Treatment effects after maxillary total arch distalization using a modified C-palatal plate in patients with Class II malocclusion with sinus pneumatization

The purpose of this study was to evaluate the treatment effects after molar distalization using modified C-palatal plates in patients with Class II malocclusion with maxillary sinus pneumatization.This study consisted of 70 lateral cephalograms derived from cone-beam computerized tomography images of 35 patients with Class II malocclusion (mean age 22.3 ± 7.4 years) who had undergone bilateral total arch distalization of the maxillary dentition using modified C-palatal plates. The samples were divided into 2 groups according to sinus pneumatization; group 1 (n = 40), cephalograms with sinus pneumatization and group 2 (n = 30) cephalograms without sinus pneumatization. Paired t tests and independent-sample t tests were used to compare the changes in each group and between groups.The distal movement of the maxillary first molars was 4.3 mm for group 1 and 3.5 mm for group 2, with the intrusion of 1.4 mm and 2.5 mm, respectively. There was no statistically significant difference between the 2 groups. Group 1 showed 3.5° of distal tipping of the maxillary second molars, which was significantly greater than the 0.2° in group 2 (P <0.05). The total treatment period, including distalization, was 2.2 years for group 1 and 1.9 years for group 2, but the difference was not significant.There was no significant difference in the amount of distal movement and intrusion of the maxillary first molars between groups 1 and 2. Therefore, these results suggest that regardless of sinus pneumatization, molar distalization using temporary skeletal anchorage devices in Class II patients can be performed as a nonextraction treatment.