Can Type of Instrumentation and Activation of the Final Irrigant Improve the Obturation Quality in Oval Root Canals? A Push-Out Bond Strength Study

To appraise the outcome of file systems and activation of the final irrigant on the push-out bond strength of root fillings in oval canals. Single-rooted mandibular premolars (n = 180) with oval canals were divided into three groups (n = 60) for instrumentation: ProTaper Next (PTN), WaveOne (WO), and Self-adjusting File (SAF). The specimens were further divided into subgroups (n = 20) and subjected to final irrigation with activation by EndoActivator or passive ultrasonic irrigation or without activation. Then, the specimens were again subdivided (n = 10) and obturated with gutta-percha and AH Plus (GP-AH) or C-Point with EndoSequence bioceramic sealer (C-EBC). One-millimeter-thick horizontal slices were cut from the apical third of the root, 5 mm from the apex, and subjected to push-out bond strength (BS) testing. Specimens for which SAF was used exhibited higher BS values than those for which PTN or WO was used (p < 0.05). Activation of the final irrigation did not affect the BS of the root fillings. Root fillings made of C-EBC presented a higher BS than those made of GP-AH (p < 0.05). Adhesive failure was more common with specimens instrumented using PTN and WO. Root canals instrumented with SAF, showed the highest bond strength values for both root filling materials. The C-EBC produced significantly higher bond strength values than those of the GP-AH.

Calcium Hydroxide Removal Using Four Different Irrigation Systems: A Quantitative Evaluation by Scanning Electron Microscopy

This study compares conventional endodontic needle irrigation, passive ultrasonic irrigation, apical negative pressure irrigation, and mechanical activation to remove calcium hydroxide from single straight root canals. Eighty-four mandibular premolars were prepared in a crown-down manner up to size #40. Two teeth represented a negative control, and another two served as a positive control. Calcium hydroxide paste was placed inside root canals. The remaining eighty samples were analyzed based on the activation techniques, and the cleanliness of the canals was quantified using Fiji’s software on 500× magnified SEM backscattered electron micrographs. Considering the whole canal, all instruments showed better performance than conventional endodontic needle irrigation in removing calcium hydroxide (p < 0.05). Irrisafe and XP-endo Finisher could remove a significantly higher amount of calcium hydroxide than Endovac (p < 0.05). Irrisafe and XP-endo Finisher have been able to remove more calcium hydroxide than EndoVac.

Advantages and application of ultrasonic irrigation in endodontics

In the current practice, evidence shows that the currently used irrigant solutions (including sodium hypochlorite combined with and without chlorhexidine or ethylenediaminetetraacetic acid) cannot achieve full cleaning outcomes of the root canal. Accordingly, recent approaches were directed to innovate more efficacious modalities that can overcome the limitations of manual instrumentation and irrigation solutions. In this context, ultrasonic irrigation has been described in the literature as a favorable approach with significantly enhanced outcomes. We have provided evidence regarding the use of ultrasonic irrigation in endodontics. Our findings indicate that passive ultrasonic irrigation is more effective than manual instrumentation in eradicating debris and achieving favorable disinfection. Besides, it has been evidenced that the modality significantly reduces the time to achieve favorable treatment outcomes compared with the traditional approaches. It has been furtherly shown that more favorable outcomes were associated with the combined use of passive ultrasonic irrigation with manual instrumentation. Therefore, it has been suggested that manual instrumentation should be used at the initial phase to achieve adequate preparation, and passive ultrasonic irrigation should be used later on to achieve root canal cleaning.

Does the Use of Use of Continuous or Passive Ultrasonic Irrigation Protocols Improve the Removal of Smear Layer? A Scanning Electron Microscopic Study

The aim of this study was to evaluate the effectiveness of smear layer removal after the use of different irrigation methods (passive ultrasonic irrigation [PUI], continuous ultrasonic irrigation [CUI], apical negative pressure irrigation and conventional irrigation) using the scanning electron microscopy (SEM) as an analytical tool. A total of 100 single-canal teeth were decoronated and randomly divided into five groups (n = 20) according to the irrigation method used: conventional irrigation with front outlet syringe, conventional irrigation with lateral outlet syringe, apical negative pressure irrigation (EndoVac), PUI with Irrisafe, and CUI with ProUltra PiezoFlow ultrasonic irrigation needle. Root canal preparation was performed with the ProTaper Gold system up to the F4 instrument and 5.25% NaOCl was used as an irrigant. After chemical-mechanical preparation, the roots were split longitudinally, and the coronal, middle and apical thirds examined. SEM digital photomicrographs were taken at ×1000 magnification to evaluate the amount of smear layer in each root canal third. CUI was more effective in removing the smear layer than the other irrigation protocols. However, none of the irrigation protocols were able to produce root canals completely free from smear layer.

Effect of Passive Ultrasonic Irrigation over Organic Tissue of Simulated Internal Root Resorption

This study aimed to evaluate the efficacy of passive ultrasonic irrigation (PUI) on dissolving the organic tissue inside simulated internal root resorption (IRR) using sodium hypochlorite (NaOCl) or chlorhexidine (CHX). A total of 40 human lower premolars were collected based on dimensional and morphological similarities. The roots were embedded in cylinders (3 cm diameter; 2.5 cm height) of self-cured acrylic resin, and then an IRR was simulated. The specimens were divided into 4 groups (n = 10) according to irrigation protocols: group 1: CHX + PUI; group 2: CHX; group 3: NaOCl + PUI; group 4: NaOCl. The total irrigation time was 150 s at a flow rate of 5 mL/min. A tissue mass of porcine palatine mucosa was used to simulate the organic tissue, it was weighed before and after the irrigation using an analytic balance, and the difference between both readings was calculated and transferred to percentage values. Data were submitted to statistical analysis using two-way ANOVA (factors: irrigant type and with/without PUI) and Tukey’s test for multiple comparisons among the experimental groups (α = 0.05). There was a significant difference in both factors (irrigant: p = 0.04 ; PUI: p ≤ 0.001 ). The groups that used PUI were more effective in dissolving the organic tissue of the IRR simulation than the groups without PUI. PUI is more effective than the syringe and needle irrigation in organic tissue dissolution.

Evaluation of Bacterial Reduction after Root Canal Shaping Using ProTaper Gold and WaveOne Gold Rotary Systems

Introduction The present study evaluated bacterial reduction promoted by the WaveOne system (Dentsply Maillefer, Ballaigues, Switzerland) and ProTaper Gold system (PTG; Dentsply Maillefer) in human extracted central incisors. Methods Sixty-two maxillary central incisors that were infected with Enterococcus faecalis (ATCC 51299) were sterilized with ethylene oxide for 21 days, and then root canal initial bacterial sample was collected with paper points and plated on M-Enterococcus agar. The specimens were randomly divided into two groups according to instrumentation: WaveOne Gold group (n = 30) and PTG group (n = 30). Each group was further subdivided into subgroup A (n = 15) where no activation of the irrigant was performed, and subgroup B (n = 15) where passive ultrasonic activation (PUI) was applied. The other two specimens without contamination were control asepsis. After instrumentation, samples were collected with the use of paper points. The bacterial reduction was calculated using colony-forming unit and quantitative real-time polymerase chain reaction. Data were collected and statistically analyzed. Results All techniques significantly reduced the number of bacteria in the root canal (p < 0.05), in which PTG showed superior bacterial reduction than WaveOne Gold (p > 0.05). The aseptic control group did not show any bacterial growth. PUI showed a significant bacterial reduction with the WaveOne Gold group. Conclusion It can be concluded that the single-file system, WaveOne Gold with the aid of passive ultrasonic irrigation, significantly reduce the bacterial number in the root canal similar to the multifile system, PTG.

Comparison of Apically Extruded Debris Associated with Different Irrigation Techniques after Removal of Intracanal Medicaments

This study aimed to compare the effect of XP-endo Finisher file (XPF), passive ultrasonic irrigation (PUI) and conventional irrigation technique using side-vented needle (SVN) on the amount of apically extruded debris after the removal of calcium hydroxide Ca(OH)2 and double antibiotic paste (DAP). Materials and Methods: Sixty extracted human mandibular premolars were used. After decronation, all canals were prepared up to the ProTaper Next X4 file (Dentsply Maillefer, Ballaigues, Switzerland). After dryness, teeth were randomly assigned into 2 groups (n=30) according to the Type of intracanal medication used; Ca(OH)2 and DAP then incubated at 37 °C and 100% humidity. After one week, Samples in each group were randomly assigned to 3 subgroups (n=10) according to the method used for medicament removal: XPF, PUI and SVN. Debris extruded during the removal procedure were collected into pre-weighed Eppendorf tubes then left to dry in an incubator at 37°C for 15 days. The amount of extruded debris was assessed with an analytical balance and calculated by subtracting the initial weight from the final weight of the tube. Data were statistically analyzed using Kruskal-Wallis and Mann-Whitney U test. Results: there was no statistically significant difference regarding the amount of apically extruded debris after using the three irrigation techniques in removal of both Ca(OH)2 and DAP (P-value = 0.141, Effect size = 0.160) and (P-value = 0.237, Effect size = 0.073) respectively. Conclusions: Neither XPF nor PUI increase the risk of intracanal medicament extrusion beyond the apex.