extensive research has been carried out in recent years regarding the unusual anatomy of permanent maxillary first molar tooth . knowledge of the common anatomic characteristics and their possible variations is essential , because the non - treatment of even one canal can lead to endodontic treatment failure . the usual root canal anatomy of maxillary first molars have been described as three roots with three canals , with the commonest variation being the presence of a second mesiobuccal ( mb ) canal . maggiore et al . , reported the maxillary first molar having six canals namely two mb , three palatal ( p ) , and one distobuccal ( db ) . the occurrence of two canals in db roots has been less frequent and has been reported in 3.6% of maxillary molars . martinez - berna and ruiz - badanelli reported three cases in which the maxillary first molars had presented six root canals ( three in mb , two in db , and one in p root ) . adanir reported six canals with one mb , two mesiopalatal ( mp ) , two db , and one p. alavi et al . , and thomas et al . , reported the incidence of two canals in the db root as 1.90% and 4.30% , respectively . currently , technological advances have witnessed the introduction of cbct to facilitate the assessment of internal anatomic variations of root canals . this imaging modality has been very useful in identifying anatomic features of the tooth and variations of the root canal system . we present two case reports and discuss the successful endodontic management of a maxillary first molar presenting with three roots and six root canals . a 19-year - old female patient presented to the department of conservative dentistry , with pain in the maxillary right first molar that had persisted for the past two days . detailed clinical examination revealed dental caries ( mesio - occlusal ) on the maxillary right first molar , which was tender to percussion . the heating test using gutta percha stick ( an endodontic dental chair side diagnostic tool ) revealed a lingering pain after the removal of the stimulus . the heating test was first performed on the contralateral tooth and then on the adjacent tooth . a preoperative radiograph in relation to the involved tooth revealed deep caries in the mesio - occlusal portion of the tooth involving the pulp space with periodontal ligament space widening in relation to mb root [ figure 1 ] . case 1 . a 19-year - old female patient with pain in the right molar . preoperative intra - oral periapical dental x - ray film shows deep caries on the mesial aspect ( white arrow ) of maxillary right first molar with pulpal involvement ( dashed arrow ) . a detailed review of the clinical and radiographic findings led to the diagnosis of acute irreversible pulpitis with acute apical periodontitis . the tooth was anesthetized with 1.8 ml ( 30 mg ) 2% lignocaine containing 1:200,000 epinephrines ( xylocaine ; astrazeneca pharma ind ltd , bangalore , india ) followed by rubber dam isolation and an endodontic access cavity was established . clinical examination with a dg-16 endodontic explorer ( hu - friedy , chicago , il ) revealed two canal openings in each of the mb , and p root and one opening in the db root . during further examination using surgical loupes the working length was determined with the help of an apex locator ( tri auto zx , j morita , tokyo , japan ) and later confirmed using a radiograph . intra - oral periapical dental x - ray film shows endodontic files in all six canals ( mb1 ( a ) , mb2 ( b ) , db1 ( c ) , db2 ( d ) , p1 ( e ) and p 2 ( f ) of maxillary right first molar . to confirm the unusual morphology it was decided to obtain a cbct image of the tooth after obtaining the informed consent of the patient . with the files placed in the mb , db , and p canals the scan was conducted . as it can be clearly seen in the cbct image [ figure 3 ] , the arrows in the figure point to the extra canals and further an intraoral image was taken to visualize the canals [ figures 4 and 5 ] . the white dots represent the position of endodontic files in the mb , db and p orifices . intra - oral photograph of the maxillary right first molar shows the two mb orifices and the two db orifices . case 1 . intra - oral photograph of the maxillary right molar shows the two p orifices . in the next appointment cleaning and shaping of the canals were performed under rubber dam isolation using protaper nickel titanium ( niti ) rotary instruments with a crown down technique , till file no . irrigation of the canals was done between each instrumentation using 2.5% naocl and 17% edta . the canals were subsequently dried with absorbent paper points and obturated using the f2 protaper cone and znoe sealer [ figure 6 ] . the tooth was then restored with a posterior composite synergy d6 ( coltene , whaledent ) . the patient was then advised to do a full coverage restoration . case 1 . intra - oral peri - apical dental x - ray film clearly shows all the canals filled with gutta percha as a filling material . ( mb1 canal , mb2 canal , db1 canal , db2 2 canal , p1 canal , p2 canal ) . a 25-year - old female patient presented to the department of conservative dentistry , with pain in the maxillary left first molar for the past two days . clinical and radiographic findings led to the diagnosis of acute irreversible pulpitis with apical periodontitis . after administration of adequate anesthesia endodontic access cavity was prepared . clinical examination with a dg-16 endodontic explorer ( hu - friedy , chicago , il ) revealed two canal openings in the mb canal . the working length was determined with the help of an apex locator ( tri auto zx , j morita , tokyo , japan ) and later confirmed using a radiograph . to confirm the extra canal and to check for any aberrations in canal anatomy an interim dressing of cavit ( 3 m , espe ) was placed and after an informed consent of the patient the cbct image of the maxilla was performed . the image clearly reveals two canals in the mb orifice of the tooth [ figure 7 ] . also a c - shaped orifice was seen in the p canal which helped to plan the correct technique for canal preparation . case 2 . a 25-year - old female patient with pain in the left first molar . cbct image of the maxillary left first molar shows the mb2 orifice ( black arrow ) and c - shaped p orifice ( white arrow ) . pulp extirpation was completed in all the canals and an interim dressing of cavit ( 3 m , espe ) was placed in the canals . in the subsequent check - up cleaning and shaping of the canals were performed under rubber dam isolation using protaper niti rotary instruments with a crown down technique till file no . irrigation of the canals was done after each instrumentation using 2.5% naocl and 17% edta . the canals were subsequently dried with absorbent paper points and obturated using the f2 protaper cone and znoe sealer [ figure 8 ] . the tooth was then restored with a posterior composite synergy d6 ( coltene , whaledent ) . the patient was then advised to do a full coverage restoration . intra - oral periapical dental x - ray film shows all the canals are filled with gutta percha as a filling material . a 19-year - old female patient presented to the department of conservative dentistry , with pain in the maxillary right first molar that had persisted for the past two days . detailed clinical examination revealed dental caries ( mesio - occlusal ) on the maxillary right first molar , which was tender to percussion . the heating test using gutta percha stick ( an endodontic dental chair side diagnostic tool ) revealed a lingering pain after the removal of the stimulus . the heating test was first performed on the contralateral tooth and then on the adjacent tooth . a preoperative radiograph in relation to the involved tooth revealed deep caries in the mesio - occlusal portion of the tooth involving the pulp space with periodontal ligament space widening in relation to mb root [ figure 1 ] . case 1 . a 19-year - old female patient with pain in the right molar . preoperative intra - oral periapical dental x - ray film shows deep caries on the mesial aspect ( white arrow ) of maxillary right first molar with pulpal involvement ( dashed arrow ) . a detailed review of the clinical and radiographic findings led to the diagnosis of acute irreversible pulpitis with acute apical periodontitis . the tooth was anesthetized with 1.8 ml ( 30 mg ) 2% lignocaine containing 1:200,000 epinephrines ( xylocaine ; astrazeneca pharma ind ltd , bangalore , india ) followed by rubber dam isolation and an endodontic access cavity was established . clinical examination with a dg-16 endodontic explorer ( hu - friedy , chicago , il ) revealed two canal openings in each of the mb , and p root and one opening in the db root . during further examination using surgical loupes the working length was determined with the help of an apex locator ( tri auto zx , j morita , tokyo , japan ) and later confirmed using a radiograph . intra - oral periapical dental x - ray film shows endodontic files in all six canals ( mb1 ( a ) , mb2 ( b ) , db1 ( c ) , db2 ( d ) , p1 ( e ) and p 2 ( f ) of maxillary right first molar . to confirm the unusual morphology it was decided to obtain a cbct image of the tooth after obtaining the informed consent of the patient . with the files placed in the mb , db , and p canals the scan was conducted . as it can be clearly seen in the cbct image [ figure 3 ] , the arrows in the figure point to the extra canals and further an intraoral image was taken to visualize the canals [ figures 4 and 5 ] . the white dots represent the position of endodontic files in the mb , db and p orifices . intra - oral photograph of the maxillary right first molar shows the two mb orifices and the two db orifices . case 1 . intra - oral photograph of the maxillary right molar shows the two p orifices . in the next appointment cleaning and shaping of the canals were performed under rubber dam isolation using protaper nickel titanium ( niti ) rotary instruments with a crown down technique , till file no . irrigation of the canals was done between each instrumentation using 2.5% naocl and 17% edta . the canals were subsequently dried with absorbent paper points and obturated using the f2 protaper cone and znoe sealer [ figure 6 ] . the tooth was then restored with a posterior composite synergy d6 ( coltene , whaledent ) . the patient was then advised to do a full coverage restoration . case 1 . intra - oral peri - apical dental x - ray film clearly shows all the canals filled with gutta percha as a filling material . ( mb1 canal , mb2 canal , db1 canal , db2 2 canal , p1 canal , p2 canal ) . a 25-year - old female patient presented to the department of conservative dentistry , with pain in the maxillary left first molar for the past two days . clinical and radiographic findings led to the diagnosis of acute irreversible pulpitis with apical periodontitis . after administration of adequate anesthesia endodontic access cavity was prepared . clinical examination with a dg-16 endodontic explorer ( hu - friedy , chicago , il ) revealed two canal openings in the mb canal . the working length was determined with the help of an apex locator ( tri auto zx , j morita , tokyo , japan ) and later confirmed using a radiograph . to confirm the extra canal and to check for any aberrations in canal anatomy it was decided to obtain a cbct image of the tooth . an interim dressing of cavit ( 3 m , espe ) was placed and after an informed consent of the patient the cbct image of the maxilla was performed . the image clearly reveals two canals in the mb orifice of the tooth [ figure 7 ] . also a c - shaped orifice was seen in the p canal which helped to plan the correct technique for canal preparation . case 2 . a 25-year - old female patient with pain in the left first molar . cbct image of the maxillary left first molar shows the mb2 orifice ( black arrow ) and c - shaped p orifice ( white arrow ) . pulp extirpation was completed in all the canals and an interim dressing of cavit ( 3 m , espe ) was placed in the canals . in the subsequent check - up cleaning and shaping of the canals were performed under rubber dam isolation using protaper niti rotary instruments with a crown down technique till file no . irrigation of the canals was done after each instrumentation using 2.5% naocl and 17% edta . the canals were subsequently dried with absorbent paper points and obturated using the f2 protaper cone and znoe sealer [ figure 8 ] . the tooth was then restored with a posterior composite synergy d6 ( coltene , whaledent ) . the patient was then advised to do a full coverage restoration . intra - oral periapical dental x - ray film shows all the canals are filled with gutta percha as a filling material . a variety of study methods such as radiographs , magnification , clinical evaluations , dye injection , tooth sectioning and scanning electron microscopy have been discussed and reported by several authors for the detection of additional root canals . newer diagnostic methods such as computerized axial tomography ( ct ) scanning greatly facilitate access to the internal root canal morphology by allowing the operator to look at multiple slices of tooth roots and their root canal systems . with ct scans , it is possible to reconstruct overlapping structures at arbitrary intervals , and , thus , the ability to resolve small subjects is increased . ct scans are still not as accurate and do not limit the dosage to low as reasonably achievable . the use of newer diagnostic imaging modality as cbct is fast gaining importance in diagnosis of unusual root canal morphology . the amount of information gained from conventional radiographs and digitally captured periapical radiographs is limited by the fact that the three - dimensional anatomy of the area is compressed into a two - dimensional image . cbct has been used in endodontics for the effective evaluation of the root canal morphology along with the diagnosis of endodontic pathology , assessing root and alveolar fractures , analysis of re - absorptive lesions , identification of non - endodontic pathology , and pre - surgical assessment before root end surgery.[79 ] the present case report emphasizes the use of cbct for the identification of multiple root canals and subsequent success of the root canal treatment . matherne et al . , in a study concluded that cbct images resulted in the identification of greater number of root canal systems than digital images . baratto filho et al . , evaluated the internal morphology of maxillary first molars by ex vivo and clinical assessments . they concluded that cbct scanning along with the use of an operating microscope can be used as a good method for initial identification of maxillary first molar internal morphology . in a study by jojo kottoor et al . , cbct axial images confirmed the presence of three roots and seven root canals , namely mesiobuccal1 ( mb1 ) , mesiobuccal2 ( mb2 ) , mesiobuccal3 ( mb3 ) , distobuccal1 ( db1 ) , distobuccal2 ( db2 ) , mesiopalatal ( mp ) and distopalatal ( dp ) . furthermore although the occurrence of mb2 in maxillary first molars is very frequent , the other point that needs to be emphasized is the revelation of the c - shaped canal orifice for the palatal canals that helps the operator to choose the required biomechanical preparation . the prognosis of an endodontic case definitely improves when cbct is used for locating the extra canals . the current cbct technology may have its limitations but one can not totally rule out the possibility of using cbct as a diagnostic tool for endodontic purposes .
the purpose of this article is to emphasize the use of cone beam computed tomography ( cbct ) for root canal treatment . 
 two case reports are presented where cbct has been used to locate and eventually treat extra canals in maxillary first molars . 
 dental clinicians should be aware of the anatomical variations in maxillary molars . 
 cbct should be an essential part of the diagnosis prior to initiating root canal treatment .