Navigating The Unseen: Radix Entomolaris (Type B) and Decoding Aberrant Canal System in Mandibular Molar

International Journal of Dental Science and Innovative Research (IJDSIR) IJDSIR : Dental Publication Service Available Online at:www.ijdsir.com Volume – 8, Issue – 5, October – 2025, Page No. : 128 - 133 Corresponding Author: Dr. Bhargavi Krishnaraj, ijdsir, Volume – 8 Issue - 5, Page No. : 128 - 133 Page128 ISSN: 2581-5989 PubMed - National Library of Medicine - ID: 101738774 Navigating The Unseen: Radix Entomolaris (Type B) and Decoding Aberrant Canal System in Mandibular Molar 1Dr. Bhargavi Krishnaraj, Third Year Post Graduate Student, Department of Conservative Dentistry and Endodontics, Krishanadevaraya College of Dental Sciences, Rajiv Gandhi University of Health Sciences, Bangalore, Karnataka, India 2Dr. Sujatha I, Professor, Department of Conservative Dentistry and Endodontics, Krishanadevaraya College of Dental Sciences, Rajiv Gandhi University of Health Sciences, Bangalore, Karnataka, India 3Dr. Jayalakshmi K.B, HOD, Department of Conservative Dentistry and Endodontics, Krishanadevaraya College of Dental Sciences, Rajiv Gandhi University of Health Sciences, Bangalore, Karnataka, India 4Dr. Neha N.C, Third Year Post Graduate Student, Department of Conservative Dentistry and Endodontics, Krishanadevaraya College of Dental Sciences, Rajiv Gandhi University of Health Sciences, Bangalore, Karnataka, India Corresponding Author: Dr. Bhargavi Krishnaraj, Third Year Post Graduate Student, Department of Conservative Dentistry and Endodontics, Krishanadevaraya College of Dental Sciences, Rajiv Gandhi University of Health Sciences, Bangalore, Karnataka, India. Citation of this Article: Dr. Bhargavi Krishnaraj, Dr. Sujatha I, Dr. Jayalakshmi K.B, Dr. Neha N.C, “Navigating The Unseen: Radix Entomolaris (Type B) and Decoding Aberrant Canal System in Mandibular Molar”, IJDSIROctober – 2025, Volume – 8, Issue – 5, P. No. 128 – 133. Copyright: © 2025, Dr. Bhargavi Krishnaraj, et al. This is an open access journal and article distributed under the terms of the creative common’s attribution non-commercial License. Which allows others to remix, tweak, and build upon the work non-commercially, as long as appropriate credit is given, and the new creations are licensed under the identical terms. Type of Publication: Case Report Conflicts of Interest: Nil Abstract The clinician’s knowledge and familiarity with root canal anatomy play a pivotal role in identifying variations such as extra canals and roots. Failure to recognize these variations often leads to endodontic failure. The mandibular first molar is one of the most commonly treated teeth and exhibits considerable anatomic variability. One such variation is an additional distolingual root known as Radix Entomolaris (RE). This case report describes the endodontic management of a mandibular first molar with a (Type B) RE, in which the canal of Radix Entomolaris bifurcated from the distolingual canal at the middle third of the distal root. Also presence of three distal canals with middle distal canal in type VIII vertucci configuration, a rare entity. Diagnosis was confirmed by cone-beam computed tomography (CBCT) and visualized under an operating microscope. This report highlights the diagnostic and clinical strategies used to decode this aberrant canal morphology and emphasizes the importance of magnification and advanced imaging in successful management. Dr. Bhargavi Krishnaraj, et al. International Journal of Dental Science and Innovative Research (IJDSIR) ©2025 IJDSIR, All Rights Reserved Page129 Page129 Page129 Page129 Page129 Page129 Page129 Page129 Page129 Page129 Page129 Page129 Page129 Page129 Page129 Page129 Page129 Page129 Page129 Keywords: Aberrant Canal, Cone-Beam Computed Tomography, Endodontic Treatment, Mandibular Molar, Radix Entomolaris Introduction Anatomic variations present a formidable challenge during endodontic therapy. The success of endodontic treatment depends on proper identification of all canals, thorough chemomechanical preparation, and threedimensional obturation¹. Failure due to unrecognized tooth morphology can compromise prognosis². The permanent mandibular first molar typically presents with two roots (mesial and distal) and three canals³,⁴. Variations, such as a third distolingual root (Radix Entomolaris, RE), have been documented⁵. Its prevalence varies: less than 5% among Indian and Eurasian populations, 3.4–4.2% among Caucasians, and up to 30% in Mongoloid populations⁶,⁷. Bilateral occurrence is reported in 50–67% of cases⁸. RE may arise due to genetic atavistic traits or environmental influences during odontogenesis⁹. Awareness of RE morphology, prevalence, and diagnostic features is vital for clinical success. This case presents a rare Type B Radix Entomolaris with a bifurcating canal in the middle third, and presence of three distal canals with middle distal canal in type VIII vertucci configuration, a rare entity, emphasizing the role of CBCT and magnification in its management. Case Report An 18-year-old female patient presented with pain in her lower right back tooth region for one month. Pain was moderate, continuous, and aggravated by mastication. The patient had undergone composite restoration on tooth 46 six months prior. On examination, tooth 46 was tender on percussion. IOPA radiograph revealed coronal radiolucency beneath the restoration suggestive of secondary caries and radiolucency was involving pulp with periapical widening. The tooth was nonresponsive to cold testing. Based on clinical and radiographic findings a diagnosis of pulpal necrosis with symptomatic apical periodontitis was given for 46. Access cavity preparation revealed an unusual distal canal configuration. Three canal orifice was located which were distobuccal canal, middle distal canal, distolingual canal and was successfully negotiated as well, yet we couldn’t find the orifice of radix entomolaris. That’s when CBCT assessment was done and we confirmed a Type B Radix Entomolaris, where the canal of Radix Entomolaris which was bifurcating from the distolingual canal, where its orifice was located at the level of middle third of distal root. Working lengths were determined by inserting a size 15 K-fle Mani, Inc, Japan) using an apex locator (Root ZX mini,J Morita, Japan),and radiographs. Cleaning and shaping used NiTi rotary HERO shaper instruments with 2.5% NaOCl and 17% EDTA irrigation. Obturation of 5 canals was completed with single cone obturation using gutta percha and AD seal sealer. The tooth was restored with composite resin. Figure 1: Preoperative radiograph Dr. Bhargavi Krishnaraj, et al. International Journal of Dental Science and Innovative Research (IJDSIR) ©2025 IJDSIR, All Rights Reserved Page130 Page130 Page130 Page130 Page130 Page130 Page130 Page130 Page130 Page130 Page130 Page130 Page130 Page130 Page130 Page130 Page130 Page130 Page130 Figure 2a: Access Cavity of 46 Figure 2b: access cavity with three distal canal accessed through operating microscope. Note the wider distolingual canal. Figure 3: Pecularity of this case, bifurcation of distolingual canal evident at the level of middle third of the distal root Figure 4: CBCT assessment Figure 5: Working Length Determination Figure 6: Master cone selection Figure 7: Obturation of 5 canals Figure 8: follow up after 1 year Discussion Anatomic variations in mandibular molars are frequent causes of endodontic failure when unrecognized. The presence of a third distolingual root (RE) significantly Dr. Bhargavi Krishnaraj, et al. International Journal of Dental Science and Innovative Research (IJDSIR) ©2025 IJDSIR, All Rights Reserved Page131 Page131 Page131 Page131 Page131 Page131 Page131 Page131 Page131 Page131 Page131 Page131 Page131 Page131 Page131 Page131 Page131 Page131 Page131 influences cleaning, shaping, and obturation¹⁰. RE prevalence varies by ethnicity: Indian and Eurasian <5%, Caucasian 3.4–4.2%, Mongoloid up to 30%¹¹. Two hypotheses explain its origin: genetic atavism and developmental/environmental factors. Understanding RE morphology is crucial. Carlsen and Alexandersen¹2 classified RE based on the cervical location: Type A (distal cervical with two distal roots), Type B (distal cervical with one distal root), Type C (mesial cervical), and Type AC (central cervical). De Moor et al.¹3 described curvature types: Type I (straight canal), Type II (curved entrance continuing straight), and Type III (coronal curve with apical buccal curve). Preoperative detection of RE requires careful clinical and radiographic examination. Clinically, inspection of crown morphology, cervical convexities, and the presence of a tuberculum paramolare may suggest an additional root¹4. Radiographically, extra PDL spaces adjacent to distal roots should be evaluated, and angulated radiographs at 20° mesial or distal views help identify the extra root¹5. The canal orifice is usually distolingual, necessitating an extension of the triangular access cavity distolingually to produce a rectangular or trapezoidal outline. When the orifice is not visible after deroofing, careful inspection of the pulp chamber floor under the dental operating microscope (DOM) is recommended¹⁶. Krasner and Rankow’s laws (symmetry and orifice location) assist in proper localization. Straight-line access, magnification, and illumination are critical because RE roots are often curved. Locating missed canals relies on a thorough understanding of the dentinal map and canal bleeding points. Tactile exploration with Pathfinder files, DG-16 explorers, and Micro-openers is beneficial. Advanced imaging modalities, such as CBCT17, micro-CT, fiberoptic illumination, orascopy, and digital radiography, enhance detection and confirmation of extra canals and roots¹⁴–¹⁶. There have been various investigations conducted on the peculiar root canal anatomy of the mandibular first molar. Baugh and Wallace reported in a review of the literature that the middle mesial canal in the mandibular first molar has been recorded in 1%-15% of instances, and there are very few case reports in the literature with the middle distal canal, which is extremely rare18. Quackenbush et al reported the existence an unusual case is presented in which there were three canals in the distal root of a mandibular first permanent molar19. According to various authors in various countries, the incidence of three canals in the distal root of the mandibular first molar is 1.7% in the populations of India and Turkey, 0.2% in Senegal, 0.7% in Burma, 1.6% in Thailand, 0.3% in Jordan, and 3% in Sudan20. Hitherto, only three case reports and one study, as mentioned above, have published with three separate distal canals (Vertucci’s type VIII). In this case, there were three separate distal canals, i.e. Vertucci’s type VIII, which is very unique in itself21. As a result, there are just a few reported cases of middle distal canals with Vertucci's type VIII root canal architecture. This case report details the successful identification and treatment of three distal root canals with the Middle Distal Canal. Additionally, a RARE CONFIGURATION of Radix Entomolaris (type B) with type II curvature, whose canal was bifurcating from the distolingual canal and whose orifice was situated at the level of the middle third of the distal root, was described. CBCT and DOM facilitated accurate diagnosis, allowing modified access and visualization, complete debridement, and proper obturation. Such meticulous evaluation prevents procedural errors and improves prognosis. Dr. Bhargavi Krishnaraj, et al. International Journal of Dental Science and Innovative Research (IJDSIR) ©2025 IJDSIR, All Rights Reserved Page132 Page132 Page132 Page132 Page132 Page132 Page132 Page132 Page132 Page132 Page132 Page132 Page132 Page132 Page132 Page132 Page132 Page132 Page132 Conclusion Failure to identify and negotiate additional canals remains a significant cause of root canal failure. This report emphasizes the importance of CBCT, DOM, and anatomical knowledge in managing complex variations. The peculiar feature of this case was, rarely reported in literature and was challenging. Early detection, modified access design, and magnification enabled successful treatment and favorable long-term prognosis. References 1. Barker BC, Parsons KC, Mills PR, Williams GL. Anatomy of root canals. Aust Dent J 1974;19 (6):408–413. 2. Vertucci FJ. Root canal anatomy of the human permanent teeth. Oral Surg Oral Med Oral Pathol 1984;58(5):589–599. 3. Carabelli G. Systematisches Handbuch der Zahnheilkunde. Vienna; 1844. 4. Calberson FLG, De Moor RJG, Deroose CAJ. The Radix Entomolaris and paramolaris: clinical approach in endodontics. J Endod 2007;33(1):58–63. 5. Curzon MEJ. Three-rooted mandibular permanent first molars in English Caucasians. J Dent Res 1973;52(1):181. 6. Tu MG, Huang HL, Hsue SS, Hsu JT, Chen SY, Jou MJ, Tsai CC. Detection of permanent three-rooted mandibular first molars by cone-beam computed tomography imaging in Taiwanese individuals. J Endod 2009;35(4):503–507. 7. Różyło TK, Piskórz MJ, Różyło-Kalinowska IK. Radiographic appearance and clinical implications of the presence of Radix Entomolaris and Radix Paramolaris. Folia Morphol 2014;73(4):449–454. 8. Ahmed HM, Dummer PMH. A new system for classifying root and root canal morphology. Int Endod J 2018;51(4):389–404. 9. Chandra SS, Chandra S, Shankar P, Indira R. Prevalence of radix entomolaris in mandibular molars: a clinical approach. J Conserv Dent 2011;14 (3):293–296. 10. Garg AK, Tewari RK, Kumar A, Hashmi SH, Agrawal N. Prevalence and morphology of threerooted mandibular first molars in Indian population. J Endod 2010;36(8):1302–1306. 11. Nagaveni NB, Umashankara KV, Poornima P, Radhika NB, Satisha TS. Radix entomolaris and paramolaris: a morphological study on mandibular first molars in Indian population. J Clin Exp Dent 2013;5(5):e218–e222. 12. Carlsen O, Alexandersen V. Radix entomolaris: identification and morphology. Scand J Dent Res 1990;98(5):363–373. 13. De Moor RJ, Deroose CA, Calberson FL. The radix entomolaris in mandibular first molars: an endodontic challenge. Int Endod J 2004;37(11):789– 799. 14. Plotino G, Grande NM, Pecci R, Bedini R, Pameijer CH, Somma F. Three-dimensional imaging using micro-computed tomography for studying tooth morphology and root canal anatomy. Ann Anat 2006;188(5):403–413. 15. Baldassari-Cruz LA, Lilly JP, Rivera EM. The use of the operating microscope in endodontics. Dent Clin North Am 1997;41(3):391–414. 16. Krasner P, Rankow HJ. Anatomy of the pulp– chamber floor. J Endod 2004;30(1):5–16. 17. Patel S, Horner K. The use of cone beam computed tomography in endodontics. Int Endod J 2009; 42 (9):755–756. 18. Baugh D, Wallace J. Middle mesial canal of the mandibular first molar: a case report and literature Dr. Bhargavi Krishnaraj, et al. International Journal of Dental Science and Innovative Research (IJDSIR) ©2025 IJDSIR, All Rights Reserved Page133 Page133 Page133 Page133 Page133 Page133 Page133 Page133 Page133 Page133 Page133 Page133 Page133 Page133 Page133 Page133 Page133 Page133 Page133 review. Journal of endodontics. 2004 Mar 1;30(3): 185-6. 19. Quackenbush LE. Mandibular molar with three distal root canals. Dental Traumatology. 1986 Feb;2(1):489. 20. Barker BC, Parsons KC, Mills PR, Williams GL. Anatomy of root canals. III. Permanent mandibular molars. Australian dental journal. 1974 Dec;19 (6):408-13. 21. Akhtar S, Pathak P, Bhagabati N, Chaudhary S. Middle distal canal: A rare morphological variation in root canal anatomy of the mandibular molar. Endodontology. 2024 Apr 1;36(2):188-92.