these dogs; and marked variation in the size and shape of mandibular condyles of all treated dogs, with early discontinuation of condylar bone formation in Se-treated dogs. Both thiouracil and Se are believed to have an inactivating effect on enzymes concerned with metabolic processes. It may be through endocrine disturbances that these substances effect tooth development, however, it is also possible that the structural and gross defects noted are due to direct toxic effects. The gross lesions noted in these dogs are not unlike those found experimentally in thyroidectomy or in the human cretin. Histologically, sections show lesions that are similar to those found in nutritional disorders or in diseases which are essentially of a metabolic or endocrinological nature.