Editing Root canal (section)

===Variation===

[[File:Root Canal Edited.png|thumb|Root canal pulp removed, cleaned and made ready for filling and placing a [[Crown (dentistry)|crown]]]]

Root canals presenting an oval cross-section are found in 50–70% of root canals. In addition, canals with a "tear-shaped" cross section are common when a single root contains two canals (as occurs, for example, with the additional mesial root seen with the lower molars), subtleties that can be more difficult to appreciate on classical [[radiographs]]. 

Recent studies have shown that use of cone-down [[CT scan]]s can detect accessory canals that would have been missed in 23% of cases, which can in turn lead to apical [[periodontitis]]. The upper [[molar (tooth)|molars]], in particular, are predisposed to have an occult accessory canal in nearly half of patients.<ref>{{cite journal |last1 = Karabucak |first1 = B |last2 = Bunes |first2 = A |last3 = Chehoud |first3 = C |last4 = Kohli |first4 = MR |last5 = Setzer |first5 = F |title = Prevalence of Apical Periodontitis in Endodontically Treated Premolars and Molars with Untreated Canal: A Cone-beam Computed Tomography Study |journal = Journal of Endodontics |date = February 10, 2016 |pmid = 26873567 |doi = 10.1016/j.joen.2015.12.026 |volume = 42 |issue = 4 |pages = 538–41 }}</ref>