Locating MB2 Canal in Maxillary First Molars with Magnification: In Vitro Study Molars: Six Months Study

Locating MB2 Canal in Maxillary First Molars with Magnification: In Vitro Study Molars: Six Months Study
Marium Iqbal1 , Asmat Jameel2 , Amynah Charania3

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IqbalM, JameelA, CharaniaA. Locatingmb2 canal inmaxillary firstmolarswithmagnification: in vitro study J PakDentAssoc. 2012 (1) : 28 – 30


To determine the ability of locating the second mesiobuccal canals in maxillary first molars with magnification (dental loupes 3.5x)


a Cross sectional study. 300 freshly extractedmaxillary firstmolarswere stored in 1% thymol solution for 1 week. Rhomboidal access cavities were prepared in these teeth and chamber cleared to look for canals first with naked eye and then with dental loupes (x3.5). If MB2 was detected two periapical radiographswere exposed with files inMB andMB2 canals. The data was analyzed using chi squared test on SPSS version 10.


In 77 out of 300 extracted teethMB2 canalwas locatedwith naked eye andwith the use of dental loupes the number of located canals increased to 265. There was a statistically significant difference between the two methods of identification of MB2 canals (p value <0.005)


Use of magnification increases the number of MB2 canals located in maxillary first molars compared to those locatedwith naked eye examination alone in vitro


magnificaton, loupes, location of canals, second mesiobuccal canal,maxillary first molar


ne of the primary objectives of endodontic treatment of a tooth is thorough cleaning and shaping of all the pulp spaces and its complete filling with an inertmaterial . Themaxillary firstmolar is reported to have a root and canal anatomywith complexity and most variations . Because of this complexity it is has the highest failure rate in endodontic treatment as mentioned by Smadi and Khraisat . Variations often lead to a missed second canal in the mesiobuccal root (MB2) that remain undetected and therefore untreated .

Hess andZurcher described the possibility of having 2 canals in themesiobuccal root inmaxillarymolars back in 1925 MB2 canal is found in more than 70% of extracted maxillary first permanent molars, . However, in vivo studies it was noted, that MB2 canal could be detected in less than 40% ofmaxillary firstmolars. .

Improvement in endodontic access cavity design and techniques for detection of canals, along with advent of illumination and magnification technology, have minimized the guesswork and facilitated in the identification and treatment of the second mesiobuccal canal ofmaxillary first molars Incidence of MB2 canal has been researched by numerous authors using various methods. In vivo clinical studies included examinations of maxillary first molar during root canal treatment both with and without magnifications, and also retrospective assessment of records and radiographs. Modification of access cavities of teeth, radiography, Dental CT and Cone Beam computed tomography, scanning electron microscopy, sectioning of teeth, decalcification techniqueswith the use of dyes have all been reported in various laboratory studies. Dental CT and Cone beam computed tomography (CBCT) offer an added advantage over the conventional imaging by providing accuracy and specific information.

Dental loupes provide a magnification of x 2.0 to x 6.0. The magnified view via loupes facilitates and increases the possibility of identification of second mesiobuccal canal. Not only this, because of better visualization it may enable the clinician to treat cases whichwere otherwise labeled as having poor prognosis or untreatable. However, it has yet to be proven by clinical studies that the use of dental loupes will actually improve the success rate. The purpose of the studywas to evaluate the incidence of MB2 canal with and without magnification using loupes in extracted maxillary first molars.


Three hundred extracted human maxillary teeth were selected for the study and were stored in 1% thymol solution for 1 week. Rhomboidal access cavities were made after the teethweremounted in stone.The studywas carried out in two stages. In the first stage pulp chamber floor was cleared and main canals were located. This was followed by further modification of the cavity to remove dentine overhangs between the mesiobuccal and palatal canal orifices. The floor was irrigated with hypochlorite (2.6%) and hydrogen peroxide (3%) to remove the debris produced during instrumentation. Teeth were checked with naked eye (unaided vision) for second canal in the mesiobuccal root with the help of explorer. In stage 2 teeth were examined with dental loupes x 3.5 magnification and examined for the presence of MB2. If MB2 was located with or without magnification size 6, 8 or 10 K-fileswere inserted in theMBandMB2 canals and 2 periapical radiographs from different angulations were exposed. The number of canals detected in each stagewas recorded and the result was statistically analyzed (SPSS version 10).


In 77 out of 300 (25.66%) extracted first molar teeth MB2 canal was found with naked eye and the number increased to 265 (88.33%) when loupes were used (p value <0.005). In 35 (11.66%) teeth second mesiobuccal canal could not be located with both naked eye and loupes.


It is of utmost importance for the clinicians to be familiar with variations in the root and root canal morphology to be able to face the challenge of diagnosis and treatment planning. Vertucci and Weine have proposed two different methods of classifying the anatomic variations in root canals in a standardized and clinically relevant approach respectively , Nevertheless, variations in individual teeth should be dealt with separately which further highlights the importance of knowledge of root canal anatomy and variations. With recent advances in magnification, illumination and instrumentation, endodontic access and canal identification has become predictable and the focus isnow on improvement of quality of treatment.

One such paradigm is that of dental loupes which by virtue of itsmagnification enhances the dentist’s ability to locate and treat the root canals, thereby minimizing the chances of treatment failure. Although many difficulties are associatedwith the use of loupes like cost, difficulty in getting used to it and the need to change it over time, it not only decreases theworking time but also enhances quality of work. An additional advantage is better posture of operator during work which minimizes muscular aches.

It is a well taken fact that there are many variations in the number and configurations of canals in maxillary first molars. These teeth have 3 roots and 3-4 canals; the fourth canal, in most cases being a second canal in the mesiobuccal root. The reported incidence of MB2 canals is 56.8% to 80.9%.This fact can be further explained by the greater buccolingual width of mesiobuccal root and concavities on its mesial and distal surfaces. Palatal and distal roots, however, usually have only one canal in most of the reported cases. In our study the extractedmaxillary molars were first examined without loupes but with adequate light and drying of chamber floor. This revealed MB2 canals in 77 out of 300 teeth that were examined. In the remaining 265 teeth a dental loupe (3.5x) was used for MB2 canal identification. Other studies found a significant difference in detection of canals with and without magnification, in extracted teeth and more so in clinical situations with magnification apparently increasing the rate of detection ofMB2 canals inmaxillary molars. Limited access, limited visibility and likelihood of perforation appears to be the reason of less number of MB2 canals identified when examined intraorally compared to extracted teeth. The better visualization by using magnification may, however, increase the possibility of a greater number of MB2 identified intra-orally aswell.


Based on these results, we conclude that the use of magnification significantly improves the location of MB2 canals in extracted maxillary first molar.


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