Effect of Orthodontic Treatment on Alveolar Bone Height

Objective: The aim of the present study was to evaluate the effects of orthodontic treatment on interproximal alveolar bone height in adolescents. Methods: Orthopantomograms from 40 patients (aged 11 to 17 years at the beginning of orthodontic treatment) were evaluated. Two calibrated examiners performed the evaluation, blinded to the name, age and moment of the radiographs. By means of a Schei ruler, the percentage of bone related to the root length was determined before and after fixed orthodontic treatment (which lasted at least 2 years). Comparisons between the final and initial bone height were made by frequency distribution of unaltered height, gains and losses of 10% and changes of 20% or more. A total of 1072 interproximal sites was analyzed. Wilcoxon rank sign test was used with an alpha level of 5%. Results: The results showed 53.9% of unaltered sites in terms of bone height, 29% of sites losing 10% and 3% losing 20% or more of bone height. Concerning positive alterations, 11.6% of the sites gained 10% and 2.5% gained 20% of more in bone height. All patients had unaltered values, gains and losses. Losses displayed statistically significant higher frequencies than gains. Losses of 10% of bone were significantly more frequent than the other alterations.Conclusion:It may be concluded that there is a limited, if existent and of clinical significance, loss of interproximal alveolar bone associated to orthodontic therapy.