Apical debridement of necrotic oval root canals with irrigation protocols activated by passive ultrasonic irrigation, R-SWEEPS, or OdneClean: an ex vivo histological study

Introduction This ex vivo study compared the histological debridement efficacy of four irrigation protocols in the apical third of necrotic oval root canals after minimally invasive preparation with TruNatomy Glider and Prime files (26/.04): syringe needle irrigation (SNI) and protocols activated by passive ultrasonic irrigation (PUI), resonant shock-wave enhanced emission photoacoustic streaming (R-SWEEPS), or the OdneClean system. Methods Sixty extracted mandibular premolars were assigned to four groups ( n = 15 per group). All canals received the same sodium hypochlorite and EDTA sequence. In the PUI and R-SWEEPS groups, each solution of the sequence was activated, whereas in the OdneClean group the non-activated sequence was followed by activation of sterile water, in accordance with the intended clinical use of each device. Residual tissue and debris areas were measured on histological sections and analyzed using Kruskal–Wallis and Dunn tests, and pairwise differences were estimated with multiplicity-adjusted confidence intervals. Results The residual area was highest for SNI (median 15.38%) and lower for PUI (7.47%), R-SWEEPS (5.49%), and OdneClean (5.49%). All three activated protocols left less residual tissue and debris than SNI ( p < 0.05), whereas no statistically significant differences were detected among them ( p > 0.05). Discussion Within this ex vivo model, activated irrigation protocols improved apical debridement compared with needle irrigation; because the OdneClean protocol also included an additional sterile-water irrigation phase, the results reflect complete irrigation protocols rather than the effect of hydrodynamic cavitation alone, and the study was not designed to establish equivalence among the activation systems.