title: The association of third molars with mandibular angle fractures: a meta-analysis.
abstract: OBJECTIVE
  To estimate the relative risk of mandibular angle fractures among people with a lower third molar compared with those without a lower third molar.
  
  
  METHODS
  Data for a case-control meta-analysis were obtained by performing a literature search in MEDLINE and EMBASE to identify suitable observational studies. To be included, studies had to present data on patients with mandibular fractures, incorporate cross-classified information about the presence of a lower third molar and indicate whether the fracture was a mandibular angle fracture on the ipsilateral side.
  
  
  RESULTS
  Six studies, involving 3,002 patients with mandibular fractures, met the inclusion criteria. Crude relative risk estimates for an angle fracture, comparing patients with a third molar with those without, ranged from 1.2 to 12.7. There was evidence of heterogeneity across the 6 studies (p = 0.001), but when 2 studies with less methodologic rigour were excluded, a test of homogeneity was no longer statistically significant (p = 0.22). The estimated relative risk across the remaining 4 studies was 2.4 (95% CI 1.9 to 3.0).
  
  
  CONCLUSIONS
  The presence of a lower third molar may double the risk of an angle fracture of the mandible. This could have a bearing on any clinical decision on whether to extract the molar.
authors.affiliation: AO Clinical Investigation and Documentation, AO ASIF Center, Davos Platz, Switzerland. beate.hanson@aofoundation.org
authors.forename: Beate P
authors.initials: BP
authors.lastname: Hanson
authors.forename: Peter
authors.initials: P
authors.lastname: Cummings
authors.forename: Frederick P
authors.initials: FP
authors.lastname: Rivara
authors.forename: Mike T
authors.initials: MT
authors.lastname: John
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D003799:Dental Stress Analysis; D005260:Female; D006801:Humans; D008297:Male; D008334:Mandible; D008337:Mandibular Fractures / Q000453:epidemiology / Q000209:etiology*; D008964:Molar, Third / Q000503:physiopathology*; D016017:Odds Ratio; D012306:Risk