Micro-CT evaluation of four final irrigation protocols on hard-tissue debris removal from mesial roots of mandibular molars containing isthmus

Objectives To evaluate by means of microcomputed tomography (micro-CT), the efficacy of four final irrigation protocols in the removal of hard-tissue debris (HTD) in mesial roots of mandibular molars containing isthmus. Materials and methods Forty standardized mesial roots of extracted mandibular molars presenting isthmus were selected. The root canals were prepared and randomly divided into 4 groups ( n = 10): EA, EndoActivator (Dentsply Sirona); EC, Easy Clean (Easy Dental Equipment, Belo Horizonte, Brazil); XPF, XP-Endo Finisher (FKG Dentaire, La Chaus-de Fonds, Switzerland); and PUI, passive ultrasonic irrigation using Irrisafe tip (Satelec Acteon, Merignac, France). Each final irrigation protocol was performed in two cycles (60 s), using, respectively, 2.5% sodium hypochlorite and 17% EDTA. Micro-CT scans were obtained pre-operatory, post-preparation, and post-irrigation. The percentage of HTD reduction was calculated. Data was analyzed statistically (ANOVA and Kruskal–Wallis, significance set at 5%). Results The percentage of HTD reduction was greatest for the XPF group (77.92%), followed by EA (62.92%), PUI (47.48%), and EC (32.65%). Statistical differences ( p < .05) were found between XPF and EC only. A significant difference ( p < .05) was found between XPF and EC in all thirds and between PUI and EC in the middle third. Conclusions XPF, EA, and PUI were similarly effective in HTD reduction. However, none of the evaluated protocols was able to completely remove all the debris. Clinical relevance Final irrigation protocols aim to clean the canal complexities that are not addressed by the shaping procedures. Micro-CT allowed to assess the removal of hard-tissue debris in the isthmus and canals of mandibular molars.