Skeletal Class II Malocclusion: Growth Modification vs Non-Growth Modification- A CBCT Study

Degree type
Master of Science in Oral Biology (MSOB)
Graduate group
Discipline
Dentistry
Subject
Orthodontics
Skeletal Class II Malocclusion
Growth Modification
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Copyright date
2024-06-25
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Author
Brianna Tucker, DDS, MHS
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Abstract

Abstract Objectives: To compare the skeletal, dentoalveolar, and soft tissue changes in Class II patients treated with Herbst or Pendex appliances using 3D cone beam computed tomography (CBCT) imaging. Materials and Methods: In Aim 1 the sample population comprised 23 Herbst patients (12.07 ± 1.49, 12 M/11F) and 23 Pendex patients (11.76 ± 1.18, 10 M/13 F). For Aim 2, 48 Pendex patients (10.61 ± 1.70, 30F/18M) were included. In Aim 3, the sample population comprised 20 Herbst (11.91 ± 1.49; 11F and 9M) and 20 Pendex (11.76 ± 1.23; 10F and 10M). Lateral cephalograms were extracted from CBCTs taken at three time points: initial (T1), 6 months after appliance removal (T2, Herbst) or immediately after appliance removal (T2, Pendex) and final (T3) and tracings were completed at each time point. To compare the soft tissue changes, profile silhouette images were generated from T1 and T3 lateral cephalograms. A survey was distributed to examiners, including 9 orthodontic faculty (7M/2F), 11 postgraduate orthodontic residents 2M/9F), 11 predoctoral dental students (5M/6F), and 12 laypersons (6M/6F). After a normality test, treatment outcomes across the three time points were compared using either ANOVA with Scheffe's posthoc test or non-parametric Friedman tests with Dunn's test. The two treatment modalities were compared using a 2-tailed unpaired t-test or non-parametric Mann-Whitney test (p < 0.05). Results: Aim 1: Changes in mandibular size and sagittal position were similar in both groups while ANB, Wits and overjet decreased significantly more in the Herbst group. Aim 2: Significant maxillary molar distalization of over 4 mm was observed and there were no significant changes in the lower anterior facial height or vertical dimension. Aim 3: The perceived improvement in the soft tissue profile was more significant in the Herbst group compared to the Pendex group. Conclusions: Both Herbst and Pendex appliances were successful in treating Class II malocclusion. The Herbst appliance demonstrated an effective Class II correction through skeletal and dental effects, while the Pendex changes were mostly dental effects. The Herbst appliance has a greater improvement in the soft tissue profile. Therefore, the Herbst appliance should be considered for patients with moderate skeletal Class II discrepancies who can benefit from improvements in their soft tissue profile.

Advisor
Jeon, Hyeran
Date of degree
2024-06-25
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