Influence of third molars in mandibular fractures. Part 2: mandibular condyle-a meta-analysis

The aim of this systematic review was to investigate the influence of the presence and position of mandibular third molars in mandibular condyle fractures. An electronic search was conducted in PubMed, Scopus, Web of Science, Cochrane Library, and VHL, through January 2016. The eligibility criteria included observational studies. The search strategy resulted in 704 articles. Following the selection process, 13 studies were included in the systematic review and 11 in the meta-analysis. In terms of the risk of bias analysis, six studies presented ≤6 stars in the Newcastle-Ottawa scale assessment. The presence of a mandibular third molar decreased the probability of condylar fracture (cross-sectional and case-control studies: odds ratio (OR) 0.26, 95% confidence interval (CI) 0.17-0.40, I2 = 87.8%; case-control studies: OR 0.30, 95% CI 0.16-0.58, I2 = 91.6%). The third molar positions most favourable to condylar fracture according to the Pell and Gregory classification are class A (OR 1.32, 95% CI 1.09-1.61, I2 = 0%) and class I (OR 1.37, 95% CI 1.05-1.77, I2 = 32.8%). Class B (OR 0.69, 95% CI 0.49-0.97, I2 = 56.0%) and class II (OR 0.71, 95% CI 0.57-0.87, I2 = 0%) act as protective factors for condylar fracture. The results suggest that the presence of a mandibular third molar decreases the chance of condylar fracture and that the positions of the third molar most favourable for condylar fracture are classes A and I, with classes B and II acting as protective factors.