2023 Volume 66 Issue 1 Pages 6-22
Although the number of roots and root canals is decided by tooth type, extra roots and additional root canals are sometimes observed and so knowledge of the morphology of these roots and root canals is required for successful root canal treatment. The mesio-buccal root of a maxillary molar often has two canals, and the second root canal, which is located palatally, is called the mesio-buccal root second canal (MB2). MB2 is relatively common, but it is often difficult to find without a loupe or microscope. The root canal orifice of MB2 is located 0.5-1.0 mm more mesial aspect from MB1 and the palatal root canal line. For the treatment of MB2, it is important to find the root canal orifice and coronal enlargement. The disto-lingual root of the mandibular molar is called Radix Entomolaris. Radix Entomolaris is often observed in Japanese, Taiwanese and Chinese populations. The treatment of Radix Entomolaris is not easy because of the curvature to the buccal aspect of this root. Coronal enlargement, negotiation with small-sized files and glide path processes are important. A very rare extra root, which is found on the mesio-buccal side of mandibular molars, is called Radix Paramolaris. The mesial root of a mandibular molar usually has two canals, but sometimes has an additional canal, called the middle mesial (MM) canal. The prevalence of MM canals depends on the race and seems to be less common in Japanese. MM canals are prepared with stainless steel files or nickel-titanium files. It has been suggested that a prepared MM canal is just part of the enlarged isthmus; preoperative CBCT is recommended to confirm this. For successful root canal treatment, it is important to understand the root and root canal morphology of each individual patient before commencing treatment.
