Comparison between digital panoramic radiography and cone-beam computed tomography for the identification of the mandibular canal as part of presurgical dental implant assessment.

PURPOSE A variety of imaging modalities (eg, panoramic radiography, tomography, or computed tomography [CT]) were compared for their efficiency in the identification of the mandibular canal. The recently introduced cone-beam computed tomography (CBCT) seems to be a promising imaging modality which also reduces patient exposure considerably, compared with ordinary CT. The literature includes no studies comparing its performance in such delicate tasks as mandibular-canal identification with other traditionally used imaging modalities. The goal of this study was to compare CBCT reformatted panoramic images and digital panoramic images for the identification of the mandibular canal as part of preimplant assessment. MATERIALS AND METHODS Panoramic images, generated by 3 different imaging modalities used for general maxillofacial diagnosis and preimplant assessment, were compared: CBCT reformatted panoramic images (I-CAT; Imaging Sciences, Hatfield, PA), direct (charge-coupled device-based) panoramic radiographs (DIMAX; Planmeca, Helsinki, Finland), and digital panoramic radiographs based on a storage phosphor system (DENOPTIX; Gendex, Chicago, IL). We used 3 independent groups of images (40 in each group) from patients examined by one of the above imaging modalities over a period of 6 months. In total, 68 randomly selected mandibular canals (out of a possible 80) per imaging modality were evaluated. Four experienced raters evaluated the images of each modality in 3 sessions under standardized conditions for clarity in the visualization of the mandibular canal in 3 locations, using a 4-point scale. RESULTS The CBCT reformatted panoramic images outperformed the digital panoramic images in the identification of the mandibular canal. CONCLUSIONS Due to the fact that the CBCT images were reformatted slices of the maxilla and mandible, they were free of magnification, superimposition of neighboring structures, and other problems inherent to panoramic radiology. This may result in very clear images that better depict the mandibular canal.