the case we present here is about a 22-year - old female patient referred to the department of conservative dentistry and endodontics with the chief complaint of pain in the left lower back tooth for the past 2 days .
her medical history was noncontributory and she gave a dental history of root canal treatment was done in that tooth before 2 months in a dental clinic . on clinical examination , it was found access opening was done in a grossly decayed left mandibular second molar .
the treatment was continued by complete caries excauation and canal exploration after rubber dam isolation . on microscopic exploration of the floor of the pulp chamber a canal
re is an extra third root in mandibular molars present on the lingual side , which is shorter in length than other two roots .
however , here , it is seen on buccal side called as rp . on careful exploration on mesial root , presence of three canals
after working length estimation done [ figure 1 ] , all the canals were enlarged until 20 size k file and biomechanical preparation was completed by protaper rotary systems .
all three mesial canals were enlarged until f1 , distal canal until f3 and the extra third root on buccal side until f2 with copious irrigation of saline simultaneously . then the master cones checkup were done as shown in figure 2 .
then the final irrigation was done with 17% ethylenediaminetetraacetic acid , 3% sodium hypochlorite and by saline .
canals were dried with paper points and obturated with gutta - percha cones of respective sizes with kerr sealer .
figure 4 shows the post obturation magnified view of floor of the pulp chamber showing the five canals with rp in middle .
working length determination post obturation radiograph microscopic image of floor of pulp chamber showing type b rp
the mandibular molars usually have two roots with two canals in mesial roots and one canal in distal root .
it is more common that mandibular molars having four canals with two in mesial and distal root viz . the first molar .
however , recent studies shows there are more chance for a 3 canal in mesial and distal root as middle mesial and middle distal , respectively .
this presence in second molar is very rare but , recently few studies of ryan et al .
and jain reported with cases of five or six canals in mandibular first molars only .
the isthmus connecting the mesiobuccal and lingual or distobuccal and lingual is debrided and left uninstrumented in most of the cases .
however , on careful exploration of this isthmus a third canal with a separate path of exit can be seen in many of the cases as reported by deepalakshmi et al . in their four cases . here , in this case of 37 with three mesial canals , all three files and gp points went until full working length independently without any fusion at the apex to exit as one .
it seems that in all three canals , there will be isthmus communicating them in between laterally as it travel , these lateral connections were debrided completely with 3% sodium hypochlorite and sealed by the root canal sealer .
re is an extra third root in mandibular molar , which is shorter than the mesial and distal roots ; seen in distolingual corner like a distolingual canal in the floor of the chamber .
the rp occurrence rate is about 0% , 2% , and 5% in mandibular first , second and third molars respectively .
carlsen and alexandersen described two different types of rp : type a : rp in which the cervical part is located on the mesial root complex ; type b : rp in which the cervical part is located centrally , between the mesial and distal root complexes , an additional cusp was present on the buccal side .
the complex root canal anatomy stresses the operator to observe the canal morphology with care without underestimating it and missing the extra root and roots canals , which can occur in any cases as a rare finding .
thus , the success of endodontics lies in the careful exploration of the canals and debridement of it . 
 mandibular first molar commonly has two roots , the mesial and the distal root . 
 surprisingly in some mandibular first molar has an unusual extra third root in between mesial and distal root . 
 this extra root is the most commonly seen in lingual side and is called as radix entomolaris . if this extra root is seen on the buccal side , it is termed as radix paramolaris ( rp ) , which is a very rare phenomenon . 
 recently , various case report studies has shown the presence of third canal in the mesial and distal roots of mandibular molars . 
 they are named as middle mesial and middle distal canal , respectively . here , 
 we present a case report of mandibular second molar showing three canals in the mesial root and a rp . 
Case Report
Discussion
Conclusion