The influence of traumatic intrusion of primary teeth on their permanent successors in monkeys. A macroscopic, polarized light and scanning electron microscopic study.

Primary maxillary and mandibular central incisors were experimentally intruded on 13 monkeys, in order to examine changes of the enamel in the permanent successors. To study the effect of removal of the displaced tooth, the left primary incisor was extracted 1 h after the trauma, whereas that on the right was left in the jaw. Six weeks later the animals were sacrificed. Macroscopically, circumscribed areas of opacities on labial enamel were noted. The SEM examination showed that non-affected parts of enamel had reached anatomical form, whereas inhibition studies and microradiographs demonstrated that the maturation process was far from complete. Arrest of enamel maturation was noted as corresponding to the extent of the surface opacity. In the SEM small areas displaying rupture of the surface enamel were seen. No differences were observed either macroscopically or histologically in relation to immediate removal or preservation of the intruded primary incisor.