Evaluation of maxillary protraction and fixed appliance therapy in Class III patients

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Abstract

The aim of this study was to examine the dentofacial changes in Class III patients treated with fixed appliances subsequent to rapid maxillary expansion (RME) and facemask therapy. The material consisted of the cephalograms and hand-wrist films of 14 (9 girls, 5 boys) skeletal Class III and 15 (10 girls, 5 boys) untreated subjects obtained at the beginning of treatment/observation (T1), immediately after orthopaedic therapy (T2), and at the end of the observation period (T3). The mean pre-treatment/control ages were approximately 11.5 years and the observation period was 3 years (T2–T1: 1 year, T3–T2: 2 years). The cephalometric films were analysed according to the structural superimposition method of Björk. All tracings were double-digitized and the measurements were calculated by a computer program. Intragroup changes and intergroup differences were statistically analysed.

Forward movement of the maxilla (P < 0.01), backward movement and rotation of the mandible, an increase in the ANB angle (P < 0.001), lower face height and overjet (P < 0.001), a decrease of overbite, and an improvement in the sagittal lip relationship (P < 0.01) presented significant intergroup differences between T2 and T1. During the second phase of treatment (T3–T2), although not statistically significant, forward movement of the maxilla was less than in the control subjects. Overall changes during the observation period (T3–T1) revealed that correction was mainly due to favourable changes in the mandibular and dentoalveolar components of the discrepancy, while these in maxillary position were not different from the control group. The soft tissue profile improved significantly (P < 0.001) in the treatment group. Comparison with the Class I controls at the end of the observation period confirmed that some Class III characteristics still remained in the treated patients.

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