Abstract: Objective To investigate the canal morphology of maxillary first premolar using cone-beam CT (CBCT) and to know its generic and variant forms. Methods 106 CBCT images of maxillary first premolar were selected. The images were analyzed with NNT software to investigate the type and distribution of the root canal. Results The canal configuration of maxillary first premolar:typeI 30 cases (8.52％), typeⅡ 92(26.1％), typeIV 225(63.9％), typeVI 3(0.85％), typeⅧ 2(0.56％). Conclusion Understanding the various morphology of the roots and complex root canals of maxillary first premolars, is of great value for the diagnosis and clinical treatment of root canal morphology.

Key words: maxillary first premolars, root canal morphology,CBCT