External apical root resorption in patients treated by serial extractions followed by mechanotherapy

IntroductionIn the course of orthodontic treatment with serial extractions (SE), spontaneous unraveling of crowded incisors occurs. It was hypothesized that SE followed by mechanotherapy will cause less external apical root resorption (EARR) than orthodontic treatment with late extractions (LE).MethodsThe records of 24 patients who underwent SE and mechanotherapy and 24 control patients who underwent LE and mechanotherapy were examined. The groups were matched for sex, central incisor root development and morphology, malocclusion class, ANB angle, and overjet. Lateral cephalograms taken before mechanotherapy (T1) and after mechanotherapy (T2) were traced and superimposed on the palatal plane with registration on the osseous details superior to the maxillary incisors and on the palatal curve. The T1 and T2 central incisor lengths, changes in the axial inclination, and horizontal and vertical apical movements were measured.ResultsThe tooth lengths in both groups were reduced: the EARR values were 1.8 mm (± 1.1) in the SE group and 2.1 mm (± 1.4) in the LE group, and the difference between the groups was not significant. The movements of the teeth in both groups were similar in absolute values.ConclusionsThe spontaneous unraveling of incisor crowding with SE treatment does not prevent the common EARR seen in patients treated with LE, when the patients are treated by mechanotherapy after the SE.