Assessment of the anterior loop of the inferior alveolar nerve using reformatted computed tomography: a retrospective study.

The anterior loop of the inferior alveolar nerve (IAN) is an important landmark in the anterior mandible that must be considered during the placement of dental implants. We measured the length and prevalence of loops of the IAN in 188 consecutive, dentate patients using reformatted computed tomography (CT). A total of 158/188 (84%) had at least one anterior loop; 111/188 (59%) had bilateral loops. The mean (SD) length of the loops in the third quadrant was 1.4 (0.7)mm; 95% CI 1.3 to 1.6; (range 0.3 - 4.0mm). The mean (SD) length of the loops in the fourth quadrant was 1.5 (0.9)mm; 95% CI 1.4 to 1.6; range 0.3 - 5.5mm. In total 42/188 (22%) had loops that were longer than 2mm in quadrants three and four. CT images that have been reformatted with specialised software may be useful to identify loops in the IAN, particularly when recent cone-beam CT images are not freely available. The prevalence of these loops is high while their length varies, which makes meticulous assessment necessary before the placement of implants.