Journal of Conservative Dentistry
Home About us Editorial Board Instructions Submission Subscribe Advertise Contact e-Alerts Login 
Users Online: 488
Print this page  Email this page Bookmark this page Small font sizeDefault font sizeIncrease font size

Table of Contents   
Year : 2017  |  Volume : 20  |  Issue : 3  |  Page : 190-193
An in vitro study to find the incidence of mesiobuccal 2 canal in permanent maxillary first molars using three different methods

Department of Conservative Dentistry and Endodontics, KVG Dental College (affiliated by Dental Council of and Rajiv Gandhi University of Health Sciences), Sullia, Karnataka, India

Click here for correspondence address and email

Date of Submission13-Jun-2016
Date of Decision17-Aug-2016
Date of Acceptance20-Oct-2016
Date of Web Publication14-Nov-2017


Aim: In-vitro study was done to evaluate the incidence of MB2 canals using three different methods (CBCT, CLINICAL ANALYSIS AND DENTAL LOUPES) and to compare the efficacy of the three methods in identifying the incidence of MB2 canals in maxillary permanent first molars. Materials and Methods: The study sample consisted of 120 extracted intact permanent maxillary molars. These extracted teeth were subjected to CBCT. Later the teeth were access opened with naked eye to find the incidence of MB2 canal, and then the teeth were visualised under dental loupe to locate MB2 canal if they were missed under naked eye. Results was statistically analysed by Mc Nemar's tests with Bonferroni correction, Chi square test and Cochran's Q test.
Result: CBCT showed high incidence (68.3%) of MB2 canal in maxillary first molars and it showed to be a reliable method in detecting MB2 canal. When compared to dental loupe (52.5%) and naked eye (25%), the dental loupe improved the detection of MB2 canal.
Conclusion: Within the parameter of this study in detecting the incidence of MB2 canal, using CBCT dental loupes and naked eye, detection of MB2 canal was significantly higher with CBCT followed by dental loupe and least with naked eye.

Keywords: Cone-beam computed tomography; dental loupe; mesiobuccal 2 canal; naked eye

How to cite this article:
Vasundhara V, Lashkari KP. An in vitro study to find the incidence of mesiobuccal 2 canal in permanent maxillary first molars using three different methods. J Conserv Dent 2017;20:190-3

How to cite this URL:
Vasundhara V, Lashkari KP. An in vitro study to find the incidence of mesiobuccal 2 canal in permanent maxillary first molars using three different methods. J Conserv Dent [serial online] 2017 [cited 2023 Oct 1];20:190-3. Available from:

   Introduction Top

An adequate cleaning and shaping of all the pulp spaces and its complete filling with an inert material is one of the primary goals of endodontic treatment. It is reported that the maxillary first molars have a root canal anatomy with maximum complexity and variations.[1] Because of this complexity, it has the highest failure rate in endodontic treatment, that often lead to a missed second canal in the mesiobuccal 2 (MB2) root, that remains undetected and therefore untreated.[2]

Incidence of MB2 canal has been researched by numerous authors using various methods. In vivo, clinical studies included examinations of the maxillary first molar during root canal treatment both with and without magnifications and also retrospective assessment of radiographs and records. However, the results were not satisfactory.[3]

Traditional means of determining its presence and location include clinical examination and conventional two-dimensional radiography.[4]

Conventional radiography, while an essential aspect of endodontic treatment, has several limitations that make it less than an ideal tool for locating MB2. Because periapical (PA) radiography shows only a two-dimensional image and the superposition of the subjacent anatomic structure with the cortical density.[5]

Various clinical studies have shown examination of the maxillary first molar during root canal treatment with and without magnification, and also modification of access cavity preparation has been researched by numerous authors by the use of newer technique such as dental computed tomography (CT), cone-beam computed tomography (CBCT), and scanning electron microscopy.

Magnification is critically essential element to consistently identify the MB2 canal orifices. Clinical studies with magnification include dental loupes which provide magnification of ×2.0–×6.0. Magnification helps the practitioner to view the pulp chamber floor and brings minute details into clear view.[6]

CBCT is a relatively recent innovation that overcomes many of the limitations of conventional radiography. It has many applications in endodontics because it's three-dimensional images allow inspection of the tooth in the axial, coronal, and sagittal planes.[7]

The purpose of this study was to evaluate the incidence of MB2 canals using three different methods (CBCT, clinical analysis, and dental loupes) and to compare the efficacy of the three methods in identifying the incidence of MB2 canals in the maxillary permanent first molars. This study may help clinician identifying, negotiating, and treating missed second canals in the permanent maxillary first molar for better prognosis.

   Methodology Top

One hundred and twenty extracted intact permanent maxillary molars were collected from Department of Oral Surgery, K.V.G Dental College and Hospital, Sullia, and private dental clinics. The collection, storage, sterilization, and handling of 120 extracted teeth were followed according to occupational safety and health administration and the Center for Disease Control and Prevention recommendations and guidelines. The teeth were cleaned of visible blood and gross debris. The teeth were stored in 1% thymol solution for 1 week. The teeth were kept in a well-constructed container with a secure lid to prevent leaking during transport. The container was labeled with biohazard symbol.

The teeth were numbered from 1 to 120. Three teeth were positioned and organized in a wax slab in a row. A gutta-percha cone was placed on the right side of the wax slab to identify in the CBCT image, later each slab was scanned with CBCT (Kodak, 9300c, U.S.A). The voxel of 0.2 mm was used with an exposure of 16 min. The record of the number of canals and their variations was recorded by two examiners, one endodontist, and one radiologist [Figure 1].
Figure 1: Detection of mesiobuccal 2 canal with cone-beam computed tomography

Click here to view

An access cavity was prepared under halogen bulbs using #2 and #4 Endo Access bur (Maillefer, Dentsply, Switzerland). Initial penetration was made in the exact center of the mesial pit, with the bur directed toward the palatal using a high-speed handpiece to the depth of dentin. The bur was directed toward the orifice of the palatal canal. When a drop was felt, the pulp chamber was reached. The larger palatal canal was located first after which safe-ended #0152 Endo-Z bur (Maillefer, Dentsply, Switzerland) was used, keeping it in contact with the floor of the pulp chamber and moved mesiobuccally to the center of the MB cusp. The MB canal was explored beneath the cusp tip, and the bur was moved distally and slightly palatally to locate the distobuccal canal orifice. A conventional triangular access was modified to a trapezoidal shape to improve access to the additional canals. Final finishing and funneling of cavity walls was done with Endo-Z fissure bur. After an adequate access cavity preparation, the contents of the pulp chamber were removed using an endodontic excavator and subsequent irrigation with a 2.5% sodium hypochlorite solution. The pulp chamber floor was explored using an endodontic explorer, DG-16 (Maillefer, Dentsply, Switzerland). Exploration of groove connecting the canal orifice was performed with the use of K-files #6, #8, or #10 (Mani, Japan). Prepared specimens were then explored for MB2 in the following sequence:

Stage 1: Teeth were checked with naked eye (unaided vision) for second canal in the MB root with the help of explorer and then k-files #6 or #8, and ethylenediaminetetraacetic acid was used to negotiate MB2 canal.

If canal was not located by naked eye, samples will be subjected to stage 2.

Stage 2: Teeth failed to locate MB2 canal were examined with dental loupes ×3.5 magnification for the presence of MB2. If MB2 was located with or without magnification, Size 6, 8, and 10 k-file was inserted in MB and MB2 canals [Figure 2]. The results were statistically analyzed by McNemar's tests with Bonferroni correction, Chi-square test, and Cochran's Q test.
Figure 2: Detection of mesiobuccal 2 canal under dental loupes

Click here to view

   Results Top

In the present study, 120 extracted teeth were subjected to CBCT, dental loupe, and naked eye to find the incidence of MB2 canal and to evaluate the efficacy of these three methods in finding MB2 canal. MB2 canal was seen with CBCT in 82/120 (68.3%) teeth. With naked eye, it was found in 30/120 (25.0%), whereas in dental loupe, MB2 canal was located in 63/120 (52.5%). This difference in frequency of locating MB2 canal with the help of CBCT, naked eye, and dental loupe is statistically significant (P < 0.001) [Table 1].
Table 1: Percentage of detection of mesiobuccal 2 canal with cone-beam computed tomography, dental loupes, and naked eye

Click here to view

With a Cochran's Q test, we found that there exists a significant difference in the ability of the methods to detect the MB2 canal (X2(2) = 8.22, P < 0.05).

A pairwise comparison using McNemar's tests with Bonferroni correction revealed that significantly more number of MB2 canals was detected using CBCT or dental loupes as compared to naked eye (P < 0.001). CBCT was also better than dental loupes in detecting the MB2 canals (P < 0.001).

[Table 2] shows a comparison of CBCT, dental loupe with the naked eye. It was seen that with the help of CBCT and naked eye, thirty (25.0%) MB2 canals were located, 52 (43.3%) MB2 canals were observed in CBCT, but not in naked eye, and 38 (31.7%) MB2 canals were not located either in CBCT or naked eye whereas thirty (25.0%) MB2 canals were located both with naked eye and dental loupe. Thirty-three (27.5%) MB2 canals were located only in dental loupes but not with naked eye and 57 (47.5%) MB2 canals were not located either with naked eye or dental loupe. This difference in locating MB2 canal is statistically significant with CBCT.
Table 2: Comparison of cone-beam computed tomography and dental loupes with naked eye

Click here to view

In 30 (25.0%) out of 82 (68.3%) extracted first molar teeth, MB2 canal was found with naked eye and the number increased to 63 (52.5%) when dental loupes were used (P < 0.001).

   Discussion Top

The historical triad states that “debridement, disinfection, and obturation” are important for success of root canal therapy,[8] for which endodontist must have comprehensive knowledge about root canal morphology. If a root canal is not located, it may reduce the chances of treatment success and is one of the main reasons for the failure of root canal therapy.[9]

The present study highlights the importance of recent advancing techniques such as CBCT in determining the root canal morphologies in the maxillary first molar and the use of magnifying loupes for locating canals which are usually missed by naked eye in general practice.

The first maxillary molar is the most bulky teeth in the mouth and presents with numerous anatomical variations such as number and disposition of the canals. Clinically, the MB root contains second MB canal, which can be identified and treated more than 70% of the time.[10] Weine in a study done in 1969 showed higher frequency of MB2 canal in the MB root region. CBCT is a newer diagnostic imaging modality used in endodontics as it demonstrates anatomic features in three dimensions. CBCT provides interrelational images in three orthogonal planes (axial, sagittal, and coronal).

Baratto Filho et al.[11] reported the frequency of finding extra canal in MB root of the maxillary first molars is 92.85% (ex vivo), 95.63% (clinical results), and 95.45% (CBCT results). Michetti et al.[12] compared CBCT reconstructions of root canal systems with histological sections. The authors found a strong correlation between data acquired through CBCT and histological sections.

Dental loupes provide a magnification of better visualization as it enables the clinician to treat cases which were otherwise labeled as having poor prognosis or untreatable. However, limited evidence has been found that the use of a magnification device in any endodontic procedure is related to a better clinical outcome as compared to the same procedure performed without magnifiers.[13]

In a study conducted by Iqbal out of 300 extracted maxillary molars, MB2 canal observed in naked eye was 77 (25.7%), whereas with the use of dental loupe, the number of location of MB2 canal was increased up to 223 (88.3%).[14]

Magnification has been found to increase the detection rate of MB2 canals from 17.2% with the naked eye to 62.5% with loupes and 71.1% using the surgical operating microscope.[15]

   Conclusion Top

In the present study, the detection of MB2 canal with naked eye was 25% and with the use of dental loupes the detection of MB2 canal increased up to 52.5%. This finding showed that magnification increases the clinical ability to locate canals is supportive with the result obtained by above studies.

This study concluded that the incidence of MB2 canal detection was increased by the use of CBCT scans and dental loupe in comparison to naked eye.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

   References Top

Vertucci FJ, Haddix JE, Britto LR. Tooth morphology and access cavity preparation. In: Cohen S, Hargreaves KM, editors. Pathways of the Pulp. 9th ed. St. Louis: Mosby Elsevier; 2006. p. 203.  Back to cited text no. 1
Smadi L, Khraisat A. Detection of a second mesiobuccal canal in the mesiobuccal roots of maxillary first molar teeth. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2007;103:e77-81.  Back to cited text no. 2
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. 3
Kulild JC, Peters DD. Incidence and configuration of canal systems in the mesiobuccal root of maxillary first and second molars. J Endod 1990;16:311-7.  Back to cited text no. 4
Patel S, Dawood A, Ford TP, Whaites E. The potential applications of cone beam computed tomography in the management of endodontic problems. Int Endod J 2007;40:818-30.  Back to cited text no. 5
Carr GB, Murgel CA. The use of the operating microscope in endodontics. Dent Clin North Am 2010;54:191-214.  Back to cited text no. 6
Scarfe WC, Levin MD, Gane D, Farman AG. Use of cone beam computed tomography in endodontics. Int J Dent 2009;2009:634567.  Back to cited text no. 7
Gutmann JL. Problem Solving in Endodontics. 5th ed. St. Louis: Elsevier; 2011. p. 85-6.  Back to cited text no. 8
Paliwal A, Loomb K, Gaur KT, Jain A, Bains R, Vats A, et al. Dental operating microscope: An adjunct in locating the mesiolingual canal orifice in maxillary first molars. Asian J Oral Health Allied Sci 2011;1:174-9.  Back to cited text no. 9
Ruddle CJ. MB2 root canal systems in maxillary first molars. Dent Today 1995;14:38, 40-1.  Back to cited text no. 10
Baratto Filho F, Zaitter S, Haragushiku GA, de Campos EA, Abuabara A, Correr GM. Analysis of the internal anatomy of maxillary first molars by using different methods. J Endod 2009;35:337-42.  Back to cited text no. 11
Michetti J, Maret D, Mallet JP, Diemer F. Validation of cone beam computed tomography as a tool to explore root canal anatomy. J Endod 2010;36:1187-90.  Back to cited text no. 12
Del Fabbro M, Taschieri S. Endodontic therapy using magnification devices: A systematic review. J Dent 2010;38:269-75.  Back to cited text no. 13
Iqbal M, Jameel A, Amynah C. Locating MB2 canal in maxillary first molars with magnification:In vitro study. J Pak Dent Assoc 2012;21:28-30.  Back to cited text no. 14
Buhrley LJ, Barrows MJ, BeGole EA, Wenckus CS. Effect of magnification on locating the MB2 canal in maxillary molars. J Endod 2002;28:324-7.  Back to cited text no. 15

Correspondence Address:
V Vasundhara
Department of Conservative Dentistry and Endodontics, KVG Dental College (affiliated by Dental Council of India and Rajiv Gandhi University of Health Sciences), Sullia - 574 327, Karnataka
Login to access the Email id

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0972-0707.218308

Rights and Permissions


  [Figure 1], [Figure 2]

  [Table 1], [Table 2]

This article has been cited by
1 Micro-CT evaluation of maxillary first molars: interorifice distances and internal anatomy of the mesiobuccal root
Stéphanie Quadros TONELLI, Manoel Damião SOUSA-NETO, Graziela Bianchi LEONI, Manoel BRITO-JÚNIOR, Rodrigo Dantas PEREIRA, Pedro Augusto Xambre de OLIVEIRA, Eduardo NUNES, Frank Ferreira SILVEIRA
Brazilian Oral Research. 2021; 35
[Pubmed] | [DOI]
2 A case report on endodontic management of the rarest Vertucci's Type VIII configuration in maxillary second molar with three mesiobuccal canals
ShrustiAjay Govil, Geeta Asthana, Shikha Kanodia, Abhishek Parmar
Journal of Conservative Dentistry. 2021; 24(4): 404
[Pubmed] | [DOI]
3 Dental Magnification Loupes: An Update of the Evidence
Mohammad A Aldosari
The Journal of Contemporary Dental Practice. 2021; 22(3): 310
[Pubmed] | [DOI]


    Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
    Email Alert *
    Add to My List *
* Registration required (free)  

    Article Figures
    Article Tables

 Article Access Statistics
    PDF Downloaded170    
    Comments [Add]    
    Cited by others 3    

Recommend this journal