International Journal of Clinical Pediatric Dentistry
Volume 16 | Issue S-2 | Year 2023

Six Root Canals in Primary Mandibular Second Molar: Report of Two Cases

Mayur S Bhattad1, M S Muthu2, Vaibhav Wani3, Sneha M Bhattad4

1Department of Pediatric and Preventive Dentistry, Dr. Hedgewar Smruti Rugna Seva Mandal’s Dental College & Hospital, Hingoli, Maharashtra, India

2Department of Pediatric and Preventive Dentistry, Centre for Early Childhood Caries Research (CECCRe), Sri Ramachandra Institute of Higher Education and Research (Deemed to be University), Chennai, Tamil Nadu, India; Centre of Medical and Bio-allied Health Sciences Research Ajman University, UAE

3Department of Pedodontics and Preventive Dentistry, RR Kambe Dental College and Hospital, Nashik, Maharashtra, India

4Happy Tooth Laser Dental Clinic, Nanded, Maharashtra, India

Corresponding Author: Mayur S Bhattad, Department of Pediatric and Preventive Dentistry, Dr. Hedgewar Smruti Rugna Seva Mandal’s Dental College & Hospital, Hingoli, Phone: +91 9860273039, e-mail:


Anatomical variations in root morphology have been frequently encountered in pediatric endodontic practice. Due to insufficient knowledge of canal anatomy in primary teeth, having unusual canal morphologies is possibly more prone to endodontic treatment failures. Advanced investigations have given the clinician an open handed chance to recognize those variations and thus effectively manage them to achieve desired results.

This paper describes the mandibular primary second molar requiring pulp therapy having three separate and distant canals in the mesial and distal root. Such additional canals were labeled as the middle mesial (MM) canal in the mesial root and the middle distal (MD) canal in the distal root. Additional canals were identified on clinical examination and multiangled radiographs and verified with the help of cone-beam computed tomography (CBCT) imaging. In primary second molars such additional canals are bizarre. This paper describes the bizarre variations that were seen on second deciduous molars.

How to cite this article: Bhattad MS, Muthu MS, Wani V, et al. Six Root Canals in Primary Mandibular Second Molar: Report of Two Cases. Int J Clin Pediatr Dent 2023;16(S-2):S224–S228.

Source of support: Nil

Conflict of interest: None

Keywords: Case report, Cone-beam computed tomography, Middle mesial and middle distal canal, Pediatric rotary endodontics, Pulpectomy


For any successful root canal treatment, a comprehensive understanding of the root canal morphology and its variation is a primary requirement. The secondary prerequisite is accurate diagnosis, comprehensive cleaning, shaping, and obturation of the root canals. Frequently anatomical variations or additional root canals are left unobturated and as operator fail to recognize their survival. In this case report, we were able to manage additional canals which were rarely found in primary mandibular second molars.1,2

The objective of pulpectomy in primary molars are to maintain the veracity and function of the primary teeth along with their supporting tissues. However, this objective is satisfied with the endodontic success achieved by thorough extirpation of the necrotic pulp tissue, microorganisms and their by-products from the canals, and three-dimensional obturation in all the canals. Variable root canal anatomy in primary molars may lead to a missed root canal which has been related to a higher prevalence of endodontic treatment failures.3 A missed canal that is neither adequately cleaned nor filled can perhaps result in the development of periapical inflammation or cyst.4

The internal as well as external anatomy of permanent mandibular molars has been studied extensively; however, such variations are rare or not so much studied for the primary mandibular molars. There is limited information about the additional middle as well as distal canal in primary molars, and hence, it has more chances to be missed. Routinely mandibular second molars have three or four canals, mesiobuccal, mesiolingual, distobuccal, and distolingual based on their location. However, some variations such as isthmuses connecting the canals, a C-shaped root canal system, and an additional mesiobuccal or distolingual root may also be present.5,6 In addition, occasionally in between the mesiobuccal and mesiolingual canal, a third canal may be present which is known as the middle mesial (MM) canal.

The purpose of this report is to describe cases of primary mandibular second molars having six canals (three in mesial and three in distal root) each. The canal configurations observed in the respective molars are rarely reported in the literature.


Case 1

A 4.5-year-old male patient visited the pedodontics and preventive dentistry department with pain in the left mandibular region. The medical history of the patient was not contributory. Intraoral examination revealed a decayed mandibular left second primary molar with a temporary restoration (Fig. 1). The tooth was tender on percussion and had no mobility. Orthopantomograph (Fig. 2) showed deep caries involving pulp with radiolucency in the furcation area. With clinical and radiological findings, a diagnosis of chronic irreversible pulpitis with apical periodontitis was made and endodontic treatment was initiated. After the administration of local anesthesia, a rubber dam isolation was carried out. The temporary restoration was removed and access opening was done. Assessment of the pulp chamber floor showed mesiobuccal, mesiolingual, distobuccal, and distolingual canals. After pulp extirpation from all the visible canals, bleeding spots were noted between the mesiobuccal and mesiolingual canals. On careful examination of the pulp chamber, the MM canal orifice was identified below the groove joining two mesial canal orifices and later on the canal was negotiated subsequently and cone-beam computed tomography (CBCT) was carried out (Fig. 3). Additional canals were noticed not only in the mesial root but also in the distal root. They were labeled as MM and middle distal (MD) canals. The working lengths were measured with an apex locator (Dentsply, India) in the mesial and distal roots. The canals were shaped with a Pro AF baby gold (Dentobizz, India) orifice enlarger file (Fig. 4). Irrigation was done with profuse amounts of 1% sodium hypochlorite (Prime Dent, India) and normal saline. The canals were prepared by Pro AF Baby gold files and subsequent to preparation, they were irrigated with normal saline, dried out with sterilized paper points, and obturated with endoflas (Salnor, United States of America) followed by placement of stainless steel crown. Postoperative radiographs were taken to confirm the proper obturation of canals (Fig. 5). The adjacent first molar was missing, and hence impression was taken for the space maintainer. At the subsequent visit, the band and loop space maintainer were delivered (Fig. 6).

Fig. 1: Preoperative clinical picture

Fig. 2: Preoperative orthopantomogram (OPG)

Fig. 3: CBCT image showing three canals in mesial as well as distal canal

Fig. 4: Intraoperative clinic picture after biomechanical preparation (BMP) showing three canals in mesial as well as distal canal

Fig. 5: Intraoperative radiograph

Fig. 6: Postoperative clinical picture showing band and loop space maintainer

Case 2

A 5-year-old male patient visited the department with a severe throbbing type of pain in the mandibular right molar region. Past medical and family history was not contributory. Intraoral clinical and radiographic examination revealed out deep carious lesion in the right mandibular second primary molar (Fig. 7). Based on the findings, a diagnosis of chronic symptomatic irreversible pulpitis was made and endodontic treatment was initiated. Access opening was done and mesiobuccal, mesiolingual, distobuccal, and distolingual canals were prepared. On careful examination, MM and MD canals orifices were identified and the canals were subsequently negotiated and shaped with rotary instruments (Fig. 8). The irrigation protocol was followed the same as was for case 1. After the preparation, canals were irrigated with normal saline, dried with sterilized paper points and obturated with zinc oxide eugenol cement followed by a stainless steel crown. A postoperative radiograph was taken showing six obturated canals in the mandibular primary second molar (Fig. 9).

Fig. 7: Preoperative radiograph

Fig. 8: Intraoperative clinical picture showing three canals in mesial as well as distal canal

Fig. 9: Postoperative intraoral periapical radiograph (IOPA)


In primary teeth, the root canal morphology is complex and not always normal as there can be variations in shape, size, and number of the roots and their canals.7 Though, the scarcities of reports of atypical root anatomy in primary teeth do not reveal the actual condition. This may be because of the short time span between the formation and resorption of roots. Additionally, root resorption many times had already removed the evidence.8

In the literature, there are reports that disclose the anatomical variations in the permanent as well as primary molars but the occurrence of MM and MD canals in primary molars has not been yet reported. Mandibular primary second molars usually have three or four canals. Morphology of the root canal anatomy in primary teeth has been studied by many investigators, but they have rarely found an extra middle canal in the mesial and/or distal root of the primary second molar.9-12

Sarkar and Rao found that 7.1% of primary second mandibular molars had three canals in the mesial as well as in the distal root.9 Zoremchhingi et al. evaluated 15 primary second molars using CT and found only one tooth having three canals in a distal root.10 Rana et al. reported a case with three roots having five canals (three mesial and two distal) in the extracted mandibular second primary molar.11 Sim and Mah studied root morphology using CT in primary molars and concluded that the mesial roots tend to have two canals.12

Wang et al. carried out a study using CBCT on 487 root canals of primary mandibular second molars. In this study, authors observed seven different variations in the root canal anatomy of primary mandibular second molars.13 He also proposed a classification based on the number of roots and the number of canals. However, the cases observed in the present case reports could not be considered in any of the variants of his classification.

Although some of the authors11,14,15 have reported the occurrence of additional canals in the primary second mandibular molar none of them reported the existence of three independent canals, in mesial as well as distal root as observed in the present report. This particular entity itself presents as a rare anatomical variant in the primary molar. The MM and the MD canals might have an independent apical foramen or these canals might only have an individual coronal orifice that joins further apically with either of the mesiolingual or mesiobuccal canal and distolingual or distobuccal canals, respectively, ending up in a single apical opening. In this case report, six individual canals which were ended up in separate apical foramen were observed.

Hence, this report may escalate the complex nature of the canal anatomy in primary mandibular second molars and might change the approach of the clinicians to search for an extra canal in the middle of the two root canals.

The extra canals can be found by precisely looking at the pulpal floor and the wall anatomy to trace possible canal orifices. Developmental groove present between mesiobuccal and mesiolingual orifices sometimes prevents straight access to these extra canals. However, this groove can be explored carefully with a sharp endodontic probe or troughed with the help of a round bur or a fine ultrasonic tip or.3,16

Assessment of root canal system with radiographic examination using conventional intraoral periapical views has its own inherent limitation. Newer and more advanced diagnostic tools such as CBCT provide a higher and more intense understanding of canal morphology compared to conventional radiography.10,13,17 CBCT is acceptable only when one should stick to the principle of as low as diagnostically achievable being indication-oriented and patient-specific.18 Hence, to overcome the limitations of conventional radiography CBCT imaging has been used in the present case report.1

Radiation dose can be reduced by using low field of view (FOV) size, a lower amount of projections, dose settings on ultralow mode, minimizing exposure time, low beam intensity, and the use of automated exposure control. When exposing children, these above changes should maintain the radiation safety dosage along with sufficient therapeutic value.19

Various other technologies, such as the dental loupes and operating microscope also can offer an adequate visibility and illumination of the operating field and thus substantially improve the visualization of root canal orifices.20


There could be a presence of the third canal in the mesial and the distal root of the mandibular second primary molar. Thus, it should be found along the line between the two mesial and two distal canals, respectively. The inability to spot any unusual canal configuration or an extra canal might be the reason for the endodontic failure. Therefore, whenever in doubt about the opportunity of finding additional canals, it should be explored with the aid of magnification and illumination. To negotiate and manage such aberrant canal configurations, the clinician’s expertise also plays an important role.

Clinical Significance

  • This paper explains that additional canals may be found in primary molars. Pediatric dentists should always try to negotiate such additional canals in primary mandibular second molars.

  • Such variations could prevent the endodontic treatment failure.

  • Technological advancement can give an open hand to diagnose root canal variations in the pediatric dentist.


Vaibhav Wani


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