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Table of Contents   
CASE REPORT  
Year : 2015  |  Volume : 8  |  Issue : 3  |  Page : 60-63
Endodontic management of middle mesial canal in mandibular first molar


1 Department of Conservative Dentistry and Endodontics, Rayat and Bahra Dental College, Mohali, Punjab, India
2 Private Practitioner, Patiala, Punjab, India

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Date of Web Publication25-May-2015
 

   Abstract 

Deviations from the norm such as multiple orifices, apical deltas, accessory canals, and other variations are frequent in the roots of the posterior teeth.
Two clinical reports of mandibular molars are presented in which three canals in the mesial roots were treated endodontically. Review of the literature encountered a prevalence ranging from 1% to 15%.
Clinically, the third canal is difficult to find and exhibits a very variable morphology, which may present anastomosis with the other canals.

Keywords: Isthmuses, middle mesial canal, orifice location

How to cite this article:
Matta MS, Kaur M. Endodontic management of middle mesial canal in mandibular first molar. Ann Trop Med Public Health 2015;8:60-3

How to cite this URL:
Matta MS, Kaur M. Endodontic management of middle mesial canal in mandibular first molar. Ann Trop Med Public Health [serial online] 2015 [cited 2019 Oct 20];8:60-3. Available from: http://www.atmph.org/text.asp?2015/8/3/60/157631

   Introduction Top


The mandibular first molar is the earliest permanent posterior tooth to erupt. It is most frequently in need of endodontic treatment. It usually has two roots, but occasionally three, usually with a supernumerary distolingual root.

The probability of a mandibular first molar having a fifth canal is 1-15%. [1],[2],[3],[4],[5],[6],[7] The purpose of this paper is to present clinical reports of three canals in the mesial root of mandibular molars in the Indian population.

It is important to visualize and to have knowledge of internal anatomic relationships before undertaking endodontic therapy. The main objective of root canal therapy is thorough shaping and cleaning of all pulp spaces and its complete obturation with an inert filling material. The presence of an untreated canal may be a reason for failure.

The root canal system is complex and canals may branch, divide and rejoin. Weine categorized the root canal systems in any root into four basic types. [8]

Vertucci et al. utilizing cleared teeth which had their pulp cavities stained with hematoxylin dye, found a much more complex canal system and identified eight pulp space configurations. [9]

Gulabivala et al. examined mandibular molars in a Burmese population and found seven additional canal configurations. [10]

Middle mesial canal in mandibular first molar presents itself as a rare anatomical variant. According to Mortman, [11] the third mesial canal is not an extra canal but rather the sequelae of instrumenting the isthmus between the mesiobuccal and mesiolingual canals.

According to Von Arx, [12] isthmuses in the mesial root of mandibular first molars may be classified into 5 types:

  • Type I is two separate canals with no isthmus.
  • Type II is two separate canals joined by an isthmus.
  • Type III is three canals joined by an isthmus.
  • Type IV is two elongated canals that join in the centre.
  • Type V is a single, very broad and elongated canal.


The mesial root of the mandibular first molar is most frequently of Type IV or V.


   Case Report Top


Case 1

A 35-year-old female patient presented to the Department of Conservative Dentistry and Endodontics in Rayat and Bahra Dental College, Mohali with the chief complaint of pain in the lower back right tooth. She gave history of latex allergy. On clinical examination, a metal crown was present on the right mandibular first molar that was tender on percussion. Radiograph [Figure 1] showed inadequate previous endodontic therapy with secondary caries under the metal crown and periapical lesion associated with mesial root.
Figure 1: Pre-operative x-ray (Case 1)

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The crown was removed after cutting with transmetal bur (Dentsply, Switzerland). No rubber dam was applied owing to latex allergy. On the access opening and thorough irrigation with 3% sodium hypochlorite (Vishal Dentocare, Ahmedabad, India), a third canal was observed in the mesial root of the permanent mandibular first molar. The canals were prepared with hand files (Dentsply, Switzerland) using the step-back technique upto apical size 25 [Figure 2] and [Figure 3]). Calcium hydroxide powder and saline (Ammdent, Mohali, India) dressing was given for 2 weeks and tooth was temporised with temporary non eugenol filling (TMP-RS, Prime Dental Products, Mumbai, India) After 2 weeks, isolation was achieved with cotton rolls, final irrigation was done with 2% chlorhexidine (Vishal Dentocare, Ahmedabad, India) and canals were dried with sterile paper points (Hygienic Corporation,Coltene Whaledent, Deutschland). obturation was completed with lateral condensation technique [Figure 4].
Figure 2: Working length x-ray (Case 1)

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Figure 3: Master-cone x-ray (Case 1)

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Figure 4: Post-operative x-ray (Case 1)

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Case 2

A 30-year-old female presented to the private practice in Patiala with the chief complaint of pain in lower back left tooth.

Clinical examination revealed deep carious lesion and the tooth was tender on percussion. A radiograph [Figure 5] showed a small periapical lesion associated with the mesial root.
Figure 5: Pre-operatve x-ray (Case 2)

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Cotton rolls were used for isolation as patient objected to the use of rubber dam for isolation. On access opening and thorough irrigation with 3% sodium hypochlorite (Vishal Dentocare, Ahmedabad, India), a third canal was observed in the mesial root located between the mesiobuccal and mesiolingual canal.

Further angled working length radiograph ([Figure 6]) pointed out the merger of the mesiobuccal and middle mesial canal. The canals were prepared with hand files (Dentsply, Switzerland) using the step-back technique upto size 25. Calcium hydroxide powder (Ammdent, Mohali, India) and saline dressing was given for 2 weeks and tooth was temporised with temporary non eugenol filling (TMP-RS, Prime Dental Products, Mumbai, India). After 2 weeks, under isolation, final irrigation was done with 2% chlorhexidine (Vishal Dentocare, Ahmedabad, India), and canals were dried with sterile paper points (Hygienic Corporation,Coltene Whaledent, Deutschland). obturation was completed with lateral condensation technique [Figure 7].
Figure 6: Working length x-ray (Case 2)

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Figure 7: Post-operative x-ray (Case 2)

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   Discussion Top


The clinician is confronted daily with a highly complex and variable root canal system. Prior to beginning treatment, the dentist cannot precisely determine the actual number of root canals present. Microcomputed tomography has been an essential tool for the evaluation of the isthmuses in vitro, [19] but cone beam computed tomography (CBCT) has been essential tool in Identification of independent middle mesial canal in mandibular first molar in vivo. [20] Microcopmputed tomography and CBCT are still non-feasible and expensive tools in practical dental clinical practice.

There are many aids Aids in locating root canal orifices, [21] pulp chamber floor and wall anatomy being perfect guide to determine what morphology is actually present.

Variation in the mesial root of mandibular first molars can be identified through very careful observation of angled radiographs. Conventional radiographs taken at a 0° orientation provided less information than 30° radiographs. Contrast medium improved radiographic interpretation of canal anatomy, especially when used with 30° radiographs. [22]

The following are important steps to identify the canal orifices in the pulp chamber floor: Examination of the pulp chamber floor with a sharp explorer; troughing of grooves with ultrasonic tips; staining the chamber floor with 1% methylene blue dye; performing the sodium hypochlorite "champagne bubble" test; and visualizing canal bleeding points. [21]

An important aid for locating root canals is the dental-operating microscope (DOM). It brings minute details into clear view. It enhances the dentist's ability to selectively remove dentine with great precision, thereby minimizing procedural errors. Several studies have shown that it significantly increases the ability to locate and negotiate canals. [23]

An examination of the floor of the pulp chamber offers clues to the location of orifices and to the type of canal system present. When there is only one canal, it is usually located in the center of the access preparation.

If only one orifice is found that is not in the center of the preparation, it is probable that another is present and one should be searched for on the opposite side. All such orifices, particularly if oval in shape, must be thoroughly explored with apically precurved small K-type files to determine if more than one canal is present. The relationship of the two orifices to each other is also significant. The closer they are to each other, the greater the chance that the two canals join at some point within the body of the root. The direction that a file takes upon introduction into an orifice is also important. If the initial file placed into the distal canal of a mandibular molar, for example, points to the buccal or lingual, one should suspect a second canal. If two canals are present, each will be smaller than a single canal. Whenever a root contains two canals which join, the palatal/lingual canal is generally the one with straight line access to the apex. [21]

Rotary nickel titanium files must also be used with caution when this type of anatomy is present because instrument separation can occur as the file traverses the sharp curvature into the common part of the canal.

The presented case reports confirm that the third canal in the mesial root of mandibular first molars is a reality and can be encountered in almost 15% of these roots [Table 1].
Table 1: Prevalence of a third canal in the mesial root of mandibular first molars, according to different authors[6]

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During endodontic treatment of the mandibular first molar, the middle mesial canal orifice must be sought along the line between the two mesial canals. After thorough removal of the pulp chamber roof and cervical stenosis using burs or ultrasonic tips, the opening of the middle mesial canal can easily be negotiated.

 
   References Top

1.
Fabra-Campos H. Three canals in the mesial root of mandibular first permanent molars: A clinical study. Int Endod J 1989;22:39-43.  Back to cited text no. 1
    
2.
Baugh D, Wallace J. Middle mesial canal of the mandibular first molar: A case report and literature review. J Endod 2004;30:185-6.  Back to cited text no. 2
    
3.
Holtzmann L. Root canal treatment of a mandibular first molar with three mesial root canals. Int Endod J 1997;30:422-3.   Back to cited text no. 3
    
4.
Ricucci D. Three independent canals in the mesial root of a mandibular first molar. Endod Dent Traumatol 1997;13:47-9.  Back to cited text no. 4
    
5.
Lim SS. Middle mesial canal of a mandibular first molar - a case report. Dent J Malays 1985;8:13-6.  Back to cited text no. 5
    
6.
Navarro LF, Luzi A, García AA, García AH. Third canal in the mesial root of permanent mandibular first molars: Review of the literature and presentation of 3 clinical reports and 2 in vitro studies. Med Oral Patol Oral Cir Bucal 2007;12:E605-9.  Back to cited text no. 6
    
7.
McCabe PS. The middle mesial canal of mandibular first molars. J Ir Dent Assoc 2005;51:73-5.  Back to cited text no. 7
    
8.
Weine FS. Endodontic Therapy. 5 th ed. St. Louis, MO, USA: Elsevier; 1996. p. 359-61.  Back to cited text no. 8
    
9.
Vertucci FJ. Root canal morphology and its relationship to endodontic procedures. Endod Topics 2005;10:3-29.  Back to cited text no. 9
    
10.
Gulabivala K, Aung TH, Alavi A, Ng YL. Root and canal morphology of Burmese mandibular molars. Int Endod J 2001;34:359-70.  Back to cited text no. 10
    
11.
Mortman RE, Ahn S. Mandibular first molars with three mesial canals. Gen Dent 2003;51:549-51.  Back to cited text no. 11
    
12.
Weller RN, Niemczyk SP, Kim S. Incidence and position of the canal isthmus. Part 1. Mesiobuccal root of the maxillary first molar. J Endod 1995;21:380-3.  Back to cited text no. 12
    
13.
Skidmore AE, Bjorndal AM. Root canal morphology of the human mandibular first molar. Oral Surg Oral Med Oral Pathol 1971;32:778-84.  Back to cited text no. 13
    
14.
Pineda F, Kuttler Y. Mesiodistal and buccolingual roentgenographic investigation of 7,275 root canals. Oral Surg Oral Med Oral Pathol 1971;33:101-10.   Back to cited text no. 14
    
15.
Vertucci FJ, Williams RG. Root canal anatomy of the mandibular first molar. J N J Dent Assoc 1974;45:27-8 passim.  Back to cited text no. 15
    
16.
Pomeranz HH, Eidelman DL, Goldberg MG. Treatment considerations of the middle mesial canal of mandibular first and second molars. J Endod 1981;7:565-8.  Back to cited text no. 16
    
17.
Fabra-Campos H. Unusual root anatomy of mandibular first molars. J Endod 1985;11:568-72.  Back to cited text no. 17
    
18.
Goel NK, Gill KS, Taneja JR. Study of root canals configuration in mandibular first permanent molar. J Indian Soc Pedod Prev Dent 1991;8:12-4.  Back to cited text no. 18
[PUBMED]    
19.
Mannocci F, Peru M, Sherriff M, Cook R, Pitt Ford TR. The isthmuses of the mesial root of mandibular molars: A micro-computed tomographic study. Int Endod J 2005;38:558-63.   Back to cited text no. 19
    
20.
La SH, Jung DH, Kim EC, Min KS. Identification of independent middle mesial canal in mandibular first molar using cone-beam computed tomography imaging. J Endod 2010;36:542-5.   Back to cited text no. 20
    
21.
Cohen S, Hargreaves KM. Pathways of the Pulp. 9 th ed. St. Louis, MO, USA: Mosby; 2006. p. 149-150.  Back to cited text no. 21
    
22.
Naoum HJ, Love RM, Chandler NP, Herbison P. Effect of X-ray beam angulation and intraradicular contrast medium on radiographic interpretation of lower first molar root canal anatomy. Int Endod J 2003;36:12-9.  Back to cited text no. 22
    
23.
Karapinar-Kazandag M, Basrani BR, Friedman S. The operating microscope enhances detection and negotiation of accessory mesial canals in mandibular molars. J Endod 2010;36:1289-94.  Back to cited text no. 23
    

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Correspondence Address:
Dr. Mandeep Singh Matta
Rayat and Bahra Dental College, District - Kharar, Mohali, Punjab
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/1755-6783.157631

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