|Year : 2015 | Volume
| Issue : 1 | Page : 51-55
Three distal root canals in mandibular first molar with different canal configurations: Report of two cases and literature review
Parul Bansal, Vineeta Nikhil, Shashank Shekhar
Department of Conservative Dentistry and Endodontics, Subharti Dental College, Meerut, Utter Pradesh, India
|Date of Web Publication||12-Jan-2015|
58/6, Jagriti Vihar, Meerut, Utter Pradesh - 250 004
Source of Support: None, Conflict of Interest: None
With the increasing number of reports of aberrant root canal morphology, the clinician needs to be aware of the variable anatomy. Various case reports have been published with the finding of middle mesial canal in mandibular first molar, however finding of three distal canals in distal roots of mandibular first molar is rare. This article reports endodontic management of two mandibular first molars presented with three distal canals present in a single distal root (Sert and Bayirli type XVIII) and distal and distolingual root.
Keywords: Distal root, distolingual root, mandibular first molar, three distal canals
|How to cite this article:|
Bansal P, Nikhil V, Shekhar S. Three distal root canals in mandibular first molar with different canal configurations: Report of two cases and literature review. Saudi Endod J 2015;5:51-5
|How to cite this URL:|
Bansal P, Nikhil V, Shekhar S. Three distal root canals in mandibular first molar with different canal configurations: Report of two cases and literature review. Saudi Endod J [serial online] 2015 [cited 2019 Nov 15];5:51-5. Available from: http://www.saudiendodj.com/text.asp?2015/5/1/51/149090
| Introduction|| |
Successful treatment in various areas of odontology requires precise study of the morphology of human teeth with the objective of providing better oral health and restoring stomatognathic functions. All teeth may have anatomically complex and highly variable canal configuration. Mandibular first molars which have one mesial and one distal root with two mesial and one or two distal canals may have the probability of having total five or more canals. In 1974, Vertucci and William  as well as barker et al.,  described the presence of an independent middle mesial canal in mandibular first molar. Since then numerous in vitro and in vivo studies on the morphology of mandibular first molars have provided new data relating to the presence of extra roots and additional root canals. ,,,,, The present case report describes two cases of mandibular first molars with 3 distal canals.
| Case report|| |
A 65-year-old male patient reported with the chief complains of pain in the lower left back tooth since last 3 days. Clinical examination revealed a deep mesio-occlusal carious lesion in relation to left mandibular first molar. The tooth was tender on vertical percussion. Thermal and electric pulp testing elicited a negative response. Preoperative radiograph revealed radiolucency approaching the pulp space and widening of periodontal ligament space in relation to mesial root apex [Figure 1] a. A diagnosis of necrotic pulp with symptomatic apical periodontitis was established and endodontic therapy was planned.
After administration of anesthesia, endodontic access was prepared under rubber dam isolation. On examination with DG-16 endodontic explorer (Hu-Friedy), the pulp chamber had five distinct root canal orifices, two were detected mesially (mesio-buccal and mesio-lingual) and three distally (distobuccal, middle distal, and distolingual). After scouting the root canals, flaring of the coronal thirds was performed with a ProTaper SX rotary file (Dentsply, Maillefer). Working length was determined using an electronic apex locator (Propex II, Dentsply) and confirmed radiographically [Figure 1]b. Working length radiograph revealed three distal canals merging into one canal at the apex. The root canals were prepared in a crown down method using ProTaper NiTi rotary instrumentation and obturation was done with corresponding gutta-percha and AH Plus epoxy resin- based root canal sealer (Dentsply, Maillefer) [Figure 1]c-e].
|Figure 1: Preoperative radiograph revealing mesial radiolucencyapproaching the pulp (a). Working length radiograph revealing threedistal canals merging near the apex (b). Mastercone radiograph (c).Photograph of the three distal canal orifi ces (d). Post-obturation radiograph showing three distal canals (e)|
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An 18-year-old male patient reported with decayed tooth and associated pain in relation to his right mandibular first molar. Clinical examination of the right mandibular first molar revealed a deep mesio-occlusal carious lesion which was tender to vertical percussion. Thermal and electric pulp testing elicited a negative response. Preoperative radiograph revealed radiolucency approaching the pulp and periapical radiolucency related to mesial root apex [Figure 2]a. A provisional diagnosis of necrotic pulp with symptomatic apical periodontitis was made on the basis of clinical sign and symptoms as well as pulp testing results. Endodontic treatment was scheduled. After endodontic access preparation, inspection of the pulp chamber floor revealed two mesial and two distal canals. On careful examination with magnification loupes (Zumax SLE binocular loupes) one additional canal orifice (distobuccal 2) was identified in the groove, present between the distobuccal and the distolingual canal orifices and subsequently an additional canal was negotiated [Figure 2]b. Three canals (distobuccal 1, distobuccal 2 and distolingual) in the distal roots were confirmed radiographically. Working length radiograph revealed that distobuccal 1 and distobuccal 2 were merging near the apex and distolingual canal was present independently [Figure 2]c. All the Canals were instrumented with Protaper rotary system till size F3 (Dentsply, Maillefer) and obturated similar to case number 1 [Figure 2] d and e]. Post-endodontic restoration was performed in the subsequent appointment and patient was asymptomatic during the 6 months follow-up period.
|Figure 2: Preoperative radiograph showing mesial radiolucencyapproaching the pulp and apical radiolucency at the apex of the mesialroot (a). Photograph revealing three distal canal orifi ces (b). Workinglength radiograph (c). Master cone radiograph (d). Post-obturation radiograph (e)|
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| Discussion|| |
Clinical application of scrupulous knowledge of root canal anatomy and meticulous attention to treatment detail are crucial to minimize endodontic failure or subsequent need for retreatment. Hess  reported the prevalence of three root canals in mandibular molars in 78% cases. In vitro studies by Skidmore and Bjorndal  demonstrated the prevalence of two canals in the distal root to be 28.8% cases. Mandibular first molars exhibit considerable anatomical variation and abnormalities regarding the number of roots and root canals. ,,,, The presence of a third canal in the mesial root of mandibular molars is called the middle mesial canal. Baugh and Wallace  in a review of literature, reported that the prevalence of a third canal in the mesial root of mandibular first molars was 1-15%, but the existence of three canals in the distal root of mandibular first molars is uncommon.
Existence of three distal canals of mandibular first molar was first reported by Berthiaume  however, the three distal canals ended in two apical foramina. There are only few comprehensive studies reporting the incidence of three distal canals in the mandibular first molars and are summarized in [Table 1]. These studies have reported the incidence of thee distal canals to be 0.2-3% in different ethnic groups. ,,,,,,, Reuben et al., using spiral computerized tomography (SCT), examined 125 mandibular first molars in an Indian population and none of the teeth had three distal canals.  Present two cases describe the endodontic management of mandibular first molars of Indian origin, having three distal canals.
|Table 1: Prevalence of three distal canals present in mandibular fi rst molars in different ethnic group|
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Several case reports have also described the unusual anatomy of the distal root(s) of mandibular first molars. A detailed review of case reports with three canals in the distal root/roots has been summarized in [Table 2]. ,,,,,,,,,,,,,,,,
The present case report adds two more incidences of three canals in the distal root of permanent mandibular first molar. All three canals had a common apical opening that could be described as Type XVIII canal configuration according to Sert and Bayirli supplemental canal configurations of root canal morphology.  Type XVIII canal pattern in distal root of mandibular first molar has previously been reported in only few cases described by Kottoor,  Surbhi and Sachin,  and Shweta. 
|Table 2: Review of case reports with three or more distal canals in mandibular fi rst molar|
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One of the major variant of root canal system of mandibular first molar is the presence of an additional third root; a supernumerary distolingual root, called as radix entomolaris.  The frequency of radix entomolaris depends on the ethnic group of the population. The prevalence of these three-rooted mandibular first molars appears to be less than 3% in African populations, not to exceed 4.2% in Caucasians, to be less than 5% in Eurasian and Asian populations, and to be higher than 5% (even up to 40%) in populations with Mongolian traits. ,,, Walker and quackenbush  reported the occurrence of extra root unilaterally about 40% of the time, predominantly on the right side. Variations have occurred in the distal root of right mandibular molar in all previous cases reported by Stroner et al., Beatty and Interian,  Friedman et al.,  Kimura and Matumoto,  Barletta et al.  Chandra et al.,  Kottoor,  except for two cases reported by Ghoddusi et al.,  and present case 1, which have such variation on the left side.
Two authors, Lee et al.,  and Chandra et al.,  examined for bilateral occurrence of any morphological variation in the distal root/canals, using SCT and both reported no aberrant findings in the contra lateral tooth. The existence of three separate distal root canals bilaterally (in one root on left side and in two roots on right side) has also been demonstrated in two extracted mandibular first molars by Quakenbush. 
The reported case (case 2) highlights the rare incidence of a mandibular right first molar with one mesial and two distal roots with three distal canals. Same canal configuration in distal roots of mandibular first molar has been previously reported by Quackenbush. 
The increasing frequency of reports dealing with anatomical variations of mandibular molars further emphasizes the need for the clinician to carefully inspect the pulp chamber floor to locate possible accessory canal orifices. A thorough understanding of tooth and root canal morphology, angulated radiographs and exploring the root canals under magnification tools are essential prerequisites for a successful treatment outcome.
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[Figure 1], [Figure 2]
[Table 1], [Table 2]