CODS Journal of Dentistry
Volume 11 | Issue 1 | Year 2019

Three-rooted Mandibular Molars—An Endodontic Enigma: A Case Series

Gauri B Nayak1, Sheetal Mali2, Ashish Jain3, Joel Devaraj4, Neha Pol5, Akshay Punjabi6

1–6Department of Conservative Dentistry and Endodontics, Bharati Vidyapeeth (Deemed to be University) Dental College and Hospital, Mumbai, Maharashtra, India

Corresponding Author: Gauri B Nayak, Department of Conservative Dentistry and Endodontics, Bharati Vidyapeeth (Deemed to be University) Dental College and Hospital, Mumbai, Maharashtra, India, Phone: +91 9920422242, e-mail:

How to cite this article Nayak GB, Mali S, Jain A, et al. Three-rooted Mandibular Molars—An Endodontic Enigma: A Case Series. CODS J Dent 2019;11(1):19–23.

Source of support: Nil

Conflict of interest: None


The success of an endodontic treatment depends upon good chemomechanical preparation of the root canals before filling it an obturating material to form a hermetic seal. Knowledge and understanding of the presence of unusual root canal anatomy contributes to the successful outcome of the treatment. Mandibular first molar is the first permanent tooth to erupt in oral cavity and thus displays several anatomical variations. Radix entomolaris (RE) means presence of an additional root, which is found distolingually in permanent first mandibular molar. It was first described by Carabelli and can also be found in the second and third mandibular molars. The prevalence of RE is highest among the population of Chinese, Taiwanese, and Koreans and is considered to be an eumorphic root morphology among them. It is not very common in the population of African, Eurasia, Caucasian, and Indian population and is said to be a dysmorphic. This case report describes a series of mandibular molars with radix entomolaris root.

Keywords: Anatomical variations, Entomolaris, Radix, Three-rooted mandibular molars.


Mandibular first molars are the first permanent teeth to erupt in the oral cavity and can display several anatomical variations.1 Radix entomolaris (RE) is one of the anatomical variants found in a permanent mandibular molar and was first described by Carabelli. Its characteristic feature is the presence of an additional or extra third root that is typically found distolingually and can be found in the first, second, and third mandibular molars. The occurrence is least in the second and third molars.2

The prevalence of RE is reported to differ significantly with races and ranges from 0 to 33.1%. The prevalence is said to be highest in the population of Chinese, Taiwanese, and Koreans and is considered to be an eumorphic root morphology among them. Radix entomolaris is not very common in population of Africa, Eurasia, Caucasia, and India, and it is said to be a dysmorphic.3

This case report describes a series of mandibular molars with radix entomolaris root.


Case 1

A 37-year-old female reported to the dental OPD of Bharati Vidyapeeth Dental College and Hospital, Navi Mumbai, with a chief complaint of having pain in lower right back region of jaw 1 month back for which the patient had visited a local dental clinic for restoration. After the placement of restoration, 2 days later, the patient had a huge swelling after which she reported to our hospital. On extraoral examination, there was swelling seen extending from lower border of the mandible till the imaginary line extending from corner of mouth posteriorly (Fig. 1A). Intraoral examination showed slight obliteration of buccal vestibule and a temporary restoration with tooth 46 which had pain on percussion (Fig. 1B).There was no draining sinus or fistula seen. Tooth 45 had a metal crown prosthesis. Preoperative radiograph showed radiopaque material in the crown of tooth 46 and periapical radiolucency in the distal root (Fig. 1C). So, based on the examination, the diagnosis here was acute apical abscess with symptomatic apical periodontitis in tooth 46 (AAE 2013). Radiographic diagnosis was chronic apical abscess.


On the first day after administration of local anesthesia, lidocaine with adrenaline 1:200,000, access opening was done using BR-46 and EX-24 diamond points. Initially, three canals were found mesio-buccal, mesio-lingual, and distal and after troughing and careful exploration of canal, a fourth canal was found distolingually (Fig. 1D).

The working length of the canals was determined electronically using an apex locator [J Morita] and confirmed radiographically (Fig. 1E). Canals were cleaned and shaped using rotary NiTi files [ProTaper, Dentsply-Maillefer] in crown-down technique. Canals were irrigated using 5.25% sodium hypochlorite solution and flushed with 17% EDTA solution for removing the smear layer. Canal disinfection was carried out using calcium hydroxide [RC Cal, Prime Dental], and the patient was given antibiotic coverage for 5 days and recalled after that.

Figs 1A to D: (A) Preoperative radiograph; (B) Working length determination; (C) Post-obturation radiograph; (D) Post-endodontic restoration after 3 months follow-up

In the follow-up visits, when the swelling had subsided, and the patient was found asymptomatic, gutta-percha master cones [ProTaper, Dentsply Maillefer] were selected (Fig. 1A), and obturation was carried out with corresponding master cones and AH plus sealer [Dentsply, Konstanz, Germany] in cold lateral compaction technique (Fig. 1B). The access opening was restored with temporary restoration (Fig. 1C), and the patient was called later for postendodontic treatment (Fig. 1C). After 3 months, there was healing of peri-apical tissue seen (Fig. 1D).

Case 2

A 19-year-old female patient reported to our department with a chief complaint of pain on having food in lower left back region of jaw from past 4 weeks. The tooth had secondary carious lesion and was moderately sensitive to percussion (Fig. 2A). Radiographic examination of tooth 36 revealed caries extending to the pulp and a small indistinct periapical radiolucency around the distal root. A double distal root outline was also seen indicating the presence of an RE (Fig. 2B).


The tooth 36 showed delayed response to electric pulp testing and was not responding to any thermal tests, so the diagnosis was made of pulp necrosis with chronic apical periodontitis. Root canal treatment was started by applying rubber dam (Fig. 2C). Local anesthesia was given, the old restoration was removed, pre-endodontic build up was done using light cure resin, and then access opening was made. Examination of the floor of the pulp chamber showed three canal orifices. However, due to the radiographic findings, further modification of the access opening was carried out. The pulp chamber floor was explored using an endodontic explorer, and after observation under a surgical microscope an extra canal orifice was seen which was situated distolingually confirming the presence of RE.

Figs 2A to D: (A) Preoperative radiograph; (B) Working length determination; (C) Master cone; (D) Post-obturation radiograph

The endodontic procedure was carried out similar to case 1. Following canal negotiation, working length was determined (Fig. 2A), and canals were cleaned and shaped in a crown-down manner using rotary NiTi files Hyflex system (20/04) and 5.25 % sodium hypochlorite and 17% EDTA solutions as irrigants during instrumentation. Calcium hydroxide was given as an intracanal medicament in-between the visits, after which the canals were obturated with gutta-percha point and AH plus sealer (Fig. 2B and C). The postendodontic restoration was done with composite resin (Fig. 2D), and the patient was suggested to undergo full coverage restoration.

Case 3

A 27-year-old male patient reported to our department with a chief complaint of pain on having food in lower right back region of jaw for 2 months. The tooth was sensitive to percussion. Radiographic examination of tooth 46 revealed the pulpal extent of the caries along with apical widening of the periodontal ligament space. It also showed a double distal root indicating the presence of an RE (Fig. 3A).


The same protocol was followed as explained in above cases. The working length was determined (Fig. 3B), and the biomechanical preparation was done using Edge Endo files 20/06 in crown down technique. Thorough chemo-mechanical preparation was done, and the canals were obturated with the corresponding gutta percha points (Figs 3A and D). A postendodontic restoration with composite resin matrix was done 1 week after obturation.

Figs 3A to D: (A) Preoperative radiograph; (B) Working length determination; (C) Master cone; (D) Post-obturation radiograph

Figs 4A to D: (A) Preoperative radiograph; (B) Working length determination; (C) Master cone; (D) Post-obturation radiograph

Figs 5A to D: (A) Preoperative radiograph; (B) Working length determination; (C) Master cone; (D) Post-obturation radiograph

Case 4

A 31-year-old male patient reported to our department with a chief complaint of pain on having food in lower right back region of jaw for past 4 months. The tooth was sensitive to hot and cold water and was tender on percussion. Radiographic examination of tooth 37 revealed the pulpal extent of the caries along with apical widening of the periodontal ligament space. It also showed a double distal root outline indicating the presence of an RE (Fig. 4A).


As explained in the previous cases, local anesthesia was administered, and rubber dam isolation was done. Using diamond points BR46 and EX 24, access cavity was prepared for tooth 37 (Fig. 4B). Working length was determined (Fig. 4C), and biomechanical preparation was done using rotary NiTi files Hyflex system till 25/05 size after chemo mechanical preparation, the canals were obturated using 25/04 gutta percha points (Figs 4A and D). The access cavity was then sealed with a permanent restoration and was referred to department of Prosthodontics for crown with tooth 37.

Case 5

A 50-year-old female patient was referred to our department for endodontic treatment of the lower right first molar for fractured restoration. The tooth was sensitive to percussion and had secondary caries on the distal wall (Fig. 5A). Radiograph also revealed radiolucency approaching pulp of tooth 46 (Fig. 5B).


After removal of old restoration and carious lesion, pre-endodontic build up was done using Palodent matrix system. Then, rubber dam was placed to keep a sterile environment, and access opening was done for tooth 46 (Fig. 5C).

After locating all four canals, working length was determined (Fig. 5D), and the canals were prepared using Edge Endo files up to size 20/06. Irrigation protocol was followed using 5.25% sodium hypochlorite and 17% EDTA.

Following preparation, the corresponding master cones were selected and obturated using A H Plus sealer with cold lateral compaction technique (Figs 5E and F). A postendodontic restoration was then done using polymerizable resin matrix (Fig. 5G).


Variations in root and canal morphology especially in multi-rooted teeth remain a constant challenge for diagnosis as well as management. A detailed knowledge of root canal anatomy and configuration is important for a successful endodontic therapy.4 Mandibular molars can have an additional root that is located lingually (Radix Entomolaris) or buccally (Radix Paramolaris). Carabelli was the first one to report RE. Such anomalies do possess a challenge to the dentist and is most commonly seen with first, second, and third mandibular molars with maximum chance of occurrence in first molar and least in the second molar.5

Radix Entomolaris and its Prevalence

Certain ethnic groups are also related to presence of a separate RE in the first mandibular molar. In African populations, a maximum frequency of 3% is found,6 while in Eurasian and Indian populations the frequency is less than 5%.7 The frequency of RE in Mongoloid traits (such as the Chinese, Eskimo and American Indians) ranges from 5% to more than 30%.814 According to studies, bilateral occurrence of the RE ranges from 50 to 67%. Bolk14 reported the occurrence of a buccally located additional root, the Radix Paramolaris which is very rare and occurs less frequently than the RE. As observed by Visser, the prevalence of RP, as Ref. 15 was found to be 0% for the first mandibular molar, 0.5% for the second, and 2% for the third molar. Some studies have reported first mandibular molar with RP.

Etiology of Radix Entomolaris

The exact etiology determining the formation of RE is unknown. Formation of supernumerary root might be associated with external factors during tooth formation, i.e., odontogenesis is often related to the dysmorphic trait. Atavistic gene or polygenetic system also adds to the etiology of the same.16 In eumorphic roots, the racial genetic factors result in a more pronounced phenotypic manifestation. Curzon had suggested high degree of genetic penetrance in the ‘three-rooted molar’ trait and the prevalence of the trait was similar in both pure Eskimo and Eskimo/Caucasian mixes.17

Anatomy of the Radix Entomolaris

The Radix Entomolaris root is present distolingually, and its coronal portion is partially attached to the distal root. The dimensions may vary from a short conical extension to a “mature” root with normal length and canal. The pulpal extension is radiographically visible. The RE root is often smaller than the distobuccal and mesial roots and may be separate or partially fused with the other roots.

Carlsen and Alexandersen18 gave a classification depending upon the location of the cervical part of the RE: types A, B, C and AC.

Types A and B refer to a distally located cervical part of the RE having two normal and one normal distal root components, respectively.

Type C refers to the cervical part located mesially, while type AC refers to the cervical part in a central location, between the distal and the mesial root components.

In the apical two-thirds of the root, a moderate to severe mesially or distally orientated inclination can be present. In addition to this, the RE root could be straight or curved to the lingual.

De Moor et al.19 gave a classification on based on the curvature of the separate RE variants in bucco-lingual orientation.

Type I refers to the orientation of a straight root/root canal, while type II refers to a root canal which is initially curved and continues as a straight root/root canal.

Type III refers to an initial curve present in the coronal third of the root canal and a second curve which begins in the middle third and continues to the apical third.


The presence of a RE or an RP has clinical implications in endodontic treatment. “Missed canal” is often a complication associated with the diagnosis of these supernumerary roots. Because the (separate) RE is mostly situated in the same bucco-lingual plane as the distobuccal root, a superimposition of both roots can appear on the preoperative radiograph, resulting in an inaccurate diagnosis.

Use of certain conventional methods like champagne test, bubble test, transillumination, white line, and red line test would help in determining the canal orifices. Apart from it, CBCT and magnification aids like loupes and surgical microscope also help in diagnosing and enhancing the treatment outcome.

A thorough inspection of the preoperative radiograph and interpretation of particular marks or characteristics, such as an unclear view or outline of the distal root contour or the root canal, can indicate the presence of a “hidden” RE. A second radiograph should be taken from a more mesial or distal angle (30°) to reveal the extra root. In this way, the radix root can be identified.

Manual agitation of the root canals with 17% EDTA and 5.25% sodium hypochlorite is necessary for a good chemo-mechanical preparation and to dissolve the necrotic debris. It also helps in providing an antimicrobial effect.

Ledge formation, straightening of the root canal, canal transportation, and loss of working length are often seen due to severe root inclination or canal curvature, mainly in the apical third of the root that can be corrected by making use of flexible nickel–titanium rotary files, thus allowing a more centered preparation with restricted enlargement of the canal.

Sometimes instrument separation can occur and is more likely with severe curvature or narrow root canals. Step-by-step actions should be taken to avoid any procedural errors,20 including the relocation and enlargement of the orifice of the RE. Initial root canal exploration with small files (size 10 or less) helps in curvature determination and creation of a glide path before preparation.

Then, the working length should be determined with the help of electronic apex locator and then confirmed radiographically.

Apart from the above-mentioned methods, using an ideal root canal sealer with the gutta percha and a coronal restoration provides a three-dimensional hermetic seal. In this way, a clinician can achieve success in treating the extra root and provide satisfactory results. Thus, the success of a root canal depends right from its preoperative diagnosis, root preparation to its complete coronal seal.


It is of paramount importance for the clinicians to be well known about the unusual morphological variations about radix entomolaris in terms of location of the extra root, root canal anatomy, and the root canal curvature. Thus, a careful clinical approach is needed to see the morphological variations of the RE such as root inclination and root canal curvature so as to avoid or overcome procedural errors during endodontic therapy. A knowledge of occurrence and the associated complication of such cases with preoperative radiographs would assist in better treatment outcomes.


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