Objectives: To investigate the prevalence and amount of root resorption after six months of active orthodontic treatment with fixed appliances and study the correlation of root resorption with risk factors.
Materials and Methods: One hundred patients, with an age range from nine to eighteen years diagnosed as Class I malocclusion with crowding and a treatment plan including full fixed appliance in both jaws and four premolar extractions were examined with Cone Beam Computed Tomography before treatment and after six months of active treatment. One to two exposures, each covering a volume of 6x6 cm were performed and all teeth from incisors to first molar, bilateral and in both jaws were included. An index (Malmgren et al 1982) was used to evaluate the degree of root resorption (0-4). Registrations of predisposing factors were made by a specially designed questionnaire.
Results: Minor resorption was noted in 8%. Severe root resorption more than 2 mm was found in 3 patients and one case was diagnosed as borderline between index 2 and 3. Root resorption was seen more frequently in the upper jaw and especially the lateral incisors.
There were no statistically significant correlations of root resorption with any of the predisposing factors.
Conclusions: After six months of active treatment, clinically significant root resorption was diagnosed in 3-4 per cent of the patients. The presence of what traditionally is considered as predisposing factors for root resorption does not have any impact on the amount of resorption after 6 months of active treatment.