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

  • Qin Liye
  • Zhou ZhongweiEmail author
  • Sun XiaojuanEmail author
  • Wang Min
  • Liu Pingping
  • Cao Kun
Review Article



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.


PubMed, EMBASE, SpringerLink, Cochrane Library, and Web of Science databases were searched independently by two researchers from January 2008 to May 2018.


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).


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.


Mandibular third molar Mandibular canal Panoramic radiology Meta-analysis 


Compliance with ethical standards

Conflict of interest

Author Qin Liye, Author Zhou Zhongwei, Author Sun Xiaojuan, Author Wang Min, Author Liu Pingping and Author Cao Kun declare that they have no conflict of interest.

Ethical approval

All procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1975, as revised in 2008 (5).


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Copyright information

© Japanese Society for Oral and Maxillofacial Radiology and Springer Nature Singapore Pte Ltd. 2019

Authors and Affiliations

  1. 1.Ningxia Medical UniversityYinchuan CityChina
  2. 2.Department of Oral and Maxillofacial SurgeryGeneral Hospital of Ningxia Medical UniversityYinchuan CityChina

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