Publications by authors named "Rodrigo Ricci Vivan"

71 Publications

Comparative study of Vertucci and Ahmed classifications to evaluate the main root canal configuration of mandibular incisors in a Brazilian population.

Aust Endod J 2021 Oct 9. Epub 2021 Oct 9.

Department of Conservative Dentistry, Federal University of Rio Grande do Sul - UFRGS, Porto Alegre, Brazil.

This study aimed to compare the main root canal configurations of mandibular incisors (MI) in a Brazilian population using Vertucci and Ahmed et al. classifications. One hundred and sixty-five human permanent MI were scanned using a micro-CT. Two examiners classified the samples according to Vertucci and Ahmed et al. classification. Kappa coefficient was employed. The majority of MI had a single root canal (52.1%). Type III Vertucci and MI Ahmed et al. was the most common 2-canal MI (20%). In the apical third, the presence of one, two and three canals was found in 81.8%, 15.2% and 3% respectively. In the cervical and middle thirds, one, two and three canals were found in 86%, 12.2% and 1.8% respectively. Ahmed et al. classification was able to classify the entire sample studied, whereas 11 teeth (6.66%) did not fit Vertucci's classification.
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http://dx.doi.org/10.1111/aej.12576DOI Listing
October 2021

Influence of conservative endodontic access cavities on instrumentation of oval-shaped straight root canals.

Int Endod J 2021 Sep 24. Epub 2021 Sep 24.

Department of Dentistry, Dental School, Federal University of Pará, Belém, Brazil.

Aim: To evaluate the influence of the design of endodontic access cavities on the percentage of unprepared areas of canal walls and flexural fatigue of instruments activated by reciprocating movement in oval-shaped straight root canals of extracted teeth.

Methodology: Forty-two mandibular incisors with oval canals were scanned by a microcomputed tomography (micro-CT) device for homogeneous selection and distribution of the samples. Then, the teeth were divided into two groups (n = 21) according to the design of access cavity being tested: ultraconservative endodontic access cavity (UltraAC) and traditional access cavity. The canals were accessed with the aid of a surgical microscope, instrumented with the WaveOne Gold Medium system and irrigated with 2.5% NaOCl and 17% EDTA. The unprepared areas of the canal wall were analysed by overlaying images before and after instrumentation and expressed as percentages. micro-CT data were analysed using t-test, Mann-Whitney and Wilcoxon tests. The endodontic instruments used during instrumentation were subjected to static flexural fatigue testing using an artificial stainless steel canal with a 60° angle of curvature and a radius of 5 mm, located 5 mm from the tip of the instrument. The instruments were activated until fracture occurred, and the time in seconds for the fracture was recorded using a digital timer. The number of cycles to fracture was calculated and analysed statistically. For flexural fatigue data, an anova test complemented by a Tukey range test was used. The significance level of 5% was used for all analyses.

Results: There was no significant difference between the groups related to unprepared areas by the instrument during canal preparation (p > .05). The difference in flexural fatigue resistance between the groups was not significant.

Conclusion: The use of UltraAC did not interfere with the canal instrumentation of extracted mandibular incisors with straight and oval canals. There was no difference in the flexural fatigue resistance of the instruments in relation to access cavity design.
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http://dx.doi.org/10.1111/iej.13635DOI Listing
September 2021

Tracing the toxic ions of an endodontic tricalcium silicate-based sealer in local tissues and body organs.

J Trace Elem Med Biol 2021 Dec 13;68:126856. Epub 2021 Sep 13.

Departmento de Dentística, Endodontia e Materiais Odontológicos, Faculdade de Odontologia de Bauru, FOB/USP, Bauru, Brazil.

Background: This study aimed to track the toxic ions released by MTA Fillapex, BioRoot RCS, and an experimental tricalcium silicate-based sealer (CEO) into local and distant tissues as well as to investigate their potential adverse effects. In addition, the chemical constituents of the sealers were also evaluated. The main components of the dry powders, pastes, and mixed sealers were characterized.

Material And Methods: Dry powder and sealer discs were each set for 72 h and their main components were characterized by energy dispersive X-ray spectroscopy. Polyethylene tubes filled with sealers were used to measure silicon and calcium ions. Polyethylene tubes filled with sealers or empty tubes were implanted into the dorsal connective tissue of Wistar rats. On days 7, 15, 30, and 45, the animals were euthanized and their brains, livers, kidneys, and subcutaneous tissues were removed and processed to determine the concentrations of chromium, cobalt, copper, lead, iron, magnesium and nickel using an inductively coupled plasma optical emission spectrometer.

Results: The main compounds in all sealers were carbon, oxygen, silicon, and calcium. MTA Fillapex release more Si while highest levels of Si were found in presence of BioRoot. The release of Si and Ca ions promoted by MTA Fillapex raise by time. No traces of cobalt, chromium, or magnesium were detected in any tissue. Irrespective of the sealer, no traces of copper and lead were found in the subcutaneous tissue; however, they were observed in the organs. The highest concentration of iron was identified in the liver. All sealers exhibited similar nickel traces in the brain, kidney, and liver except for MTA Fillapex, which demonstrated levels higher than CEO in the subcutaneous tissue on day 7. Tracing nickel ions over time revealed that lowest concentrations were found in subcutaneous tissue.

Conclusion: Taken together, our data demonstrate that CEOs have chemical compositions similar to those of other commercial sealers. Furthermore, none of them exhibited a threat to systemic health. Moreover, the minimal amounts of iron and nickel detected were not related to the sealers.
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http://dx.doi.org/10.1016/j.jtemb.2021.126856DOI Listing
December 2021

Evaluation of foramen locating accuracy of an endodontic motor integrated with electronic foramen employing optimal glide path kinematics.

Clin Oral Investig 2021 Aug 18. Epub 2021 Aug 18.

Post-Graduate Program in Dentistry, Federal University of Ceará, Fortaleza, Ceará, Brazil.

Objective: This study aimed to evaluate the accuracy of the auto apical function in the maintenance of the apical limit of instrumentation during glide path procedures when associated to OGP kinematics of Tri Auto ZX2, compared to the continuous rotation of the same motor, as well as Root ZX II and VDW Gold.

Materials And Methods: Forty-eight extracted human mandibular single-rooted premolars were selected. After endodontic access, cervical pre-flaring was performed using size 30, 0.10 taper rotary instruments, and the apical foramen size was standardized to 200 μm. Teeth were randomly divided into four groups (n = 12) according to the device and kinematics. For all the groups, the Auto Apical Stop function (AAS) was set to the 0.0 mark. Glide path instruments size 25, .01 taper were activated inside the canals until the apical limit was reached. Then, the files were fixed with cyanoacrylate to the teeth and decoupled from the equipment. Data were statistically analyzed in GraphPad Prism 6.0 software with the significance set at 5% (Kruskal-Wallis tests).

Results: There was no difference in the mean deviation between the groups. No significant difference was found among the groups when the distributions and percentages of differences between the file tip and the apical foramen were compared (P > 0.05).

Conclusion: The use of auto apical function at the 0.0 mark of all tested devices provided an adequate control of the apical limit during glide path preparation. Foramen locating accuracy of Tri Auto ZX2 in OGP kinematics was similar to those of Tri Auto ZX2, Root ZX II, and VDW Gold in continuous kinematics.

Clinical Relevance: Clinical strategies in canal negotiation and glide path as OGP motion associated to electronic foramen locators could reduce iatrogenic risk of deviation and file fractures and create an easier initial preparation to facilitate endodontic procedures.
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http://dx.doi.org/10.1007/s00784-021-04103-3DOI Listing
August 2021

Effect of Irrigating Agitation after Root End Preparation on the Wall Cleaning and Bond Strength of Calcium Silicate Material in Retrograde Obturation.

Eur J Dent 2021 Oct 24;15(4):707-713. Epub 2021 Jul 24.

Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Bauru, São Paulo, Brazil.

Objective: This study aimed to evaluate the cleaning efficacy of irrigant activation with a new ultrasonic tip in root-end preparations and to determine its influence on the bond strength of calcium silicate-based material.

Materials And Methods: Maxillary canines were prepared and filled, and their root ends resected. Root-end cavities were ultrasonically prepared and randomly distributed into four groups according to the final irrigation protocols: G1 (ultrasonic irrigation [UI] + saline solution [SS]), G2 (syringe irrigation [SI] + SS), G3 (UI + ethylenediaminetetraacetic acid [EDTA]), and G4 (SI + EDTA). Cleaning efficacy analysis employed 72 specimens ( = 18) split longitudinally for imaging of the same areas by scanning electron microscopy (SEM). The percentage of dentinal tubules opened before and after irrigation was used as evaluation parameter. Push-out testing employed 40 specimens ( = 10) sectioned apical region perpendicularly, which slice was placed on a testing machine for the bond strength measurement and failure mode was assessed by SEM. The data were statistically analyzed (α ≤ 0.05).

Results: G3 (UI + EDTA) removed the smear layer more effectively, showed the best tubule opening ( < 0.05), and presented the highest mean bond strength values ( < 0.05). Failure modes were predominantly adhesive, except for the G3 (UI + EDTA) group, in which they were mainly mixed (80%).

Conclusion: The results of this study suggest that EDTA 17% agitation promoted better cleaning and smear layer removal, improving the push-out bond strength of calcium silicate material in retrograde obturation.
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http://dx.doi.org/10.1055/s-0041-1729454DOI Listing
October 2021

Analysis of Instrumentation Protocols Regarding the Quality of Mesial Canal Preparation in Mandibular Molars: A Micro-computed Tomographic Study.

J Endod 2021 Sep 15;47(9):1481-1486. Epub 2021 Jun 15.

Department of Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Bauru, São Paulo, Brazil.

Introduction: This study aimed to use micro-computed tomographic imaging to analyze the quality of the endodontic preparation of mesial canals in mandibular molars provided by 3 instrumentation protocols.

Methods: Forty-five extracted mandibular molars with 2 independent mesial canals were selected, and the initial micro-computed tomographic imaging was performed. The initial volume values of the canals were submitted to statistical analysis for paired division. The groups were determined according to the final enlargement of the canal and the working length adopted (ie, G25.06/+1 mm, G35.05/foramen, and G50.01/-1 mm). At the end of each instrumentation sequence, the root canals were scanned and analyzed with regard to the increase in the total and apical volume, centralization, and preparation transportation and the percentage of the total and apical uninstrumented walls.

Results: For the intragroup comparison, the Wilcoxon test was used, and for the intergroup analysis, the Kruskal-Wallis and Dunn tests were used (P < .05). In the analysis of the canal total volume, a statistical difference was found between G25.06/+1 mm and the remaining groups (P < .05). In the apical third, a statistical difference was observed between G25.06/+1 mm and G50.01/-1 mm (P < .05). No statistical difference was found between the groups in terms of centralization and transportation of the preparation or in terms of the percentage of the total or apical uninstrumented walls.

Conclusions: The preparation of the mesial canals of mandibular molars up to larger tip files but with a lower taper at 1 mm before the foramen resulted in a larger volume of apical preparation, kept the preparation centralized, and provided safe apical dentin wear without excessive cervical wear.
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http://dx.doi.org/10.1016/j.joen.2021.06.008DOI Listing
September 2021

Evaluation of type of kinematics on glide path procedures and torsional fatigue resistance after preparation of moderately curved canals.

Braz Oral Res 2021 31;35:e064. Epub 2021 May 31.

Universidade de São Paulo - USP, Bauru School of Dentistry, Department of Dentistry, Endodontics and Dental Materials, Bauru, SP, Brazil.

Sixty moderately curved canals of mandibular molars classified as Vertucci's type IV canal configuration were selected by micro-CT 1174. The teeth were divided into two groups according to the kinematics used, whether reciprocating or rotary motion (n=30, totaling 60 mesial root canals). The instruments used to perform the glide path procedures had identical features (0.15 mm of tip size, 0.04 mm/mm taper, thermal treatment, and square cross-section), but differed in the direction of the cutting blade. The duration of the procedure and the absolute and percentage frequency of the instruments to reach the full working length were recorded. The torsional test (3630-1; 1992) was performed on both used and unused instruments, to evaluate a possible reduction in the torsional resistance when using the glide path procedure. Statistical analysis was performed using the unpaired t-test and the chi-square test, and the level of significance was set at 5%. The type of kinematics used affected the duration of glide path procedures, and the reciprocating motion seemed to induce less torsional stress during glide path procedures.
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http://dx.doi.org/10.1590/1807-3107bor-2021.vol35.0064DOI Listing
June 2021

Optimum glide path motion is safer than continuous rotation of files in glide path preparation.

Aust Endod J 2021 Apr 29. Epub 2021 Apr 29.

Post Graduation Program in Dentistry, Department of Restorative Dentistry, Faculty of Dentistry, University of São Paulo, Bauru, Brazil.

This study evaluated the resistance to flexural fatigue and torsional strength of files for glide path preparation in continuous rotation or Optimum Glide Path motion (OGP). ScoutRace 15.02 and ProGlider 16.02 files were used in a dynamic testing device during preparation of simulating curved root canals (40-degree curvature and 5 mm radius). For the torsional test, a machine was used to test torsion measured maximum torsional strength (N.cm). Two-way anova and Tukey's multiple comparisons test were used for statistical analysis. Files in OGP motion had a statistically better resistance to flexural fatigue (P < 0.05). ProGlider files took longer time to failure than ScoutRace files only when OGP was used (P < 0.05). The torsional test revealed that OGP produced significantly less torsional stress than rotary motions for both types of glide path files (P < 0.05) In conclusion, OGP motion increased substantially the mechanical safety of endodontic glide path files.
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http://dx.doi.org/10.1111/aej.12519DOI Listing
April 2021

Safety of large preparation with different instruments in the buccal canals of maxillary molars.

Aust Endod J 2021 Apr 26;47(1):81-89. Epub 2020 Dec 26.

Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Bauru, Brazil.

This study aimed to evaluate the influence of large apical preparations with Reciproc (REC), Hyflex CM (HCM) and Twisted File Adaptive (TFA) systems using micro-computed tomography (MCT). Ninety mesiobuccal (MB) and distobuccal (DB) root canals of maxillary molars (n = 45) were scanned using MCT before and after the shaping procedures. The root canals (n = 15) were prepared until REC 40.06, HCM 40.04 and TFA 35.04. The root canal transportation (RCT), centring ability (CA), change in volume of the root canal and at different levels (VC), remaining dentine thickness (RDT), removal of dentine wall (RDW) and working time (WT) were evaluated. Data were analysed using the Kruskal-Wallis and Dunn tests, and the one-way ANOVA and Tukey tests with a level of significance set at 5%. No significant difference among the instruments was found regarding the RCT, CA, RDT, RDW and WT (P > 0.05), in larger apical preparations in curved MB and straight DB canals of maxillary molars.
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http://dx.doi.org/10.1111/aej.12481DOI Listing
April 2021

Evaluation of the mechanical properties of different nickel-titanium retreatment instruments.

Aust Endod J 2021 Aug 9;47(2):265-272. Epub 2020 Dec 9.

Department of Conservative Dentistry, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.

This study investigated the cyclic fatigue, bending, torsional resistance and angular deflection of Pro-R 25.08, Logic RT 25.08, MK Retreatment 25.08 (MK RT) and ProTaper Retreatment D2 instruments. Cyclic fatigue test was performed until fracture in a custom stainless-steel device with water bath equipment to simulate body temperature. Fracture time was recorded. A number of cycles were calculated. Resistance to bending at 45°, torsional resistance and angular deflection were evaluated. The fracture surfaces were examined by scanning electron microscopy. Statistical analysis was performed with one-way ANOVA and Tukey and Kruskal-Wallis and Dunn tests. Pro-R and Logic RT presented the highest cyclic fatigue (P < 0.05). D2 had higher strength to bend than Pro-R and Logic RT (P < 0.05). Logic RT showed the highest torque and angular deflection (P < 0.05), without differences when compared to D2 (P > 0.05). Instrument performances were dependent on their geometrical features and heat treatments.
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http://dx.doi.org/10.1111/aej.12474DOI Listing
August 2021

Can kinematics, file diameter, and PUI influence the intracanal decontamination and apical bacterial extrusion?

Braz Oral Res 2020 13;35:e003. Epub 2020 Nov 13.

Universidade de São Paulo - USP, Bauru School of Dentistry, Department of Operative Dentistry, Endodontics and Dental Materials, Bauru, SP, Brazil.

The present study investigated the intracanal decontamination and apical extrusion of bacteria and debris from root canals instrumented with rotary and reciprocating systems (ProDesign Logic or ProDesign R), with different file diameters and using conventional syringe irrigation (CSI) or passive ultrasonic irrigation (PUI). Eighty extracted mandibular premolars were contaminated with Enterococcus faecalis and randomly assigned to eight experimental groups according to the root canal instrumentation and irrigation technique employed (n = 10): G1: Prodesign Logic 25.06; G2: Prodesign R 25.06; G3 and G4 were instrumented with the same single-file systems, respectively, using 35.05 diameters and CSI. G5, G6, G7, and G8 were instrumented like the previous groups, but with PUI. Apically extruded debris during instrumentation was collected into pre-weighed microtubes. The weight of the empty microtube was subtracted from the final weight to establish the amount of extruded debris. Bacteria from root canals and extruded debris were collected for a microbiological evaluation of colony forming units (CFU/mL). For statistical analyses, the Mann-Whitney and Kruskal-Wallis followed by the Dunn's tests were used (α = 0.05). All instruments caused extrusion of debris. For irrigation techniques, PUI promoted greater debris and bacterial extrusion (p < 0.05). The CFU/mL count indicated that the instrumentation of the experimental groups were equally effective in the decontamination of the root canal (p > 0.05). The systems tested (regarding file diameter and kinematics) were associated with similar amounts of apically extruded debris and root canal decontamination. PUI was associated with greater debris and bacterial extrusion.
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http://dx.doi.org/10.1590/1807-3107bor-2021.vol35.0003DOI Listing
January 2021

Knowledge about Coronavirus disease 19 (COVID-19) and its professional repercussions among Brazilian endodontists.

Braz Oral Res 2020 Sep 4;34:e117. Epub 2020 Sep 4.

Centro Universitário Christus, School of Dentistry, Post-graduation Program of Dental Sciences, Fortaleza, CE, Brazil.

The aim of this study was to assess Brazilian endodontists' level of knowledge about the coronavirus disease (COVID-19) and examine its professional repercussions. The link to the online survey that was created for this study was shared with Brazilian endodontists through social networking applications. The questionnaire contained questions that pertained to COVID-19 and its impact on dental practice. The collected data were analyzed using t-test, chi-square analysis, and analysis of variance, and the level of significance was set at 0.05. A total of 2,135 participants responded to the questionnaire, and all five Brazilian regions were represented in the sample. A total of 98.50% of endodontists reported that dental procedures can transmit COVID-19. Complete social distancing was practiced by 96.68% of the participants, and approximately 25% knew someone who had COVID-19. Moreover, in their daily practice, 72.13% of them implemented biosecurity measures that are ineffective in preventing COVID-19. Furthermore, 91.7% of them reportedly suspended elective dental procedures. Only 55.69% of them reported that they performed only emergency procedures in their workplaces. Those who believed that COVID-19 cannot be transmitted during dental procedures were less knowledgeable about the symptoms of COVID-19 (p = 0.0095). Endodontists who believed that personal protective equipment cannot prevent contamination were more knowledgeable about the symptoms of COVID-19 than their counterparts (p = 0.0003). The participating Brazilian endodontists demonstrated adequate knowledge about the risk of contamination during dental procedures and the main symptoms of COVID-19. Only some professionals reported providing emergency dental care during the pandemic.
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http://dx.doi.org/10.1590/1807-3107bor-2020.vol34.0117DOI Listing
September 2020

Influence of Different Coronal Preflaring Protocols on Electronic Foramen Locators Precision.

Braz Dent J 2020 Sep 4;31(4):404-408. Epub 2020 Sep 4.

Post-graduate Program in Dentistry, UFC - Universidade Federal do Ceará, Fortaleza, CE, Brazil.

The aim of this study was to evaluate the influence of different coronal preflaring protocols (absent, conservative and conventional) on the accuracy of Root ZX II, Raypex 6, and RomiApex A-15 electronic foramen locators (EFLs). Twenty mandibular molars with Vertucci's type IV mesial roots were subjected to endodontic exploration and foraminal patency confirmation. Under 16x magnification, its real lengths (RL) were measured and registered (RL1). The canals were then irrigated with 2.5% sodium hypochlorite and electronically measured (EM1) employing the alginate model; all measurements were performed in triplicate by a blind operator using adjusted endodontic hand-files introduced until the apex foramen. Coronal preflaring procedures were sequentially performed with #25/.06 (conservative) and #25/.12 (conventional) instruments; new RLs extents were performed after each coronal preparation protocol (RL2/RL3), as same as electronic measurements (EM2/EM3). The devices error (mm) was evaluated considering the difference between RLs and EMs at each preparation stage; their precision was stablished adopting ±0.5 mm as tolerance margin. The EFLs error significantly reduced after conventional coronal preflaring protocol (p<0.05), which not occur after the conservative one. The best precisions values were noted after conventional preparation as 90% (Root ZX II), 97.5% (Raypex 6), and 92.5% (RomiApex A-15). No significant differences were found in EFLs comparisons, regardless of the coronal protocol tested (p>0.05). Under the conditions tested it can be concluded that the EFLs evaluated were precise. Moreover, the preflaring protocols influences its accuracy's, where the less conservative one produced the best results.
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http://dx.doi.org/10.1590/0103-6440202003282DOI Listing
September 2020

Comparison of Canal Transportation and Centering Ability of ProGlider and WaveOne Gold Glider in Curved Canals.

Eur J Dent 2020 Oct 31;14(4):639-643. Epub 2020 Aug 31.

School of Health Sciences, Universidade Positivo, Curitiba, Paraná, Brazil.

Objectives:  The aim of this study was to compare the volume variation and maintenance of the root canal position when using the ProGlider 16.02 (PG) and the WaveOne Gold Glider 15.02 (WOGG) file systems for glide path preparation.

Materials And Methods:  Twenty-four moderately curved mesiobuccal canals of maxil-lary first molars were selected and randomly divided into two groups: PG and WOGG. The selected teeth were scanned using microtomography before and after root canal preparation to assess centralization and linear transport at 1, 3, 5, and 7 mm from the apical foramen.

Statistical Analysis:  The data were analyzed with the Mann-Whitney U test. The level of significance was 5%.

Results:  There were no significant differences in volume variation or root canal transport ( > 0.05). There was a significant difference in the centralization of the root canal at 3 mm from the foramen ( < 0.05).

Conclusions:  WOGG and PG instruments presented similar results regarding the root canal volume increase and transport. WOGG caused higher decentralization at 3 mm from the apical foramen.
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http://dx.doi.org/10.1055/s-0040-1715780DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7536097PMC
October 2020

Cyclic Fatigue Resistance of Nickel-Titanium Reciprocating Instruments after Simulated Clinical Use.

J Endod 2020 Nov 18;46(11):1771-1775. Epub 2020 Aug 18.

Department of Dentistry, Endodontics, and Dental Materials, School of Dentistry of Bauru, University of São Paulo, São Paulo, São Paulo, Brazil.

Introduction: The aim of this study was to evaluate the cyclic fatigue resistance of different heat-treated nickel-titanium reciprocating instruments in 2 different situations: new and used instruments after preparing 3 curved canals.

Methods: A total sample of 60 nickel-titanium instruments of 3 systems (n = 20 per system) were used in this study: ProDesign R (tip 25, 0.06 taper; Easy Dental Equipment, Belo Horizonte, Brazil), Reciproc Blue (tip 25, 0.08v taper; VDW, Munich, Germany), and WaveOne Gold (tip 25, 0.07v taper; Dentsply Sirona, Ballaigues, Switzerland). Thirty new instruments (n = 10 per system) were used to prepare 90 curved single-rooted mandibular premolars (n = 30). Each instrument was used to prepare 3 root canals, and after each canal preparation the instrument was ultrasonic cleaned and submitted to autoclave sterilization procedures. The other 30 instruments (n = 10 per system) were kept without use. Then, the new and used instruments were subjected to the cyclic fatigue test in an artificial canal with a 30° angle and a 5-mm radius of curvature. The time and number of cycles to fatigue were recorded. Data were analyzed using the unpaired t test for intragroup comparison. For intergroup comparison, analysis of variance and the Tukey test for multiple comparisons were used.

Results: The intergroup comparison of new instruments showed that ProDesign R had the highest cyclic fatigue resistance followed by Reciproc Blue and WaveOne Gold (P < .05). Regarding the used instruments, WaveOne Gold had the lowest cyclic fatigue resistance (P < .05). The intragroup comparison between new and used instruments showed that WaveOne Gold and ProDesign R presented a significant reduction in the cyclic fatigue resistance after simulated clinical use (P < .05); no difference was found with the Reciproc Blue instruments (P > .05).

Conclusions: ProDesign R had the highest cyclic fatigue resistance, whereas WaveOne Gold had the lowest for new and used instruments. Simulated clinical use affected the cyclic fatigue resistance of ProDesign R and WaveOne Gold but not of Reciproc Blue instruments.
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http://dx.doi.org/10.1016/j.joen.2020.08.010DOI Listing
November 2020

Comparison of the Self-Adjusting File and Hedström File Used as Supplementary Instruments for the Remaining Filling Material Removal During Retreatment of C-Shaped Canals: A Micro-CT Study.

Eur Endod J 2020 11;5(2):112-117. Epub 2020 Jun 11.

Department of Endodontics, Faculdade de Odontologia de Bauru, São Paulo University, Bauru, São Paulo, Brazil.

Objective: The aim of this study was to evaluate the use of Self-adjusting file (SAF) system and Hedström (H) file for removing remaining filling material (RFM) from C-shaped canals.

Methods: 20 C-shaped mandibular second molars with C1 configurations were instrumented, filled with tagger´s hybrid technique. Samples were divided into 2 groups (n=10). Reciproc R25 and a Mtwo 35/04 file were used for retreatment in both groups. Then, a 2.0 SAF file (group I) and a #35 H file (group II) were used as supplementary steps for RFM removal. Micro-CT scanning was performed after every procedure. Total volumes were calculated and converted into percentages. Also, the minimum wall thickness at 3, 5, 7 mm from apex was calculated. The Prism 7.0 software was used as the analytical tool with a significance of 5%.

Results: Initial obturation removal was approximately 64% in group I and 67% in Group II. The apical third had the highest values of RFM. The use of a H file significantly reduced the RFM compared to SAF in the total canal length respectively (30% vs 18%) and at 1-3 mm and 3-6 mm when compared to the use of SAF. A statistically significant decrease of RFM and minimum wall thickness were observed in both groups (P<0.05).

Conclusion: None of the retreatment techniques completely removed RFM. The apical region was the more unaffected area. Also, the SAF file was less effective than the H file in removing the RFM. Although C-shaped canals possesses thinner dentinal wall thickness, no excessive dentine removal was observed after each instrument use.
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http://dx.doi.org/10.14744/eej.2019-07-067DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7398992PMC
September 2021

Influence of the Preparation Order in Four-Canal Maxillary Molars with WaveOne Gold System.

J Endod 2020 Sep 10;46(9):1291-1296. Epub 2020 Jun 10.

School of Health Sciences, Universidade Positivo, Curitiba, Paraná, Brazil; Department of Dentistry, Universidade da Região de Joinville, Joinville, Santa Catarina, Brazil.

Introduction: The aim of this study was to evaluate the effect of the order of preparation of four-canal maxillary molars on volume variation, instrument deformation, cyclic fatigue, and preparation time by using the WaveOne Gold Primary (WOG 25.07).

Methods: We selected 48 permanent, human, four-canal maxillary molars. The teeth were divided into 4 groups according to the order of initiation of the canal preparation sequence: (1) mesiobuccal (MB), distobuccal (DB), palatal (P), second mesiobuccal (MB2); (2) DB-P-MB2-MB; (3) P-MB2-MB-DB and (4) MB2-MB-DB-P. Pre- and post-preparation microtomography scanning was performed to obtain initial and final canal volume measurements. The instruments were also evaluated by using scanning electron microscopy to determine the wear and deformation present after use. The active instrumentation time was also recorded. The data were statistically compared by using a significance level of 5%.

Results: No statistically significant difference was found between groups for volume variation and time of preparation of the canals with the WOG system (P > .05); however, a statistically significant difference was observed in the deformation of the instruments. In the comparison between the groups for MB-DB-P-MB2 and P-MB2-MB-DB, the latter presented greater deformation of the instruments.

Conclusions: Root canal preparation sequence affected deformation of the instruments but did not influence the volume variation or the canal preparation time with the WOG system. To minimize instrument deformation, the preparation order should be MB-DB-P-MB2.
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http://dx.doi.org/10.1016/j.joen.2020.05.018DOI Listing
September 2020

Influence of cervical preflaring and root canal preparation on the fracture resistance of endodontically treated teeth.

BMC Oral Health 2020 04 16;20(1):111. Epub 2020 Apr 16.

Departamento de Odontologia Conservadora, Universidade Federal do Rio Grande do Sul, 2492 Ramiro Barcelos Street, Porto Alegre, RS, 90035-003, Brazil.

Background: Evaluate the fracture resistance of endodontically treated teeth after cervical preflaring and root canal preparation and to assess the volume of the root canal and the amount of remaining root dentin before and after cervical preflaring.

Methods: Forty-four mandibular incisors were selected using micro-CT scanning and distributed into 4 groups (n = 11) according to the instrument used for cervical preflaring: control group - no cervical preflaring; Gates Glidden - burs size #2 and #3; WXN - 25.07 Navigator instrument; and Easy - 25.08 ProDesign S instrument. Coronal opening was performed, and the canals were prepared with Wave One Gold Primary and filled with an epoxy-resin based sealer and gutta-percha cones. Micro-CT scans were performed before and after root canal instrumentation. All images were reconstructed and assessed for the thickness of mesial and distal root dentin at 3 mm and 5 mm from the cement -enamel junction and for the volume of cervical portion of the canal after preparation. Fracture resistance test was performed applying compressive loads at a crosshead speed of 0.5 mm/min, applied on the palatal aspect of specimens at 135° along the long axis of the tooth. The data were analyzed using ANOVA and Tukey's test (P = .05).

Results: Cervical preflaring and canal preparation reduced the dentin thickness (P < .05) and increased the canal volume (P < .05) in all groups at 3 mm an 5 mm. Cervical preflaring with Gates Gliden burs reduced the fracture resistance of endodontically treated teeth (P < .05).

Conclusions: All instruments reduced the dentin thickness and increased the canal volume in the cervical at 3 mm and 5 mm. Gates Glidden reduced fracture resistance of mandibular incisors submitted to cervical preflaring, whereas NiTi instruments did not.

Clinical Relevance: Cervical preflaring assumes particular importance previously to the root canal preparation because it minimizes the occurrence of operative accidents, and permits more accurate determination of working length and the apical diameter.
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http://dx.doi.org/10.1186/s12903-020-1050-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7161170PMC
April 2020

Volumetric Analysis of Irrigant Extrusion in Immature Teeth after Different Final Agitation Techniques.

J Endod 2020 May 2;46(5):682-687. Epub 2020 Mar 2.

Department of Endodontics, São Leopoldo Mandic Dental Research Center, Campinas, São Paulo, Brazil.

Introduction: The aim of this study was to evaluate the volume of irrigant extrusion by different final agitation techniques in experimental models of immature teeth.

Methods: Fifteen single roots of mandibular premolars with a length of 14 mm and an open apex were used to form 6 groups according to the final agitation technique: group 1, positive pressure and no agitation; group 2, ultrasonic agitation with Irrisonic (Helse Dental Technology, Santa Rosa de Viterbo, Brazil); group 3, ultrasonic agitation with Irrisonic Power (Helse Dental Technology); group 4, mechanical agitation with Easy Clean (Easy Dental Equipment, Belo Horizonte, Brazil); group 5, mechanical agitation with XP-endo Finisher (FKG Dentaire, La Chaux-de-Fonds, Switzerland); and group 6, sonic agitation with Eddy (VDW, Munich, Germany). A prototype was made from an Eppendorf plastic tube filled with agar to fix the tooth and to collect the extruded irrigant. Ioditrast 76 (Justesa Imagen Mexicana, Tlalpan, Mexico) contrast solution was used to simulate the irrigant. The volume of irrigant extruded in cubic millimeters was calculated by micro-computed tomographic imaging. Data were analyzed using Kruskal-Wallis and Dunn tests with a significance level of 5%.

Results: The values for the volume of irrigant extruded were as follows: 0.67 (group 5), 0.76 (group 1), 2.28 (group 2), 3.14 (group 3), 3.15 (group 4), and 17.19 (group 6). There was a statistically significant difference (P < .05) when the values of group 6 were compared with those of the other groups.

Conclusions: All techniques caused irrigant extrusion. The higher extrusion values occurred when sonic agitation was performed with the Eddy instrument.
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http://dx.doi.org/10.1016/j.joen.2020.01.014DOI Listing
May 2020

Torsional fatigue strength of reciprocating and rotary pathfinding instruments manufactured from different NiTi alloys.

Braz Oral Res 2019 28;33:e097. Epub 2019 Oct 28.

Universidade de São Paulo - USP, Bauru School of Dentistry, Department of Operative Dentistry, Endodontics, and Dental Materials, Bauru, SP, Brazil.

To evaluate the torsional properties of engine-driven pathfinding instruments manufactured from different NiTi alloys - R-Pilot (tip size 12.5;.04 taper; M-Wire) and One G (tip size 14;.03 taper; Conventional NiTi). A total of 40 NiTi instruments from engine-driven pathfinding instruments (n = 20) were used. The torsion tests followed ISO 3630-1 (1992). Three millimeters of each instrument tip was fastened to a small load cell by a lever arm linked to the axis of torsion. During the test, the torsion testing machine software measured the maximum torsional strength and angle of rotation (0) before instrument failure. The fractured surface of each instrument was assessed by scanning electron microscopy (SEM). In addition, a supplementary examination was performed to measure the cross-sectional area and the metal mass volume of each instrument 3 mm from the tip. Data were analyzed using a t-test, with significance level set at 5%. R-pilot had significantly higher torsional strength than did One G (p < 0.05). Regarding the angle of rotation to fracture, One G had higher angles than did R-Pilot (p < 0.05). The supplementary examination showed that R-Pilot had the highest cross-sectional area and volume of metal mass at 3 mm from the tip (p < 0.05). R-pilot (M-Wire NiTi alloy) had a significantly higher torsional strength and One-G (superelastic NiTi alloy) had the highest angle of rotation to fracture.
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http://dx.doi.org/10.1590/1807-3107bor-2019.vol33.0097DOI Listing
November 2019

Effect of association of non-steroidal anti-inflammatory and antibiotic agents with calcium hydroxide pastes on their cytotoxicity and biocompatibility.

Clin Oral Investig 2020 Feb 28;24(2):757-763. Epub 2019 May 28.

Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Bauru, São Paulo, Brazil.

Objectives: Evaluate the cytotoxicity and biocompatibility of calcium hydroxide paste [Ca (OH)] associated with 5% diclofenac sodium, ibuprofen, or amoxicillin.

Materials And Methods: Pre-osteoblast-like cells were cultivated and the MTT test was used to determine the cytotoxicity of the paste extracts after time intervals of 24, 48, 72 h, and 7 days. Tubes containing Ca (OH) pastes associated with the drugs and empty tubes were implanted in subcutaneous tissue of 30 rats. After 7 and 30 days, the specimens were removed and submitted to histological analysis. The data obtained were submitted to Kruskal-Wallis and Dunn tests (p ≤ 0.05).

Results: All the Ca (OH) pastes promoted cell viability after all periods. At 7 days, there was greater inflammatory tissue reaction adjacent to the implants. At 30 days, there was a significant reduction in the number of inflammatory cells, and increase in fibroblasts in all groups. In this period, a lower number of inflammatory cells and a higher number of fibroblasts were observed in the capsules adjacent to the association with diclofenac, when compared with the other mixtures (p ≤ 0.05); the capsule thickness was greater at 7 days than at 30 days.

Conclusions: The Ca (OH) pastes associated with the drugs were not cytotoxic and presented biocompatibility after implantation in rat subcutaneous tissues.

Clinical Relevance: Ca (OH) pastes with anti-inflammatory or antibiotic may be clinical alternatives as intracanal medication to reduce resistant microorganisms in root canal system.
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http://dx.doi.org/10.1007/s00784-019-02923-yDOI Listing
February 2020

Ultrasonic tips as an auxiliary method for the instrumentation of oval-shaped root canals.

Braz Oral Res 2019 Feb 11;33:e011. Epub 2019 Feb 11.

Universidade de São Paulo - USP, Bauru School of Dentistry, Department of Operative Dentistry, Endodontics and Dental Materials, Bauru, SP, Brazil.

To evaluate the influence of novel ultrasonic tips as an auxiliary method for the rotary preparation of flattened/oval-shaped canals. Forty-five mandibular incisors were selected and divided into one of three experimental groups (n = 15): Group PFCP - ProDesign Logic 25/.05 + Flatsonic + Clearsonic + Prodesign Logic 40/.01; Group FCP - Flatsonic + Clearsonic + ProDesign Logic 40/.01; and Group PP - Prodesign Logic 25/.05 + Prodesign Logic 40/.05. The teeth were scanned preoperatively and postoperatively using microcomputed tomography. The percentage values for increase in volume, non-instrumented surface area, dentin removal, degree of canal transportation, and centering ratio between the experimental groups were examined. Data were analyzed using the non-parametric Kruskal-Wallis and Dunn's tests (p < 0.05). Group PFCP showed the greatest volume increase in the total portion of the root canal and the lowest percentage of non-instrumented surface area. Regarding the degree of transportation in the buccolingual direction, statistically significant differences between groups PFCP and PP were observed at the coronal third of the canal. In the mesiodistal direction, no statistically significant differences were observed at the coronal, middle, and apical thirds. As for the centering ratio, statistically significant differences were found in the buccolingual direction. In the mesiodistal direction, no statistically significant differences were observed at the coronal, middle, and apical thirds. The use of novel ultrasonic tips combined with rotary instruments in group PFCP provided a significant increase in volume and reduced the percentage of non-instrumented areas during the preparation of flattened/oval-shaped canals.
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http://dx.doi.org/10.1590/1807-3107bor-2019.vol33.0011DOI Listing
February 2019

Antimicrobial activity of intracanal medications against both Enterococcus faecalis and Candida albicans biofilm.

Microsc Res Tech 2019 May 29;82(5):494-500. Epub 2018 Dec 29.

Department of Restorative Dentistry, Dental Materials and Endodontics, Bauru Dental School, University of São Paulo, Bauru, São Paulo, Brazil.

Enterococcus faecalis and Candida albicans have been associated with cases of secondary and persistent root canal infections, been resistant to calcium hydroxide. So, the evaluation of the susceptibility of these microorganisms biofilms to new drugs is an important practice for establishing the best drug and consequently success of treatment. For this, in vitro biofilm formation of E. faecalis and C. albicans was induced separately on blocks obtained from bovine teeth. After the period of specimen incubation for biofilm maturation, the samples were immersed in the pastes: 1 - calcium hydroxide (CH), 2 - chlorhexidine (C), 3 - ciprofloxacin (CP), 4 - metronidazole (MT), 5 - ketoconazole (KE), 6 - double antibiotic (DB), 7 - triple antibiotic (TA), 8 - ciprofloxacin + ketoconazole (CPKE); 9 - ciprofloxacin + metronidazole + ketoconazole (CPMTKE), 10 - metronidazole + ketoconazole (MTKE), and 11 - control (CO) for 7 days. Next, the specimens were live/dead stained for analysis by confocal microscopy. By means of the Bioimage program, the biovolume and percentage of live cells were measured. The data were statistically compared (p = .05). For the C. albicans biofilm, the best antimicrobial action was found for MTKE, CPKE, and MT groups. Whereas for E. faecalis biofilm, the lowest percentage of live bacteria was found in TA, DB, and CP groups; however, KE, CPKE, CPMTKE, and MTKE groups shown to be effective. The authors concluded calcium hydroxide paste and chlorhexidine was not effective for both biofilms. The MTKE and CPKE pastes presented effectiveness for both biofilms. TA and DB pastes were effective just in the E. faecalis biofilms.
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http://dx.doi.org/10.1002/jemt.23192DOI Listing
May 2019

Evaluation of Physicochemical Properties of New Calcium Silicate-Based Sealer.

Braz Dent J 2018 Nov-Dec;29(6):536-540

Departament of Conservative Dentistry, UFRGS - Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.

This study aimed to evaluate the physicochemical properties of a calcium silicate-based sealer (Sealer Plus BC; MK Life, Porto Alegre, Brazil) compared with an epoxy-resin sealer (AH Plus; Dentsply DeTrey GmbH, Konstanz, Germany). Initial and final setting time was assessed based on ISO 6876:2012 and ASTM C266:03. Calcium ion release and pH were evaluated by filling polyethylene tubes with sealers and then immersing them in 10 mL of deionized water. Following experimental periods of 1, 24, 72 and 168 hours, the samples were measured regarding pH and calcium ion release with a pH meter and a colorimetric spectrophotometer, respectively. The flow was examined based on ISO 6876:2012. Rings of 10 mm in diameter with 1 mm thickness were prepared to analyze the radiopacity (ISO 6876:2012 and ADA n.57) and solubility (ISO 6876:2012). The data were analyzed by variance analysis, Student-T and Tukey tests (p<0.05). The calcium ion release and pH values were significantly higher for the Sealer Plus BC compared with the AH Plus (p<0.05). Lower setting time, flow and radiopacity were observed for the bioceramic sealer than for AH Plus (p<0.05). Sealer Plus BC exhibited higher solubility compared with AH Plus (p<0.05). Sealer Plus BC showed physicochemical properties as setting time, pH, calcium release, flow, and radiopacity following the required standards, but higher solubility than the minimum values required by ISO 6876:2012.
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http://dx.doi.org/10.1590/0103-6440201802088DOI Listing
April 2019

Effect of temperature on the cyclic fatigue resistance of thermally treated reciprocating instruments.

Clin Oral Investig 2019 Jul 5;23(7):3047-3052. Epub 2018 Nov 5.

Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Al. Octávio Pinheiro Brisolla, 9-75, Bauru, SP, 17012-901, Brazil.

Objectives: The aim of this study was to evaluate the impact of body temperature on the cyclic fatigue resistance of different NiTi alloys used for the manufacturing of Reciproc Blue R25 (RB 25.08; VDW, Munich, Germany), X1 Blue File 25 (X1 25.06; MK Life Medical and Dental Products, Porto Alegre, Brazil) and WaveOne Gold Primary (WOG 25.07; Dentsply Maillefer, Ballaigues, Switzerland).

Materials And Methods: Sixty instruments of the RB 25.08, X1 25.06 and WOG 25.07 systems were used (n = 20). Cyclic fatigue tests were performed at room temperature (20° ± 1 °C) and at body temperature (37° ± 1 °C). The instruments were reciprocated until fracture occurred in an artificial stainless steel canal with a 60° angle and a 5-mm radius of curvature. The time to fracture (TTF) was recorded. Also, the number of cycles to fracture (NCF) was calculated. Data were analysed using one-way ANOVA and Tukey's tests for inter-group comparison at both temperatures and for the reduction of cyclic fatigue at body temperature. For intra-group comparison at the different temperatures, the unpaired t test was used.

Results: The cyclic fatigue test at 20 °C showed that RB 25.08 and X1 25.06 presented significantly higher TTF and NCF than WOG 25.07 (P < 0.05). At 37 °C, all groups presented significant reduction of TTF and NCF (P < 0.05). RB 25.08 presented significant higher TTF than WOG 25.07 (P < 0.05). Regarding the NCF, there was no significant difference among the groups (P > 0.05). The WOG 25.07 presented the lowest percentage reduction of cyclic fatigue (P < 0.05).

Conclusion: The body temperature treatment caused a marked reduction of the cyclic fatigue resistance for all reciprocating instruments tested. The RB 25.08 and X1 25.06 systems presented similar results at both temperatures tested. However, WOG 25.07 presented the lowest percentage reduction in fatigue resistance at body temperature.

Clinical Relevance: The cyclic fatigue resistance of NiTi reciprocating instruments has been evaluated at room temperature. However, the fatigue resistance significantly decreases upon exposure to body temperature, which could affect the mechanical behaviour of the NiTi instruments during root canal preparation.
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http://dx.doi.org/10.1007/s00784-018-2718-1DOI Listing
July 2019

Tricalcium silicate-based cements: properties and modifications.

Braz Oral Res 2018 Oct 18;32(suppl 1):e70. Epub 2018 Oct 18.

University of Birmingham, School of Dentistry, Birmingham, United Kingdom.

Mineral trioxide aggregate (MTA) has been widely used for different reparative procedures in endodontics. The extensive use of this cement for pulp capping, apexifications, apical surgeries, and revascularization is related to its ability to induce tissue repair and to stimulate mineralization. Several research studies have tested modifications in the composition of MTA-based cements in order to enhance their clinical performance. Novel formulations have been introduced in the market with the aim of increasing flowability. Important properties such as appropriate radiopacity and setting time, color stability, alkaline pH, release of calcium ions, and biocompatibility have to be considered in these new formulations. The latest research studies on the physical, chemical, and biological properties of tricalcium silicate-based cements are discussed in this critical review.
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http://dx.doi.org/10.1590/1807-3107bor-2018.vol32.0070DOI Listing
October 2018

Penetrability of a new endodontic sealer: A confocal laser scanning microscopy evaluation.

Microsc Res Tech 2018 Nov 8;81(11):1246-1249. Epub 2018 Oct 8.

Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Bauru, São Paulo, Brazil.

This study aimed to evaluate the penetration of a new endodontic sealer into the dentinal tubules. Twenty single-rooted teeth were selected. The crown was sectioned, and the canals were instrumented with a reciprocating system. Irrigation was performed with 2 mL of 2.5% sodium hypochlorite between each file change. After instrumentation, the root canals were irrigated with 2 mL of17% EDTA for 3 min followed by saline solution. The specimens were randomized into two groups (n =10) according to the endodontic sealer: AH Plus (AP) or Sealer Plus (SP). All specimens were filled using the lateral compaction technique. Rhodamine B dye (red) was incorporated to the sealers to provide the fluorescence which will enable confocal laser scanning microscopy (CLSM) assessment. The roots were sectioned 2, 4, and 6 mm from the apex and assessed by CLSM. The root canal level affected the penetration of the sealer, but no statistical significant differences were found between the two experimental groups (p > .05). SP presented similar dentinal penetration and perimeter integrity to the gold standard (AP). RESEARCH HIGHLIGHTS: Sealer Plus presents dentinal penetrability and perimeter integrity similar to the gold standard sealer (AH Plus), demonstrating excellent ability of filling areas of difficult access.
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http://dx.doi.org/10.1002/jemt.23129DOI Listing
November 2018

Comparisons by microcomputed tomography of the efficiency of different irrigation techniques for removing dentinal debris from artificial grooves.

J Conserv Dent 2018 Jul-Aug;21(4):383-387

Department of Restorative Dentistry, Dental Materials and Endodontics, Bauru Dental School, University of Sao Paulo, Bauru, Sao Paulo, Brazil.

Aim: The aim of this study was compare the capacity of different irrigation protocols for debris removal from artificial grooves and assess the effectiveness of Easy Clean used in different kinematics by means of micro-CT.

Methodology: Fifty acrylic prototyped maxillary incisors were instrumented and included in a muffle. The specimens were longitudinally sectioned, and a longitudinal groove was made on the inner surface of the root canal in one of hemisections, and the dentin debris was inserted into the grooves. The specimens were divided into five groups ( = 10): G1: Conventional with open-ended needle; G2: Conventional with double side-vented needle; G3: Easy Clean in reciprocating movement; G4: Easy clean in continuous rotation (ECCR); and G5: Passive ultrasonic irrigation (PUI). All specimens were scanned using microcomputed tomography before and after the irrigation technique and calculated the volume (mm) of dentin debris. The paired -test and Tukey test were the statistical tests used, with significance set at 5%.

Results: There were no significant difference ( > 0.05) between PUI and ECCR. ECCR was significantly ( < 0.05) more effective than the groups of conventional irrigation techniques.

Conclusions: PUI and ECCR favored the removal of a larger volume of dentin debris from the groove.
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http://dx.doi.org/10.4103/JCD.JCD_286_16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6080189PMC
August 2018

A novel ultrasonic tip for removal of filling material in flattened/oval-shaped root canals: a microCT study.

Braz Oral Res 2018 Aug 13;32:e88. Epub 2018 Aug 13.

Universidade de São Paulo - USP, Bauru School of Dentistry Department of Operative Dentistry, Endodontics and Dental Materials, Bauru, SP, Brazil.

The aim of this study was to evaluate the influence of a novel ultrasonic tip as an auxiliary method for removing filling material from flattened/oval-shaped canals. The null hypothesis tested was that this method does not influence removing the filling material in flattened/oval-shaped canals. Forty-five mandibular incisors were selected and randomly divided into three experimental groups (n = 15) according to different protocols for removing root canal filling material. Group R: Reciproc R25/.08, Group RC: Reciproc R25/.08 + Clearsonic tip, and Group CR: Clearsonic tip + Reciproc R25/.08. The teeth were scanned pre and post-operatively by means of a micro-computed tomography system. Data were analyzed using non-parametric Kruskal-Wallis and Dunn tests (p < 0.05). The percentage of residual root canal filling material between the experimental groups was examined. Statistically significant differences between the experimental groups were found in the root canal. Group R had the highest percentage of residual root canal filling material when compared with Groups RC and CR. The lowest percentage of residual root canal filling material was observed in Group CR. In the apical third of the root canal, statistically significant differences were found between the different protocols. The use of the ClearSonic tip followed by the Reciproc 25/.08 file to remove filling material resulted in the lowest percentage of residuals in the whole root canal and in the apical third.
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http://dx.doi.org/10.1590/1807-3107bor-2018.vol32.0088DOI Listing
August 2018

Canal Transportation, Centering Ability, and Cyclic Fatigue Promoted by Twisted File Adaptive and Navigator EVO Instruments at Different Motions.

J Endod 2018 Sep 2;44(9):1425-1429. Epub 2018 Aug 2.

Department of Conservative Dentistry, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil.

Introduction: This study compared the cyclic fatigue and the canal transportation promoted by Twisted File (TF) Adaptive and Navigator EVO systems when used with 2 different motions.

Methods: Forty mesiobuccal roots of maxillary molars were scanned by using micro-computed tomography imaging before and after root canal preparation with the 2 instrument systems used with 2 motions (adaptive and continuous rotation). Samples were divided into 4 groups: TFA, TF Adaptive instruments under adaptive motion; TFC, TF Adaptive instruments under continuous motion; NA, Navigator instruments under adaptive motion; and NC, Navigator instruments under continuous motion. Root canals were prepared until 35.04 instruments. Apical transportation was analyzed by using micro-computed tomography at 3 levels: 3, 6, and 9 mm from the apex. The cyclic fatigue tests were performed by using a custom-made device. Ten instruments of each brand were activated by using a 6:1 reduction handpiece powered by a torque-controlled motor using the preset programs "custom mode" and "TF Adaptive" to activate 25.06 and 35.04 instruments. Kruskal-Wallis and Dunn tests were used to assess canal transportation, centering ability, and canal volume. The Student t test was used to evaluate cyclic fatigue (P = .05).

Results: At 3 and 9 mm, the canal transportation and centering ability were similar in all groups (P > .05). At 6 mm, TFC presented higher canal transportation toward furcal region than NA and NC (P < .05). After canal preparation, TFA promoted great dentinal excision, presenting higher canal volume than NA and NC (P < .05). Higher cyclic fatigue resistance was observed under continuous than adaptive motion regardless of system or tip/diameter of the instrument (P < .05).

Conclusions: Both systems can be used under adaptive or continuous rotation. However, the life span of the instruments was higher when used under continuous rotation. Small canal transportation occurred when mesiobuccal root canals from maxillary molars were prepared until 35.04 instruments.
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http://dx.doi.org/10.1016/j.joen.2018.06.002DOI Listing
September 2018
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