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Paper text:
a 30-year - old male patient reported to the department of conservative dentistry and endodontics with decayed tooth and associated pain over his left mandibular region .
the tooth exhibited no mobility , was mildly tender to percussion , and gave a negative response to heat test and a mild reaction to an electric pulp tester .
the preoperative diagnostic radiograph of 37 [ figure 1 ] revealed a deep carious lesion involving the pulp with widening of the apical periodontal ligament space .
a provisional diagnosis of necrotic pulp with apical periodontitis was made and endodontic treatment was scheduled .
preoperative radiograph of 37 after administration of local anesthesia and rubber dam isolation , the carious lesion was removed and an adequate endodontic access made .
inspection of the pulp chamber floor showed orifices corresponding to mesiobuccal , mesiolingual , and distal canals [ figure 2 ] . on careful examination of the groove between the mesiobuccal and mesiolingual canal orifices ,
the middle mesial canal orifice was identified and the canal subsequently negotiated [ figure 3 ] .
intraoral mirror image of 37 with three canals in mesial root intraoral mirror image of 37 with three canals in mesial root the working lengths were established with an electronic apex locator , and size 10 k files of 21 mm length ( dentsply , maillefer , ballaigues , switzerland ) were used to confirm three canals in the mesial root radiographically [ figure 4 ] .
the canals were instrumented with stainless steel hand instruments  k files of 21 mm length ( dentsply , maillefer )  and the orifices were shaped with gates glidden drills .
working length radiograph irrigation was done with copious amounts of 3% sodium hypochlorite ( nice chemicals pvt . ltd . ,
cochin , india ) and 17% ethylenediaminetetraacetic acid ( edta ; pulpdent corporation , massachusets , usa ) .
the canals after preparation were finally flushed with sterile saline , dried with sterile paper points , and a calcium hydroxide dressing was given .
at the subsequent visit after a week , the tooth was asymptomatic and was obturated with gutta percha cones ( dentsply , maillefer ) using ah - plus sealer ( dentsply detrey gmbh , konstanz , germany ) [ figures 5 and 6 ] .
post - obturation radiograph of 37 the patient experienced no postoperative sequelae and an appropriate post - endodontic restoration was performed in a subsequent appointment to ensure an adequate coronal seal .
there are number of reports that reveal the anatomic variations of root canals in mandibular molars .
the presence of a third canal ( middle mesial ) in the mesial root of the mandibular molars has been reported to have an incidence of 0.9515% .
although many authors have agreed on the presence of three foramina in the mesial root , only a few have reported the presence of three independent canals , which presents itself as a rare anatomic variant .
this additional canal may be independent with a separate foramen or the additional canal may have a separate foramen and join apically with either the mesiobuccal or the mesiolingual canal . the clinician should accurately observe the pulp chamber floor to locate possible canal orifices .
pulp chamber floor and wall anatomy provide a guide to determine the root canal morphology .
krasner and rankow[1821 ] made a rational approach to study the relationship of the pulp chamber to the clinical crown and the pulp chamber floor .
their observations , presented in the form of laws , are valuable aids to the clinician searching for elusive canals . failure to identify extra canals and to recognize any unusual canal configuration
is implicated as one of the most common reasons for the failure of endodontic therapy.[2224 ] a round bur or an ultrasonic tip can be used for removal of any protuberance from the mesial axial wall , which would prevent direct access to the developmental groove between mesiobuccal and mesiolingual orifices .
this developmental groove should be carefully checked with the sharp tip of an endodontic explorer .
if depression or orifices are located , the groove can be troughed with ultrasonic tips at its mesial aspect until a small file can negotiate this intermediate canal ( vertucci , 2005 ) .
radiographic examination using conventional intraoral periapical views is important for the evaluation of the canal configuration .
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 ) imaging has been shown to provide comparable images at reduced dose and costs to be considered as an alternative to multidetector ct imaging in endodontics .
la et al . in 2010 suggested clinical detection and management of an independent middle mesial canal in mandibular first molar by using cbct imaging .
cbct imaging prior to initiation of therapy can be done for accurate diagnosis and management of the unusual canal morphology .
various diagnostic aids like dyes , champagne bubble test , ultrasonics , micro openers and trans - illumination 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 .
newer technologies , such as the dental operating microscope and dental loupes , offer magnification and illumination of the operating field and substantially improve the visualization of root canal orifices ( de carvalho ) .
the present report confirms that the third canal in the mesial root of mandibular second molar does occur and must be sought along the line between the two mesial canals after accessing the pulp chamber and any cervical stenosis in this zone that might cover the opening of the canals , using burs or ultrasonic tips.[3033 ]
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 second 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 number and morphology in mandibular second should be done using various diagnostic methodologies with magnification and illumination , which would pave the way for long - term success of endodontic therapy .
the primary objective of endodontic therapy is to achieve a three - dimensional obturation of the root canal space after adequate preparation of the canal space to remove the tissue debris , microorganisms , and their byproducts . 
 anatomical variations have frequently been encountered in endodontic practice and have to be adequately managed by the clinician . missed roots and canals are a major reason for failure of therapy . 
 technological advances have given the clinician ample opportunity to identify and treat these aberrations successfully . 
 the present report describes a left mandibular second permanent molar requiring root canal treatment , found to have three separate canals in the mesial root . 
 this case demonstrates a rare anatomical configuration and emphasizes the need for the clinician to be aware of and look out for such variations and use adequate diagnostic methodologies prior to and during therapy to detect such variations . 
 the possibility of additional canals , whenever in doubt , should be explored with the assistance of technologies such as those of magnification and illumination and various diagnostic aids . 
 operator experience has also shown to be a key factor in negotiation and management of these aberrant canal configurations .