Conclusions: The roots of maxillary first premolars possesses a variety of canal system types.
结论：上颌第一前磨牙的根管类型相对复杂。
Objective To investigate root canal curvatures of human maxillary first premolars in buccolingual directions.
目的研究上颌第一前磨牙根管颊舌向的弯曲情况。
PURPOSE: to investigate the effect of root canal anatomy in maxillary first premolars on root canal treatment difficulty.
目的：探讨上颌第一前磨牙的根管解剖形态对根管治疗术难度的影响。
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