SRM Journal of Research in Dental Sciences

: 2013  |  Volume : 4  |  Issue : 2  |  Page : 69--72

Endodontic management of the mandibular first molar having independent middle mesial canal and radix entomolaris within the same tooth

Avinash A Patil, Sanjana A Patil, Preeti K Dodwad 
 Department of Conservative Dentistry and Endodontics, K.L.E.V.K. Institute of Dental Sciences, Belgaum, Karnataka, India

Correspondence Address:
Avinash A Patil
A-14/10, Staff Quarters, Jawaharlal Nehru Medical College Campus, Nehru Nagar, Belgaum, Karnataka


The aim of this case report is to present the clinical management of mandibular first molar with three separate mesial canals including independent middle mesial canal and an extra distal root; radix entomolaris (RE). The left mandibular first molar of a male patient was a root canal treated. Mesiobuccal and mesiolingual canals were found in their normal locations. Third canal; the middle mesial canal was identified after a thorough examination of the pulpal floor under the operating microscope. Radiographically, it ended in its own distinct foramen. In addition, an extra distal root; RE was also present. Therefore, five canals (mesiobuccal, middle mesial, mesiolingual, distobuccal and distolingual) were identified, instrumented and obturated to the accepted lengths. Many reports deal with three orifices in the mesial root, but very few describe three independent canals and RE within the same tooth, indicating a rare anatomical configuration.

How to cite this article:
Patil AA, Patil SA, Dodwad PK. Endodontic management of the mandibular first molar having independent middle mesial canal and radix entomolaris within the same tooth.SRM J Res Dent Sci 2013;4:69-72

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Patil AA, Patil SA, Dodwad PK. Endodontic management of the mandibular first molar having independent middle mesial canal and radix entomolaris within the same tooth. SRM J Res Dent Sci [serial online] 2013 [cited 2020 Jul 6 ];4:69-72
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The goal of root canal therapy is a thorough cleaning and obturation of root canal system in all its dimensions. [1] Knowledge of both normal and abnormal anatomy of the root canal system dictates the parameters for execution of root canal therapy and can directly affect the outcome of endodontic treatment. [2] Anatomical variations have been described in the mandibular first molar. Since Vertucci and Williams [3] first reported the presence of a middle mesial canal in a mandibular molar, there have been multiple case reports of aberrant canal morphology in the mesial root. [4],[5],[6],[7]

Pomeranz et al. reported on 12 of 100 cases and classified middle mesial canal into three morphologic categories: Fin, confluent and independent. According to their classification, an independent canal implies the canal originated as a separate orifice and terminated as a separate foramen and identified only two cases as independent. [7] Goel et al. reported incidence of middle mesial canal as 15% with only 6.7% as independent; [8] thus, presenting independent middle mesial canal as a rare anatomic variant. [9]

Like the number of root canals; the number of roots may also vary. Mandibular first molar usually has two roots; a mesial and a distal. An additional third root, first mentioned in the literature by carabelli, is called the radix entomolaris (RE). This supernumerary root is located distolingually in mandibular molars, mainly first molars. An additional root at the distobuccal side is called the radix paramolaris. [10] The presence of separate RE in the first mandibular molar is associated with certain ethnic groups. In African populations, a maximum frequency of 3% is found while in Eurasian and Indian populations the frequency is less than 5%. In Caucasians, RE occurs with a maximum frequency of 3.4-4.2% and is considered to be an unusual or dysmorphic root morphology. [10],[11],[12]

Thus, the present case is one of its own kind having RE and independent middle mesial canal within the same tooth. In this report, we present clinical detection and management of an independent middle mesial canal in mandibular first molar using radiographs and magnification.

 Case Report

A 21-year-old male patient presented to the Department of Conservative Dentistry and Endodontics, with a chief complaint of pain on chewing associated with the left mandibular first molar. On clinical examination, the tooth revealed a deep carious lesion involving pulp. The tooth was painful on percussion and gave exaggerated responses to thermal and electric pulp tests. After thorough clinical and radiographic examination [Figure 1], a diagnosis of chronic irreversible pulpitis with apical periodontitis was made and the patient was prepared for root canal treatment.{Figure 1}

Patient received local anesthesia of 2% lidocaine and rubber dam was placed. After removing the caries, a conventional endodontic access opening was made. Radiographic evaluation of the tooth revealed two distal and one mesial root. This additional third root located distolingually was RE. On clinical examination, mesiobuccal, mesiolingual, distobuccal and distolingual canals were identified. After careful probing using the diglyme 16 endodontic explorer (dentsply, maillefer); a small hemorrhagic point was noted between a groove connecting mesiobuccal and mesiolingual orifice. This area was carefully inspected again under the operating microscope at high magnification (×16-25). This examination revealed another orifice between mesiobuccal and mesiolingual orifices. A #10 K-file was inserted into this orifice and ruled out for perforation using apex locator (Dentaport ZX, J Morita mfg corp., Kyoto, Japan). It was confirmed to be an additional canal in the mesial root; the middle mesial canal. Thus, there were five canals, mesiobuccal, middle mesial, mesiolingual, distobuccal and distolingual.

After cervical flaring with Protaper Universal Shaping files S1 and SX (dentsply, maillefer), working length of each canal was estimated by means of an apex locator (Dentaport ZX, J Morita corp.) and confirmed with intraoral periapical radiograph [Figure 2]. Accordingly, with regard to Pomeranz's classification, the middle mesial canal found in this case was classified as independent. Biomechanical preparation was performed using the crown-down technique with Protaper Universal (dentsply, maillefer) rotary NiTi files. [Figure 3] shows the photograph of the chamber floor after instrumentation. Master cone radiograph was taken [Figure 4]. Final irrigation was carried out with 3% sodium hypochlorite followed by a rinse with normal saline. The canals were dried with paper points and obturated with gutta-percha and AH plus sealer (dentsply, maillefer). The access was temporarily restored with cavit-G and patient was recalled after a week for post-endodontic restoration. Post-treatment radiograph [Figure 5] revealed three independent root canals in the mesial root obturated efficiently with gutta-percha to the accepted lengths in all three canals.{Figure 2}{Figure 3}{Figure 4}{Figure 5}

A 2-year follow-up radiograph revealed the integrity of the root canal therapy and a normal periapex [Figure 6]. Patient was completely asymptomatic.{Figure 6}


Mandibular molars are known to have complex anatomy and can be deceptively difficult to treat. Mandibular first molar is typically a two-rooted form with a mesial and a distal root having two canals in the mesial root 95.8% of the time. [13] However, in the presented case, an extra distal root was present on the lingual aspect (RE). In addition, an extra canal was present in the mesial root (middle mesial canal). This canal was found to have an independent course and foramen.

Radiographic examination using conventional intraoral periapical views is important for the evaluation of the canal configuration. However, it has its inherent limitation to assess the root canal system completely. In the present case, there was no radiographic suggestion of an additional canal in the mesial root, but there was an indication of extra distal root, RE. Recently, newer diagnostic techniques like cone beam computed tomography (CBCT) imaging have also been used in endodontics for accurate diagnosis and management of the unusual canal morphology. [14] La et al. in 2010 suggested clinical detection and management of an independent middle mesial canal in mandibular first molar by using CBCT imaging. [15]

Extensive exploration of the grooves under magnification revealed additional orifice between mesiobuccal and mesiolingual canals. This was middle mesial canal with separate orifice and apical termination. A round bur or an ultrasonic tip can also be used for removal of any protuberance from the mesial axial wall, which would prevent direct access to the developmental groove between mesiobuccal and mesiolingual orifices. This developmental groove should be carefully checked with the sharp tip of an endodontic explorer. If depression or orifices are located, the groove can be troughed with the ultrasonic tips at its mesial aspect until a small file can negotiate this intermediate canal. [16]

Various diagnostic aids such as dyes, champagne bubble test, ultrasonics, micro openers and trans-illumination aids, irrigators to improve pulp chamber visibility (Stropko) and observing the chamber for bleeding spots could be used by the clinician as an effective means to locate additional canal orifices. [14]

In the present case, all the five canals were carefully instrumented, cleaned and obturated until correct apical termination. The present report confirms that the third canal in the mesial root of mandibular first molar does occur and must be sought along the line between the two mesial canals after accessing the pulp chamber and any cervical stenosis in this zone that might cover the opening of the canals, using burs or ultrasonic tips.


Treating additional aberrant canals can be challenging, but the inability to find root canals may cause failures. Although such cases occur infrequently, these canal systems do exist and alert the dentist to proceed with a thorough examination of the pulp chamber floor even after the expected number of canals have been identified. The use of operating microscope can enable the clinician to investigate the root canal system and to clean, shape and obturate it more efficiently.


1Maggiore F, Jou YT, Kim S. A six-canal maxillary first molar: Case report. Int Endod J 2002;35:486-91.
2Reeh ES. Seven canals in a lower first molar. J Endod 1998;24:497-9.
3Vertucci FJ, Williams RG. Root canal anatomy of the mandibular first molar. J N J Dent Assoc 1974;45:27-8 passim.
4Weine FS. Case report: Three canals in the mesial root of a mandibular first molar(?). J Endod 1982;8:517-20.
5Fabra-Campos H. Unusual root anatomy of mandibular first molars. J Endod 1985;11:568-72.
6Bond JL, Hartwell GR, Donnelly JC, Portell FR. Clinical management of middle mesial root canals in mandibular molars. J Endod 1988;14:312-4.
7Pomeranz HH, Eidelman DL, Goldberg MG. Treatment considerations of the middle mesial canal of mandibular first and second molars. J Endod 1981;7:565-8.
8Goel NK, Gill KS, Taneja JR. Study of root canals configuration in mandibular first permanent molar. J Indian Soc Pedod Prev Dent 1991;8:12-4.
9Holtzmann L. Root canal treatment of a mandibular first molar with three mesial root canals. Int Endod J 1997;30:422-3.
10Calberson FL, De Moor RJ, Deroose CA. The radix entomolaris and paramolaris: Clinical approach in endodontics. J Endod 2007;33:58-63.
11Sperber GH, Moreau JL. Study of the number of roots and canals in senegalese first permanent mandibular molars. Int Endod J 1998;31:117-22.
12Walker RT, Quackenbush LE. Three-rooted lower first permanent molars in Hong Kong Chinese. Br Dent J 1985;159:298-9.
13Cleghorn BM, Goodacre CJ, Christie WH. Morphology of teeth and their root canal systems In: Ingle JI, Bakland LK, Baumgartner JC, editors. Endodontics. 6 th ed., Hamilton, Ontario L8N 3K7 Canada,: BC Decker Inc; 2008. P. 202-4.
14Cotton TP, Geisler TM, Holden DT, Schwartz SA, Schindler WG. Endodontic applications of cone-beam volumetric tomography. J Endod 2007;33:1121-32.
15La SH, Jung DH, Kim EC, Min KS. Identification of independent middle mesial canal in mandibular first molar using cone-beam computed tomography imaging. J Endod 2010;36:542-5.
16Vertucci FJ. Root canal morphology and its relationship to endodontic procedures. Endod Top 2005;10:3-29.