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 Table of Contents  
Year : 2017  |  Volume : 29  |  Issue : 1  |  Page : 82-85

C-shaped canal in mandibular second premolar: A rare entity with cone-beam computed tomography-aided diagnosis and its endodontic management

Department of Conservative and Endodontics, M.P. Dental College and Hospital, Vadodara, Gujarat, India

Date of Web Publication25-May-2017

Correspondence Address:
Vineet S Agrawal
15, Sakar Bunglows, Nr Ward Office 6, Akota, Vadodara - 390 020, Gujarat
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/endo.endo_15_17

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C-shaped root canal configuration is an aberration of normal root canal anatomy whereby the main anatomic feature is the presence of a fin or web connecting the individual root canals. The incidence of the presence of such C-shaped root canal is extremely rare in the case of mandibular second premolars. Such canal configuration poses a challenge to the clinician during cleaning, shaping, and obturation of root canal. This case, reports a rare finding of C-shaped root canal in mandibular second premolar, confirmed taking cone-beam computed tomography and under dental operating microscope. Furthermore, it addresses clinical techniques used against challenges in endodontic disinfection of the C-shaped root canal and its meticulous endodontic management.

Keywords: Cone-beam computed tomography; C-shaped root canal configuration; dental operating microscope; mandibular second premolar.

How to cite this article:
Agrawal VS, Soni B, Kapoor S. C-shaped canal in mandibular second premolar: A rare entity with cone-beam computed tomography-aided diagnosis and its endodontic management. Endodontology 2017;29:82-5

How to cite this URL:
Agrawal VS, Soni B, Kapoor S. C-shaped canal in mandibular second premolar: A rare entity with cone-beam computed tomography-aided diagnosis and its endodontic management. Endodontology [serial online] 2017 [cited 2022 Jul 5];29:82-5. Available from: https://www.endodontologyonweb.org/text.asp?2017/29/1/82/207001

  Introduction Top

Mandibular premolars show a higher incidence of aberrant root canal anatomy. Variations in mandibular second premolar are not as common as that of mandibular first premolars. Mandibular second premolar has shown variations such as multiple root canals [1],[2],[3],[4] and C-shaped canal configuration.[5],[6],[7] The prevalence of C-shaped canals among all tooth types ranges from 2.7% to 8%, and most commonly found in mandibular second molars, followed by mandibular first premolars, mandibular third molars, mandibular second premolars, and maxillary first molars.[8],[9] Till date, two prevalence studies [5],[6] with the prevalence of only 0.2%–6% and four case reports [7],[10],[11],[12] presenting C-shaped root canals in mandibular second premolars have been published [Table 1].
Table 1: Studies and case reports of mandibular second premolar with C-shaped canal

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C-shaped root canal configuration represents in pulp chamber as a single C-shaped orifice with an 180° arc or more, and the root canal system may present either with a single, C-shaped canal from the orifice to apex or with two or more canals below the C-shaped orifice.[11] Due to small root thicknesses and the presence of concavities in C-shaped mandibular premolars, it poses a challenge to meticulous cleaning and shaping of root canals.[7],[11] Improper mechanical instrumentation leads to removal of excessive dentin leading to strip perforation and presence of isthmuses also hinders complete removal of necrotic pulpal tissues. Therefore, prior evaluation of root canal morphology and dentin thicknesses using three-dimensional cone-beam computed tomography (CBCT) can be useful during chemomechanical debridement of root canal system of mandibular premolars.

This case report describes the rare occurrence of the C-shaped canal in mandibular second premolar which was confirmed on CBCT and subsequently describes the meticulous endodontic management of C-shaped mandibular second premolar.

  Case Report Top

A 20-year-old male patient with noncontributory medical history reported to the Department of Conservative and Endodontics with a chief complaint of pain in lower right back tooth when he chews food. Intra-oral clinical examination revealed deep carious lesion in tooth #45 and it was slightly sensitive to percussion. The tooth was nonresponsive to electric pulp testing and cold testing. Periapical radiographs [Figure 1] revealed deep carious lesion and periradicular radiolucency in relation to tooth #45. Examination of periapical radiograph [Figure 1] also revealed a complex and unusual root canal anatomy in #45. Periapical radiograph [Figure 1] apparently shows a central canal divided into two separate mesial and distal canals at the level of middle third of the root but did not provide any clue regarding the three-dimensional structure and internal morphology of the root canals. Tooth #45 was diagnosed with chronic apical periodontitis secondary to carious pulpal exposure and to ascertain the three-dimensional morphology, tooth #45 was subjected to CBCT scan (i-CAT, Imaging Sciences International, Hatfield, PA, USA). Reports of CBCT scan confirmed that there is single root present with evidence of C-shaped canal configuration [Figure 2]. The single canal gets distributed in two canals below the middle third of the root [Figure 3].
Figure 1: Preoperative radiographs

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Figure 2: Arrows shows the C-shape canal configuration in CBCT scan

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Figure 3: Arrows shows the bifurcation of canals in middle third in CBCT scan

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An informed consent of the patient was obtained, and the tooth was prepared for endodontic therapy. After administration of local anesthesia and placement of rubber dam, access to the pulp chamber was gained. Examination of the floor of pulp chamber revealed a long pulp chamber with a C-shaped canal configuration under a dental operating microscope (Carl Zeiss Meditec Inc., Dublin, CA, USA). Initial instrumentation was performed with #10 K file under irrigation with 5.25% sodium hypochlorite. Then after obtaining the patency of canals, working length was estimated using the electronic apex locator (Root ZX, Morita, Tokyo, Japan) and later confirmed by a radiograph [Figure 4]a. Mesial and distal canals were prepared using circumferential filing motion until size 35 K file (Maillefer, Switzerland) with the intermediate use of 5.25% sodium hypochlorite and normal saline as irrigating solutions. After shaping the canals to remove any tissues in isthmus areas, 5.25% sodium hypochlorite was agitated for 1 min using an ISO size 15 K-type ultrasonic file mounted on ultrasound generator using the passive ultrasonic technique. Nearly, 17% ethylenediaminetetraacetic acid was used to remove the smear layer. After drying the canals with paper points, a thick mixture of calcium hydroxide was placed in the canals for 2-week interval, and the temporary coronal seal was established with cavity (3M ESPE, St. Paul, MN, USA).
Figure 4: (a) Working length radiograph. (b) Master cone radiograph. (c) Obturation radiograph. (d) Prosthesis placement

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At 2 weeks recall, the patient was asymptomatic, canals were dried thoroughly, and a hybrid technique of root canal obturation was followed. Master cone fit was checked and confirmed on radiograph [Figure 4]b. The sectional method of obturation was used to obturate the mesial and distal canal spaces until the level of canal bifurcation and the C-shape was later obturated using the thermoplasticized gutta-percha technique [Figure 4]c. The tooth was then restored with a composite restoration, and later prosthesis was given on tooth #45 [Figure 4]d.

  Discussion Top

Endodontic management of mandibular premolars requires thorough knowledge of the root canal system presented due to their wide anatomical variations. C-shaped root canal is rarely encountered entity in mandibular second premolars, and its management poses a great challenge to the clinician. To best of our knowledge, after an extensive search of literature, there are only two clinical cases, that is, by Chauhan et al.[12] and Bertrand and Kim [7] that describes the endodontic management of C-shaped root canal configuration in mandibular second premolar. Our case described the successful endodontic management of C-shaped canal in mandibular second premolar, which is confirmed with the aid of CBCT.

CBCT scan was performed to analyze the aberrant C-shaped anatomy before chemomechanical preparations. C-shaped premolar has a greater chance of having complications during and after mechanical instrumentation due to the presence of concavity (danger zone), isthmuses, fins, etc., Aggressive instrumentation around concavity may lead to strip perforations. Jafarzadeh and Wu [8] recommended that the isthmuses should not be instrumented with files larger than size 25 to prevent strip perforations. In our case, the canals were cleaned with the hand files in circumferential filling motion cleaning all the isthmuses and fins present. Furthermore, passive ultrasonic activation using 5.25% of sodium hypochlorite was carried out to necessitate the flow of irrigant in the uninstrumented complex anatomy to maximally debride the root canal system.[13] For the first obturation, both the canals were obturated till bifurcation in the middle third using sectional obturation technique which was followed by thermoplasticized obturation which leads to a better flow of gutta-percha in all canal complexities of C-shaped configuration.[14]

Studies have also shown that all C-shaped premolars have shallow or deep radicular grooves (concavity) located on the external mesiolingual surface of the root. These grooves usually start 3 mm below the cementoenamel junction and may or not extend to the apex. The mean depth of the grooves at some areas on the root can be around 1.5 mm. This must be taken into consideration during cleaning and shaping.[15]

In our case, both CBCT and dental operating microscope were used to diagnose C-shaped canal because radiographs only give an idea about the aberrant anatomy but not the confirm diagnosis. Advantages of CBCT is that it provides a small field of view three dimensional digital images at low dose with sufficient spatial resolution for applications in endodontic diagnosis, treatment guidance, and posttreatment evaluation. The combination of sagittal, coronal, and axial CBCT images gives the clinician an in-depth understanding of the root canal morphology. Although CBCT scan has some disadvantages such as susceptibility to movement artefacts, low contrast resolution, limited capability to visualize internal soft tissues, and owing to distortion of the Hounsfield units, CBCT cannot be used for the estimation of bone density.

The present case report describes the effective use of CBCT and dental operating microscope in the diagnosis of rare C-shape canal in mandibular premolar, which in turn has led to meticulous endodontic management of it.

  Conclusion Top

This case report addresses and reports a rare case of C-shaped canal in mandibular premolar using three-dimensional imaging modalities such as CBCT and dental operating microscope. Furthermore, it describes the successful endodontic management of C-shaped canal in mandibular premolar.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Awawdeh LA, Al-Qudah AA. Root form and canal morphology of mandibular premolars in a Jordanian population. Int Endod J 2008;41:240-8.  Back to cited text no. 1
Zillich R, Dowson J. Root canal morphology of mandibular first and second premolars. Oral Surg Oral Med Oral Pathol 1973;36:738-44.  Back to cited text no. 2
Rhodes JS. A case of unusual anatomy: A mandibular second premolar with four canals. Int Endod J 2001;34:645-8.  Back to cited text no. 3
Sachdeva GS, Ballal S, Gopikrishna V, Kandaswamy D. Endodontic management of a mandibular second premolar with four roots and four root canals with the aid of spiral computed tomography: A case report. J Endod 2008;34:104-7.  Back to cited text no. 4
Yu X, Guo B, Li KZ, Zhang R, Tian YY, Wang H, et al. Cone-beam computed tomography study of root and canal morphology of mandibular premolars in a Western Chinese population. BMC Med Imaging 2012;12:18.  Back to cited text no. 5
Rahimi S, Shahi S, Yavari HR, Manafi H, Eskandarzadeh N. Root canal configuration of mandibular first and second premolars in an Iranian population. J Dent Res Dent Clin Dent Prospects 2007;1:59-64.  Back to cited text no. 6
Bertrand T, Kim SG. Endodontic treatment of a C-shaped mandibular second premolar with four root canals and three apical foramina: A case report. Restor Dent Endod 2016;41:68-73.  Back to cited text no. 7
Jafarzadeh H, Wu YN. The C-shaped root canal configuration: A review. J Endod 2007;33:517-23.  Back to cited text no. 8
Cleghorn BM, Christie WH, Dong CC. Root and root canal morphology of the human permanent maxillary first molar: A literature review. J Endod 2006;32:813-21.  Back to cited text no. 9
Cleghorn BM, Christie WH, Dong CC. Anomalous mandibular premolars: A mandibular first premolar with three roots and a mandibular second premolar with a C-shaped canal system. Int Endod J 2008;41:1005-14.  Back to cited text no. 10
Shah DY. C-shaped root canal configuration in mandibular second premolar: Report of an unusual case and its endodontic management. J Int Clin Dent Res Organ 2012;4:18-20.  Back to cited text no. 11
  [Full text]  
Chauhan R, Singh S, Chandra A. A rare occurrence of bilateral C-shaped roots in mandibular first and second premolars diagnosed with the aid of spiral computed tomography. J Clin Exp Dent 2014;6:e440-3.  Back to cited text no. 12
van der Sluis LW, Versluis M, Wu MK, Wesselink PR. Passive ultrasonic irrigation of the root canal: A review of the literature. Int Endod J 2007;40:415-26.  Back to cited text no. 13
Bowman CJ, Baumgartner JC. Gutta-percha obturation of lateral grooves and depressions. J Endod 2002;28:220-3.  Back to cited text no. 14
Fernandes M, de Ataide I, Wagle R. C-shaped root canal configuration: A review of literature. J Conserv Dent 2014;17:312-9.  Back to cited text no. 15
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  [Figure 1], [Figure 2], [Figure 3], [Figure 4]

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