Hindawi Publishing Corporation International Journal of Dentistry Volume 2012, Article ID 814789, 9 pages doi:10.1155/2012/814789 Clinical Study A New Anatomically Based Nomenclature for the Roots and Root Canals—Part 2: Mandibular Molars Denzil Valerian Albuquerque, 1 Jojo Kottoor, 2 and Natanasabapathy Velmurugan 3 1 Private Practice, Mumbai 400050, India 2 Department of Conservative Dentistry and Endodontics, Mar Baselios Dental College, Kothamangalam, Ernakulam, Kerala 686691, India 3 Department of Conservative Dentistry and Endodontics, Meenakshi Ammal Dental College and Hospital, Alapakkam Main Road, Maduravoyal, Tamil Nadu, Chennai 600 095, India Correspondence should be addressed to Denzil Valerian Albuquerque, dr.denzil@gmail.com Received 29 September 2011; Accepted 14 October 2011 Academic Editor: Igor Tsesis Copyright © 2012 Denzil Valerian Albuquerque et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Several terminologies have been employed in the dental literature to describe the roots and root canal systems of mandibular molars with no consensus being arrived at, thus far. The anatomical relation of roots and their root canals were identified and a naming system was formulated. The proposed nomenclature attempts to make certain essential modifications to the traditional approach to accommodate the naming of various aberrations presented in mandibular molars. A simple, yet extensive nomenclature system has been proposed that appropriately names the internal and external morphology of mandibular molars. 1. Introduction Nomenclature refers to a set of terms used in communication by persons in the same profession that enables them to better understand one another. The comprehension of these terms aids in diagnosing and treating disease and defects of the teeth [1]. The mandibular first molar, the earliest permanent posterior tooth to erupt, is considered to be the most frequently involved tooth in endodontic procedure [2]. In its typical form, it is described as a two rooted tooth containing either three or four canals. Most commonly, mandibular molars present with two principle roots, the mesial and the distal [3, 4]. The mesial root commonly presents with two principle canals, the mesiobuccal (MB) and the mesiolingual (ML). The distal root however has two common canal config- urations wherein it may contain a single canal termed as the distal (D) or may contain two separate canals, the distobuccal (DB) and the distolingual (DL). Thus, in the distal root the principle canals could either be the distal (D) or the disto- buccal (DB) and distolingual (DL), as the case may be [3]. As with any tooth anatomy, mandibular molars have also been reported with numerous variations with regards to their root and root canal morphology. Variations in their root anatomy have ranged from 2 roots, as described earlier, to as many as 4 distinct roots [4–6], while canal variations have ranged from a single root canal to as many as seven root canals [7–11]. A literature search revealed that multiple atyp- ical and diverse terms have been used in the dental literature to describe the same morphologic variation in these teeth (Table 1). Alternatively, the same names have also been used to name two nonidentical anatomical variations. For in- stance, a canal located between the DB and DL canal has been alternately termed as the middle distal, distal, and the third distal canal [7, 12]. Additionally, canals located in similar anatomical positions have been differentiated by using numbers as suffixes to a common name, analogous to the traditional names of their maxillary counterparts, as MB1, MB2, ML1, ML2 [7]. Also, few authors have described the variation of multiple canals within a root by merely mentioning the number of canals (e.g., 2 mesial or 3 distal canals, 2DB canals, etc.) [9, 13]. The numbers convey only the presence of an additional canal(s) with no descriptive information of the variant canal system. Of the various ter- minologies, the use of numbers (MB1, MB2, ML1, ML2,