Three-rooted premolar analyzed by high-resolution and cone beam CT.

OBJECTIVES: The aim of this study was to analyze the variations in canal and root cross-sectional area in three-rooted maxillary premolars between high-resolution computed tomography (µCT) and cone beam computed tomography (CBCT). MATERIALS AND METHODS: Sixteen extracted maxillary premolars with three distinct roots and fully formed apices were scanned using µCT and CBCT. Photoshop CS software was used to measure root and canal cross-sectional areas at the most cervical and the most apical points of each root third in images obtained using the two tomographic computed (CT) techniques, and at 30 root sections equidistant from both root ends using µCT images. Canal and root areas were compared between each method using the Student t test for paired samples and 95 % confidence intervals. RESULTS: Images using µCT were sharper than those obtained using CBCT. There were statistically significant differences in mean area measurements of roots and canals between the µCT and CBCT techniques (P < 0.05). Root and canal areas had similar variations in cross-sectional µCT images and became proportionally smaller in a cervical to apical direction as the cementodentinal junction was approached, from where the area then increased apically. CONCLUSION: Although variation was similar in the roots and canals under study, CBCT produced poorer image details than µCT. CLINICAL RELEVANCE: Although CBCT is a strong diagnosis tool, it still needs improvement to provide accuracy in details of the root canal system, especially in cases with anatomical variations, such as the three-rooted maxillary premolars.

Accuracy of linear measurements and visibility of the mandibular canal of cone-beam computed tomography images with different voxel sizes: an in vitro study.

BACKGROUND: The major use of cone-beam computed tomography (CBCT) is in implant planning. Although CBCT has been shown to be a reliable tool for measurements, we were unable to find studies comparing the differences between images acquired using different voxel sizes for implant planning. The aims of the present in vitro study are to verify the accuracy of linear measurements and to analyze the visibility of the mandibular canal on CBCT images obtained using different voxel sizes. METHODS: Twelve dry human hemimandibles were scanned using voxel sizes of 0.2, 0.3, and 0.4 mm, and 108 transversal CBCT images were generated, on which two examiners performed 648 linear measurements and evaluated the visibility of the mandibular canal. RESULTS: The global mean ± SD error between measurements on images and direct measurements was 0.23 ± 0.20 mm. CBCT measurements underestimated direct measurements in 390 cases (60.2%). All measurement errors found were <1 mm. There was a statistically significant difference (P = 0.0001 and P = 0.0028) between the two examiners only when measuring the width in two posterior sites. There was a statistically significant difference (P = 0.0242) between voxel sizes only for one of the examiners, for a measurement of height. It was possible to visualize the mandibular canal in all of the 108 images evaluated. CONCLUSIONS: Transversal CBCT images are adequate for linear measurements in the posterior region of the mandible and provide adequate visualization of the mandibular canal using voxel sizes of 0.2, 0.3, or 0.4 mm. A voxel of 0.3 mm is a good compromise between image quality and low radiation dose.