[Effect of premolar extractions on third molar angulation changes: a meta-analysis]

Area of Science:

• Orthodontics
• Dental Surgery
• Maxillofacial Radiology

Background:

• Third molar angulation is a critical factor in orthodontic treatment outcomes.
• The impact of premolar extractions on third molar development remains a subject of investigation.

Purpose of the Study:

• To evaluate the influence of premolar extractions on third molar angulation changes in orthodontic patients.
• To compare the effects of first versus second premolar extraction on mandibular third molar angulation.

Main Methods:

• A systematic literature search was conducted across multiple databases (Cochrane, PubMed, Embase, etc.) from 1990 to 2014.
• Meta-analysis was performed on ten studies involving 712 patients, comparing extraction and control groups.
• The extraction group was subdivided into first and second premolar extraction cohorts.

Main Results:

• Premolar extractions significantly altered third molar angulation in both maxillary and mandibular arches compared to controls (P<0.05).
• Average angulation differences were 5.19° in the maxilla and 3.55° in the mandible.
• No significant difference in mandibular third molar angulation was observed between first and second premolar extraction subgroups (P>0.05).

Conclusions:

• Orthodontic treatment with premolar extractions positively impacts maxillary third molar angulation.
• Second premolar extraction is identified as the optimal choice for improving maxillary third molar angulation.