Effect of the Passive Ultrasonic Irrigation and the Apical Diameter Size on the Debridement Efficacy of Infected Root Canals: A Multivariate Statistical Assessment of Histological Data

The removal of necrotic and vital pulp substrates microorganisms their toxins from the root canal system (RCS) has been found to be basis for a successful endodontic treatment. In this study, our aim was evaluate effect passive ultrasonic irrigation (PUI) on elimination organic remnant tissue infected, narrow curved mandibular canals during instrumentation. For purpose, mesiobuccal first molars were instrumented with RaCe rotary system, using PUI activation or conventional (CI) two apical diameters (#25 #35). cleanness samples evaluated by microscopy modified Langeland’s ordinal scale. Parametric non-parametric statistical analyses principal coordinates analysis (PCoA) performed. When used, there significant reduction in enlargement 25 at 2 mm apex (p < 0.001). After pooling groups, regardless depth observation (2 4 apex), pair #35 + vs. #25 CI showed statistically differences explained 65% overall variance when compared samples. use reduced material infected an #35. is not biomechanical instrumentation up diameter ≥#35 recommended.