Comparison of rotary NiTi files with ultrasonic irrigation and manual K-files with syringe irrigation in primary molar pulpectomy: A retrospective cohort study

Objective: Pulpectomy is the standard treatment for irreversibly inflamed or infected primary molars. The success of pulpectomy in primary molars depends on effective root canal cleaning and shaping. Traditional manual preparation and irrigation techniques face challenges when dealing with complex root canal systems in primary teeth. This study aims to retrospectively evaluate the clinical and radiographic outcomes of two tapered rotary nickel-titanium file systems (M3 and S3) combined with ultrasonic irrigation, compared to conventional manual K-files and syringe irrigation, in pulpectomy for primary molars. Methods: A single-center retrospective analysis enrolled children aged 4–9 years who underwent pulpectomy at the Pediatric Dentistry Clinic of the Third Hospital of Hebei Medical University. Participants were categorized into three groups based on the instrumentation technique: M3 rotary files with ultrasonic irrigation (n=98), S3 rotary files with ultrasonic irrigation (n=84), and manual K-files with conventional irrigation (n=78). Instrumentation time was measured using a digital stopwatch. Obturation quality was radiographically classified as optimal, underfilled, or overfilled. Postoperative pain was assessed at 24, 48, and 72 hours using the Wong-Baker FACES scale. Clinical and radiographic outcomes at the 12-month follow-up were categorized as success, uncertain, or failure. Results : The M3 rotary group showed the shortest instrumentation time (210.45 ± 6.85 s) and the highest rate of optimal obturation (87.1%), significantly outperforming the S3 and manual file groups ( P <0.05). Both rotary systems led to significantly lower pain scores at 24 and 48 hours compared to manual instrumentation ( P <0.01). No significant differences were observed in pain at 72 hours or in 12-month therapeutic success rates among the groups ( P >0.05). Conclusion: This study demonstrates that combining modern NiTi rotary instrumentation (specifically the 0.04 tapered M3 system) with ultrasonic irrigation significantly outperforms conventional manual techniques in operative efficiency, obturation quality, and postoperative pain control. Clinical Significance: The integration of NiTi and ultrasound translates into a clinically superior, patient-beneficial protocol for primary teeth pulp therapy, optimizing procedural experience without compromising therapeutic success.