Factors affecting the duration of orthodontic treatment in children. A retrospective study.

Factors that affect the duration of orthodontic treatment in children were studied from treatment records, dental and cephalic radiographs, and dental plaster casts of a random sample of 93 orthodontic patients who were treated during the period 1983-1994 and were aged 7 to 13 years at the start of treatment. The duration of treatment and 15 variables describing the patients' age at the start of treatment, the gender distribution of the patients, the progress of treatment, the occlusal status, skeletal deviations, malocclusion classes (Angle), and patients' age at the start of treatment, were recorded. The data were analysed by means of analysis of variance, chi-square test, and multiple regression analysis. The mean treatment time was 2.9 years. The regression analysis revealed that the variations in sex variables, malocclusion class, patients' age at the start of treatment, type of appliances used, number of appliances used, number of missed appointments, and main additional diagnosis explained about 41% of variation in treatment time. Treatment of Class I and Class II/1 patients with combinations of fixed and removable appliances, early start, high number of appliances used, and high number of missed appointments prolonged the duration of treatment. Treatment of Class I patients with frontal crossbite was relatively short.