Efficacy of ultrasonic activation of NaOCl and orange oil in removing filling material from mesial canals of mandibular molars with and without isthmus

Abstract

Objectives The aim of this study was to evaluate the volume of remaining filling material after passive ultrasonic irrigation (PUI) of sodium hypochlorite (NaOCl) and orange oil in mesial canals of mandibular molars, with and without isthmus.Material and Methods Thirty mesial roots of mandibular molars were divided according to the presence or absence of isthmus. Canals were prepared and filled (Micro-CT #1). Filling was removed using rotary instruments, and specimens were sub-divided into three groups according to the irrigation procedures: Conventional – conventional irrigation with NaOCl, PUI/NaOCl – PUI of NaOCl (three activations, 20 seconds each), and PUI/orange oil – PUI of orange oil (Micro-CT#2). Specimens were enlarged using the X2 and X3 ProTaper Next instruments and submitted to the same irrigation protocols (Micro-CT #3).Results No differences were found between the experimental groups in each stage of assessment (P>0.05). The volume of residual filling material was similar to those in Micro-CT #2 and Micro-CT #3, but lower than those observed in Micro-CT #1 (P<0.05). When groups were pooled according to the presence or absence of an isthmus, volume of residual filling material was higher in specimens presenting isthmus (P<0.05).Conclusions PUI of NaOCl or orange oil did not improve filling removal. Isthmus consists in an anatomical obstacle that impairs the removal of filling material.

Evaluation of the efficacy of filling material removal and re-filling after different retreatment procedures

“…This occurs because the isthmus area represents a major challenge for proper cleaning and disinfection, considering that the mechanical instrumentation of this area is unfeasible. 29,30 None of the protocols yielded root canal walls that were completely free of filling material, a finding corroborated by previously published studies using different methodologies. 10,11,14 The PTR + PUI technique presented lower values of residual filling in the canal area.…”

Retreatability of two hydraulic calcium silicate‐based root canal sealers using rotary instrumentation with supplementary irrigant agitation protocols: a laboratory‐based micro‐computed tomographic analysis

“…, Barreto et al . ). Possibly, differences in root canal morphology (straight vs. severely curved canals and round vs. oval canals), type of filling material (resin‐based vs. calcium silicate‐based), and/or retreatment procedures (use of solvents and different instruments), methods used for assessment (two‐dimensional techniques such as scanning electron microscopy or stereomicroscopy vs. three‐dimensional methods such as computer tomography) and storage time (short‐term vs. long‐term) can explain the conflicting results.…”

“…Findings from previous studies using ultrasonic activation and micro-CT evaluation were inconclusive. Some studies reported a significant improvement in filling removal when using ultrasonically activated irrigation, after instrumentation with various rotary systems (Bernardes et al 2016, Jiang et al 2016, whereas other studies found no significant differences (Fruchi et al 2014, da Rosa et al 2015, Barreto et al 2016. Possibly, differences in root canal morphology (straight vs. severely curved canals and round vs. oval canals), type of filling material (resin-based vs. calcium silicate-based), and/ or retreatment procedures (use of solvents and different instruments), methods used for assessment (twodimensional techniques such as scanning electron microscopy or stereomicroscopy vs. three-dimensional methods such as computer tomography) and storage time (short-term vs. long-term) can explain the conflicting results.…”

Influence of solvent and a supplementary step with a finishing instrument on filling material removal from canals connected by an isthmus

“…Previous studies using micro‐CT imaging have also demonstrated that the use of solvents did not significantly improve filling material removal from isthmus‐connected root canals (Gergi & Sabbagh , Barreto et al . ). An important differential in the present study, however, was that an exclusive analysis of the isthmus was performed, allowing for a better understanding of the initial and remaining material volume in this region.…”

“…Some studies observed the formation of a film of softened gutta-percha on the canal surface after the use of solvents, making retreatment even more difficult and slower (Ferreira et al 2001, Takahashi et al 2009, Betti et al 2010. The majority of retreatment studies using solvents in molars did not consider the presence of isthmuses (Gergi & Sabbagh 2007, Fruchi et al 2014, Saglam et al 2014 or did not evaluate the presence of filling material remnants entrapped in these areas separately , Barreto et al 2016.…”