Abstract: Objective: To observe the short-term effect of two nickel titanium motors, Protaper and Wave one, on one-time molar root canal therapy. Methods: Ninety teeth with pulpitis or asymptomatic nonvital teeth were randomly divided into 3 groups: group P (ProTaper for root canal preparation and warm gutta percha for immediately filling), W group (Wave one for root canal preparation and warm gutta percha for immediately filling), and group K (K file for root canal preparation and cold gutta percha for immediately filling). The curative effect and postoperative reaction of three groups were evaluated after one-time root canal treatment. Results: Ninety teeth was treated with one single root canal preparation and immediately filled. The pain of group P and group W within one week was significantly lower than that of group K. After 3 months and 6 months observation, the success rate of group P and group W was obviously higher than that of group K. The root canal preparation time was in the sequence of group W<group P<group K. Conclusion: The clinical efficacy of group P and group W was significantly better than that of group K, and the average preparation time of group W was shorter than that of group P. Nickel titanium motor has the advantages of saving time and high efficiency, and can reduce the postoperative reaction.

Key words: Molar, Root canal therapy , ProTaper , WaveOne