Comparison of Periapical Radiography and Limited Cone-Beam Computed Tomography in Mandibular Molars for Analysis of Anatomical Landmarks before Apical Surgery

Introduction: The purpose of the present study was to evaluate the detectability and dimensions of periapical lesions, the relationship of the mandibular canal to the roots of the respective teeth, and the dimension of the buccal bone by using limited cone-beam computed tomography (CBCT) in comparison to conventional periapical (PA) radiographs for evaluation of mandibular molars before apical surgery. Methods: The study comprised 38 molars with 75 roots. The type of PA lesion as diagnosed on PA radiographs was compared with the type of lesion seen on sagittal and coronal CBCT sections. The distances of the apices of the first mandibular molars and basal border of the PA lesion to the coronal lining of the mandibular canal were assessed with PA radiographs and corresponding sagittal and coronal CBCT images. Furthermore, coronal CBCT images were used to measure the distance from the apices to the buccal bone surface and the corresponding width of the cortical bone plate. Results: Of 58 detected PA lesions, 15 (25.9%) lesions diagnosed with sagittal CBCT slices were missed with PA radiography. The distance between the apices and the upper border of the mandibular canal was only measurable in 24 of 68 radiographs (35.3%) by using PA images. The cortical bone wall had a mean thickness of 1.7 mm, whereas the total buccal bone wall (cortical and spongious) measured 5.3 mm on average. Conclusions: The present study highlights the advantages of using limited CBCT for treatment planning in mandibular molars before apical surgery. (J Endod 2011;37:151-157)