Effects of three-dimensional bimetric maxillary distalizing arches and cervical headgear on dentofacial structures

The aim of this study was to compare the dentofacial effects of an intraoral technique, the three-dimensional bimetric maxillary distalizing arch (3D-BMDA), with an extraoral technique, cervical headgear (CH), in subjects requiring maxillary molar distalization. Twenty-one patients (12 females, 9 males; mean age at the start of treatment: 14.7 years) were treated with 3D-BMDA and 18 subjects (11 females, 7 males; mean age at the start of treatment: 13.3 years) with CH. Since the treatment period was longer in the CH group, the results for this group were also compared with a separate 'untreated' control group of 17 subjects (12 females, 5 males; mean age at the start of observation: 13.1 years). The measurements were carried out on lateral cephalometric radiographs which were taken at two time points (T(1): start of treatment/control, T(2): end of molar distalization/control). Paired t-tests were performed within, and analysis of variance to determine the differences between the groups. The total amount of distalization for the 3D-BMDA and CH was similar (3.55 and 4.56 mm, respectively). However, there were statistically significant differences in the total treatment period (3.4 and 10.2 months, respectively) and the monthly amount of distalization (1.11 and 0.55 mm, respectively). The 3D-BMDA system did not have a significant effect on mandibular rotation (an increase of 0.01 degrees), while the CH group showed a mean posterior rotation of the mandible of 1.08 degrees. The most significant differences between the two maxillary first molar distalization techniques were observed in the mandibular dental arches. Moderate anchorage loss in the mandibular dental arch was observed in the 3D-BMDA group. While the 3D-BMDA and CH techniques are both effective in distalizing maxillary molar teeth, the distalization time and rate of molar movement were significantly shorter with the 3D-BMDA than the CH.