Abstract: Objective: To study the clinical effect of M3 nickel-titanium ( NiTi) for primary teeth in root canal therapy in children. Methods: 80 teeth with chronic pulpitis in 80 patients aged 3-8 years were divided into two groups by case-control design: M3 rotary nickel-titanium group and stainless steel K files group with 40 cases in each group. The operation time, postoperative pain degree, and postoperative X-ray were recorded, respectively. Results: There was no difference in postoperative X-ray evaluation and the pain degree in day 7 between two groups(P>0.05). The differences of the operation time and the pain degree at day 1 and day 3 were statistically significant (P<0.05). The experimental group needed shorter operation time and the level of pain at day 1 and day 3 was lower. Conclusion: M3 nickel-titanium (NiTi) for primary teeth should be promoted because it can shorten the root canal treatment time and reduce the degree of postoperative pain of patients.

Key words: M3 nickel-titanium, primary teeth, root canal therapy