Traumatic intrusion of primary teeth and its effects on the permanent successors: a clinical follow-up study.

Objective: Owing to the anatomic proximity between the root of the primary tooth and its permanent successor, trauma to primary dentition may cause developmental disturbances in unerupted permanent teeth.
Study Design: This report presents the findings of a prospective 7-year study examining developmental disturbances of permanent teeth attributed to intrusive injury of their primary predecessors based on initial patient records and clinical observation. Intrusive injuries were diagnosed and grouped according to World Health Organization classifications, as modified by Andreasen et al.
Results: A total of 78 children (aged 12-48 months) presenting with intrusive trauma to 138 primary incisors were available for follow-up examinations. The most frequently intruded primary teeth were maxillary incisors (93.47%), with the right central primary incisor representing 41.3% of all intruded teeth. In 23 patients, 36 teeth were scheduled for extraction during the first visit. During the course of follow-up, 41 of the remaining teeth exhibited post-traumatic consequences, including pulp necrosis (78.0%), internal and/or external root resorption (14.6%), ankylosis (4.9%), and obliteration of the pulp canal (2.5%). In 74 permanent successors (53.6%), >or=1 of the following developmental disturbances were observed: enamel hypoplasia (28.3%), crown and/or root deformation (16.7%), and ectopic eruption (16.7%).
Conclusion: There was no significant correlation between age of intrusion and frequency of subsequent developmental disturbances (P > .05).