The mandibular canal is an important anatomical structure that contains the neurovascular bundle, i.e., the inferior alveolar nerve and artery. The location of the mandibular canal must be correctly identified prior to dental implant surgery to avoid complications including intraoperative and postoperative hemorrhage and neurosensory loss. Cone beam computed tomography (CBCT) is considered the imaging modality of choice for this purpose [1, 2] and is widely used for dental implant treatment planning. Several studies have evaluated the visibility of the mandibular canal on CBCT images [3,4,5,6,7,8]. However, the results varied widely, around 50–90%, among the studies. Further, no study has evaluated the superior and inferior walls of the canal separately by CBCT, although the location of the former is more important than that of the latter.

Another issue that should be noted for CBCT is the large variability in spatial resolution among devices. High-resolution devices offer the smallest voxel sizes, as small as 0.08 mm or even less [9, 10]. However, the previous studies all evaluated CBCT images having voxel sizes of 0.2 mm or more [3,4,5,6,7,8], which does not sufficiently reflect the diagnostic advantage of CBCT in demonstrating fine structures. Thus, further study is necessary to evaluate the diagnostic ability of CBCT in identifying the mandibular canal.

The purpose of our study was to evaluate the visibility of the superior and inferior walls of the mandibular canal using limited-volume CBCT with a small voxel size.