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Mandibular changes in persons with untreated and treated Class II division 1 malocclusion
1Department of Orthodontics, College of Dentistry, University of Iowa, Iowa City 52242, USA.
Summary
This study on Class II malocclusion found that untreated individuals show subtle differences from normal growth, with mandibular changes more apparent early on. Orthodontic treatment, with or without premolar extraction, effectively normalized skeletal relationships.
Area of Science:
- Orthodontics and Dental Growth
Background:
- Class II malocclusions are prevalent and impact facial growth.
- Understanding mandibular and maxillomandibular relationships is crucial for orthodontists.
- Evaluating treatment effects on these relationships is essential.
Purpose of the Study:
- To assess changes in mandibular length and relationship in untreated Class II subjects from deciduous to permanent dentition.
- To evaluate the effects of orthodontic treatment (with and without first premolar extraction) on these skeletal relationships.
- To compare Class II subjects with matched normal, untreated individuals.
Main Methods:
- Cross-sectional and longitudinal analysis of cephalometric data from untreated Class II division 1 (Class II/1) subjects (n=30) at three developmental stages.
- Comparison with matched normal, untreated individuals (n=35) from a longitudinal growth study.
- Evaluation of Class II/1 subjects treated with first premolar extraction (n=44) versus non-extraction (n=47) using edgewise appliances, extraoral traction, and Class II elastics.
Main Results:
- Few consistent cross-sectional differences were found between untreated Class II/1 and normal subjects; mandibular differences were more evident in early development.
- Longitudinal growth trends were similar, but untreated Class II/1 subjects exhibited greater skeletal convexity and a tendency for a more retruded mandible.
- Treated Class II/1 subjects showed normalized mandibular and maxillomandibular skeletal relationships after 5 years, with more pronounced changes in the extraction group compared to normal subjects.
Conclusions:
- Untreated Class II malocclusion exhibits subtle, primarily early-stage, deviations in mandibular growth compared to normal development.
- Orthodontic treatment effectively normalizes skeletal discrepancies in Class II malocclusion, regardless of first premolar extraction.
- First premolar extraction may lead to more significant normalization of skeletal relationships in treated Class II malocclusion.