Effects of the XbowTM appliance on class II malocclusion in difference facial patterns

Abstract

The objective of this study was to determine skeletal and dental post-treatment changes in patients with different facial patterns treated with the XbowTM appliance. A retrospective sample of 38 subjects from a private orthodontic practice with Class II malocclusions were studied. The subject’s growth patterns were divided into mesocephalic, dolichocephalic and brachycephalic based on Y-axis and MPA pre-treatment values. Intra- and inter-examiner reliability of the cephalometric measurements were assessed using an interclass correlation coefficient (ICC) test. An analysis of variance (ANOVA) statistic was performed on the cephalometric variables being assessed to analyze skeletal and dental changes following treatment with the XbowTM appliance between the different facial patterns. The results demonstrated correction of Class II malocclusions with the XbowTM appliance owing to a reduction of the Class II skeletal relationship represented by a decrease in Wits appraisal (-2.88±2.88mm to -2.60±1.77mm, p<0.05) and ANB values (-1.86°±2.11° to -1.56°±2.10°, p<0.05), reduction in the SNA value for mesocephalic patients indicating a restrictive headgear effect (-2.01°±3.56°, p<0.05), mild to moderate amounts of proclination represented by IMPA (+1.89°±4.18° to +3.54°±6.29°, p<0.05) and major amounts of protrusion of the lower incisors represented by L1 to A-Po (+3.06±4.01mm to +5.78±5.31mm, p<0.05). Insignificant changes to the angulation and position of the maxillary incisors were found which also supported Class II dental correction. Conclusion drawn from this study are that most Class II correction in growing patients that are treated with the XbowTM appliance is owing to dental changes with minor amounts from skeletal changes. Clinicians should be aware that different growth patterns can produce variations in the presence and magnitude of skeletal and dental changes when treated with the XbowTM appliance.