The effect of toxic doses of 1,25-dihydroxycholecalciferol on dental tissues in the rat

Vitamin D-depleted rats 4-weeks old were divided into three groups and given daily for 5 weeks cholecalciferol (0.25 μg) or 1,25(OH)₂D₃ (0.075 μg). The third group received no treatment with vitamin D sterols. A fourth control group was fed a diet containing vitamin D. The animals were killed after 5 weeks, plasma was prepared for calcium analysis, and incisors and molars were taken for histology. Growth was monitored throughout. Plasma calcium, body weight and the physical condition of the 1,25(OH)₂D₃-treated animals indicated that they were toxaemic. The pulp-dentine complex of their incisors showed premature aging of fibroblasts and odontoblasts, disturbances in the dentinal matrix and osteodentine formation. That of molars was not affected. There was hypercementosis and bone-like tissue formation in the periodontal-ligament which in the incisors was considerably enlarged; some molars were ankylosed. The pulp-dentine complex of the incisors and molars of the rats in the remaining three groups appeared normal except for zones of hypomineralization in incisors of the third group. The supporting tissues of the teeth of the rats in the other three groups were within normal limits. Thus toxic doses of 1,25(OH)₂D₃ affected the dental tissues of both developing and mature teeth.