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Mandibular form and position in 10-year-old boys
1Department of Orthodontics, University of Glasgow, Scotland, United Kingdom.
Summary
Malocclusion with jaw discrepancy is not solely due to mandibular size but also its anterior position and rotation, particularly in Class III cases. Class II, Division 2 malocclusion appears primarily dentoalveolar.
Area of Science:
- Orthodontics
- Craniofacial Morphology
- Dental Anthropology
Background:
- Malocclusion, characterized by jaw discrepancy, presents an etiological puzzle.
- The origins may lie in mandibular position, size, or a combination of factors.
- Understanding these variations is crucial for effective orthodontic diagnosis and treatment planning.
Purpose of the Study:
- To investigate the etiological factors contributing to malocclusion, specifically jaw discrepancy.
- To differentiate between mandibular position and size variations as causes of malocclusion.
- To clarify the skeletal versus dentoalveolar nature of Class II, Division 2 malocclusion.
Main Methods:
- Cephalometric analysis of 124 10-year-old boys across different Angle malocclusion classes.
- Computer plotting technique used to generate mandibular outlines.
- Superimposition of mean plots on S-N and Go-Gn planes for comparative analysis.
Main Results:
- Mandibular form and size were found to be similar between Class I, Class III, and Class II groups.
- Class III mandibles exhibited a more anterior position and forward rotation relative to the cranial base.
- Statistical analysis confirmed these positional differences and suggested Class II, Division 2 malocclusion is primarily dentoalveolar.
Conclusions:
- Jaw discrepancy in malocclusion is significantly influenced by mandibular position rather than size alone.
- Class III malocclusion is characterized by an anteriorly positioned and rotated mandible.
- Class II, Division 2 malocclusion appears to be predominantly a dentoalveolar issue, not skeletal.