[Deciduous tooth intrusions and the odontogenesis of the permanent teeth. Developmental disorders of the permanent teeth following intrusion injuries to the deciduous teeth].

Traumata to primary teeth occur very often in small children. The highest prevalence of developmental disturbances of permanent teeth after trauma to their predecessors has been recorded after intrusive injuries of primary teeth. In the present survey 47% of the recalled children had such developmental disturbances. The majority of developmental disturbances consisted of enamel hypoplasia (59%) which included discoloration, defects or a combination of both. In some cases the clinical feature of enamel defects could be diagnosed radiographically before tooth eruption. However, the total number of all enamel discolorations was to be detected after complete tooth eruption only. The so-called pre-eruptive calciotraumatic lines on radiographs corresponded clinically to circular enamel defects or crown dilacerations. Generally, a high correlation was found between the degree of intrusion (of the primary tooth) and the frequency and severity of developmental disturbance (of the permanent tooth). No correlation was found, however, concerning the treatment of intruded primary teeth and the occurrence of developmental disturbances. Whether intruded primary teeth were removed immediately or left to spontaneous re-eruption did not affect the incidence and type of developmental disturbances.