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 Table of Contents  
ORIGINAL ARTICLE
Year : 2021  |  Volume : 33  |  Issue : 3  |  Page : 133-138

Analysis of root and canal morphologies of maxillary second molars in a South Indian population using cone-beam computed tomography: A retrospective study


Former Professor, Department of Conservative Dentistry and Endodontics, Sri Ramachandra Faculty of Dental Sciences, Sri Ramachandra Institute of Higher Education and Research (DU), Chennai, Tamil Nadu, India

Date of Submission01-May-2021
Date of Decision02-Jun-2021
Date of Acceptance21-Aug-2021
Date of Web Publication30-Sep-2021

Correspondence Address:
Dr. Arathi Ganesh
Department of Conservative Dentistry and Endodontics, Sri Ramachandra Faculty of Dental Sciences, Sri Ramachandra Institute of Higher Education and Research (DU), Porur, Chennai-116, Tamil Nadu
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/endo.endo_93_21

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  Abstract 


Aim: The aim of the present study was to analyze the morphological variations and complexities in root canal systems of the maxillary second molars in South Indian population, using cone beam computed tomography (CBCT).
Subjects and Methods: The CBCT images of 500 participants were examined at different slice thickness of 125 micrometers. Root canal systems of the 500 maxillary second molars were analyzed according to Vertucci, HMA Ahmed et al., and Kim et al. classifications in the Indian subpopulation.
Statistical Analysis Used: Interobserver variability was analyzed using Kappa statistics.
Results: Among the tooth analyzed, 63% had three roots, with a single canal in each root in 65.2% tooth. About 41.8% of the tooth had fusion of mesiobuccal and distobuccal roots. The most commonly found root canal configuration was Type I (65%) according to Vertucci's classification. According to HMA Ahmed et al. classification, 67.9% tooth had the configuration of 327 MB1 DB1 P1/317 MB1 DB1 P1. Nearly 20.8% tooth had MB2 canal. The most common isthmus type was Type II (55.2%) according to Kim's classification, and the prevalence of isthmus was 2–5 mm from the root apex.
Conclusions: The number of roots, canals, their configuration, and occurrence of isthmus has not been reported in the South Indian population. The importance of understanding the knowledge of the anatomy of teeth during the treatment of maxillary second molars would contribute to successful endodontic outcomes.

Keywords: Cone-beam computed tomography, maxillary molars, morphology, retrospective study, root canal


How to cite this article:
Rosaline H, Kanagasabai A, Shaji A, Bose S, Saeralaathan S, Ganesh A. Analysis of root and canal morphologies of maxillary second molars in a South Indian population using cone-beam computed tomography: A retrospective study. Endodontology 2021;33:133-8

How to cite this URL:
Rosaline H, Kanagasabai A, Shaji A, Bose S, Saeralaathan S, Ganesh A. Analysis of root and canal morphologies of maxillary second molars in a South Indian population using cone-beam computed tomography: A retrospective study. Endodontology [serial online] 2021 [cited 2021 Dec 1];33:133-8. Available from: https://www.endodontologyonweb.org/text.asp?2021/33/3/133/327276




  Introduction Top


The success of endodontic treatment depends primarily on the predictable disinfection of microorganisms from the pulp space, wherein recognition of the canal morphology becomes imperative.[1],[2] Most often, the complex internal canal anatomy of the pulp space is underestimated due to the relatively simple external anatomy.[2] The maxillary second molars are especially challenging in endodontics due to the variations in their anatomy.[3],[4] Sperber has stated that the internal anatomy of a root canal is determined genetically and plays a pivotal role in anthropology.[5] In general, the Indian population is considered to be a conglomerate of several ethnic groups with the characteristics of Mongoloid, Caucasian, and Dravidian races.[6] Numerous studies have been conducted in many countries studying the anatomical and morphological features of the root canal systems of the maxillary second molars[7],[8],[9] revealing the existing differences in morphology based on ethnicity.

Various methods are available for analyzing the root canal morphology such as tooth clearing, intraoral radiographs, and radiographic assessment with contrast[10] of which, clearing method is considered to be the gold standard.[11],[12],[13] With the introduction of cone-beam computerized tomography (CBCT) in the field of endodontics, the root canal anatomy could be more accurately analyzed.[14]

Lack of detailed morphological information specifically in the root canal configuration of maxillary second molars in the South Indian ethnical population was observed in comparison to the existing information available. Therefore, the objective of the current observational study was to retrospectively evaluate the number of roots, fusion of roots, number of canals, Second mesio buccal canal (MB2) prevalence, canal configuration, isthmus types, distance of the isthmus from apex, and the relation between the fusion of roots and the isthmus in maxillary second molars among South Indian subpopulation, using CBCT.


  Subjects and Methods Top


A total of 570 CBCT images of patients of the age group of 20–55 years taken for diagnostic and treatment planning purpose with prior informed consent were collected from a tertiary scan center in Chennai. The present retrospective study was conducted in accordance to the STROBE guidelines. Ethical clearance was obtained from Institutional Ethics Committee of our university. The selection criteria followed for the present study were (i) CBCT images having at least one maxillary second molar with fully formed roots, (ii) without open apices, (iii) without calcifications, (iv) without any root canal treatment, and (v) without any fillings and artifacts. Among the 570 CBCT images, 500 images meeting the criteria were included for the analysis. The images were evaluated in coronal, sagittal, and axial sections with radiant DICOM viewer software. Each section of the image was evaluated at 0.3 mm interval meticulously. Among the CBCT images, one maxillary second molar was selected randomly and evaluated for number of roots, number of canals, fusion of roots, canal configuration,[13],[15] MB2, isthmus type,[16] and prevalence of isthmus from the apex. All the samples were evaluated separately by six evaluators for a period of two months between May 2018 and July 2018. Any conflict encountered was discussed and rectified with no bias. The interobserver agreement was assessed by Fleiss' Kappa statistics and was found statistically significant. The statistical analysis was done using SPSS version 26 Software 9 SPSS software ( IBM SPSS Statistics for Windows, Version 26.0,Armonk,NY:IBM Corp).


  Results Top


The percentage of variations in maxillary second molars of 500 CBCT images was calculated in the present retrospective observational study as follows:

Number of roots and root canals

Among the 500 samples, maxillary second molars had three roots in 315 samples (63%), two roots in 135 samples (27%), one root in 49 (9.8%) samples, and four roots in only 1 sample (0.2%). Based on the number of canals, three canals were seen in 326 (65.2%) samples followed by four canals in 102 (20.4%) samples, two canals in 64 (12.8%) samples [Figure 1], and one canal in 8 (1.6%) samples [Table 1].
Figure 1: CBCT image showing the presence of 2 roots with 2 canals in maxillary second molar

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Table 1: Percentage of number of roots and number of root canals in maxillary second molars in South Indian population

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Mesiobuccal second canal

Mesiobuccal second canal was seen in 104 (20.8%) samples [Figure 2].
Figure 2: CBCT image showing the presence of 2 canals in mesiobuccal root

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Fusion of roots

Fusion of roots was seen in 172 (34.4%) samples. Among the examined tooth, the mesiobuccal and palatal roots were fused in 45 (26.3%) samples [Figure 3]a. Similarly, fusion of distobuccal and palatal roots was seen in 13 (7.5%) samples. The mesiobuccal and distobuccal roots were fused in 72 (41.8%) samples [Figure 3]b while 42 (24.4%) samples had a single fused root [Figure 4]. Among the fused roots, fusion of mesiobuccal and palatal in 45 (26.3%) [Figure 3]a, fusion of mesiobuccal and distobuccal in 72 (41.8%) [Figure 3]b, fusion of distobuccal and palatal in 13 (7.5%), and single fused root in 42 (24.4%) [Figure 4] were observed.
Figure 3: (a) CBCT image showing fusion of mesiobuccal and palatal roots (b) CBCT image showing fusion of mesiobuccal and distobuccal roots

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Figure 4: CBCT image showing the presence of a single fused root

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Root canal configuration

According to Vertucci classification,[13] the root canal configuration was configured and tabulated in [Table 2]. It was noted that the percentage of Type I configuration was highest in the two rooted (M-59.3% and D-42.8%) and three rooted second upper molars. In single-rooted molars, Vertucci Type IV canal configuration was the most predominantly observed type (42.86%). In single-rooted molar, 42.86% had Type IV canal configuration.
Table 2: Canal configuration of maxillary second molar in South Indian population according to Vertucci 1984

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According to the newer system of classification by Ahmed et al.,[15] the canal configurations are summarized in [Table 3]. Among the samples reviewed, the commonly observed classification was MB1 DB1 P1 which suggested that the canal in each root begins and exits the apical foramen as a single canal. The occurrence of configurations of MB2-1-2DB1 P1 implied that in the MB root, two canals joined as one in the middle third and further branched out into two as it exited. The dominant configurations that prevailed were M2D1 and B1P1, M1D2-1-2, B2-1-2P1, and B1-2-1P1 in two rooted maxillary second molars.
Table 3: Canal configuration of maxillary second molar in South Indian population according to Ahmed and Dummer 2017

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Isthmus was observed in 276 (55.2%) samples of which 90 (32.6%) were between MB1 and MB2 canals, 14 (5.07%) were between mesiobuccal and palatal canals, 12 (4.34%) were between mesiobuccal and distobuccal canals, nine (3.26%) were between buccal and palatal canals, and eight (2.89%) were between distobuccal and palatal canals.

According to Kim et al. classification, among the examined maxillary second molars, 47 (17.02%) were Type I isthmus, 85 (65.2%) were Type II isthmus, and 25 (17.79%) were Type III isthmus; the level of the isthmus from the root apex was also analyzed [Table 4].
Table 4: Percentage of isthmus distance from root apex in maxillary second molar in South Indian population

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  Discussion Top


According to the knowledge of the authors, the present study is the first of its kind to evaluate the number of roots and canals, identify the presence of fused roots, classify the isthmus, and to categorize the root canal morphology according to the newer classification by Ahmed et al., in addition to Vertucci classification in an Indian subpopulation. Since the root canal anatomy is complex, it is of utmost importance to have a clear understanding of the prevalence of the fusion and isthmus in addition to the number of canals and roots to clean and shape the root canals more effectively.

The variations in the present study showed the presence of four, three, two, and single-rooted maxillary second molars in a South Indian population, with the highest prevalence of three rooted maxillary second molars. The above-mentioned results were consistent with a previous study[17] on a Chinese sub-population reported that 82% of maxillary second molars had three separate roots, 9% had two roots, and 10% had a single root. Another study also reported three roots with three separate canals.[18] A review of the literature on the anatomy of the maxillary second molar revealed that maxillary second molars have three roots in its standard form of anatomy.

The root canal morphological complexities of maxillary molars were mostly related to the presence of the MB2 canal. MB2 canals marked their presence with an overall percentage of 20.8% among the study samples. A study in Brazilian population[19] showed a percentage of 34.32% MB2 canals in maxillary second molars. A Western Indian population study showed the prevalence of MB 2 canals in 56.3% samples. The mesiobuccal root had Vertucci Type I, Type II, or Type IV canal configuration whereas, the palatal and distobuccal root had only Vertucci Type I canal configuration.[20] About 34.39% of maxillary second molars had MB2 canal in the Korean population.[1] According to Zhang et al., 18% maxillary second molars had MB2[17] and Weng et al., 14% of maxillary second molars had MB2 in Chinese sub-population.[21]

The process of fusion entails the epithelial and mesenchymal germ layer often resulting in a nonuniform tooth morphology.[22] Maxillary second molars showed a higher prevalence of fused roots compared to maxillary first and mandibular second molars. The highest incidence of fusion in South Indian population was between the mesiobuccal and distobuccal (41.8%) followed by mesiobuccal and palatal (26.3%), fusion of distobuccal and palatal in (7.5%) while single fused roots were 42 (24.4%). On the other hand, in the Taiwanese population,[23] 40.1% showed a prevalence of fused roots in maxillary second molars with palatal root fused with the mesiobuccal root in 18.1% and with the distobuccal root in 2.6%. Further, the palatal root was fused with the mesiobuccal and distobuccal roots in 8.1% of the molars. The incidence of fused roots was 23.9% for second molars, whereas the canal fusion within fused roots was observed in 10.6% of the second molars.[24]

The newer system suggested[15] a more standardized approach in classifying the root and canal morphology. The above classification is based on the formula RTN RnO-C-F where R represents number of roots, TN represents tooth number, Rn represents each separate root, and O-C-F represents orifice, canal, and foramen. The commonly observed classification was MB1 DB1 P1 which suggested that the canal in each root begins and exits the apical foramen as a single canal. The occurrence of configurations of MB2-1-2DB1 P1 implied that in the MB root, two canals joined as one in the middle third and further branched out into two as they exited. The dominant configurations that prevailed were M2D1 and B1P1, M1D2-1-2, B2-1-2P1, and B1-2-1P1 in two rooted molars. The ability to use the above classification as an “integrated system” helped us to describe common and unusual variations of the root and canal morphology in a simpler format. It was also noted that the classification did not address the degree of root curvature and root canal curvature, degree of root/canal separation, the exact level of bifurcation of canals/roots, type of root fusion, accessory canals (lateral and furcation canals), or apical deltas.

Isthmus can be present between any two canals irrespective of whether it exists in the same or in different roots.[25] The classification of isthmuses by Kim et al. was prototyped in the present study. Type II isthmus configuration was the most prevalent (65.2%). Despite observing the significant percentage of fusion between the MB and DB canals (41.8%), the presence of isthmus was also observed between the MB1 and MB2 roots. An isthmus is formed when an individual root projection is unable to close itself off, forming a constriction. Alternatively, partial fusion results in the formation of two root canals with an isthmus formed.[16] The distance of isthmus from the root apex was also analyzed. Most of them surfaced at an average distance of 2–5 mm from the root apex. The above finding was consistent with a study[26] that high amount of isthmus was found in mesial-buccal roots of upper molars at 2.5–7.0 mm from the apex. The clinical implication of the finding related to isthmus highlighted the difficulty in disruption of bacterial biofilms in the isthmus. Therefore, a rigorous strategy of irrigation and intracanal dressing for better bacterial control should be recommended.


  Conclusion: Top


Within the limitations of the present study, it was concluded that there are anatomical variations in the maxillary second molars with regard to number of roots, fusion, and isthmus in the South Indian population. The maximum number of roots was three with a single canal each. The highest prevalence of fusion in the South Indian population was between mesiobuccal and distobuccal canal with Type II isthmus. The distance of isthmus from the root apex was measured to be between 2 and 5 mm. The operating clinician should be assiduous in having knowledge of these variations while evaluating every case preoperatively and intraoperatively to have more predictable and enduring clinical outcome.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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24.
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25.
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26.
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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]



 

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