Impact of the lower third molar and injury mechanism on the risk of mandibular angle and condylar fractures

Background: Previous studies have shown the influence of the mandibular third molar on mandibular angle and condylar fractures, but have not comparatively analyzed the impact of the injury mechanism on these fractures. The purpose of this study was to evaluate the influence of the lower third molar (M3) and injury-related factors (fracture etiology and site of impact of the traumatic force) on the risk of mandibular angle and condylar fractures.

Material and methods: The study included 615 patients who sustained a mandibular fracture in a 13-year period (from January 2000 to December 2013). The independent variables were presence, position and the root number of the M3, fracture etiology, and site of impact of the force. The outcome variables were mandibular angle and condylar fractures. Other variables included in the study were patients' gender and age. The data were analyzed using the chi-square test. Univariate and multivariate binary logistic regression analyses were used to evaluate the relationship between angle and condylar fractures and to show potential determinants.

Results: Angle fractures were significantly influenced by the M3, site of impact, and age, but the main predictors were the eruption status and vertical position of the M3 (classified by Pell and Gregory) and site of impact of the force. Condylar fractures were significantly influenced by the M3 and site of impact of the force, but only the last showed as a predictor.

Conclusions: Factors related to the M3 showed more significant influence on angle fractures than on condylar fractures.