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The association of third molars with mandibular angle fractures: a meta-analysis
Beate P Hanson1, Peter Cummings, Frederick P Rivara
1AO Clinical Investigation and Documentation, AO ASIF Center, Davos Platz, Switzerland. beate.hanson@aofoundation.org
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.
