ABSTRACT

Objectives

To compare the dental and skeletal treatment effects after total arch distalization using modified C-palatal plates (MCPPs) on adolescent patients with hypo- and hyperdivergent Class II malocclusion.

Materials and Methods

The study group included 40 patients with Class II malocclusion (18 boys and 22 girls, mean age = 12.2 ± 1.4 years) treated with MCPPs. Fixed orthodontic treatment started with the distalizing process in both groups. Participants were divided into hypo- or hyperdivergent groups based on their pretreatment Frankfort mandibular plane angle (FMA) ≤22° or ≥28°, respectively. Pre- and posttreatment lateral cephalograms were digitized, and 23 variables were measured and compared for both groups using paired and independent t-tests.

Results

The hyper- and hypodivergent groups showed 2.7 mm and 4.3 mm of first molar crown distalizing movement, respectively (P < .001). The hypodivergent group had a slight 2.2° crown distal tipping of first molars compared with 0.3° in the hyperdivergent group. After distalization, the FMA increased 3.1° and 0.3°, in the hypodivergent and hyperdivergent groups, respectively (P < .001). SNA decreased in the hypodivergent group, while other skeletal variables presented no statistically significant differences in the changes between the groups.

Conclusions

The hypodivergent group showed more distal and tipping movement of the maxillary first molar and increased FMA than the hyperdivergent group. Therefore, clinicians must consider vertical facial types when distalizing molars using MCPPs in Class II nonextraction treatment.

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Author notes

a

Resident, The Catholic University of Korea, Seoul, Korea.

b

Professor and Chair, Postgraduate Orthodontic Program, Arizona School of Dentistry & Oral Health, A.T. Still University, Mesa, Ariz, USA; and International Scholar, Graduate School of Dentistry, Kyung Hee University, Seoul, Korea.

c

Resident, Department of Orthodontics, Seoul St Mary's Hospital, The Catholic University of Korea, Seoul, Korea.

d

Professor, Department of Orthodontics, Seoul National University Bundang Hospital, Seongnam, Korea.

e

Associate Professor and Chair, Department of Orthodontics, Seoul St Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.

f

Professor, Department of Orthodontics, Seoul St Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.