Endodontic management of Mandibular first molar with five canals

Dr. Rafeza Sultana

Ms- Resident, Department of Conservative Dentistry & Endodontic.

BSMMU

Abstract: The purpose of this study was to demonstrate the importance of knowledge of the internal anatomy of root canals for the success of endodontic treatment. Lack of knowledge of anatomic variations & their characteristics in different teeth has been pointed out as one of the causes of endodontic therapy failure. The present report  describes a right mandibular first permanent molar requiring root canal therapy, found to have three separate canals ( type-1 configuration) in the mesial  root & two separate canals ( type-1 configuration) in the distal root . So emphasizes the need for the clinicians to be aware of & look out for such variation & use adequate diagnostic methodologies prior to & during therapy to detect such variations. The operator experience has also shown to be a key factor in negotiation & management of this aberrant canal configuration.

Key Word: Mandibular 1^st Molar, Middle Mesial canal, % root canal, Root canal anatomy.

Introduction: Knowledge of internal dental anatomy is fundamental to the success of endodontic treatment. Incomplete instrumentation, inadequate cleaning & shaping, & the subsequent defective obscuration of root canals are the main causes of endodontic treatment failure¹. Anatomical characteristics of the different types of teeth and their possible variations are challenges routinely faced by practitioners performing endodontic treatment.

The correct access into the pulp chamber, which should allow access to the orifices of the root canals and an optimum view of the chamber floor, is a fundamental step in endodontic therapy as it enables the identification of any variation in the number and position of root  canals² .

The middle mesial canal has been more commonly located in mandibular 1^st molar¹⁰.  Several studies have evaluated the degree of variation in the number of roots and root canals in mandibular 1^st molars¹⁰ .  Fabra  campons¹⁰ studies 145 mandibular 1^st molars & found that 2.75% of the teeth had five canals. Martinez-burna and Badanelli⁵ conducted a canal investigation & found 29 teeth with five root canals in a sample of 2362 mandibular permanent molars and reported that 12 out of 100 molars studied had a third mesial canal.

Aminsobhani et all studied the occurrence and location of the middle mesial canal of mandibular 1^st molar & second molar in relation to other two mesial canals that were treated in private practice that middle mesial canalwas located in the middle of the distance between the mesiobuccal and mesiolingual canals. The canal configuration  was found in 6 2^nd molars & 21 1^st molars. Middle mesial canals in all of the cases joined to mesiobuccal or mesioligualcanals. None of the teeth consisted  of three independent canals with three apical foramina . Beatty & krell described  a mandibular 1^st molar with three independent canals in the mesial root . Author Dr. carlos Heibom et  al reported the number of roots, total number of canals, the number of middle mesial canals & number of foramina in the following chart

Number of roots Number of molars studied                  18,781                        3-rooted molars in %                  13 % (2,450)

Total number of canals Number of molars studied                   4,745         61.3 % 3 canals        35.7 % 4 canals       0.8 % 5 canals

Number of canals in mesial root Number of mesial roots studied           4,535         3.3 % 1 canal            94.2 % 2 canals      2.6 % 3 canals

Mesial and distal roots. Canal system configuration                                                                            Type I (1-1)   Type II (2-1)   Type IV (2-2)   Type VIII (3-3) Number of mesial roots studied           4,331                               35 %               52.3 %                0.9 % Number of distal roots studied             2,992         62.7 %           14.5 %            12.4 %

Number of foramina in mesial and distal roots                                                                                    1 foramen                2 foramina                   3 foramina Number of mesial roots studied          4,817                  38.2 %                      59.2 %                         1.6 % Number of distal roots studied            3,378                  77.2 %                      22.2 %

Intercanal communications. Type V isthmuses                                                                                               Mesial root                                 Distal root Number of molars studied                   1,615             54.8 % middle & apical 1/3              20.2 % middle 1/3

According to ingle¹² one of the most important causes of endodontic treatment failure is the incomplete obturation of the root canal system. Therefore, the correct location, instrumentation & obturation of all canals are indispensable procedures. 

Case report: A 19 years old male patient reported to the department of conservative dentistry & endodontics BSMMU with decayed tooth & associated pain over his right mandibular region. Intra oral examination revealed class 1 deep carious lesion in mandibular right 1^st molar. The tooth exhibited no mobility, was mildly tender to percussion and gives a negative respond to vitality test. The pre operative diagnostic radiograph of the tooth revealed a deep carious lesion involving the pulp with widening of apical periodontal space. A diagnosis of necrotic pulp with apical periodontitis was made and endodontic treatment was scheduled. After administration of local anesthesia & isolation, the carious lesion was removed and an

Endodontic access was made. Inspection of pulp chamber floor showed orifices corresponding to mesiobuccal, mesioligual, distobuccal abd distolingual canals. On careful examination of the groove between the mesiobucccl and mesiolingual canal orifice was identified and subsequently negotiated. The working length was established (MB-20mm, ML-20mm, Middle Mesial-19mm,DB-19.5mm,DL-19mm).The canals were instrumented with NiTi  file and irrigation was done with  2.5% NaOCl solution. After preparation the canal was finally flushed with normal saline & dried with sterile paper points and Ca(OH)2 was given at the full length of the canals with Lentulo-spiral  for 1 week. At the subsequent visit the Ca(OH)2 dressing was removed, the master cone fit was cheeked and the root canal was dried with absorbent paper point and was obturated with GP cone.

Discussion: Before root canal treatment clinician should adequate knowledge of the pulp chamber and anatomy of teeth. All root canals should be accessed, cleaned and shaped to achieve a hermetic obturation of the entire root canal space.

There is an abundant amount of reports that relate the anatomic variations of the mandibular molars. This should induce the clinician to observe the pulp chamber floor to locate possible canal orifices. This will increase the long term prognosis of endodontic therapy. Searching for additional canal orifice should be standard practice for clinician. A round bur or ultrasonic tip can be used for removal of any protuberance from the mesial axial wall would prevent direct access to the developmental groove between MB & ML orifices. This developmental groove should be carefully cheeked with sharp endodontic explorer (DG-16, JW-17). If orifices are located the groove can be troughed with ultrasonic tip, its mesial aspect until small file can negotiate this intermediate canal^{4 .} New technology such as dental operating microscopes and dental loupes offer magnification and illumination of the operating field and substantially improved the visualization of the root canal orifices^5-6. But we did not use these new technologies during treatment session.

Numerous studies in the past decade have described the morphology of teeth including mandibular molars⁷. The morphology of mesial root canals in mandibular molar is complex and high frequency of intercanal communication and or isthmuses ^{(7,8,9,10-13)}.

The presence of third canal (middle mesial) in the mesial root of the mandibular molars has been reported to have an incidence of 0.95% to 15%^{(4,7,11,14,15,19)}.In almost all of the clinical cases  reported until today these canals joined the mesiobuccal & mesiolingual canal in the apica third²⁰.

Radiographic examination using intraoral periapical view is important for the evaluation of the canal configuration. However it has its inherent limitation to access the root canal system completely. Digital radiography at different angles with subsequent image analysis can be used effectively. Computed tomography (CT) imaging has been widely used in medicine since the 1970s and was introduced in the endodontic field in 1990. Recently cone beam CT (CBCT) and RVG imaging has been shown to provide comparable images at reduced dose and cost to be considered as an alternative to multi detector CT imaging in endodontic. La et al. 2010 suggested clinical detection and management of an independent middle mesial  canal in mandibular molar by using CBCT imaging.

Various diagnostic aids like dyes, champagne bubble test , ultrasonic’s, micro openers and transillumination  aids, irrigators to improve pulp chamber visibility (Stropko) and observing the chamber for bleeding spots could be used by the clinician as an effective means to locate additional canal orifices.

Conclusion: knowledge of dental anatomy in fundamental for good endodontic preparation. Identification of these extra canals and their instrumentation is one of the key factors in the prevention of unsuccessful treatment outcomes. In addition to the various diagnostic aids, operator experience has also been identified as a key factor in locating these aberrant canals. The clinician should be aware of the incidence of this type of variation in the mandibular first molar tooth and perform a preoperative radiological assessment from different angles, a proper access preparation, and thorough examination of the pulp chamber to locate and debride all the canals. An accurate clinical evaluation of root canal and morphology in mandibular first molar should be done using various diagnostic methodologies with magnification and illumination, which would pave the way for long-term success of endodontic therapy.

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Figure 4 Final radiograph of obturation of five canals.

F. B. Barletta et al. Mandibular Molar with Five Root Canals

© 2007 The Authors 3

Journal compilation © 2007 Australian Society of Endodontology

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