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Year : 2014  |  Volume : 4  |  Issue : 2  |  Page : 77-82

Detection and endodontic management of radix entomolaris: Report of case series

Department of Conservative Dentistry and Endodontics, Manipal College of Dental Sciences (Manipal University), Light house Hill Road, Mangalore, Karnataka, India

Date of Web Publication19-May-2014

Correspondence Address:
A. R. Vivekananda Pai
Department of Conservative Dentistry and Endodontics, Manipal College of Dental Sciences (Manipal University), Light House Hill Road, Mangalore 575 001, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/1658-5984.132723

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Radix entomolaris (RE) is considered to be an Asiatic trait. However, its prevalence in Indian population is found to be lower than in other Asian races. Nevertheless, its awareness and identification is vital to achieve endodontic success. This article presents a review on clinical approach and a case series on the detection and endodontic management of RE in mandibular first molars. Radix entomolaris was detected by identifying the presence of a double or extra root outline in the preoperative radiograph, modifying the access opening and closely inspecting the pulp chamber and was endodontically treated following cleaning, shaping, and obturation of the canals. Achieving the endodontic success in the presence of an RE requires knowledge about its prevalence, diagnosis, morphology, canal configuration, and clinical approach.

Keywords: Anatomical variation, disto-lingual root radix entomolaris, root canal system, three-rooted mandibular first molars

How to cite this article:
Vivekananda Pai AR, Jain R, Colaco AS. Detection and endodontic management of radix entomolaris: Report of case series. Saudi Endod J 2014;4:77-82

How to cite this URL:
Vivekananda Pai AR, Jain R, Colaco AS. Detection and endodontic management of radix entomolaris: Report of case series. Saudi Endod J [serial online] 2014 [cited 2023 Feb 1];4:77-82. Available from: https://www.saudiendodj.com/text.asp?2014/4/2/77/132723

  Introduction Top

Radix entomolaris (RE) is one of the anatomical variant found in a permanent mandibular molar and was first described by Carabelli. [1] It is characterized by the presence of an additional or extra third root, which is typically found disto-lingually. Radix entomolaris can be found in the first, second, and third mandibular molars, occurring the least frequently in the second molar. [2],[3],[4]

The prevalence of RE is reported to differ significantly with races and ranges from 0-33.1%. The prevalence of RE is said to be highest among the population of Mongolian origin such as Chinese, Taiwanese, and Koreans which considered to be an eumorphic root morphology among them. Radix entomolaris is not very common in African, Eurasian, Caucasian and Indian population and it is said to be a dysmorphic root morphology in them. [4],[5]

Despite RE consideration as an Asiatic trait with a high prevalence and a eumorphic root morphology in certain races such as Chinese, Taiwanese, and Koreans, the incidence of RE among the Indian population is found to be very low and only 0.2%. However, few studies have reported higher prevalence of RE, with a range from 2.19-13.3%, among the Indian population. [3],[4],[6],[7]

The relationship between the finding of RE and various other factors such as gender, right vs left side distribution and bilateral occurrence is said to be contradictory. Regarding gender predilection, although few studies found male predilection for RE, no significant difference was found in the prevalence of RE according to gender. [5] Similarly, no significant difference was found in the side occurrence, despite some studies reporting it to be more on the right side while other studies finding it more on the left side. [5] The bilateral occurrence of RE is reported to vary from 37.14 to 67%. However, since some studies have reported only unilateral occurrence of RE, further studies are required to clarify this aspect. [3],[5],[8],[9]

Despite the prevalence of RE clearly showing a racial predilection, the diagnosis and management of RE are of paramount importance from the point of endodontic success. The purpose of this article is to present a review on clinical approach for identification and endodontic management of RE and a case series on detection and root canal treatment of a mandibular first molar with RE.

  Case reports Top

Case 1

A 21-year-old female was presented with swelling on right mandibular side of the face. Clinical examination revealed deep occlusal caries in mandibular right first molar (tooth 46). The tooth was very sensitive to percussion and apical palpation. On radiographic examination of tooth 46, apart from deep occlusal caries, indistinct periapical radiolucency was seen around the roots. Further, the presence of an additional distal root outline was noticed on the radiograph [Figure 1]a. Following pulp testing, a diagnosis of pulp necrosis and acute alveolar abscess was made. The patient was suggested to undergo root canal treatment and an emergency access opening was made to allow drainage. Following the initiation of root canal treatment under rubber dam isolation, the close inspection of the pulp chamber revealed the presence of two mesial and two distal canal orifices [Figure 1]b. The presence of all the orifices were confirmed using an endodontic explorer [DG16, Hu-Friedy, Chicago] and a surgical microscope [Seiler, St. Louis, USA]. In the subsequent visits, canals were explored and negotiated using #08 and #10 size K-files [Dentsply Maillefer, Ballaigues, Switzerland]. The working length of the canals was determined electronically using an apex locator [Propex, Dentsply Maillefer] and confirmed radiographically. Canals were cleaned and shaped using rotary Ni-Ti files [ProTaper, Dentsply-Maillefer] and crown-down technique. Canals were irrigated using 2.5% sodium hypochlorite solution and flushed with 17% EDTA solution to remove smear layer. Canal disinfection was carried out using calcium hydroxide [Calcicur, VOCO, Germany]. In this patient, the finding of a separate disto-lingual canal orifice and radiographic outline of the roots in the subsequent radiographs indicated the presence of an RE. In the follow up visits, when the patient was found asymptomatic, gutta-percha master cones [ProTaper, Dentsply Maillefer] were selected [Figure 1]c]. Obturation was carried out with master cones and AH26 sealer [De Trey Dentsply, Konstanz, Germany] [Figure 1]d and 1e]. The access opening was restored with silver amalgam [Figure 1]f] and the patient was scheduled for post-endodontic treatment.
Figure 1: (a) Preoperative radiograph of mandibular right fi rst molar showing an additional distal root outline indicating the presence of an RE. (b) Clinical image of the pulp chamber floor showing the presence of an additional canal orifi ce disto-lingually (arrow). (c) Radiographic confirmation of gutta-percha master cone fit. (d) Obturation radiograph. (e) Clinical image showing the obturated disto-lingual canal orifice (arrow) of an RE along with other obturated orifi ces. (f) Follow up radiograph after access restoration with silver amalgam

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Case 2

A 56-year-old female patient was presented with dull aching pain while chewing food on mandibular left first molar (tooth 36). The tooth had deep occlusal carious lesion and was moderately sensitive to percussion. Radiographic examination of tooth 36 revealed the pulpal extent of the caries along with small indistinct periapical radiolucency around the mesial root and apical widening of the periodontal ligament space around the distal root. It also showed a double distal root outline indicating the presence of an RE [Figure 2]a]. Although tooth 36 showed a mild and delayed response to electric pulp testing, it was not responsive to thermal tests. A diagnosis of pulp necrosis with chronic apical periodontitis was made and root canal treatment was started under rubber dam isolation. After achieving adequate anesthesia, 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. Exploration of the pulp chamber floor using an endodontic explorer and observation under a surgical microscope revealed an extra canal orifice situated disto-lingually and confirmed the presence of RE.

The endodontic procedure was carried out similar to case 1. Following canal negotiation, working length was determined and canals were cleaned and shaped in a crown-down manner using rotary Ni-Ti files and 2.5% sodium hypochlorite and 17% EDTA solutions as irrigants during instrumentation. Canals were disinfected using calcium hydroxide as an intracanal medicament between the visits. Subsequently, canals were obturated with gutta-percha point master cones and AH26 sealer [Figure 2]b and 2c]. The access opening was restored with silver amalgam [Figure 2]d] and the patient was suggested to undergo full coverage restoration.
Figure 2: (a) Preoperative radiograph of mandibular left first molar revealed the extent of caries and the presence of an RE. (b) Gutta-percha master cone fit was radiographically confi rmed. (c) Radiographic verification of obturation. (d) 6 months follow up radiograph

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Case 3

A 35-year-old male reported with a complaint of severe pain in mandibular right first molar (tooth 46) since 2 days. On clinical examination, a deep proximal caries was detected on the distal side of the tooth 46. Periapical radiograph showed the proximity of caries to the pulp space without any apical widening of the periodontal ligament space. However, a distinct double root outline on distal aspect indicating the occurrence of an RE was evident [Figure 3]a].

Although tooth 46 was mildly sensitive to percussion, it gave an intense and prolonged response to thermal and electric pulp testing. Based on these findings, a diagnosis of symptomatic irreversible pulpitis was made and root canal treatment was initiated.

Access preparation and pulp chamber inspection led to the finding of an extra canal orifice toward the disto-lingual corner of the pulp chamber in addition to other three regular canal orifices. The disto-lingual orifice was found very distinct and indicated the presence of an RE.

The endodontic treatment was done as in case 1. All the canals were negotiated, cleaned, and shaped following working length determination using rotary Ni-Ti files and copious irrigation with 2.5% sodium hypochlorite and 17% EDTA solutions. Later, gutta-percha master cones were selected [Figure 3]b]. Canals were obturated with master cones and AH26 sealer [Figure 3]c]. The access opening was restored with silver amalgam [Figure 3]d].
Figure 3: (a) Preoperative radiograph showing double distal root outline suggesting the presence of an RE in mandibular right first molar. (b) Radiograph confirming the fit of the gutta-percha master cones. (c) Radiographic view of the obturated tooth. (d) Follow up radiograph showing the silver amalgam access restoration and normal periapical findings 6 months post-obturation

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Case 4

A 28-year-old female was presented with excruciating pain in a mandibular right first molar (tooth 46). Clinical examination of the tooth showed the presence of deep mesio-lingual caries. On radiographic examination of tooth 46, caries was found to be close to mesial pulp horn and periodontal ligament space around the roots was found intact without any apical widening. However, an extra root outline was evident in the radiograph suggesting the presence of an RE [Figure 4]a]. Affected tooth was non-sensitive to percussion but showed an exaggerated lingering response to pulp testing. Following a diagnosis of acute irreversible pulpitis, root canal treatment was initiated under local anesthesia and rubber dam isolation.

Access opening modification and inspection of the pulp chamber revealed an additional disto-lingual orifice apart from the three regular orifices, two mesial and one distal, confirming the presence of an RE. The endodontic procedure was carried out similar to case 1. The canals were negotiated using #08 and #10 size K-files and the working length of canals was determined using an apex locator and radiograph [Figure 4]b]. Canals cleaning and shaping were carried out using rotary Ni-Ti files and crown-down method. A total of 2.5% Sodium hypochlorite (2.5%) and 17% EDTA solutions were used for canal irrigation. In the subsequent visit, gutta-percha point master cones were selected and obturation was done using AH26 sealer [Figure 4]c]. Access opening was restored with silver amalgam. Though sealer extrusion was found post-obturation, the 1 year follow up radiograph did not reveal any significant changes [Figure 4]d].
Figure 4: (a) Preoperative radiograph of mandibular right first molar indicating the presence of an RE and proximity of caries to pulp space. (b) Radiographic verification of working length. (c) Fit of gutta-percha master cones confi rmed radiographically. (d) Follow up radiograph without any significant periapical changes despite the sealer extrusion

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  Discussion Top

Endodontic success in the presence of RE depends on its diagnosis, anatomy or morphology, canal configuration and clinical approach employed. An accurate diagnosis of RE can avoid complications like missed canal which is a common reason for endodontic failure. Detection of RE can be based on clinical examination, radiographic and imaging techniques and other accessories. [5],[10]

Clinically, apart from the awareness about the possible existence and the racial prevalence of RE, factors such as an extra cusp, prominent distolingual lobe, cervical convexity, complex external contour of the furcation can indicate the presence of an RE. Radiographically, double periodontal ligament images or an unclear view or outline of the distal root contour or the root canal can hint to the presence of an RE. However, this requires a thorough inspection of the preoperative radiograph. It is mentioned that the radiographs were successful in over 90% of the cases while identifying additional roots but superimposition of the distal roots can be limiting factor. An angled radiograph (25-30°) can be more useful in this regard and it is said that a mesial angled radiograph is better than a distal angled radiograph for RE detection. [5],[10],[11],[12],[13]

Three-dimensional imaging techniques based on computed tomography (CT) and cone beam computed tomography (CBCT) are useful for visualizing or studying the true morphology of an RE in a noninvasive manner using less radiation. However, cost and access to them are said to be the limiting factors. [3],[5]

In the present case series, radiographs alone, including preoperative ones, clearly showed the presence of RE in all the cases signifying the importance of radiographs in the detection of RE and, from patient's point of view, prevented the need for expensive investigations such as CBCT.

Modification of the conventional triangular access to obtain rectangular or trapezoidal outline form assists in locating the orifice of RE. Since canal entrances are equidistant from a line drawn in a mesio distal (MD) direction through the pulp chamber floor and lie on a line perpendicular to this MD line across the center of the floor of the pulp chamber, following the laws of symmetry helps in both detecting and locating an RE. Further, following a dark line on the floor of the pulp chamber may act as a visual aid to indicate the position of an RE canal orifice. [5],[10],[14 ],[15]

The values based on the mean inter-orifice distance between an RE canal and remaining canals, as found in a study by Tu et al., may also serve as a useful guideline to locate and treat an RE. [3],[16] In case of any calcification or overlying dentin or pulp roof remnants obscuring the orifice of an RE, use of an angled probe, ultrasonics cutting tips along with good illumination and visual aids such as loupes or surgical operating microscopes is said to facilitate the locating of an RE. [5],[10],[17]

Morphologically, an RE can vary from a short conical extension to a mature root with normal length and root canal. It is generally smaller than the distobuccal and mesial roots and can be classified into separate and non-separate categories depending on the amount of its fusion with the other roots. Further, depending on the location of its cervical part, RE has been categorized into types A, B, C, and AC. An RE having a distally located cervical part and two normal distal root components belongs to type A, while a similar RE with one normal distal root is considered as type B. Type C refers to a mesially located cervical part of an RE, while type AC refers to an RE centrally located between the distal and mesial root components. [9]

Anatomically, RE is most often found curved in a bucco-lingual plane. Depending on the amount of this curvature, it is classified into types I, II, and III. Type I refers to a straight root/root canal, while type II refers to an initially curved entrance which continues as a straight root/root canal. Type III refers to an initial curve in the coronal third of the root canal and a second curve beginning in the middle and continuing to the apical third. [3],[9],[10],[18]

This classification is further modified by adding two more newly defined variants of RE termed as small type, having the length shorter than half of the length of the distobuccal root, and conical type, looking even smaller than the small type and having no root canal in it. [19]

Canal configuration wise, despite these morphological variations, RE is reported to be typically rounder in shape with Vertucci type I configuration which can be considered to be the simplest canal anatomy of all types. [2],[4],[5],[20] In confirmation of this, all the detected RE in the present case series radiographically exhibited only Vertucci type I canal configuration.

It is said that externally, furcation contour wise, the distal furcation (furcation between disto-buccal root and RE) is significantly lower, with an average of 1 mm, than the furcation between the mesial and the distal roots and radiographically the distal furcation is not detectable. [21]

Radix entomolaris, due to variations and complexities in its anatomy coupled with its variable furcation levels, can pose multiple and significant endodontic problems in the form of furcal or strip perforation, weakening of root, vertical root fracture, straightening of the root canal, ledge formation, loss of working length, root canal transportation and instrument separation. These problems are more likely to happen during coronal pre-flaring, canal cleaning and shaping or post-space preparation, particularly in a type III RE which exhibits more curvature than other types. [5],[10]

A clinical approach to endodontically treat an RE should consist of adopting measures to minimize above complications. An initial relocation of the orifice to the lingual without excessive removal of dentin helps to achieve straight-line access and avoid perforations. Manual preflaring is recommended to prevent instrument separation. It is said that RE exhibits the greatest degrees of curvature among the other roots of a mandibular molar with its canal having relatively longer length and smaller radius of curvature. As the risk of instrument fracture significantly increases with the decrease in the radius of curvature, canal preflaring with manual use of stainless steel files is suggested to overcome instrument fracture. initial root canal exploration with small files (size 10 or less), creation of a glide path along with the proper determination of the canal curvature and working length would reduce the procedural errors such as ledging and transportation. Finally, use of nickel-titanium rotary files having a taper of not more than 0.04 taper and crown down technique is said to allow a more centered, rounder and conservative canal preparation than the use of stainless steel instruments in RE. [5],[10],[22]

  Conclusion Top

Failure to identify and treat an RE can significantly affect the outcome of an endodontic treatment in mandibular molars displaying RE. Although angulated radiographs can play a key role in the identification and endodontic management of an RE, the knowledge about prevalence, diagnosis, morphology, canal configuration of an RE and clinical approach to treat it would be a very important prerequisite to achieve endodontic success in a mandibular molar with an RE.

  References Top

1.Carabelli G. Systematisches Handbuch der Zahnheilkunde. 2 nd ed. Vienna: Braumuller und Seidel; 1844. p. 114.  Back to cited text no. 1
2.Segura-Egea JJ, Jimenez-Pinzon A, Rios-Santos JV. Endodontic therapy in a 3-rooted mandibular first molar: Importance of a thorough radiographical examination. J Can Dent Assoc 2002;68:541-4.  Back to cited text no. 2
3.Tu MG, Huang HL, Hsue SS, Hsu JT, Chen SY, Jou MJ, et al. Detection of permanent three-rooted mandibular first molar by cone-beam computed tomography imaging in Taiwanese individuals. J Endod 2009;35:503-7.  Back to cited text no. 3
4.Garg AK, Tewari RK, Kumar A, Hashmi SH, Agrawal N, Mishra SK. Prevalence of three-rooted mandibular permanent first molars among the Indian Population. J Endod 2010;36:1302-6.  Back to cited text no. 4
5.Abella F, Patel S, Duran-Sindreu F, Mercade M, Roig M. Mandibular first molars with disto-lingual roots: Review and clinical management. Int Endod J 2012;45:963-78.  Back to cited text no. 5
6.Chandra SS, Chandra S, Shankar P, Indira R. Prevalence of radix entomolaris in mandibular permanent first molars: A study in a South Indian population. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2011;112:e77-82.  Back to cited text no. 6
7.Bharti R, Arya D, Saumyendra VS, Kulwinder KW, Tikku AP, Chandra A. Prevalence of radix entomolaris in an Indian population. Indian J Stomatol 2011;2:165-7.  Back to cited text no. 7
8.Tu MG, Tsai CC, Jou MJ, Chen WL, Chang YF, Chen SY, et al. Prevalence of three-rooted mandibular first molars among Taiwanese individuals. J Endod 2007;33:1163-6.  Back to cited text no. 8
9.Carlsen O, Alexandersen V. Radix entomolaris: Identification and morphology. Scan J Dent Res 1990;98:363-73.  Back to cited text no. 9
10.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. 10
11.Chen YC, Lee YY, Pai SF, Yang SF. The morphologic characteristics of the distolingual roots of mandibular first molars in a Taiwanese population. J Endod 2009;35:643-5.  Back to cited text no. 11
12.Walker RT, Quackenbush LE. Three-rooted lower first permanent molars in Hong Kong Chinese. Br Dent J 1985;9:298-9.  Back to cited text no. 12
13.Somogyl-Csizmazia W, Simons AJ. Three-rooted mandibular first molars in Alberta Indian Children. J Can Dent Assoc 1971;37:105-6.  Back to cited text no. 13
14.Krasner P, Rankow HJ. Anatomy of the pulp-chamber floor. J Endod 2004;30:5-16.  Back to cited text no. 14
15.Gu Y, Lu Q, Wang H, Ding Y, Wang P, Ni L. Root canal morphology of permanent three-rooted mandibular first molars-part I: Pulp floor and root canal system. J Endod 2010;36:990-4.  Back to cited text no. 15
16.Yew S, Chan K. A retrospective study of endodontically treated mandibular first molars in a Chinese population. J Endod 1993;19:471-3.  Back to cited text no. 16
17.Bahcall JK. Visual enhancement. In: Ingle JI, Bakland LK, Baumgartner JC, editors. Ingle's Endodontics. 6 th ed. Hamilton: BC Decker Inc; 2008. p. 870-6.  Back to cited text no. 17
18.De Moor RJ, Deroose CA, Calberson FL. The radix entomolaris in mandibular first molars: An endodontic challenge. Int Endod J 2004;37:789-99.  Back to cited text no. 18
19.Song JS, Choi HJ, Jung IY, Jung HS, Kim SO. The prevalence and morphologic classification of distolingual roots in the mandibular molars in a Korean population. J Endod 2010;36:653-7.  Back to cited text no. 19
20.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. 20
21.Gu Y, Zhou P, Ding Y, Wang P, Ni L. Root canal morphology of permanent three-rooted mandibular first molars - part III: An odontometric analysis. J Endod 2011;37:485-90.  Back to cited text no. 21
22.Schafer E, Lohmann D. Efficiency of rotary nickel-titanium FlexMaster instruments compared with stainless steel hand K-Flexofile-Part I. Shaping ability in simulated curved canals. Int Endod J 2002;35:505-21.  Back to cited text no. 22


  [Figure 1], [Figure 2], [Figure 3], [Figure 4]

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