Varied canal morphology and the narrow area of the irregular C-shaped canals in the mandibular second molars can cause incomplete cleaning of the root canal and partial detection of voids in root fillings. Cone-beam computed tomography(CBCT) can clearly display the three-dimensional forms(axial, sagittal, and coronal) of the C-shaped root canal. CBCT presents clear images with high resolution. CBCT can also select the appropriate vision for viewing clear images and can save image information in a optical disc. This technique requires less cupping artifact, low-dose radiation, and short scanning time, and is thus convenient for clinical doctors in carefully performing multi-level and multi-dimensional views on a computer. Panoramic images without distortion and magnification can be generated with the axial, sagittal, and coronal view of the C-shaped root canal in the mandibular second molar. C-shaped root canal treatment in the mandibular second molar is difficult to perform because of the relatively large number of independent root canals, traffic, and roottube bending, which may impede the entrance of traditional instruments in the gorge area. CBCT combined with a dental operating microscope can improve the effect of the C-shaped root canal treatment on the mandibular second molar. Application of CBCT before root canal therapy can help doctors prevent excessive cutting and side wearing. This article aims to review the applications and research progress with regard to the use of CBCT in the mandibular second molar before C-shaped root canal treatment.
