THE EFFECT OF PROPYLTHIOURACIL ON THE DEVELOPMENT OF MOLAR TEETH OF RATS

¹ Division of Dental Research, University of Toronto, Toronto, Canada

Rats were given daily subcutaneous injections of a 0.1 per cent solution of 6-n-propyl-2-thiouracil in 0.9 per cent saline solution beginning the day after birth. Littermate controls received 0.9 per cent saline solution by the same route and in equivalent amounts.

Animals were sacrificed in pairs, an experimental rat and its control at 5, 10, 15, 20, and 25 days of age.

Grenz ray pictures were made of one half the mandible of each specimen, and histologic sections were made of the developing molar teeth.

The following observations were recorded:

1. Cretinism occurred in each of the rats that had received the drug.

2. Retardation in development of the mandible was apparent in the grenz ray at 10 days of age.

3. At 15 days the odontogenic end of the mandibular incisor in each of the treated rats was farther forward in relation to the third molar than it was in the controls.

4. Retardation, but not cessation, of each of the processes associated with tooth development occurred.

5. By 10 days cancellous bone in the mandibles of the thiouracil-treated rats appeared denser than in the controls. This was apparent histologically and by grenz ray examination, and the difference increased with age to 25 days.