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Effects of Two-Phase Treatment with Functional Appliances Followed by Extraction versus One-Phase Treatment with
Ka Fai Wong1, Wener Chen1, Jianhan Ren1
1Division of Paediatric Dentistry and Orthodontics, Faculty of Dentistry, The University of Hong Kong, Hong Kong SAR, China.
Journal of Clinical Medicine
|December 23, 2022
Summary
The two-phase orthodontic treatment, involving functional and fixed appliances with premolar extraction, yielded superior improvements in intermaxillary relationship and facial convexity compared to the one-phase approach for Class II division 1 malocclusion in Asian patients.
Area of Science:
- Orthodontics
- Dentofacial Orthopedics
- Craniofacial Growth
Background:
- Class II division 1 malocclusion often requires complex orthodontic treatment, particularly in the Asian population.
- Premolar extraction is frequently necessary to address crowding and enhance facial aesthetics.
- Two-phase treatment (functional followed by fixed appliances with extraction) is a common approach, but its efficacy compared to one-phase treatment needs evaluation.
Purpose of the Study:
- To compare the treatment efficacy of a two-phase (functional + fixed appliance with extraction) versus a one-phase (fixed appliance with extraction) approach for Class II division 1 malocclusion.
- To identify cephalometric changes in skeletal, dental, and soft tissue characteristics between the two treatment modalities.
- To determine factors influencing the choice between one-phase and two-phase treatment strategies.
Main Methods:
- A comparative study involving growing skeletal Class II patients with significant overjet (≥6 mm).
- Two groups were analyzed: 29 patients in the two-phase group and 30 in the one-phase group.
- Pre- and post-treatment lateral cephalograms were assessed for skeletal, dental, and soft tissue parameters; statistical analysis included independent and paired t-tests and discriminant analysis.
Main Results:
- Both groups showed no significant baseline differences in age, gender, or cervical vertebral maturation.
- The two-phase group exhibited greater baseline Class II skeletal discrepancies (ANB, Wits appraisal).
- The two-phase treatment resulted in significantly greater improvements in intermaxillary relationship (ANB, Wits) and facial convexity (p < 0.01), with increased L1/APog distance (p < 0.05).
Conclusions:
- Two-phase orthodontic treatment with premolar extraction offers superior outcomes in improving intermaxillary relationship and facial convexity compared to one-phase treatment for Class II division 1 malocclusion.
- Facial convexity and Wits appraisal were key predictors for selecting a one- or two-phase treatment approach.
- This suggests a tailored approach based on specific skeletal and aesthetic parameters can optimize treatment results.
