Effect of timing on the outcomes of 1-phase nonextraction therapy of Class II malocclusion

Introduction: The aim of this cephalometric study was to evaluate the role of timing in relation to skeletal maturity on the outcomes of nonextraction comprehensive Class II therapy. Methods: Three samples of patients with Class II Division 1 malocclusion were treated with headgear combined with fixed appliances and Class II elastics. Lateral cephalograms were taken of all subjects before therapy (T1) and at an average interval of 6 months after therapy (T2). The first sample (23 subjects) was treated before the pubertal growth spurt, the second sample (24 subjects) received therapy during the pubertal growth spurt, and the third sample (13 subjects) was treated at a postpubertal stage of development. The average T1 to T2 interval was approximately 30 months for all patients, with an average treatment duration of 24 months. Longitudinal observations of a group of 17 subjects with untreated Class II malocclusions were compared with the treated groups at the 3 skeletal maturation intervals with nonparametric statistics. Results: Class II treatment before or during the pubertal growth spurt induced significant favorable skeletal changes (restricted maxillary advancement in prepubertal patients and enhanced mandibular growth in pubertal patients). Patients treated after the pubertal growth spurt had only significant dentoalveolar changes. Conclusions: The greatest amount of dentoskeletal correction of Class II malocclusion with 1-phase nonextraction treatment occurred in patients treated during the pubertal growth spurt. (Am J Orthod Dentofacial Orthop 2009;136:501-9)