The Effect of Lower Third Molar Presence and Position on Fracture of the Mandibular Angle and Condyle

Studies have consistently reported that patients with impacted mandibular third molars (M3s) are at increased risk of suffering mandibular angle fracture compared to patients without impacted M3s [1]. Select studies have also shown that the risk of fracture is directly related to the severity of M3 impaction. Based on these findings, some investigators have advocated for the prophylactic removal of impacted M3s as a means of preventing angle fracture, especially in young athletes involved in contact sports. However, more recent studies have found that patients without M3s are more susceptible to mandibular condyle fracture, which can be technically difficult to repair and carries a greater risk of post-operative complications [2]. To further investigate this issue, we conducted a retrospective cohort study to assess the relationship between the presence and position of M3s on the incidence of mandibular angle and condylar fracture. Using hospital charts and panoramic radiographs from patients presenting to the Division of Oral and Maxillofacial Surgery from April 2007 to March 2012, information was collected on patient demographics, etiology and type of mandibular fracture, and the presence/absence of M3s. The position of M3s was recorded and classified according to the Pell and Gregory classification and angulation was determined based on relation to the mandibular occlusal plane. Data was analyzed by calculating the mean and standard deviation and cohort comparisons were made using chi square test (with P < 0.05 considered significant), Student’s t-test, and analysis of variance. The study sample consisted of 446 patients with 731 total mandibular fractures. Our results showed that the incidence of mandibular angle fracture was significantly higher in both patients and mandible sides with an impacted M3, whereas the rate of condylar fracture was significantly higher in both patients and mandible sides lacking an impacted M3. However, a relationship between the position and angulation of M3s in relation to incidence of angle and condylar fractures could not be demonstrated. We also found that patients with a normally erupted M3 were at increased risk of angle fracture and a decreased risk of condylar fracture, compared to patients with no M3. The present study suggests a relationship exists between the presence of M3s and the rate of angle and condylar fracture but further investigations are required which can account for other factors known to influence the pattern of mandibular fracture.

1. Lee JT, Dodson TB. The effect of mandibular third molar presence and position on the risk of angle fracture. J Oral Maxillofac Surg 58:394, 2000

2. Iida S, Nomura K, Okura M, Kogo M. Influence of the incompletely erupted lower third molar on mandibular angle and condylar fractures. J Trauma 57:613, 2004