title: Does Orthodontic Extraction Treatment Improve the Angular Position of Third Molars? A Systematic Review.
abstract: OBJECTIVE
  To systematically assess the available evidence on the effect of orthodontic extractions on third molar (M3) angulation.
  
  
  METHODS
  Three databases were searched up to April 25, 2016 to identify orthodontic studies comparing M3 angular changes in patients with and without extraction. Information on methodology, treatment procedures, and outcome was retrieved from each study. Assessment of overall and individual quality of the included studies was performed using validated criteria.
  
  
  RESULTS
  Fourteen retrospective studies were considered eligible for this systematic review. Two studies achieved a moderate evidence score, whereas the lowest grade was assigned to 12 studies. The overall evidence level was classified as limited. Meta-analysis was not feasible because of the high heterogeneity across studies. Based on the best available evidence, premolar extraction followed by fixed orthodontic appliances can substantially improve the angular position of M3s by 10° to 18°.
  
  
  CONCLUSIONS
  There is limited evidence that orthodontic extractions can substantially enhance the uprighting of M3s. Clinicians should be aware of the potentially beneficial effect of orthodontic extraction treatment on M3 development, although well-designed prospective studies are necessary to strengthen this statement.
authors.affiliation: Assistant Professor, Department of Orthodontics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands. Electronic address: c.livas@umcg.nl.
authors.forename: Christos
authors.initials: C
authors.lastname: Livas
authors.affiliation: Oral Medicine Specialist, Department of Oral and Maxillofacial Surgery, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Konstantina
authors.initials: K
authors.lastname: Delli
mesh_terms: D006801:Humans; D008964:Molar, Third / Q000502:physiology*; D009971:Orthodontics, Corrective; D014081:Tooth Extraction; D014095:Tooth, Impacted / Q000517:prevention & control