Objective: To determine the magnitude of the skeletal and dental movements in subjects with different facial patterns following Class II correction using the XbowTM appliance. Materials and Methods: A retrospective sample of 134 subjects exhibiting Class II malocclusions was used. Subjects were categorized into three growth types according to pre-treatment cephalometric variables (MPA and Y-axis), which yielded 27 brachycephalic, 70 mesocephalic, and 37 dolichocephalic subjects. A ANOVA test statistic was used to investigate the differences between the three facial groups at pre and post-treatment time points. Results: Dental changes induced by the XbowTM appliance included: proclination of the lower incisors (L1-MP 7.3-12.3o±1.0o), protrusion of the lower incisors (L1-APo 2.1-3.8mm±0.3mm), mesial movement of the mandibular first molar (5.5-6.9mm±0.7mm) and retrusion of the maxillary incisor (2.4-3.1mm±0.4mm). Retroclination of the maxillary incisor (U1-PP 0.2-0.8o±0.7o) and distal movement of the maxillary molar (0.4-0.7mm±0.3mm) were not significantly influenced by XbowTM treatment. Reduction of the skeletal Class II relationship was represented by a significant decrease of the Wits value (2.4-4.5mm±0.5mm) in all three groups. The p value was considered significant at <0.05. Conclusions: Class II correction with the XbowTM appliance is the result of mesial movement of the mandibular molar, proclination/protrusion of the lower incisor and retrusion of the upper incisor. Skeletal correction must be validated by more than one cephalometric variable. Facial growth pattern appears to be unrelated to the amount of dental movement and there is a trend for pronounced dental movements of the lower incisor in brachycephalic patients.

Objective: To determine the magnitude of the skeletal and dental movements in subjects with different facial patterns following Class II correction using the XbowTM appliance. Materials and Methods: A retrospective sample of 134 subjects exhibiting Class II malocclusions was used. Subjects were categorized into three growth types according to pre-treatment cephalometric variables (MPA and Y-axis), which yielded 27 brachycephalic, 70 mesocephalic, and 37 dolichocephalic subjects. A ANOVA test statistic was used to investigate the differences between the three facial groups at pre and post-treatment time points. Results: Dental changes induced by the XbowTM appliance included: proclination of the lower incisors (L1-MP 7.3-12.3o±1.0o), protrusion of the lower incisors (L1-APo 2.1-3.8mm±0.3mm), mesial movement of the mandibular first molar (5.5-6.9mm±0.7mm) and retrusion of the maxillary incisor (2.4-3.1mm±0.4mm). Retroclination of the maxillary incisor (U1-PP 0.2-0.8o±0.7o) and distal movement of the maxillary molar (0.4-0.7mm±0.3mm) were not significantly influenced by XbowTM treatment. Reduction of the skeletal Class II relationship was represented by a significant decrease of the Wits value (2.4-4.5mm±0.5mm) in all three groups. The p value was considered significant at <0.05. Conclusions: Class II correction with the XbowTM appliance is the result of mesial movement of the mandibular molar, proclination/protrusion of the lower incisor and retrusion of the upper incisor. Skeletal correction must be validated by more than one cephalometric variable. Facial growth pattern appears to be unrelated to the amount of dental movement and there is a trend for pronounced dental movements of the lower incisor in brachycephalic patients.