Rate of infraposition of reimplanted ankylosed incisors related to age and growth in children and adolescents.

In growing individuals, infraposition of a reimplanted, ankylosed tooth may disrupt normal alveolar development and compromise prosthetic treatment. The aims of this study were to analyze the rate of infraposition of ankylosed incisors in growing subjects and to provide guidelines for the timing of extraction. The subjects comprised 30 boys and 12 girls, selected consecutively from patients on annual post-trauma follow-up, and observed for periods ranging from 1 to 10 years. Only patients with one replanted ankylosed maxillary central incisor were included, the homologous teeth with healthy periodontal ligaments serving as controls. Growth intensity was evaluated from analyses of annual body height measurements. The following four periods were established: before the growth spurt, from initial to maximal growth spurt, from maximal growth spurt to the end and after the growth spurt. In 11 patients, cephalograms were taken at diagnosis and at extraction. Progression of infraposition varied individually. Diagnosis before the age of 10 or before the growth spurt was associated with very high risk of severe infraposition. In these cases the ankylosed tooth should be removed within 2-3 years. If ankylosis develops during the growth spurt, the tooth should be monitored regularly, but no intervention is indicated provided the adjacent teeth do not tilt and infraposition is minor or stable. Annual body height measurements, indicating the intensity of skeletal growth, are an aid to assessment. Cephalometric radiographs are important for evaluating the direction of growth of the jaws since there is a difference between horizontal and vertical growers.