RESUMO
AIM: The purpose of this study was to compare the effects of a differently designed functional appliance (the R- appliance) with Fränkel-2. STUDY DESIGN: Twenty-seven patients (16 girls and 11 boys) with a mean age of 9.8 (SD 1.6) years were treated with the R-appliance for 15.4 (SD 0.4) months and twentyseven (15 girls and 12 boys) patients with a mean age of 9.1 (SD 1.1) years were treated with a Fränkel-2 appliance for 19 (SD 5.6) months. All patients had Class II division 1 malocclusions due to mandibular deficiency and all of them had prepubertal stages of skeletal development. Lateral cephalograms obtained at the beginning (T1) and at the end (T2) of the study were analysed. RESULTS: Paired t-tests showed that SNB significantly increased in both groups. The incisor mandibular plane angle (IMPA) was reduced in the R- appliance group by 2.2 (SD 4.9) degrees (P<0.03) but increased by 2.2 (SD 2.6) degrees (P<0.001) in the Fränkel-2 group. The SNA in the R-appliance group showed an increase of 0.2 (SD 2) degrees (P<0.6), while it was decreased by 0.4 (SD 0.5) degrees (P<0.6) in the Fränkel-2 group. CONCLUSIONS: Both treatment modalities were successful in moving the mandible forward. However, with the R-appliance, this was achieved without proclination of the lower incisors.
