Abstract: Objective: To evaluate the Clinical effect of M3 minimally invasive nickel-titanium instrument combined with single-cone obturation in root canal treatment of molars in patients with restricted mouth opening. Methods: From January 2020 to August 2020, 90 patients with endodontic disease with restricted mouth opening who could not be treated with conventional root canal treatment were selected for the study, and they were randomly divided into two groups. The observation group was prepared with M3 minimally invasive instruments nickel-titanium and single-cone obturation, and the control group was prepared with Protaper Gold and warm vertical condensation. The indexes and therapeutic effects of two groups were analyzed. Results: The feasibility rate of root canal treatment in the observation group was higher than that in the control group, however, not statistically significant (P>0.05). The root canal preparation time and root canal filling time were shorter in the control group, and the difference was statistically significant (P<0.05). There was no significant difference in the success rate, proper filling rate, and pain incidence between two group (P>0.05). Conclusion: The M3 minimally invasive instrument preparation combined with Single-cone obturation has high feasibility rate and save time for the treatment of molars in patients with restricted mouth opening.

Key words: restricted mouth opening, minimally invasive instruments, single-cone obturation