Histopathology of the interactions between alveolar bone and impacted dental germs in osteopetrotic op/op rats.

Osteopetrosis, a general increase in bone density, is well-known as an autosomal recessive disease in several mammalian species. Compared with normal littermates, the osteopetrotic rats suffered from a complete failure of tooth eruption. Histologic and microradiographic studies show that the molars and the incisors developed a progressive ankylosis, the bone invades the germs and finally dissociates them. As early as the first days after birth, the incisors and the first molars are affected by the osteopetrotic process while the second and the third molars remain untouched. The periodontal membrane of the incisors is rapidly invaded by the osteopetrotic bone trabeculae. After the eleventh day, the process reached all molars. The germs were overlaid by an occlusal unresorbed bone. The formation of the gebernacular canal appeared to be independent of the prefunctional eruption.