Case Report/Clinical Techniques

A Rare Root Canal Configuration of Bilateral Maxillary FirstMolar with 7 Root Canals Diagnosed Using Cone-beamComputed Tomographic Scanning: A Case ReportGautam P. Badole, MDS,* Manjusha M. Warhadpande, MDS,† Pratima R. Shenoi, MDS,*Chandrakant Lachure, BDS,‡ and Shital G. Badole, BDS*

Abstract

Introduction: The complexity of the root canal system ofmaxillary molars presents a constant challenge in thediagnosis and treatment of these teeth. This case reportdescribes the importance of a surgical operating micro-scope and cone-beam computed tomographic (CBCT)imaging.Methods: Root canal treatment of a left maxil-lary first molar with 3 roots and 7 canals was successfullyperformed. Seven canals were identified with the help ofa surgical operating microscope and CBCT imaging. CBCTimages also confirmed the 3 roots and 7 canals in theright maxillary first molar. Results: CBCT imagesconfirmed a type IV canal pattern in the distal and palatalroot, whereas the mesial root had a type VIII canalpattern. Conclusions: The use of a surgical operatingmicroscope and CBCT imaging helps the clinician to diag-nose unusual anatomy of a tooth and facilitate successfulendodontic treatment. (J Endod 2014;40:296–301)

Key WordsCone-beam computed tomographic imaging, maxillaryfirst molar, root canal anatomy, surgical operatingmicroscope

From the *Department of Conservative Dentistry and End-odontics, VSPM’s Dental College and Research Center, Nagpur,India; †Department of Conservative Dentistry and Endodontics,Government Dental College and Hospital, Nagpur, India; and‡Government Dental College and Hospital, Nagpur, India.

Address requests for reprints to Dr Gautam P. Badole,Department of Conservative Dentistry and Endodontics,VSPM’s Dental College and Research Center, Digdoh hills, Hin-gna road, Nagpur (Maharashtra), India 440019. E-mail address:badole_g15@yahoo.co.in0099-2399/$ - see front matter

Copyright ª 2014 American Association of Endodontists.http://dx.doi.org/10.1016/j.joen.2013.09.004

296 Badole et al.

Successful root canal treatment depends on diagnosis and treatment planning andthorough knowledge of root canal system with its frequent variations (1). A major

cause of post-treatment failure is the inability to locate, debride, or fill all canals of theroot canal system (2). Weine et al (3) observed that failures in endodontic treatment ofmaxillary molars were most commonly associated with the mesiobuccal root and thatthese teeth showed the presence of 4 canals more frequently than 3 canals (51.5% vs48.5%).The mesiobuccal root of the maxillary first molar has generated more researchand clinical investigation than any other root (4). Numerous studies have examined theroot and root canal anatomy of different populations using different methods likesectioning (5), canal sectioning and tooth clearing techniques (6), conventional radi-ography (7), digital radiographic techniques (8), contrast medium-enhanced radiog-raphy (9), and computed tomographic scanning (10, 11). Tooth clearing methods (ie,making the tooth transparent and staining the canals for study) (12) generally havebeen considered the gold standard for analyzing root canal anatomy, but theseex vivomethods require the extraction of a tooth. The incidence of secondmesiobuccalcanals has been reported to be between 18% and 96.1% (13, 14). It is generallyaccepted that the most common form of the permanent maxillary first molar has 3roots and 4 canals (15). There are variations found in the number of roots (16,17). The studies of Beatty (18), Favieri et al (19), and Ferguson et al (20) reported5 root canals showing 3 canals in the mesiobuccal root. Gray (21) observed 5 canalsin 2.4% of the maxillary first molars with 2 mesiobuccal canals, 2 distobuccal canals,and 1 palatal canal. The incidence of 5 canals reported is as low as 2.25% (21) and2.4% (22). The incidence of 6 canals decreases to 0.31% (10) and 0.88% (23).The presence of a second distobuccal canal in maxillary first molars has been reportedto be as low as 1.7% (4) and 1.25% (11). Zheng et al (10) reported additional canals in1.12% of distobuccal roots and 1.17 of palatal roots. Case reports with more than 4 rootcanals also have been reported in 3-rooted maxillary first molars (Table 1). Of thevarious comprehensive maxillary first molar ex vivo studies in the dental literature,only Baratto Filho et al (46) reported 1 maxillary first molar out of 140 samples having3 roots and 7 canals. They identified 3 mesiobuccal canals, 3 distobuccal canals, and 1palatal canal. Kottoor et al (41, 42) reported the endodontic treatment of the maxillaryfirst molar with 7 and 8 canals, respectively. This case report discusses the diagnosisand treatment of an unusual root canal configuration of a maxillary first molarshowing 3 roots and 7 canals.

Case ReportA 28-year-old man presented to the Department of Conservative Dentistry and End-

odontics, VSPM’s Dental College and Research Center, Nagpur, India, with a complaint ofa toothache duringmastication in themaxillary left posterior region lasting for 7 days. Thepatient gave a history of persistent, excruciating pain in the left maxillary first molar inwhich he had undergone a root canal treatment 4 days ago. A clinical examination re-vealed temporary restoration and pain on vertical percussion with 26. The tooth was peri-odontally healthy. The patient’s medical history was noncontributory. A preoperativeintraoral periapical radiograph revealed a maxillary first molar with a prepared accesscavity and 3 roots with periradicular periodontal ligament widening in the mesiobuccalroot (Fig. 1A). From the clinical and radiographic findings, a diagnosis of symptomatic

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TABLE 1. Variations Reported in Canal Configuration in 3-rooted Maxillary First Molars

Year Author

Canal configuration

Mesiobuccal Distobuccal Palatal

1981 Stone et al (24) 1 1 21982 Cecic et al (25) 2 1 21982 Hartwell and Bellizzi (26) 2 1 21983 Mart�ınez et al (3 cases) (23) 3 2 11984 Beatty (18) 3 1 11988 Bond et al (27) 2 2 21991 Wong (28) 1 1 31997 Holtzman (29) 2 1 21997 H€ulsman (30) 1 2 12001 Johal (31) 2 1 22002 Maggiore et al (32) 2 1 32005 Ferguson et al (20) 3 1 12006 Chen and Karabucak (33) 1 2 12006 Favieri et al (19) 3 1 12008 Poorni et al (3 cases) (34) 1 1 22009 Aggarwal et al (35) 1 1 22009 Holderrieth and Gernhardt (36) 2 1 22009 de Almeida-Gomes et al (37) 2 2 22010 Patil et al (38) 1 2 12010 Karthikeyan and Mahalaxmi (39) 2 2 22010 Albuquerque et al (40) 2

232

12

2010 Kottor et al (41) 3 2 22011 Kottor et al (42) 3 3 22012 Sharath Chandra et al (43) 2

322

11

2012 Pais et al (44) 3 1 12012 Prabha et al (45) 1 1 2

Case Report/Clinical Techniques

apical periodontitis associated with tooth 26 was made. The patient pro-vided informed consent for endodontic treatment.

The tooth was anesthetized with 1.8 mL 2% lignocaine con-taining 1:200,000 adrenaline (LOX 2%; Neon Laboratories Ltd,East Mumbai, India) followed by rubber dam isolation. The tempo-rary dressing was removed. On clinical examination with a DG 16

Figure 1. (A) A preoperative radiograph of the left maxillary first molar. (B and

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endodontic explorer (Hu-Friedy, Chicago, IL), 1 canal opening wasobserved in each mesiobuccal and distobuccal root and 2 canalopenings in the palatal root. During examination with a surgicaloperating microscope (3D Medisys Exports, Ambala, India), anadditional mesiobuccal orifice (MB3) was located between the firstmesiobuccal (MB1) and mesiopalatal (MP) orifices. A second

C) The working length radiographs. (D) The obturation radiograph.

A Rare Root Canal Configuration 297

Figure 2. CBCT images of (A–C) left and (D–F) right maxillary first molars showing 3 roots and 7 canals.

Case Report/Clinical Techniques

distobuccal (DB2) orifice was located palatally to the first disto-buccal (DB1) canal. The working length was determined in allidentified canals and noted using an apex locator (Root ZX; Morita,Tokyo, Japan). The working length was confirmed by diagnosticradiography (Fig. 1B). Sterile cotton was placed in the pulp cham-ber, and the access cavity was sealed with IRM cement (DentsplyDe Trey GmbH, Konstanz, Germany). A cone-beam computed tomo-graphic (CBCT) (Kodak 9000; Carestream Dental, Atlanta, GA) scanof the left maxilla was performed with a tube voltage of 70 KV and atube current of 10 mA for 10.8 seconds to confirm the number ofthe roots and canals of the left maxillary first molar. AdditionalCBCT imaging was also performed for the right-side maxillary firstmolar because it showed a presence of deep proximal caries clin-

298 Badole et al.

ically. The morphology of the left and right maxillary first molarswas obtained. CBCT images showed the presence of 3 roots and6 canals (2 mesiobuccal, 2 distobuccal, and 2 palatal) in leftmaxillary first molar (Fig. 2A–C). A careful examination of the me-siobuccal root showed that the MB3 orifice present between thecenter of the MB1 and MP orifices and the radiolucent line extend-ing from the MB3 orifice toward MB1 suggest the presence of aseventh orifice between MB1 and MB3 (Fig. 2A). The right maxil-lary first molar showed deep proximal caries extending up to themiddle of the dentinal thickness. A similar pattern of rootmorphology and canal configuration as the left maxillary first molarwas found with the right maxillary first molar on CBCT imaging(Fig. 2D–F).

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Case Report/Clinical Techniques

At the second appointment, the tooth was anesthetized with 1.8 mL

2% lignocaine. During re-examination of the pulp chamber floor with asurgical operating microscope, a seventh canal (ie, MB2) was located(Fig. 3A and B). Because of the long-standing caries, the canal was calci-fied, and several attempts were required to explore the MB2 canal withEDTA (Prime Dental Pvt Ltd, Mumbai, India) and an ISO #8 K-file (Dents-ply Maillefer, Ballaigues, Switzerland). The working length was deter-mined with apex locator and confirmed with intraoral periapicalradiograph (Fig. 1C). Cleaning and shaping were performed using NiTiRotary ProTaper files (Dentsply Maillefer) with the crown-down tech-nique. Mesial and distal canals were enlarged with ProTaper F1 files,whereas palatal canals were enlarged with ProTaper F3 files. The root ca-nals were frequently irrigated with 2.5% sodium hypochlorite (PrimeDental Products, Thane, India), normal saline, 17% EDTA (Pulpdent Cor-poration, Watertown, MA), and 2% chlorhexidine gluconate (Endo-CHX;Prime Dental Product, Mumbai, India) as the final irrigant. The canalswere dried with absorbent paper points (Dentsply Maillefer). The canalswere then obturatedwith the single-cone obturating technique using com-plementing gutta-percha points (Dentsply Maillefer) in each canal and AHPlus sealer (Dentsply Maillefer, Konstanz, Germany) (Fig. 1D). A secondCBCT scan of the left maxillary first molar was taken to confirm adequateobturation and verify the pattern of canals in the root as it was not clearlyshown the first one because of calcification of the canals (Fig. 4). Thetooth was then restored with a posterior composite resin (P60; 3MDentalProducts, St Paul, MN), and the patient was advised to have a full-coverageporcelain crown. Indirect pulp capping with calcium hydroxide andrestoration was completed with 16. The patient was asymptomatic atthe 2-month follow-up.

DiscussionPrior knowledge of root and root canal anatomy facilitates the ac-

curate detection of all root canals in a tooth during root canal treatment.Anatomic aberrations are not uncommon in maxillary first molars,sometimes ranging from1 to 8 canals. Failure to identify and treat acces-sory canals can negatively influence treatment outcome. Endodonticallyretreated teeth were found to contain more undetected second mesio-buccal canals than teeth treated for the first time (47). Many studies ofthe root and canal morphology of maxillary first molar have been con-ducted because of its complexity (6).

In the present case, CBCT scanning was used for a better understand-ing of the complex root canal anatomy. A surgical operating microscopeand CBCT scan confirmed the presence of 3 roots and 7 canals in the leftmaxillary first molar, namely MB1, MB2, MB3, DB1, DB2, mesiopalatal,and distopalatal. Axial images showed that themesial root presented a Ver-tucci type VIII canal pattern (48) (all 3 canals had a separate canal orifice

Figure 3. (A and B) Access opening at different magnifications showing 7 root c

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and apical exit). The distal root and palatal root presented a Vertucci typeIV canal pattern (48) (all 2 canals have a separate canal orifice and apicalexit) (Fig. 4A–C). CBCT scanning also confirmed the presence of 3 rootsand 7 canals with a right maxillary first molar: 3 mesiobuccal (MB1,MB2,andMB3), 2 palatal (MP and DP), and 2 distal (DB1 and DB2). The distalcanal showed the signal orifice, which is divided into 2 (Fig. 2D–F).

In clinical conditions, conventional periapical radiographs and dig-ital radiographs taken in different angulations are an essential part ofendodontic treatment for the identification of root and canal configura-tion; however, they are taken in a buccal-lingual direction and give only2-dimensional information about a 3-dimensional object (8). In recentyears, advanced techniques like computed axial tomography scanningare being used to evaluate root canal morphology as a 3-dimensionalimage. It allows the operator to view the tooth roots and their root canalsystems at different levels (49) and helps to identify a larger number ofmorphologic variations than conventional radiographs (50).

The newer 3-dimensional system, CBCT imaging, was introducedin endodontics in 1990 (51). Less time (10–70 seconds) is requiredfor scanning with CBCT imaging because of its ability to acquire thewhole 3-dimensional volume of data in a single rotation (52). BarattoFilho et al (46) evaluated the internal morphology of extractedmaxillaryfirst molars and concluded that CBCT scanning can be used as a goodadjunct to visualize the complexity of the internal anatomy of these teeth.The major advantages of CBCT scanning over the conventional CT scansare x-ray beam limitation (53), rapid scan time (54), and effective dosereduction (55). It uses a cone-shaped beam instead of the fan-shapedone used in regular computed tomographic scanners (54, 55).Limitations of CBCT imaging includes the creation of an inherentimage ‘‘noise’’ that reduces image clarity and may limit adequatevisualization of structures in the dentoalveolar region (49). Even thoughthe use of CBCT scanning involves less radiation than conventionalcomputed tomographic scanning, the radiation dose is still higherthan regular conventional intraoral radiographs (56).

The presence of additional canals in mesiobuccal root has beenreported frequently by many researchers (6). An increased incidenceof MB2 canals in ex vivo when compared with in vivo was reported(5). Laboratory studies reported a high frequency of 2 canals in the me-siobuccal root ranging from 96% (13) to 25% (57) compared within vivo clinical studies ranging from 80% (58) to 19% (26). Maximumvariations were found in the mesiobuccal root, with 2 canals predom-inantly showing a type IV followed by a type II canal system (6, 7). Threecanals in the mesiobuccal root are reported by various authors(Table 1). Additional mesiobuccal canals were commonly found inthe age group of 20 to 40 years (11, 58). As the age advances, thecanal morphology becomes simpler probably because of thecalcification of root canal ramifications. Therefore, the clinicians

anal orifices. DB, distobuccal; DP, distal palatal; MB, mesiobuccal.

A Rare Root Canal Configuration 299

Figure 4. Post-obturation CBCT images of left maxillary first molar at the (A) cervical, (B) middle, and (C) apical levels.

Case Report/Clinical Techniques

should pay more attention to searching for additional canals in theyounger population.

Studies on maxillary first molars have reported that the most com-mon canal system morphology of the distobuccal root was a single canal(98.8%) (11, 59). The presence of 2 canals in the distobuccal root invarious studies was reported only in 1.12%–9.5% (4, 6, 10, 50) ofcases, and 97%–98% of the times these exited as a single foramen (4,6). This shows that the second distobuccal canal is a rare occurrence.Various case reports have documented 2 canals in the distobuccalroot (Table 1). Two canals of the distobuccal root predominantly hadtype II followed by type III and type IV morphologic patterns (11, 59).

Cleghorn et al (4) reviewed 14 articles and reported that thepalatal root has a single canal and a single foramen 99% and 98.8%,respectively. There are various case reports of 2 palatal canals within3-rooted maxillary first molars (Table 1). Shahi et al (60) found0.73% of 2 canals in the palatal root showing a type V canal system.Other investigators reported a 1.76%–4% incidence of 2 canalsin the palatal root with type IV followed by type II systems (10, 59).

Post-obturation radiographic evaluation immediately after rootcanal obturation is necessary to assess the apical sealing, condensation,and containment of the root canal filling material within the root canalsystem. Several intraoral views at different horizontal angulations maybe necessary for complex root canal configuration so that all the gutta-percha points will be evaluated in relation to the apex (61). However,it should be noted that multiple intraoral radiographs at different angu-lations do not guarantee the identification of all relevant anatomy andmaynot reveal much more than a single exposure (62). Depending on the x-ray beam angulation and tooth position, even an improper root canaltreatment with insufficient condensation and adaptation can be assumedappropriate (63). For this reason, a postobturation CBCT scan was per-formed in this case, which facilitates the assessment of the integrity of rootcanal fillings (64). The use of limited field of view CBCT imaging mayactually reduce the potential radiation exposure of the patient during

300 Badole et al.

the course of endodontic treatment. This technology can provide imagesof several teeth in 1 exposure with approximately the same radiation doseas 2 to 3 periapical radiographs, and theymay provide a dose savings overmultiple traditional images in complex cases (65, 66).

In the present case, CBCT imaging of the contralateral tooth wasperformed because there was a presence of proximal caries. Bilateralsymmetry of the presence of MB2 was found in 88.10% (11) and71.11% (10) of maxillary first molars. The incidence of additional ca-nals in bilateral maxillary first molars was higher (58.78%) than that ofunilateral maxillary first molars (52.40%) (10). There is an increasedchance of complex anatomy with tooth 16, and CBCT images confirmedthe presence of 3 roots and 7 canals in the right maxillary first molar.Also, the software necessary for CBCT data reconstruction can be run onpersonal computers, potentiating its use as a chairside diagnostic andtreatment planning tool that can be used in the future for referencewhen any pulpal damage and calcification takes place within canals.

ConclusionsThis case report indicates that clinicians must have the knowledge of

the anatomic variation during all phases of endodontic diagnosis and treat-ment. Variations in the root canal morphology of maxillary first molars arequite common. A clinician should use newer diagnostic techniques likeCBCT imaging and a surgical operatingmicroscope to help in the detectionof such abnormalities and the eventual success of endodontic therapy.

AcknowledgmentsThe authors deny any conflicts of interest related to this study.

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