Comparative Study of Manual Versus Mechanized Techniques for Removal of Root Canal Filling Material

Background: Successful nonsurgical endodontic retreatment hinges on the complete removal of existing root canal filling materials to allow for effective disinfection and re-obturation. While manual techniques have long been the standard, various mechanized nickel-titanium (NiTi) systems, including continuous rotary and reciprocating instruments, have been introduced to improve the efficiency and efficacy of this procedure. Methods: Sixty extracted human mandibular premolars with single, straight canals were prepared and obturated with gutta-percha and a bioceramic sealer. The teeth were randomly assigned to three retreatment groups (n=20 each): Group 1 (Manual H-files), Group 2 (ProTaper Universal Retreatment - PTUR), and Group 3 (WaveOne Gold - WOG). The efficacy of filling material removal was evaluated by calculating the percentage of remaining material volume using micro-computed tomography (micro-CT). Safety was assessed by quantifying the weight of apically extruded debris. Efficiency was determined by measuring the total time required for the retreatment procedure. Data were analyzed using one-way ANOVA and Tukey’s post-hoc test (α = 0.05). Results: The mean percentage of remaining filling material was significantly higher in the Manual group (15.89 ± 5.21%) compared to both the PTUR group (8.22 ± 3.10%) and the WOG group (6.15 ± 2.45%) (p < 0.001). The WOG group left significantly less residual material than the PTUR group (p = 0.041). The Manual group produced the highest amount of apically extruded debris (0.62 ± 0.18 mg), which was significantly more than the PTUR (0.34 ± 0.11 mg) and WOG (0.41 ± 0.13 mg) groups (p < 0.001). The retreatment procedure was significantly faster with the WOG system (248 ± 55 s) and the PTUR system (295 ± 68 s) compared to the Manual technique (612 ± 93 s) (p < 0.001). Conclusion: Within the limitations of this in vitro study, both mechanized NiTi systems were significantly more effective and efficient than the manual H-file technique for gutta-percha removal. The WaveOne Gold reciprocating system demonstrated the highest efficacy in removing filling material and was the fastest technique, although no system achieved complete removal.