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Introduction: The success of endodontic treatment is based on microbial reduction promoted by the interaction of chemical and mechanical procedures. Photodynamic therapy (PDT) is used as an adjunct to conventional treatment, with significant microbial reduction. This study aimed to evaluate the influence of passive ultrasonic irrigation (PUI) of the photosensitizer (PS) used in PDT on microbial reduction in the root canal system., Materials and Methods: Forty-five mesiobuccal root canals from extracted human mandibular molars that were inoculated with standard strains of Enterococcus faecalis , Candida albicans , and Streptococcus mutans for 21 days were selected. The root canals were prepared using the ProTaper Next system and randomly divided into 3 groups ( n =15): 1) PDT: PDT alone; 2) PUI+PDT: PUI followed by PDT; and 3) PUI/PS+PDT: PUI of the PS followed by PDT. Microbiological samples were collected from the canals before and after using the protocols described above. The data were analyzed by analysis of variance (Tukey's test) at a significance level of 5%., Results: Microbial counts before PDT, PUI+PDT, and PUI/PS+PDT did not differ significantly ( P >0.05), showing methodological standardization in the microbial contamination of the root canal system. There was a significant reduction in microbial counts after PDT (61.05%), PUI+PDT (65.04%), and PUI/PS+PDT (68.58%) ( P <0.01), but with no statistically significant difference between the three groups ( P >0.05)., Conclusion: Based on the present findings, it was concluded that the combination of PUI with PDT or PS activation did not influence microbial reduction achieved by PDT alone., Competing Interests: None.

Aim: To assess dentin-post bond strength and mode of failure through tensile strength testing of two endodontic post systems: CAD/CAM custom-milled fiber posts vs Splendor SAP., Materials and Methods: Thirty extracted single-rooted mandibular premolars were sectioned 2 mm coronal to the cementoenamel junction. Root length was standardized at 15 mm, and the root canals were instrumented with #20 K-files followed by 30/0.03 and 30/0.05 ProDesign Logic rotary files, under irrigation with 2.5% NaOCl, and then submitted to final irrigation with 17% EDTA. Canals were filled with gutta-percha and AH PLUS sealer. After 24 hours, the teeth were prepared for post placement to a depth of 10 mm and randomly allocated into two experimental groups ( n = 15): CAD/CAM (CC) and Splendor SAP (SS). All posts were cemented with RelyX U200 dual-cure self-adhesive resin cement. The roots were embedded in acrylic resin, and the specimens were stored for 7 days in moist heat (37°C). Tensile strength testing until failure was then performed in a universal testing machine using a crosshead speed of 0.5 mm/minute. The final failure load was tabulated for statistical analysis, and the G test was used to compare the failure modes observed under light microscopy (5× magnification)., Results: There was no significant difference between groups regarding tensile bond strength to root dentin ( p = 0.325). Conversely, failure mode differed significantly between groups ( p = 0.037)., Conclusion: The tensile bond strength observed for the CAD/CAM and Splendor SAP post systems was similar. Adhesive failure was predominant in both groups; however, the CAD/CAM custom-milled fiber posts failed predominantly at the dentin-resin cement interface, whereas Splendor SAP posts failed mostly at the post-resin cement interface., Clinical Significance: A strong post-dentin bond is a key to the success of dental restorations and prosthetic rehabilitation. In teeth with severe coronal decay and wide canals, both of the tested systems would be able to achieve good cervical fit.

Introduction: Successful endodontic treatment requires an effective coronal sealing to prevent the penetration of saliva and microorganisms into the root canal system. We aimed to investigate the sealing capacity of Maxxion R, Intermediate Restorative Material (IRM), Mineral Trioxide Aggregate-like material (Biodentine), White Cimpat, Flow Resin and Z250 Resin against Enterococcus ( E. ) faecalis infiltrates, when used as coronal sealants after endodontic treatment., Materials and Methods: Sixty-six roots of adult lower premolars were randomly divided into 6 experimental groups with 10 roots each ( n =10), and two control groups (positive and negative) with three roots each. The root canals were instrumented to ProTaper F3 file, irrigated with 2.5% NaOCl and 17% EDTA, and filled using Tagger's Hybrid technique with AH-Plus cement. After removing 2 mm of the coronal third filling with a Gates Glidden #6 drill, the cervical portion of each of the sixty roots was sealed with a 2 mm-thick plug, plus the respective material being tested in this study. All roots were fitted to silicone devices (Eppendorf) with cut extremities and sterilized with ethylene oxide; experimental procedures were performed in a laminar flow chamber for aseptic chain maintenance. All specimens were inoculated with E. faecalis , and the culture medium was renewed every 3 days for 60 days. Medium turbidity was evaluated daily. The obtained data were subsequently submitted to analysis of variance (ANOVA-R) complemented by Student's t -test at a significance level of 5%. Analyzes of variance were calculated using the SAS system GLIMMIX procedure., Results: Biodentine (56.90), Z250 Resin (54.90) and White Cimpat (53.30) resisted contamination for a longer time compared to Maxxion R (51.30), Flow Resin (50.70), and IRM (48.70) over a period of 60 days., Conclusion: Biodentine, Resin Z 250 and White Cimpat presented the lowest infiltration averages when compared to the other tested materials., Competing Interests: ‘None declared’.

Introduction: The aim of this study was to evaluate the effectiveness of 2.5% sodium hypochlorite associated with 17% Ethylenediaminetetraacetic acid (NaOCl-EDTA), versus that of 1% peracetic acid (PA), in removing the smear layer, as assessed by scanning electron microscopy (SEM), and in exerting bactericidal action against Enterococcus faecalis ( E. faecalis ) , as assessed by the real-time polymerase chain reaction (real-time PCR)., Methods and Materials: Fifty-five extracted mandibular single-rooted premolars were selected, and divided into two experimental groups (NaOCl-EDTA and PA; n =25) and one control group (0.9% saline; n =5). Pre- and post-instrumentation samples were collected and assessed for the presence of E. faecalis using real-time PCR. The teeth were instrumented using hand files and the ProTaper Universal system (hybrid technique) for a standardized time of 7 min. A total of 20 mL of NaOCl followed by 5 mL of EDTA were applied during instrumentation in the NaOCl-EDTA group, whereas 20 mL of PA and 20 mL of saline were applied in the PA and control groups, respectively. An additional 5 mL of saline was applied in all the groups to neutralize the environment. A scoring system was used to conduct the SEM assessment. The results were submitted to the Kruskal-Wallis test, complemented by Dunn's test (SEM analysis) ( P <0.05)., Results: A significant microbial reduction was observed in both the PA and the NaOCl-EDTA groups ( P <0.05). In the PA group, the presence of a smear layer in the apical third was significantly greater than in the cervical third ( P <0.05); no significant differences were observed between the middle and cervical thirds, or between the middle and apical thirds ( P >0.05). In the NaOCl-EDTA group, the smear layer scores were significantly higher in the apical third than in the cervical and middle thirds ( P <0.05)., Conclusion: This in vitro study showed that there was no significant difference between PA and NaOCl-EDTA irrigation regimens regarding either antimicrobial action against E. faecalis or removal of the smear layer, except for greater removal in the middle third by the NaOCl-EDTA group., Competing Interests: ‘None declared’.

The aim of this study was to evaluate the cytotoxic effects of 2. 5% sodium hypochlorite (NaOCl), 17% ethylenediamine tetraacetic acid (EDTA), and 1% peracetic acid (PAA) on human fibroblasts. FG11 and FG15 cell lines were cultured in 24-well cell culture plates for cell proliferation assessment and 96-well cell culture plates for the methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay; Dulbecco's modified Eagle's medium (DMEM) was used as control data. The experimental solutions were used at 0. 01%, 0. 05%, and 0. 1% dilutions and assessed at 1-, 2-, and 4-hour intervals. Data were subjected to statistical analysis by two-way analysis of variance (ANOVA), followed by the Bonferroni test at a significance level of p <0. 05. The assessment of cell proliferation in this study showed cytotoxicity to the fibroblasts with 2. 5% NaOCl for all three dilutions at all time intervals, 17% EDTA for the 0. 05% and 0. 1% dilutions at the 2- and 4-hour intervals, and 1% PAA for all three dilutions at the 4-hour interval. The cell viability assay (MTT assay) for fibroblasts showed 2. 5% NaOCl to be cytotoxic at the 0. 05% and 0. 1% dilutions at all time intervals, 17% EDTA to be cytotoxic at the 0. 1% dilution at the 2- and 4-hour intervals, and 1% PAA to be cytotoxic at the 0. 1% dilution at the 2- and 4-hour intervals. In conclusion, 1% PAA was less cytotoxic than 2. 5% NaOCl and 17% EDTA., (Sociedad Argentina de Investigación Odontológica.)

Introduction: The aim of this in vitro study was to identify the formation of dentinal defects on the external apical root surface of teeth instrumented at different working lengths by using WaveOne reciprocating files., Methods: Sixty human single-rooted mandibular premolars were divided into 3 groups (n = 20) according to the file used for instrumentation: WaveOne Small (WOS), premolars presenting mechanical resistance to the penetration of #10 K-file 1 mm short of the apical foramen; WaveOne Primary (WOP), this limit easily reached with #10 K-file; and WaveOne Large (WOL), this limit easily reached with #20 K-file or higher. A closed system and a muffle were created to allow alternating sessions of root canal instrumentation and image acquisition. The teeth were further divided according to 3 different working lengths: 1 mm short of the apical foramen, flush with the apical foramen, and 1 mm beyond the apical foramen. Micrographs of the external apical root surface of each specimen at baseline and after instrumentation up to each working length were examined for the presence of dentinal defects. Inter-examiner agreement was evaluated by using Pearson correlation test, and the Kruskal-Wallis test was used to analyze intragroup and intergroup differences (P < .05)., Results: Inter-examiner agreement was high in all experimental groups (r = 1.0000, r = 0.8885, and r = 0.7867 for WOS, WOP, and WOL, respectively). There was no significant difference in the number of teeth with dentinal defects in the intergroup (P = .8119) or intragroup analyses (P = .9309, .8648, and .4772 for WOS, WOP, and WOL, respectively)., Conclusions: Instrumentation with different WaveOne files up to different working lengths was not associated with the formation of dentinal defects., (Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)