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 Table of Contents  
Year : 2022  |  Volume : 14  |  Issue : 1  |  Page : 32-34

Radix entomolaris with “three distal canals:” A rare case report

1 Department of Conservative Dentistry and Endodontics, Sri Venketeshwara Group of Institutions, Sri Venketeshwara Dental College and Hospital, Puducherry University, Puducherry, Tamil Nadu, India
2 Department of Conservative Dentistry and Endodontics, Tamil Nadu Government Dental College and Hospital, The Tamil Nadu Dr. MGR Medical University, Chennai, Tamil Nadu, India
3 Department of Dentistry, Government Mohan Kumaramangalam Medical College, The Tamil Nadu Dr. MGR Medical University, Salem, Tamil Nadu, India

Date of Submission03-May-2021
Date of Decision02-Jun-2021
Date of Acceptance20-Jun-2021
Date of Web Publication31-Dec-2021

Correspondence Address:
Srilekha Jayakumar
Department of Conservative Dentistry and Endodontics, Sri Venketeshwara Group of Institutions, Sri Venketeshwara Dental College and Hospital, Puducherry University, Ariyur, Puducherry
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijds.ijds_53_21

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The intricate and atypical morphology of mandibular molars makes root canal therapy challenging both in diagnosis and during clinical procedure. The clinician should have knowledge on precise nature of the root canal structure and morphology. Better understanding allows good cleaning, shaping, and disinfection of the canal space, followed by its three-dimensional obturation. This paper illustrates the management of radix entomolaris with “three distal canals” in first mandibular molar – a rare entity.

Keywords: Middle distal canal, middle mesial canal, radix entomolaris, radix paramolaris

How to cite this article:
Jayakumar S, Ambalavanan N, Balasubramanian R, Subramanian A. Radix entomolaris with “three distal canals:” A rare case report. Indian J Dent Sci 2022;14:32-4

How to cite this URL:
Jayakumar S, Ambalavanan N, Balasubramanian R, Subramanian A. Radix entomolaris with “three distal canals:” A rare case report. Indian J Dent Sci [serial online] 2022 [cited 2022 Jan 24];14:32-4. Available from: http://www.ijds.in/text.asp?2022/14/1/32/334524

  Introduction Top

The success and prognosis of root canal therapy rely on good cleaning, shaping, and disinfection followed by proper obturation of the canal space. An exhaustive understanding of the canal structure and anatomy would prevent failures that are arising because of improper canal debridement and obturation.[1] Therefore, it is necessary to know the canal structure and morphology prior to initiation of root canal procedure and also during treatment. The permanent mandibular molars are usually teeth with two roots – mesial root with two canals and distal root with one or two canals.[2] The intricate and precise root canal morphology of mandibular first molar has been immensely studied and analyzed in various literatures. The major variation in the canal anatomy is the presence of a “middle mesial canal” which ranges about 1%–15% frequency.[3] Very rarely, these teeth disclosed the presence of three canals distally with the frequency of 0.6%. Numerous studies revealed that the presence of three canals distally varies in different world population, which is about 1.7% among Indians, 0.2% among Senegalese, 1.7% among Turkish, 0.7% among Burmese, 1.6% among Thai population.[4]

As the root canal shows variation in the presence of an additional or extra canal, the root also shows variation in number, which has been studied widely in the literature. The third root in mandibular first molar when present distolingually is termed as “Radix entomolaris” was first described by Carabelli in literature. Furthermore, if the extra root is present at the mesiobuccal aspect, it is called “radix paramolaris.” The present report illustrates successful root canal treatment in a radix entomolaris presenting with “three distal canals” – a rare entity.[5]

  Case Report Top

A 27-year-old male patient reported with the chief complaint of pain in the lower left back tooth for the past 1 week. His medical history was noncontributory. He gave a history of attempted root canal procedure 1 week prior to reporting to us. Intraoral examination was done which revealed the presence of temporary restoration in left first mandibular molar #36 [Figure 1]. Tenderness on percussion was also present. There was no pain on palpation in relation to the buccal and lingual aspects of tooth # 36. The status of mobility of the tooth and periodontal probing was within normal limits. The preoperative radiograph demonstrated temporary restoration in # 36 and revealed periodontal ligament space widening in both the root apices (mesial and distal roots) [Figure 1]. However, a distinctive double root outline on distal side was very evident indicating “radix entomolaris.” The history, clinical examination and radiographic assessment led to the diagnosis of the tooth as “Previously initiated root canal therapy in #36.” The root canal treatment followed by post endodontic restoration in # 36 was planned and patient consent was obtained.
Figure 1: Preoperative intraoral periapical and clinical photograph

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Local anesthesia was administered, and following rubber dam isolation, the access cavity preparation was done on tooth # 36. Careful and thorough examination of the pulp chamber floor revealed five separate root canal orifices, two were present on the mesial aspect (“mesio-buccal and mesio-lingual canals”) and three were on distal aspect (“disto-buccal, middle distal and disto-lingual canals”) [Figure 2]. Following the location of the orifices, a radiographic evaluation was done to confirm the presence of three distinct canals distally. Working length was estimated [Figure 2]. The working length radiograph also revealed that the middle distal canal merged with the disto-buccal canal forming single canal at the apex. Following which cleaning and shaping of the canals were performed. Crown-down technique was performed with rotary Ni-Ti files. Irrigation of the canals was done with 2.5% sodium hypochlorite and 17% ethylenediaminetetraacetic acid solutions during entire instrumentation process. Calcium hydroxide was placed as intracanal medicament for additional disinfection of the canals between the visits. The obturation of the canal space was done using gutta-percha points with AH plus sealer (Dentsply, Konstanz, Germany) in subsequent visit [Figure 2]. A radiograph was taken which also clearly showed the merging of two canals i.e “middle distal canal merging with distobuccal canal”. The access cavity was sealed with composite and full coverage restoration was given later [Figure 3]. No symptoms were reported by the patients during follow-up periods.
Figure 2: Access cavity preparation – “two mesial and three distal canals identified” (DB: distobuccal, MD: middle distal, and DL: distolingual), working length estimation and obturation

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Figure 3: Crown preparation and post endodontic management

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  Discussion Top

According to “Ingle,” the main root of cause for the failure of root canal treatment is incomplete canal obturation. “Vertucci” also reported that the main cause of failure of root canal therapy is because of anatomical variations like the presence of extra canals that are usually not present.[2] The literature by various authors, suggest the clinicians to focus more on, canal morphology and its variations, proper interpretation of preoperative radiographs, to prepare proper access cavity and also necessary to clearly inspect the pulpal floor for any variations, which are considered as important perquisites for a successful root canal treatment and its outcome. Morphologic variations in the canal anatomy should always be focused on the initiation of the treatment procedure. To reduce and overcome the risk of treatment failure, a good knowledge on the intricate nature of canal morphology is much essential. This report showed a successful management of “radix entomolaris with three distal canals.”[6]

“Stroner et al” reported the presence of three canals distally in mandibular first molar as early as 1984, yet there are very few literatures available on the incidence and presence of middle distal canal.[4] The hypothesis behind the emergence of extra canals is because of the secondary dentin apposition that occurs during the maturation process of tooth which results in the formation vertical partitions in dentin inside the root canal space, thus resulting in formation of additional canals. The third or the extra canal when present is usually situated in the center between the two major canals. The diameter of these extra canals, which are present in the middle, is usually smaller in size when compared to the other two. The occurrence of middle distal canal in mandibular molars is found to be much less when compared to middle mesial canal as reported by Martınez-Berna and Badanelli.[6],[7] Secondly, the incidence and occurrence of radix entomolaris are related to certain groups of population. The presence of “Radix entomolaris” is 3% in African population, 5 % or less in Eurasian and Indian population. It varies between 5 to 30 % in mongoloid traits. It is about 3.4 to 4.2 % in Caucasians.[8],[9]

It is much needed for the clinician to have knowledge on laws of access cavity preparation and must properly inspect and visualize the chamber floor with appropriate aids to detect any variation. Instruments such as endodontic explorer, DG 16 probe, pathfinder files, ultrasonics, and micro-openers can be utilized by the clinician to locate additional canals if suspected. “The champagne bubble test” using sodium hypochlorite is an another aid for locating any extra canal orifice.[10] Imaging techniques such as digital radiographs, Cone beam computed tomography (CBCT), micro-CT, and magnetic resonance imaging also aid in confirmation of additional canals. Better illumination strategy with the use of “loupes or endodontic microscope” aids in better visualization of the chamber floor.[11],[12] The clinician should be aware of all kinds of additional aids available and must focus to use them appropriately to analyze the intricate and precise canal anatomy, in location of the extra canals, to perform effective cleaning, shaping, and disinfection and also for good obturation of entire pulp space.

  Conclusion Top

The variations in the canal morphology must always be evaluated and scrutinized before the initiation of the root canal procedure. This case illustrated successful management of “radix entomolaris with three distal canals.” Although the frequency of occurrence of three distal canals is rare, each case must be subjected to in-depth clinical and radiographic evaluation to identify the existence of any additional or extra canals.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Vertucci FJ. Root canal anatomy of the human permanent teeth. Oral Surg Oral Med Oral Pathol 1984;58:589-99.  Back to cited text no. 1
Vertucci FJ. Root canal morphology and its relationship to endodontic procedures. Endod Top. 2005;10:3-29.  Back to cited text no. 2
Holtzmann L. Root canal treatment of a mandibular first molar with three mesial root canals. Int Endod J 1997;30:422-3.  Back to cited text no. 3
Stroner WF, Remeikis NA, Carr GB. Mandibular first molar with three distal canals. Oral Surg Oral Med Oral Pathol 1984;57:554-7.  Back to cited text no. 4
Calberson FL, De Moor RJ, Deroose CA. The radix entomolaris and paramolaris: Clinical approach in endodontics. J Endod 2007;33:58-63.  Back to cited text no. 5
Martinez-Berna A, Badanelli P. Mandibular first molars with six root canals. J Endod 1985;11:348-52.  Back to cited text no. 6
Fabra-Campos H. Unusual root anatomy of mandibular first molars. J Endod 1985;11:568-72.  Back to cited text no. 7
SeguraEgea JJ, JimenezPinzon A, RiosSantos JV. Endodontic therapy in a 3rooted mandibular first molar: Importance of a thorough radiographic examination. J Can Dent Assoc 2002;68:5414.  Back to cited text no. 8
Davini F, Cunha RS, Fontana CE, Silveira CF, Bueno CE. Radix entomolaris – A case report. RSBO 2012;9:340-4.  Back to cited text no. 9
Reuben J, Velmurugan N, Kandaswamy D. The evaluation of root canal morphology of the mandibular first molar in an Indian population using spiral computed tomography scan: An in vitro study. J Endod 2008;34:212-5.  Back to cited text no. 10
Agarwal M, Trivedi H, Mathur M, Goel D, Mittal S. The radix entomolaris and radix paramolaris: An endodontic challenge. J Contemp Dent Pract 2014;15:496-9.  Back to cited text no. 11
Navarro LF, Luzi A, García AA, García AH. Third canal in the mesial root of permanent mandibular first molars: Review of the literature and presentation of 3 clinical reports and 2 in vitro studies. Med Oral Patol Oral Cir Bucal 2007;12:E605-9.  Back to cited text no. 12


  [Figure 1], [Figure 2], [Figure 3]


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