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CASE REPORT
Year : 2018  |  Volume : 8  |  Issue : 2  |  Page : 139-143

A clinical approach to the successful management of variations of middle mesial canals: A case series


Department of Conservative Dentistry and Endodontics, P.M.N.M. Dental College and Hospital, Bagalkot, Karnataka, India

Date of Web Publication5-Apr-2018

Correspondence Address:
Dr. Raghavendra Penukonda
Department of Conservative Dentistry and Endodontics, P.M.N.M. Dental College and Hospital, Bagalkot - 587 101, Karnataka
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/sej.sej_13_17

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  Abstract 

The possible variations of anatomical and morphological characteristics of the teeth are very important especially for the endodontic practitioners for successful treatment. Mandibular molars are most commonly affected by dental caries and require endodontic treatment. Mandibular molars exhibit variations in its internal anatomy; one among those is the presence of an extra canal in the mesial root called as middle mesial (MM) canal. Detection of these minute canals requires a proper clinical knowledge and radiographic examination. This article presents the treatment of three cases of mandibular first molars with MM canals without the aid of any magnification devices.

Keywords: Anatomical variation, mandibular first molar, middle mesial canal, root canal treatment


How to cite this article:
Penukonda R, Saraf PA, Patil TN, Vanaki SS. A clinical approach to the successful management of variations of middle mesial canals: A case series. Saudi Endod J 2018;8:139-43

How to cite this URL:
Penukonda R, Saraf PA, Patil TN, Vanaki SS. A clinical approach to the successful management of variations of middle mesial canals: A case series. Saudi Endod J [serial online] 2018 [cited 2019 Dec 8];8:139-43. Available from: http://www.saudiendodj.com/text.asp?2018/8/2/139/229345


  Introduction Top


The main objective of endodontic therapy is to thoroughly clean, shape, disinfect, and obturate the root canal system to prevent reinfection. An awareness and complete understanding of the presence of unusual root canal morphology can thus contribute to the successful outcome of the root canal treatment.[1]

Mandibular molars are the common teeth to be endodontically treated and show numerous variations in the internal anatomy.[2] The variations include an extra distolingual root called as radix entomolaris,[3] C-shaped anatomy of roots and canals,[2] a ribbon-shaped communication present between the mesiobuccal (MB) canal and mesiolingual (ML) canal called as isthmus,[4] and a third canal in the mesial root known as middle mesial (MM) canal, first mentioned by Vertucci.[2],[5]

The incidence of MM canals ranges between 2.07% and 13.3%,[6],[7] and incidence of radix entomolaris in Indian population is <5%.[8] Several methodologies and diagnostic aids are used to detect the number of roots, root canals, and their configurations. The conventional techniques include sound knowledge of the internal anatomy of the tooth and intraoral periapical radiographs.[9]

Pomeranz et al. and Ballullaya et al. classified the MM canals into three anatomic variants. (a) Originates as a separate orifice and joins the MB and ML canal near the apex (confluent type). (b) When an instrument could pass freely between the MM canal and MB or ML canal (fin type). (c) The MM canal can occur as an independent canal.[5],[10]

This case series emphasizes on the clinical detection and successful management of different types of MM canals without the aid of magnification.


  Case Reports Top


Case 1

An 18-year-old female patient with noncontributory medical history was referred to the Department of Endodontics with the chief complaint of intermittent pain in the lower left back teeth region since 2 months. Initially, the pain was minimal but gradually increased in intensity, frequency, and duration to the present level seeking for the dental advice. The pain used to intensify by thermal and physical stimuli. The patient gave a past dental history of congenitally missing the second premolar, which was replaced with a three unit fixed partial denture. The fixed partial denture was removed 2 weeks before due to repeated failures of the prosthesis. Clinical examination revealed deep occlusal caries and tenderness on vertical and horizontal percussion with the first molar. The electric pulp testing (Parkels Electronic Division, Farmindale, NY, USA) revealed a delayed response, while cold test (dry ice) revealed a lingering response. Radiographic examination revealed a deep carious lesion which was involving the pulp and a horizontally impacted second premolar was seen associated with that of the root apices of the first molar [Figure 1]a. Based on the clinical and radiographic interpretation, a final diagnosis of symptomatic irreversible pulpitis with symptomatic apical periodontitis was made of the mandibular first molar (#36), and root canal therapy was initiated.
Figure 1: (a): Preoperative radiograph of lower left first molar (a). Clinical photograph showing three separated orifices on mesial aspect of the pulp chamber (b). The red arrow pointed to the middle mesial canal orifice. Working length (c) and postobturation (d) radiograph showing the middle mesial canal (red arrow)

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Tooth was anesthetized, rubber dam isolation was done, and access was obtained using a large round bur and safe end bur (Dentsply Maillefer, Switzerland). Pulp chamber was inspected carefully for the root canal orifices. Canal orifices were located using endodontic explorer (Dentsply Maillefer, Switzerland). Four root canal orifices were detected, two mesial and two distal canals. The pulp chamber was thoroughly disinfected using 3% of sodium hypochlorite (Pyrex, Prime Dental Products, Mumbai, India) and flushed using normal saline. A tiny bleeding point appeared between the MB and ML canal, and champagne bubble test ascertained the presence of an extra canal which was confirmed when a small number instrument (6, 8# No K File, Mani Inc., Japan) advanced into the third orifice in the mesial root with a watch winding motion [Figure 1]b.

Working length was estimated using an apex locater (Reypex, VDW, Germany), and a radiograph was taken to confirm the working lengths. A radiograph taken from mesial angulation revealed a MM canal which was coinciding with the ML canal at the apical third of the root canal [Figure 1]c.

Canals were instrumented using Protaper rotary files (Dentsply Maillefer, Switzerland) and irrigated with 3% sodium hypochlorite (Pyrex, Prime dental products, Mumbai, India) and 17% ethylenediaminetetraacetic acid (EDTA) solution (Dent Wash, Prime Dental Products, Mumbai). The root canals were dried using paper points (Dentsply Maillefer, Switzerland) and obturation (Apexit Sealer, Ivoclar Vivadent, and gutta-percha cones by Dentsply Maillefer, Switzerland) was done. The access cavity was sealed with a permanent restoration [Figure 1]d.

Postobturation radiograph revealed three distinct orifices with two separate apical terminus of mesial canals. Hence, this was a case of confluent MM canal “Pomeranz et al.'s classification.”[5]

Case 2

A 24-year-old male patient with noncontributory medical history reported with a chief complaint of intermittent pain in the lower right back teeth region since 1 month. The pain used to intensify by thermal and physical stimuli. On clinical examination, a deep proximal caries was seen on the first molar, and the tooth was tender on percussion. The electric pulp testing revealed a delayed response, whereas the cold test (dry ice) responded normally. On radiographic examination, the carious lesion was involving the pulp with no apical changes [Figure 2]a. The case was diagnosed as asymptomatic irreversible pulpitis with symptomatic apical periodontitis in relation to right mandibular first molar (#46). Root canal therapy was initiated. After anesthesia and rubber dam isolation, the access cavity was prepared. Totally five distinct orifices, three on the mesial root and two on the distal root were detected [Figure 2]b. The working length radiograph confirmed five distinct canal orifices and four apical terminus [Figure 2]c.
Figure 2: Preoperative radiograph of lower right first molar showing deep distal caries exposing the pulp (a). Clinical photograph showing a fin type configuration of the middle mesial canal (red arrow) (b). Working length. (c) Master cone (d) and post-obturation radiographs, (e) showing the middle mesial canal (red arrow)

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Canals were instrumented using Protaper rotary files and irrigated with 3% of sodium hypochlorite and 17% EDTA solution was done. At the end of the chemomechanical preparation, the MM canal orifice united with ML canal orifice, permitting the free movement of the file between the orifices indicating a fin type of anatomic variation of MM canal “Pomeranz et al.'s classification.”[5],[10] The root canals were dried using paper points and obturation with Apexcit Sealer and gutta-percha cones was done [Figure 2]d and [Figure 2]e. The access cavity was sealed with a permanent restoration.

Postobturation radiograph revealed three distinct orifices with two separated apical terminus of mesial canals.

Case 3

A 22-year-old male patient with noncontributory medical history reported with the chief complaint of severe pain in the lower right back teeth region since 1 week. The pain used to intensify by thermal and physical stimuli. Sometimes the pain used to accentuate by the postural changes such as lying down and bending over. On clinical examination, there was deep occlusal caries present with the right mandibular first molar (#46). The electric pulp testing revealed a delayed response, whereas the cold test no response. Tooth was tender on percussion. On radiographic examination, the carious lesion was involving the pulp and there was a large radiolucency associated with the mesial root of the tooth [Figure 3]a. The case was diagnosed as necrotic pulp with symptomatic apical periodontitis.
Figure 3: Preoperative radiograph of lower right first molar with deep occlusal caries exposing the pulp and radiolucency associated with the mesial root (a). Clinical photograph showing three separated orifices mesial aspect of the pulp chamber (b). Note the middle mesial canal (red arrow). Working length radiograph (c) showing the distal radix entomolaris. Postobturation radiograph showing the middle mesial canal (red arrow) (d)

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The pulp chamber was opened using a large round bur and the access cavity was refined using EZ bur (Dentsply Maillefer, Switzerland). Canal orifices were located using endodontic explorer (Dentsply Maillefer, Switzerland). Four root canal orifices were detected, two mesial, and two distal canals.

Exploring the fissure between the main mesial canals with a sharp endodontic explorer a catch was encountered. A MM canal was found which was equidistant between the MB and ML canal orifices [Figure 3]b. A small instrument (#6 and 8 K-File, Mani Inc., Japan) was inserted into the canal using watch-winding motion and slowly advanced into the root canal.

Working length was estimated using Reypex apex locater, and a radiograph was taken to confirm the working lengths. The radiograph revealed that the tooth had an independent MM canal and a radix entomolaris [Figure 3]c.

Canals were instrumented using Protaper rotary files and irrigated with 3% sodium hypochlorite and 17% EDTA solution. The root canals were dried using paper points and obturation was done using Apexcit Sealer and gutta-percha cones. The access cavity was sealed with amalgam [Figure 3]d.

Postobturation radiograph revealed three separated apical terminus of mesial canals “Pomeranz et al.'s classification.”[5]


  Discussion Top


The three anatomical variants of MM canals classified by Pomeranz et al.[5] were seen in this case series.

Fabra-Campos reported that the incidence of the MM canals is about 2.6% where 1.7% of the third canal joined the MB canal in the apical third, which is the most common; 1.6% converged with the ML canal and 0.13% as an independent canal.[6] The occurrence of three independent canals in the mesial root similar to the third case in this case series which is rarely encountered and is the most uncommon manifestation.[2],[5],[10] The presence of MM canals in North Indian population is quite high.[11]

Alenezi reported a case of permanent mandibular first molar with six canals in which the MM canal is joining the MB indicating the confluent type.[12]

The incidence of the MM canals is more in the younger age patients compared to middle and old aged patients. Patients aged 20 or younger showed the incidence of 32.1% of negotiable MM canals.[2],[11] Another clinical finding was the association, between radix entomolaris and MM canal, which is a very rare occurrence (case #3 of present case series).[3]

A thorough knowledge about internal anatomy is helpful in detection of root canal orifices. Careful troughing of the mesial pulpal groove up to 2 mm toward the mesio-apical direction away from the furcation is the significant factor in detection and negotiation of the MM canals. In general, the orifices of the MM canal are located toward the ML canal and sometimes at the center of MB and ML canals.[11]

The clinical detection rate of root canal orifices without any magnification is less compared to microscopes.[13] The use of dental operating microscope or loupes will offer an excellent magnification and illumination of the operating field that substantially improves the visualization of canal orifices.[14] In the present case series, we were not equipped with magnification device which presented a greater challenge in managing the cases. All the cases were treated without the aid of any magnification device which suggests that the coronal internal anatomy if followed properly during conventional techniques can be a great tool in successfully treating the cases with different anatomical variations. Conventional techniques that are used for detection of the root canal orifices include dyes, champagne bubble test, observing the chamber for bleeding spots, and inspecting the pulpal floor with explorer.[15]

Conventional radiographs although provide a valuable information have inherent disadvantages such as superimposition, distortion, foreshortening, elongation, interpretation variability, and lack of three dimensional representation. It may be more advantageous if advanced radiographic techniques such as cone beam computed tomography are utilized for the detection of MM canals which provide more accurate information than the conventional radiographs.[16],[17]

The incidence of detecting the MM canal was reported decreased with age.[2],[5],[11] In the present case series, the conventional techniques were useful as the patients treated were young in the age range of 18–24 years. It is difficult to treat the older patients having MM canals by conventional techniques alone as they possess calcifications and reduction in the size of the canals. The magnification tools are of greater help in the detection and successful endodontic treatment of such patients, which are challenging to the conventional techniques.


  Conclusion Top


Detection of anatomical variations of teeth is essential and must always be considered before beginning the treatment. Endodontic success in teeth with variable morphology requires a correct diagnosis and inspection. Proper clinical and radiographic examination is a key in managing the different variations of extra canals when the aid of magnification device is not available.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

1.
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2.
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Sherwani OA, Kumar A, Tewari RK, Mishra SK, Andrabi SM, Alam S. Frequency of middle mesial canals in mandibular first molars in North Indian population – An in vivo study. Saudi Endod J 2016;6:66-70.  Back to cited text no. 11
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Alenezi MA. Endodontic management of a permanent mandibular first molar with six canals. Saudi Endod J 2016;6:36-9.  Back to cited text no. 12
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Patil AA, Patil AS, Dadwad KP. Endodontic management of the mandibular first molar having independent middle mesial canal and radix entomolaris within the same tooth. SRM J Res Dent Sci 2013;4:69-72.  Back to cited text no. 15
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