3Navarro LF, Luzi A, Garcia AA, et al. Third canal in the mesial root of permanent mandibular first molars : Review of the literature and presentation of 3 clinical reports and 2 in vitro studies[J]. Med Oral Patol Oral Cir Bucal, 2007,12 (8) :E605 -609.
4Yew SCH, Chan K. A retrospective study of endodontically treatedmandibular firstmolars in a Chinese population [J]. J Endod, 1993,19(9) : 471 - 473.
5Kimura Y, Matsumoto K. Mandibular first molar with three distal root canals [ J ]. Int Endod J, 2000,33 ( 5 ) : 468 - 470.
6Holtzmann L. Root canal treatment of a mandibular first molar with threemesial root canals [ J ]. Int Endod J, 1997, 30(6 ) : 422 - 423.
7Fabra-Campos H. Unusual root anatomy of mandibular first molars [ J ]. J Endod, 1985,11 ( 12 ) : 568-72.
8De Moor RJ,Deroose CA,Calberson FL.The radix entomolaris in mandibular first molars:an endodontic challenge[J].Int Endod J,2004,37(11):789-799
9Gulabivala K,Opasanon A,Ng YL,et al.Root and canal morphology of Thai mandibular molars[J].Int Endod J,2002,35(1):56-62
10Yew SC,Chan k.A retrospective study of endodontically treated mandibular first molars in a Chinese population[J].J Endod,1993;19(9):471-473