Treatment effects of R-appliance and Fränkel-2 in Class II division 1 malocclusions.

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.

Class II malocclusion division 1: a new classification method by cephalometric analysis.

AIM: The purpose of this study was to analyse the craniofacial and dentofacial skeletal characteristics in untreated subjects with Class II, division 1 malocclusion by mandibular retrusion and to identify different types and their prevalence. MATERIALS AND METHODS: In 152 subjects with Class II, division 1 malocclusion by mandibular retrusion, the differences were determined by lateral cephalograms analysis of variance and chi-square test, respectively. P<0.05 was considered significant. Seven types of mandibular retrusion were identified: three pure, dimensional, rotational and positional, and four mixed. RESULTS: All patients showed significant inter-group differences with P between 0.005 and 0.001. The dimensional type was the most common (28.9%) and the rotational-positional type was the rarest (5.9%). The pure dimensional type had the shortest mandibular body; the pure rotational type had larger SN/GoMe and the lowest AOBO; the pure positional type presented the flattest cranial base, high AOBO. In the mixed types, dento-skeletal features changed depending on how the main types assorted. CONCLUSIONS: Identifying the type of mandibular retrusion is important for differential diagnosis in clinical practice and research.

Unilateral posterior crossbite in adolescents: surface electromyographic evaluation.

AIM: Unilateral posterior crossbite (UPCB) is characterised by an inverse relationship of the upper and lower buccal dental cusps and may involve one or several teeth. The aim of this study was to compare the electromyographic outcomes of patients with UPCB and those of healthy controls. MATERIALS AND METHODS: Fifteen patients (mean age 11.5 years) with UPCB and fifteen healthy controls (mean age 12 years) were examined at the Department of Orthodontics, Second University of Naples. Surface electromyography was performed on patients and controls. RESULTS AND CONCLUSION: Patients with UPCB had less muscle activation than healthy subjects (p<0.0001) and an asymmetric muscle activation with 89.23% muscle balancing for temporals and 83.21% for masseters. The control group showed a 99.32% of muscle balancing for temporals and 97.77% for masseters. These findings suggest that asymmetric muscle activation may influence maxillary and mandibular growth in adolescents with UPCB.