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Table of Contents   
ORIGINAL ARTICLE  
Year : 2022  |  Volume : 25  |  Issue : 5  |  Page : 531-535
Prevalence of C-shaped canal and related variations in maxillary and mandibular second molars in the Indian Subpopulation: A cone-beam computed tomography analysis


Department of Conservative Dentistry and Endodontics, ITS Dental College Hospital and Research Centre, Greater Noida, Uttar Pradesh, India

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Date of Submission24-Apr-2022
Date of Decision29-May-2022
Date of Acceptance14-Jun-2022
Date of Web Publication12-Sep-2022
 

   Abstract 

Aim: The aim of this study was to evaluate the prevalence and anatomical configuration of the C-shaped canal in permanent maxillary and mandibular second molars in the Greater Noida population by compiling the results of data that used cone-beam computed tomography (CBCT) analysis.
Subjects and Methods: CBCT images were taken from the archive in the department of oral medicine and radiology taken for diagnostic purposes referred by other departments in the dental college. Five hundred CBCT records of patients, between the age group of 15–40 years, containing maxillary second molars and mandibular second molars were selected and reviewed.
Statistical Analysis: Statistical analysis was done using the Chi-square test to find out the most common configuration of the C-shaped canal between maxillary and mandibular second molars.
Results: Hundred and ten out of 500 patients had C-shaped canals (22%). Among them, 58 teeth (52.7%) were continuous C-shaped canals, 41 teeth (37.3%) were semicolon-shaped canals and 11 teeth (10%) had separated canals. (Chi-square test value = 8.26, P = 0.024). Statistically significant difference was found in configuration types. Among the jaw type, 62 maxillary second molar presented with C-shaped canal (25.1%) and 48 mandibular second molar presented with C-shaped canal (18.9%) (Chi-square test value = 3.87, P = 0.276). However, the difference was statistically insignificant in relation to the jaw type.
Conclusions: Within the limitation of the study, we can conclude that the overall prevalence of C-shaped canals was 22% and the most common C-shaped canal configuration type was continuous (52.7%). However, no statistically significant difference was found in relation to jaw type.

Keywords: Cone-beam computed tomography; C-shaped; mandibular molar; maxillary molar; prevalence

How to cite this article:
Singh T, Kumari M, Kochhar R, Iqbal S. Prevalence of C-shaped canal and related variations in maxillary and mandibular second molars in the Indian Subpopulation: A cone-beam computed tomography analysis. J Conserv Dent 2022;25:531-5

How to cite this URL:
Singh T, Kumari M, Kochhar R, Iqbal S. Prevalence of C-shaped canal and related variations in maxillary and mandibular second molars in the Indian Subpopulation: A cone-beam computed tomography analysis. J Conserv Dent [serial online] 2022 [cited 2022 Sep 25];25:531-5. Available from: https://www.jcd.org.in/text.asp?2022/25/5/531/355900

   Introduction Top


In endodontics, root canal treatment of a tooth with varied anatomy is a rule rather than exception. The C-shaped root canal system is one example of an anatomic variation. Cooke and Cox originally described the C-shaped canal system in 1979, based on a cross-section of the root and canal that matches the form of the letter C.[1] They described examples in which the root canals of the teeth resembled the capital letter “C” on the pulp chamber floor. The canals are linked by a continuous slit on the pulp chamber floor,[1] and their key anatomic characteristic is the existence of fins or isthmuses linking the different root canals, while the orifice may appear as a single ribbon-shaped aperture with an arc of 180° or more, causing the canal cross-section and 3D geometry to vary along the root.[2] This morphological intricacy causes significant obstacles for debridement, disinfection, and canal filling processes, which may eventually affect the prognosis of root canal therapy.[3] As a result, for effective root canal therapy, a full understanding of potential anatomical variations of the C-shaped canal is required.

The mandibular second molar is the most common location for a C-shaped canal, but it can also be seen in the mandibular first premolar,[4],[5] mandibular first molar,[6] maxillary first molar,[7],[8] and maxillary second molar.[9],[10] Several studies have addressed the morphological features, reporting differences in the prevalence of C-shaped canals among various groups of teeth and populations, such as a 2.7%–7.6% prevalence in a study of the Caucasian population,[1],[11],[12] the prevalence was higher in middle Asia, up to 10.6% in Saudi Arabians[13] and 19.14% in Lebanese.[14] In northeast Asia, 31.5% of Chinese[15] and 32.7% of Koreans were affected.[16] There is, however, a paucity of information on the incidence of C-shaped canals in the Indian population.

Most studies on the frequency and anatomical features of a C-shaped canal employed extracted or endodontically treated teeth. The crosscut section method, dye infiltration method, and transparent model approach were used to investigate canal layouts on excised teeth. However, the loss of tooth features and artefacts as a result of the sophisticated techniques used during specimen preparation was cited as an unavoidable mistake.[11] To prevent these inaccuracies, several researchers employed periapical radiographs collected during the root canal treatment; however, it was difficult to see the existence of narrow connecting fins in normal periapical radiographs. Root canal instrument convergence at the apex or being centered and entering the furcation were utilized as indicators.[17] Other researchers have employed cone-beam computed tomography (CBCT) or microcomputed tomography to define the C-shaped root canal system.[2],[18],[19] With the development of CBCT in the area of endodontics, the C-shaped canal architecture could be more properly evaluated before operation.

Therefore, the aim of this study was to evaluate the prevalence and characteristic anatomical configurations of C-shaped canals in permanent maxillary and mandibular second molars by compiling the results of data that used CBCT analysis.


   Subjects and Methods Top


Source of data

The present study was carried out in the department of conservative dentistry and endodontics in collaboration with the department of oral medicine and radiology at the dental institute.

Sample selection

After the approval of the ethical committee, the CBCT scans of patients who visited the dental institute between January 2016 and December 2019 were reviewed from the archive in the department of oral medicine and radiology taken for diagnostic purposes referred by other departments in the dental college. Five hundred CBCT records of patients between the age group of 15–40 years, containing maxillary second molars and mandibular second molars were selected and reviewed. CBCT scans of maxillary and mandibular second molars with fully formed apices and without signs of resorption were included in the study. Scans of teeth with previous endodontic treatment, immature and open apices, root resorption, restorative material below the roof of the pulp chamber, developmental disorders, and pathologies were excluded from the study.

Imaging method

CBCT scan was performed with CS 9300 scanner at resolution (0.18 mm × 0.18 mm × 0.18 mm) and with FOV-10*5. Panoramic, 3D, and cross-sectional images at an interval of 1 mm were done. Images were examined using Carestream 3D imaging software. The level of the images was adjusted using the image processing tool in the software to ensure optimal visualization.

Image evaluation and data extraction

All the CBCT scans under evaluation were analyzed in three planes (coronal, sagittal, and axial) using Carestream 3D imaging software. Serial axial, coronal, and sagittal CBCT images were examined by carefully rolling the toolbar from the pulp chamber to the apex. The radiographic images generated by CBCT were processed and analyzed for these parameters of current research. The identification of C-shaped canal and canal configuration according to the classification by Melton et al.[20] are:

  • Category 1: Continuous-shaped canal (any C-shaped canal outline without any separation) [Figure 1]a
  • Category 2: Semicolon-shaped canal (dentin separating one distinct canal from a buccal or lingual C-shaped canal in the same section) [Figure 1]b
  • Category 3: Separate and discrete canals (two or more discrete and separate canals) [Figure 1]c.
Figure 1: Categories of the canal configuration by Melton. (a) Sagittal and axial CBCT view of continuous type C-shaped canal (category 1). (b) Sagittal and axial CBCT view of semicolon type C-shaped canal (category 2). (c) Sagittal and axial CBCT view of separated type C-shaped canal (category 3). CBCT: Cone-beam computed tomography

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Based on the above classification, data were collected for further analysis:

  1. Identification of C-shaped canal (present/absent); the presence of a fin or web connecting the individual root canals were considered as C-shaped canals
  2. Whether a C-shaped canal is more prevalent in the maxillary or mandibular second molar
  3. The most common configuration of the C-shaped canal in the maxillary and mandibular second molar.


CBCT records evaluation was performed individually by two calibrated endodontists, twice within a 2-month interval between the assessments. To confirm the reliability of the data, intraexaminer calibration was performed before the experiment. In cases of disagreement, CBCT images were reviewed by a specialist in the department of oral medicine and radiology until a final consensus was reached among the three evaluators.


   Results and Statistical Analysis Top


Five hundred CBCT images from 292 males and 208 females in the age group of 15–40 years (mean age 29.95) were used in this analysis [Table 1] and [Table 2].
Table 1: Descriptive statistics of gender in the study population

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Table 2: Age group distribution

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One hundred and ten out of 500 patients had C-shaped canals (22%) [Table 3].
Table 3: Prevalence of C-shaped canal

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Among them, 58 teeth (52.7%) had continuous C-shaped canal, 41 teeth (37.3%) had semicolon-shaped canals, and 11 teeth (10%) had separated canals. (Chi-square test value = 8.26, P = 0.024). Statistically significant difference was found in relation to the configuration type [Table 4].
Table 4: Descriptive statistics of the most common C-shaped canal configuration

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Among the jaw type, 62 maxillary second molar presented with C-shaped canal (25.1%) and 48 mandibular second molar presented with C-shaped canal (18.9%) (Chi-square test value = 3.87, P = 0.276). However, the difference was statistically insignificant in relation to the jaw type [Table 5].
Table 5: Comparison of “C“-shaped canal occurrence between maxillary second molar and mandibular second molar

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   Discussion Top


The diversity of the root canal system of posterior teeth complicates both endodontic diagnosis and therapy. In normal endodontic therapy, C-shaped root canals constitute a significant variance. Numerous studies have shown that the incidence of C-shaped canals varies by race and is higher in the Asian populations.[21],[22] Yang et al. found that 31.5% of Chinese teeth had C-shaped canals in 581 extracted teeth.[15] Similarly, Seo and Park observed that after evaluating 272 root canal-treated teeth and 96 extracted teeth, the prevalence of C-shaped canals in Korean was 32.7% and 31.3%, respectively.[16] There have been very few research in this area among the Indian population, which is a heterogeneous community. According to one study conducted on the North Indian population, the total incidence of C-shaped root canals is 6.72%.[23] Another research found a 7% prevalence rate in a southern Indian community.[24] Other investigations found a prevalence incidence of 7.5%–2% in an Indian subpopulation.[25],[26] However, in this study, 110 of 500 maxillary and mandibular second molars (22%) in the Greater Noida population had C-shaped canals [Table 3].

The total prevalence rate of C-shaped canals in mandibular second molars in the current study was 18.9%, which is lower than the 44% reported by Jin et al.[27] and the 19.14% reported by Haddad et al.[14] in the Lebanese community. However, the prevalence rate was greater than the 2.7% reported by Weine et al.[11] and the 8% reported by Cooke and Cox,[1] with manning reporting a frequency of 12.7% in a mixed Asian community.[28]

Yang et al.[15] discovered C-shaped canals in 4.9% of Chinese maxillary second molars using a clearing procedure in 1988. These canals related to both mesial and distal C-shapes. In contrast, 7.69% of single-rooted maxillary second molars had a link between distobuccal and distolingual root components,[10] which is slightly discordant with the current study. In the current study, the total prevalence of C-shaped canals in maxillary second molars was 25.1%. However, no statistically significant difference was detected in regard to jaw type (P = 0.276).

In Jin et al.[27] report a continuous C-shaped canal was identified in 21.8% of the pulp chamber floor level, 44.5% was a semicolon, and 7.7% was separated, but in the current study, it was 52.7% continuous, 37.3% semicolon, and 10% separated.

One of the major distinctions between this study and earlier studies was the absence of “old teeth” in this study. The average age of all patients was 29.95 [Table 2].

Extracted teeth or teeth requiring root canal therapy may have already undergone significant aging changes in the pulp-dentin complex, causing alterations in the root canal systems.[18],[19]

As a result, CBCT images that were distorted by massive restorations and root canal-treated teeth were eliminated from this study.

Thus, emphasis has been put on the correct detection of canal systems that may be overlooked in two-dimensional Intraoral periapical radiograph (IOPA) radiographs. The existence of these canals in mandibular and maxillary second molars was investigated in this study. The prevalence is high enough to require a proper identification of these defects, which will improve the prognosis of therapy.

Techniques such as fiber-optic transillumination, computer-aided tomography, and magnetic resonance imaging aid in three-dimensional anatomy diagnosis. However, owing of its low radiation dosage, simplicity of use, and economic sustainability, CBCT has risen dramatically as the diagnostic tool of choice for such patients. However, histological confirmation of the CBCT findings was not achievable. As a result, further research will be required to validate the accuracy of CBCT utilizing different modalities.


   Conclusions Top


Therefore within the limitation of the study, it can be concluded that:

  • The overall prevalence of C-shaped canals was 22%
  • The most common C-shaped canal configuration was continuous (52.7%)
  • No statistically significant difference was found in relation to jaw type.


Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

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Carlsen O, Alexandersen V. Root canals in two-rooted maxillary second molars. Acta Odontol Scand 1997;55:330-8.  Back to cited text no. 9
    
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Carlsen O, Alexandersen V, Heitmann T, Jakobsen P. Root canals in one-rooted maxillary second molars. Scand J Dent Res 1992;100:249-56.  Back to cited text no. 10
    
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Weine FS, Pasiewicz RA, Rice RT. Canal configuration of the mandibular second molar using a clinically oriented in vitro method. J Endod 1988;14:207-13.  Back to cited text no. 11
    
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Weine FS. The C-shaped mandibular second molar: Incidence and other considerations. Members of the Arizona Endodontic Association. J Endod 1998;24:372-5.  Back to cited text no. 12
    
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Haddad GY, Nehme WB, Ounsi HF. Diagnosis, classification, and frequency of C-shaped canals in mandibular second molars in the Lebanese population. J Endod 1999;25:268-71.  Back to cited text no. 14
    
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Min Y, Fan B, Cheung GS, Gutmann JL, Fan M. C-shaped canal system in mandibular second molars Part III: The morphology of the pulp chamber floor. J Endod 2006;32:1155-9.  Back to cited text no. 18
    
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Zheng Q, Zhang L, Zhou X, Wang Q, Wang Y, Tang L, et al. C-shaped root canal system in mandibular second molars in a Chinese population evaluated by cone-beam computed tomography. Int Endod J 2011;44:857-62.  Back to cited text no. 19
    
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DOI: 10.4103/jcd.jcd_234_22

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