Does the presence of mandibular third molars increase the risk of angle fracture and simultaneously decrease the risk of condylar fracture?

Previous studies have shown that impacted mandibular third molars (M3s) increase the risk of mandibular angle fractures and decrease the risk of mandibular condylar fractures. This study attempted to verify these relationships and identify the influence of mechanism and cause of injury. The incidence of fractures was compared in 700 patients with and without impacted M3s. The results showed that patients with impacted M3s had a lower risk of condylar fracture and a higher risk of angle fracture than those without impacted M3s when injured by moderate trauma force. Such relationships could not have been identified when patients were injured by high trauma force. Patients with impacted M3s had a higher risk of angle fracture than those without impacted M3s no matter how they were injured (assault, fall, motor vehicle accident, other). When patients were injured by assault or in a motor vehicle accident, those with impacted M3s were less likely to have a condylar fracture. M3s were a dominant factor for developing a mandibular angle fracture and preventing condylar fracture. The risk of angle fracture was much more affected by impacted M3s than that of condylar fracture, when injury mechanism and cause were taken into consideration.