3Tu MG,Huang HL,Hsue SS,et al.Detection of permanent threerooted mandibular first molars by cone-beam computed tomography imaging in Taiwan Residents individuals[J].J Endod,2009,35(4):503-507.
4Scott RG,Turner CG 2nd.The Anthropology of Modern Human Teeth[M].London,Cambridge University Press,1997.
5Kim Y,Lee S,Woo J.Morphology of maxillary first and second molars analyzed by cone-beam computed tomography in a Korea population:variations in the number of the roots and canals and incidence of fusion[J].J Endod,2012,38(8):1063-1068.
6Vertucci FJ.Root canal anatomy of the human permanent teeth[J].Oral Surg,1984,58(5):589-599.
7Versiani MA,Pécora JD,de Sousa-Neto MD.Root and canal morphology of four rooted maxillary second molars:a micro-computed tomography study[J].J Endod,2012,38(7):977-982.
8Hess W.The Anatomy of the Root Canals of the Teeth of the Permanent Dentition[M].London:John Bale,Sons and Danielsson Ltd,1925:44-49.
9Thomas RP,Moule AJ,Bryant R.Root canal morphology of maxillary permanent first molar teeth at various ages[J].Int Endod J,1993,26(5):257-267.
10Peiris HR,Pitakotuwage TN,Takahashi M,et al.Root canal morphology of mandibular permanent molars at different ages[J].Int Endod J,2008,41(10):828-835.