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Over-bite and vertical changes following first premolar extraction in high angle cases
G C Ramesh1, M C Pradeep, G Arun Kumar
1Department of Orthodontics, Sharavathi Dental College and Hospital, Shimoga, Karnataka, India. ramsmilecare@gmail.com
The Journal of Contemporary Dental Practice
|February 14, 2013
Summary
First premolar extraction in high-angle cases did not decrease vertical facial dimension or overbite. Mandibular plane angle remained stable, challenging the wedge hypothesis in this patient group.
Area of Science:
- Orthodontics
- Cephalometric analysis
- Dentofacial orthopedics
Background:
- Nonextraction treatment typically increases lower anterior face height (LAFH), while extraction treatment decreases it.
- The "wedge hypothesis" suggests vertical dimension reduction after first bicuspid extraction.
Purpose of the Study:
- To investigate cephalometric changes in overbite and vertical dimension after first premolar extraction in adult patients with high mandibular plane angles.
- To evaluate the validity of the wedge hypothesis in this specific orthodontic context.
Main Methods:
- Cephalometric analysis of 45 adult patients with a high mandibular plane angle (Gonial angle-SN ≥ 32°) and Class I molar/canine relationships.
- Comparison of pre- and post-treatment lateral cephalograms to assess changes in overbite, vertical dimension, and mandibular plane angle.
Main Results:
- No statistically significant decrease in overbite was observed following first premolar extraction.
- No significant decrease in vertical facial dimension or mandibular plane angle occurred.
Conclusions:
- The findings do not support the wedge hypothesis, as vertical facial dimension and overbite did not decrease after first premolar extraction in high-angle cases.
- Residual growth and orthodontic mechanics may maintain mandibular plane angle stability, even with inferior movement.
- Results should be interpreted cautiously due to the study's small sample size.
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