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Upper headgear versus lower headgear, yokes, and class III elastics
The Angle Orthodontist
|January 1, 1978
Summary
The headgear-yoke-Class II (HGY-II) mechanism offers faster molar distalization than maxillary headgear, potentially due to consistent Class II elastic forces. Both methods are effective, with HGY-II suited for cases with most permanent teeth present.
Area of Science:
- Orthodontics
- Craniofacial development
Background:
- Orthodontic treatment often requires molar distalization to correct Class II malocclusions.
- Various headgear appliances are used to achieve this, each with distinct biomechanical effects.
Purpose of the Study:
- To compare the efficacy and cephalometric changes associated with a lower headgear-yoke-Class II (HGY-II) mechanism versus traditional maxillary headgear.
- To evaluate the speed and type of tooth movement and skeletal changes induced by each appliance.
Main Methods:
- Cephalometric analysis was performed to assess changes in molar position and skeletal relationships.
- The study compared the outcomes of HGY-II mechanism and maxillary headgear in orthodontic patients.
Main Results:
- The HGY-II mechanism demonstrated faster distalization of molars compared to maxillary headgear.
- Greater distal tipping of molars was observed with the HGY-II mechanism, likely due to the continuous force from Class II elastics.
- Minor orthopedic changes in the maxilla were noted, including a reduction in the SNA angle and slight clockwise rotation of the palatal plane.
Conclusions:
- Both HGY-II and maxillary headgear are indicated orthodontic appliances.
- HGY-II is particularly useful when most permanent teeth are available, allowing for completion within a single treatment phase.
- Maxillary headgear may be preferred when complete therapy is hindered by unerupted permanent teeth.