the objective of root canal treatment is thorough cleaning and shaping of all the pulp spaces to be filled with an inert filling material . a major cause of failure of the root canal treatment is the inability to locate , debride , or adequately fill all canals of the root canal system . a successful root canal treatment depends on the diagnosis , treatment planning , good knowledge of the root canal system , and its frequent variations . there are numerous studies that examine the root and root canal anatomy of different populations using different methods like sectioning , canal sectioning , and tooth clearing techniques , conventional radiography , digital radiographic techniques , contrast medium - enhanced radiography , and computed tomographic scanning . the tooth clearing methods have generally been considered the gold standard for analyzing the root canal anatomy , which involves making the tooth transparent and staining the canals for study , but these ex - vivo methods require the extraction of a tooth . there are case reports of the incidence of second mesiobuccal ( mbi ) canals ranging between 18 and 96.1% . the incidence of five canals is reported to be 2.25 2.4% , and the incidence of six canals is reported to be 0.31  0.88% . the incidence of a second distobuccal ( dbi ) canal in the maxillary first molars has been reported to be as low as 1.7 and 1.25% . case reports with more than four root canals have also been reported in three - rooted maxillary first molars [ table 1 ] . , reported one maxillary first molar out of 140 samples having three roots and seven canals . kottoor et al . , reported the endodontic management of the maxillary first molars with seven and eight canals , respectively . incidence of multiple canals in maxillary first molars this case report discusses the endodontic management of an unusual root canal configuration in a maxillary first molar showing three roots and seven canals . this unusual morphology was confirmed with the help of cone beam computerized tomography ( cbct ) scans . an 18-year - old male patient reported to the department of conservative dentistry and endodontics , sinhgad dental college and hospital , pune , with the chief complaint of spontaneous pain in the upper left posterior region of the jaw for the past five days . the patient gave a history of intermittent pain for the last two months , which had increased in intensity in the preceding five days . on clinical examination , a deep disto - occlusal carious lesion , which was tender on percussion , with no mobility , was seen in tooth 14 . vitality testing of the involved tooth with heated gutta - percha ( dentsply maillefer , ballaigues , switzerland ) caused an intense lingering pain , whereas , an electronic pulp tester ( parkell , usa ) gave an early response . a preoperative radiograph revealed disto - occlusal radiolucency approaching the pulp space , with the periodontal ligament space widening in relation to the mesiobuccal root . from the clinical and radiographic examination , a diagnosis of symptomatic irreversible pulpitis with symptomatic apical periodontitis was made and nonsurgical endodontic treatment was recommended . radiographic evaluation of the involved tooth did not indicate any variation in the root canal anatomy . local anesthesia was induced using 1.8 ml of 2% lignocaine and adrenaline ( aqua fine injecta pvt . ltd . , pune , india ) . after caries excavation , the distal surface of the tooth was built up with composite resin ( matrix , medicept dental prod , uk ) to enable optimal isolation . initially , the mb1 , db1 , and two palatal canals ( mesiopalatal ( mp ) and the distopalatal ( dp ) ) were located . when viewing the floor of the pulp chamber under a dental operating microscope ( dom ) ( moller wedel , germany ) , three additional root canal orifices ( mb2 , mb3 , and db2 ) were located and conventional triangular access was modified to a trapezoidal shape , to improve access to the additional canals [ figure 1a and b ] . the patency of the canal was confirmed with iso # 10 k - files ( mani , japan ) . to confirm this unusual morphology , it was decided to perform cbct imaging of the tooth . a sterile cotton pellet was placed in the pulp chamber and cavit g ( 3 m espe dental products , st paul , mn ) was used to seal the access cavity . informed consent was obtained from the patient , and a multislice cbct scan of the maxilla was performed with a tube voltage of 100 kv and a tube current of 8 ma . the involved tooth was focused and the morphology was obtained in the transverse , axial , and sagittal sections , of 0.5 mm thickness . the cbct scan slices revealed seven canals ( three mesiobuccal , two palatal , two distobuccal ) in the left maxillary first molar [ figures 2a and b , 3a and b ] . ( a ) access opening ( b ) access opening ( a ) coronal section ( b ) coronal section ( a ) apical section ( b ) apical section the cbct images provided valuable information regarding the canal configuration and confirmed the seven canals that were not clearly seen in the conventional radiograph . at the next appointment , after two weeks , the patient was asymptomatic . the working lengths were determined with the help of an apex locator ( root zx , j morita , tokyo , japan ) , under rubber dam isolation , and intraoral periapical radiographs of the mesiobuccal , distobuccal , and palatal root were taken to confirm the working lengths [ figure 4a and b ] . cleaning and shaping were performed using nickel - titanium rotary instruments ( m2 , dentsply vdw , germany ) using the crown - down technique . during root canal preparation , final rinsing of the canals was performed using 2% chlorhexidine digluconate ( asep rc , stedman anabond , chennai , india ) together with passive ultrasonic agitation . the canals were dried with absorbent points ( dentsply maillefer , ballaigues , switzerland ) and obturation was performed using cold lateral compaction of the gutta - percha ( dentsply maillefer , ballaigues , switzerland ) and ah plus resin sealer ( dentsply detrey , konstanz , germany ) . a radiograph was taken to establish the quality of the obturation [ figure 5a and b ] . after completion of root canal treatment , the tooth was restored with a posterior composite filling ( matrix , medicept dental products , uk ) and the patient was advised to have a full coverage porcelain crown . mb root ( a ) obturation ( b ) clinical view of the pulp chamber post obturation before undergoing root canal treatment , prior knowledge of the roots and root canal anatomy of the teeth is required . in the maxillary molars , anatomic variations are not uncommon , with the number of canals , from one to eight . recently , 14 new additional canal types were reported by sert and bayirli , highlighting the complexity of the root canal systems . in this case , it helped to confirm the presence of multiple canals , which were otherwise not able to be identified , except through the microscope . the tenet of  as low as reasonably achievable ( alara ) was considered , but the advantage of using cbct outweighed the risks of additional exposure . a cbct scan and surgical operating microscope confirmed the diagnosis of three roots and seven canals in the left maxillary first molar , namely , mb1 , mb2 , mb3 , db1 , db2 , mp , and dp . the cbct axial images showed the mesiobuccal root had a sert and bayirli type xv canal configuration . the mb2 and mb3 joined together to exit as one and the db1 and db2 joined to exit as one . in clinical conditions , conventional periapical radiographs and digital radiographs taken in different angulations are an essential part of endodontic treatment for the identification of root and canal configuration . however they are taken in a buccal - lingual direction and give only two - dimensional information about a three - dimensional object . in recent years , advanced techniques like computed axial tomography scanning are being used to evaluate root canal morphology , as a three - dimensional image . it allows the operator to view the tooth roots and their root canal systems at different levels , which helps to identify a larger number of morphological variations than in the conventional radiographs . cbct images are reconstructed using significantly lower radiation doses when compared with the alternative conventional computed tomography scanning . this is because , with cbct scanning , the raw data are acquired in the course of a single sweep of a cone - shaped x - ray source and reciprocal detector around the patient 's head . of the various comprehensive maxillary first molar ex - vivo studies in dental literature , of the 140 extracted maxillary first molars evaluated , only one tooth showed seven root canals , which contained three mesiobuccal , three distobuccal , and one palatal canal . the frequency of the mb2 canals in the mesiobuccal root was reported to be 92.85% ( based on ex - vivo results ) , 95.63% ( based on clinical results ) , and 95.45% ( based on cbct results ) , whereas , the corresponding figures for the distobuccal root ( db2 ) were 1.15% ( ex - vivo ) and 3.75% ( clinical ) , and those for the palatal root ( second palatal canal ) were 2.05% ( ex - vivo ) , 0.62% ( clinical ) , and 4.55% ( cbct ) . three canals in the mesiobuccal root were reported by various authors [ table 1 ] . additional mesiobuccal canals were commonly found in the age group of 20 to 40 years . in the present case , the use of a dental operating microscope helped in the location and identification of additional canal orifices . as an additional finding , the contralateral maxillary first molar had additional root canals , which were clearly appreciable in the cbct . thorough knowledge of the root canal anatomy is an essential pre - requisite for endodontic success . the knowledge that aberrant canals are more common than earlier assumed is increasingly being proven . the clinician should use increased magnification and advanced diagnostic aids similar to cbct , to ensure identification and location of additional canals .
the main objective of root canal treatment is thorough cleaning and shaping of the entire pulp space and its complete filling with an inert filling material . 
 a major cause of post - treatment disease is the inability to locate , debride or adequately fill all canals of the root canal system . 
 the form , configuration , and number of root canals in the maxillary first molars have been discussed for more than half a century . 
 maxillary first molars commonly present with three roots and three canals , with a second mesiobuccal canal ( mb2 ) also present . with the advent of improved magnification 
 there are reports of multiple root canals in the maxillary first molars . 
 nonsurgical endodontic therapy of a left maxillary first molar with three roots and seven root canals was successfully performed under a dental operating microscope . 
 the diagnosis of multiple root canals was confirmed with the help of cone beam computed tomography ( cbct ) images .