When the error range was set to 0,the accuracy of EAL were 97.06%(before root canal widening),90.91%(after routine root canal widening),and 80.0%(after excess root canal widening) respectively.

• 电测长度与实测长度误差为0时；根管扩大前、常规扩大后、过度扩大后准确率为97.；06%25、90