The removal of impacted mandibular third molars is one of the most common surgical procedures performed and can be complicated by inferior alveolar nerve damage.¹  Injury to the inferior alveolar nerve has been related to deeply impacted teeth² and to roots in close approximation to the inferior dental canal (IDC).³  Thus, accurate assessment of the position of the inferior alveolar nerve in relation to the impacted third molar might reduce injuries to this nerve.  Anatomically, the nerve lies in the IDC which is enclosed within a tube of dense bone.  The tube is seen on radiographs as two parallel radiopaque lines; one representing the roof of the canal and the other the canal floor.  Oliver⁴ studied 50 dry specimens of mandibles and found in 60% of them a distinct IDC contained the whole of the inferior alveolar neurovascular bundle, while in the remaining 40% the vessels and branches of this bundle were spread out of the canal so a well-defined canal was not present.  Carter and Keen⁵ radiographically examined 80 dried mandible specimens and found 61% of them showed a single bony canal with unbroken margins near the roots of molar teeth, while a bony canal with a broken upper wall was seen close to the molar roots in 14% of radiographs.  The remaining 25% of the mandibles showed bony patterns lacking definite mandibular canals.  Based on radiographic examination of a 100 edentulous human mandibles, Schroll⁶ concluded the position of the IDC was variable.  This finding has been confirmed by Nortje et al.^7,8 who reviewed 3612 panoramic radiographs and found the position of the IDC was either touching or within 2 mm of the apices of molar teeth in 46.7% of the subjects.  In 48.9% the IDC was touching or within 2 mm of the cortical plate of the lower border of the mandible and intermediately positioned between tooth apices and the lower border in 3.3% of the subjects.

A literature search revealed a lack of studies on the location of the IDC in relation to the impacted mandibular third molar by using conventional or computed tomography (CT) on Arabic populations.  Therefore, the aim of this study was to determine the radiographic relationship of the IDC to the roots of impacted mandibular third molars in a Jordanian population group.