Can narrowing of the mandibular canal on pre-operative panoramic radiography predict close anatomical contact of the mandibular canal with the mandibular third molar? A meta-analysis

Purpose Inferior alveolar nerve injury is a common complication following mandibular third molar extraction. Accurate pre-operative assessment of the anatomical relationship between the mandibular third molar and the mandibular canal could help to avoid this injury. We performed a eta-analysis to investigate whether panoramic radiography could be used to assess the relationship between these two structures. Methods PubMed, EMBASE, SpringerLink, Cochrane Library, and Web of Science databases were searched independently by two researchers from January 2008 to May 2018. Results Seven articles were identified. Statistical analyses were performed using Revman 5.3 and Meta-disc 1.4 software tools. The pooled sensitivity and specificity were 0.19 (95%CI:0.16-0.22) and 0.90 (95%CI:0.88-0.92), respectively. The pooled positive likelihood ratio and negative likelihood ratio were 2.34 (95%CI:1.42-3.87) and 0.86 (95%CI:0.78-0.96), respectively. The area under the curve was 0.86 (95%CI:0.78-0.96). Conclusions According to the sign of narrowing of the mandibular canal, panoramic radiology used to assess the relationship between the mandibular third molar and the mandibular canal yielded high specificity, but low sensitivity. The absence of narrowing of the mandibular canal indicated that there was no close contact between these two structures. However, the presence of narrowing of the mandibular canal could not be used to accurately evaluate the relationship between these two structures, although it might indicate a high probability of close anatomical contact between these two structures. Further tests should be performed for providing adequate pre-operative risk assessment while planning for the surgery to reduce the risk of inferior alveolar nerve injury, as well as to enable an open discussion with the patient to decrease the risk of medical disputes.