Saudi Journal of Oral Sciences

: 2021  |  Volume : 8  |  Issue : 1  |  Page : 53--56

Endodontic management of permanent mandibular first molar with middle mesial canal: A case report

Hadi Rajeh Alfahadi1, Fawaz Hamad Alkazman1, Ahmed Bamanie2, Mesfer Saleh Alwadai1,  
1 Department of Endodontics, Riyadh Elm University, Riyadh, Saudi Arabia
2 Department of Endodontics, King Fahad Medical City, Ministry of Health, Riyadh, Saudi Arabia

Correspondence Address:
Dr. Hadi Rajeh Alfahadi
Department of Endodontics, Riyadh Elm University, P.O. Box 84891, Riyadh 11681
Saudi Arabia


Endodontic treatment of a permanent mandibular first molar is often difficult due to its related complex variations. The root cause of endodontic failure is the inability of a practitioner to recognize and manage an irregular root canal system. Knowledge of dental anatomy, thorough examination, and utilization of recent diagnostic tools are required for an effective root canal treatment. A 31-year-old Saudi male patient presented to the endodontic clinic for endodontic treatment of the mandibular left first molar (#36). Clinical examination using a dental operating microscope (DOM) followed by radiographic examination including cone-beam computed tomography (CBCT) revealed the diagnosis of asymptomatic apical periodontitis in a previously attempted root canal therapy which was incomplete. The periapical disease involved middle mesial canal (MMC) intermingling with the mesiobuccal (MB) in the mesial root. The root canal treatment was successfully carried out with no symptoms during 6 months of follow-up period. This case reports the presence of unusual presentation of MMC and MB canal in the mandibular first molar, which had resulted in postendodontic complications, which was diagnosed using CBCT and successfully managed with good prognosis. Dentists can use technical and imaging advancements including the DOM and CBCT to recognize anatomical variations in the root canal system, especially in cases of postendodontic failures or complications.

How to cite this article:
Alfahadi HR, Alkazman FH, Bamanie A, Alwadai MS. Endodontic management of permanent mandibular first molar with middle mesial canal: A case report.Saudi J Oral Sci 2021;8:53-56

How to cite this URL:
Alfahadi HR, Alkazman FH, Bamanie A, Alwadai MS. Endodontic management of permanent mandibular first molar with middle mesial canal: A case report. Saudi J Oral Sci [serial online] 2021 [cited 2022 Oct 5 ];8:53-56
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Understanding of the root canal system is required for the successful of endodontic treatments. System is required for the consistency of endodontic treatments. The primary cause of root canal therapy failure is an inability to understand the inner tooth structure, followed by inadequate endodontic treatment.[1] Widely, the first mandibular molar contains two roots (mesial and distal) having two mesial canals and 1–2 distal canals.[2]

In the case of the first mandibular molar, 86% of the missing canals are located in the distal root while 14% in the mesial root.[3] There is an extra canal termed the middle mesial canal (MMC), found uncommon in the mesial root. This canal occurs in the developmental groove in between the mesiolingual (ML) and mesiobuccal (MB) canals. The frequency of an MMC ranges from 0% to 37.5%.[4]

It can be due to anatomical variations and abnormalities in the root and root canals, intracanal connections, and curvatures, which are not evident in traditional radiographs.

Awareness of radicular tooth anatomy and possible differences in the root canal are also essential for practitioners. Cone-beam computed tomography (CBCT) may be used to further validate the root canal morphological diagnosis.[5]

CBCT is an innovative practical method for noninvasive and three-dimensional (3D) image enhancement. CBCT is a more effectiveness diagnostic tool for the confirmation of root canal morphology, number of roots, curvature, and bifurcation in both sagittal and axial planes.[6],[7]

Methodological differences are unusual, and the chances of finding numerous root and root canal systems have recently improved due to the advent of specialized devices, such as dental operating microscope (DOM).[8]

This case report describes the successful endodontic treatment of a mandibular first molar with the MMC under the DOM and diagnosed by CBCT evaluation.

 Case Report

A 31-year-old Saudi male patient was referred to the endodontic clinics for nonsurgical endodontic treatment of the mandibular left first molar (#36). He had no history of systemic or allergy problems. The chief complaint was to complete the previously initiated root canal treatment. The tooth was not tender to percussion or palpation. Radiographs were obtained revealing widening of the apical periodontal ligament, suggestive of periradicular pathosis[Figure 1]. A CBCT scan was taken before the procedure for advanced information on the root and root canals in the same tooth, and the images were viewed using Viewer Plus software (J. Morita, Kyoto, Japan)[Figure 2]. After clinical and radiographic examinations, the tooth was diagnosed as previously initiated therapy with asymptomatic apical periodontitis.{Figure 1}{Figure 2}

The tooth was isolated with a dental rubber dam under local anesthesia. Furthermore, access was gained by the use of a large round bur and a safe-end bur (Dentsply Maillefer, Ballaigues, Switzerland). The pulp chamber was closely examined for root canal orifices. Canal orifices were found using an endodontic explorer (Dentsply Maillefer, Ballaigues, Switzerland) along with the assistance of a magnifying DOM (Global Dental Microscopes, Global Surgical Corporation, United States of America). The mesiobuccal (MB), mesiolingual (ML), distobuccal (DB), and distolingual (DL) canal orifices were established. The MMC found in the structural groove between the ML and MB canals. The MMC was detected and negotiated to full length with #8 and #10 K hand file. The MMC was joined with MB [Figure 3]a and [Figure 3]b.{Figure 3}

The working length was measured by a radiograph and verified by an electronic apex locator, Root ZX II (J. Morita CORP, Kyoto, Japan) [Figure 4]a and [Figure 4]b.{Figure 4}

Instrumentation was carried out with X1, X2 ProTaper Next rotary files (ProTaper Next, Dentsply Maillefer Ballaigues, Switzerland). The canals were irrigated with 2.5% sodium hypochlorite followed by 17% ethylene diamine tetra acetic acid during instrumentation and then dried with paper points. The canals were filled with matching gutta-percha cone and AH-Plus resin-based sealer (Dentsply, Dentsply, Germany). The access cavity was closed by Coltosol® F temporary filling material (Coltene, Switzerland), and the patient was sent for final restoration [Figure 5],[Figure 6],[Figure 7].{Figure 5}{Figure 6}{Figure 7}

The patient was followed up for a period of 6 months. There were no recurring symptoms or discomfort in the same tooth as reported by the patient. The prognosis of the treatment was good during the end of 6 months of follow-up period.


The ultimate purpose of endodontic management should be to preserve the tooth mechanism without discomfort through instrumentation, irrigation, and obturation of the root canal system. The lack of understanding of the anatomy in addition to the lack of ability to find all the root canals for consequent irrigation and obturation may promote failure and periapical diseases.[9]

Managed to missing canal is a significant cause of failure root canal therapy. The frequency of posttreatment disease is more observed in multirooted molars than the incisors.[10] In this case, as shown by Pomeranz et al., 1981, the MMC can be described as confluent because the prepared canal existed as a single orifice but had been successfully joined to the MB canal.[11]

Alenezi reported a similar clinical case of a permanent mandibular first molar with MMC joining with the MB canal.[12] The mandibular first molar is acknowledged as displaying a complex morphology of its root canal system. This study concludes that the permanent mandibular first molar with the MMC. Three root canals existing in the mesial root divided to mesiolingual (ML), mesiobuccal (MB) canals and presence of the middle mesial canal (MMC) joined with mesiobuccal (MB) canal. The anatomy of mandibular molars was already detected by different methods such as clearing, troughing, tooth sectioning, traditional radiographs, and CBCT.

A recent study by Prade AC et al., 2019 used identifying the location of MMCs. They noted that MMCs have been observed to be 18.2% in the mesial root of the mandibular molars.[13] Recently, in vivo studies have shown that MMCs were found 39.6% and explored after controlled troughing to within 2 mm depth using a 1-mm diameter round bur head as a depth guide.[4]

Magnification will enhance the possibility of a practitioner to locate and negotiate unexpected root canal morphology. A study on mandibular molars showed that the DOM enhances the chance of locating and resolving MMCs.[14]

CBCT has the capability of providing images with high diagnostic quality, which has shorter scanning times and lower dosages when compared to the conventional computed tomography scans. It is a noninvasive 3D reconstruction imaging used as a practical tool in endodontic practice.[15]

CBCT was used throughout the current case to clarify the number of roots and canals and the existence of MMCs. The limited field of CBCT view images offers a noninvasive advanced diagnostic aid with low radiation dosage.[16] Cross-sectional and axial views have been extremely beneficial in identifying the variables of MM canals. The presence of such MMC in the mandibular first molar as seen in our case had been studied in various populations. However, the detection and prevalence of middle mesial canal (MMC) may vary based on the sample size and the population in the studies. The prevalence rates identified across various studies were 9.52% (105 extracted mandibular molars),[13] 3.41% (1174 CBCT scans),[14] 8.1% (100 molar teeth from 60 CBCT scans),[15] 13.33% (120 extracted mandibular molars),[16] and 9.03% (1100 CBCT scans).[17]


Effective endodontic management relies on the skill of an endodontist to identify and search for anatomical variations. In vitro and retrospective studies reveal that the overall rate of occurrence of MM is below 15%. Hence, endodontic practitioners should be vigilant in the detection of cases with the presence of MMC. Utilizing advanced diagnostic techniques such as CBCT and DOM are effectiveness in improvement the accurate diagnosis and the success of the endodontic treatments.

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Conflicts of interest

There are no conflicts of interest.


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