Comparative analysis of torsional and cyclic fatigue resistance of ProGlider, WaveOne Gold Glider, and TruNatomy Glider in simulated curved canal.

Objectives: This study aimed to compare the torsional and cyclic fatigue resistance of ProGlider (PG), WaveOne Gold Glider (WGG), and TruNatomy Glider (TNG). Materials and Methods: A total of 15 instruments of each glide path system (n = 15) were used for each test. A custom-made device simulating an angle of 90° and a radius of 5 millimeters was used to assess cyclic fatigue resistance, with calculation of number of cycles to failure. Torsional fatigue resistance was assessed by maximum torque and angle of rotation. Fractured instruments were examined by scanning electron microscopy (SEM). Data were analyzed with Shapiro-Wilk and Kruskal-Wallis tests, and the significance level was set at 5%. Results: The WGG group showed greater cyclic fatigue resistance than the PG and TNG groups (p < 0.05). In the torsional fatigue test, the TNG group showed a higher angle of rotation, followed by the PG and WGG groups (p < 0.05). The TNG group was superior to the PG group in torsional resistance (p < 0.05). SEM analysis revealed ductile morphology, typical of the 2 fracture modes: cyclic fatigue and torsional fatigue. Conclusions: Reciprocating WGG instruments showed greater cyclic fatigue resistance, while TNG instruments were better in torsional fatigue resistance. The significance of these findings lies in the identification of the instruments' clinical applicability to guide the choice of the most appropriate instrument and enable the clinician to provide a more predictable glide path preparation.

Impact of the final agitation system in the irrigant diffusion inside the root canal: A micro-CT analysis.

This study evaluated, through micro-computed tomography (micro-CT), the volume of irrigant diffusion by different techniques of final agitation. Sixty mesiobuccal canals were scanned in a micro-CT and standardised according to the volume. They were instrumented with the MTwo 40/04 system and using the Terebrix 35 contrast solution as irrigant, were divided into six groups (n = 10): Conventional irrigation with syringe and needle (CI), EndoActivator (EA), EasyClean (EC), RinsEndo (RE), Utrasonic agitation (UI) and XP-Clean (XP). A second micro-CT scan was performed and the total irrigant volume and in the final 3 mm apical were determined. The data were analysed using the Anova, Kruskal-Wallis and Dunn tests (p < 0.05). UI and XP showed a higher percentage of total diffusion than CI, EA and RS groups (p < 0.05). In apical diffusion, there was no significant difference between groups (p > 0.05). The final agitation system increases the diffusion of irrigating agents inside the root canal.

Comparison of the Physicochemical Properties, Antimicrobial Action, and Cytotoxicity of Ambroxol Hydrochloride, N-acetylcysteine, and Calcium Hydroxide Pastes.

OBJECTIVE: To evaluate the solubility, pH, antimicrobial action, and cytotoxicity of ambroxol hydrochloride (AMB), N-acetylcysteine (NAC), and calcium hydroxide (CH) pastes for use as intracanal medications. METHODS: Solubility was determined by micro-CT, based on the paste volume remaining after immersion in water for 7 days. pH was measured by immersing acrylic tubes containing the pastes in ultrapure water and then measuring pH after 3 hours, 3 days, and 7 days. Antimicrobial action against Enterococcus faecalis was assessed based on the percentage of living cells, using the live/dead staining method under confocal microscopy. Cytotoxicity was assessed based on the cell viability of L929 fibroblast-like cells after 6, 24, and 48 hours. Cytotoxicity data were compared using the ANOVA and Tukey tests, and the antimicrobial data were compared using the Kruskal-Wallis and Dunn tests. The significance level used was 5% (α=0.05). RESULTS: The solubility values for all the study groups were significantly different (P<0.05), where the highest values were for NAC, followed by AMB, and then CH. Likewise, the pH levels were all significantly different (P<0.05), where NAC and AMB levels were acidic, and CH levels were alkaline. The antimicrobial action of AMB was significantly higher than that of CH (P<0.05), and that of NAC was also higher than that of CH, albeit not significantly. AMB and NAC were more cytotoxic than CH, and higher dilutions of CH promoted higher cell viability levels than lower dilutions of the same paste (P<0.05). CONCLUSION: The NAC and AMB pastes were more soluble and cytotoxic than the CH paste and had acidic pH levels. The AMB paste displayed the highest antimicrobial action against Enterococcus faecalis biofilm.

Penetrability of AH Plus Sealer into Dentinal Tubes after Retreatment Procedure with Rotary or Reciprocating Systems and Two Additional Cleaning Methods.

Introduction: The aim of this study was to evaluate the AH Plus sealer penetration into dentinal tubules after root canal retreatment followed by two additional cleaning methods. Methods and Materials: Thirty-two mandibular premolars with single canal were prepared up to the F4 ProTaper Universal instrument and filled by a single cone technique with the addition of Rhodamine B dye to Endofill sealer. For the retreatment procedure, the teeth were randomly divided into four experimental groups (n=8) as follows: Reciproc R40 with ultrasonic activation (RU), Reciproc R40 with sonic agitation (RS), ProTaper Next until X4 instrument with ultrasonic activation (PTNU), and ProTaper Next (X4) with sonic activation (PTNS). A new root canal filling was done using a System B technique, and the AH Plus sealer was mixed with Fluorescein dye. The roots were axial sectioned at 3, 5, and 7 mm from the apex and were assessed by a confocal laser scanning microscopy using the method of epifluorescence with wavelengths of absorption and emission for rhodamine B and fluorescein. In the obtained images, the sealer penetration into the dentinal tubules was evaluated. The data were converted into percentages and submitted to Mann-Whitney and Kruskal-Wallis followed by Dunn's tests (P<0.05). Results: In all groups were found penetration of the AH Plus into the dentinal tubules. Statistical difference was found (P<0.05) in the ProTaper Next groups in relation the Reciproc groups for 3 mm root canal level regardless of additional cleaning method used. For the other sections the sealer penetration was similar (P>0.05) for all groups. Conclusion: Based on this ex vivo study the retreatment with ProTaper Next showed significantly greater penetration of AH Plus sealer into dentinal tubules in the apical third. The additional cleaning methods did not improve the removal of filling material in all sections evaluated.

Fracture incidence of Reciproc instruments during root canal retreatment performed by postgraduate students: a cross-sectional retrospective clinical study.

OBJECTIVES: To evaluate the fracture incidence of Reciproc R25 instruments (VDW) used during non-surgical root canal retreatments performed by students in a postgraduate endodontic program. MATERIALS AND METHODS: From the analysis of clinical record cards and periapical radiographs of root canal retreatments performed by postgraduate students using the Reciproc R25, a total of 1,016 teeth (2,544 root canals) were selected. The instruments were discarded after a single use. The general incidence of instrument fractures and its frequency was analyzed considering the group of teeth and the root thirds where the fractures occurred. Statistical analysis was performed using the χ2 test (p < 0.01). RESULTS: Seven instruments were separated during the procedures. The percentage of fracture in relation to the number of instrumented canals was 0.27% and 0.68% in relation to the number of instrumented teeth. Four fractures occurred in maxillary molars, 1 in a mandibular molar, 1 in a mandibular premolar and 1 in a maxillary incisor. A greater number of fractures was observed in molars when compared with the number of fractures observed in the other dental groups (p < 0.01). Considering all of the instrument fractures, 71.43% were located in the apical third and 28.57% in the middle third (p < 0.01). One instrument fragment was removed, one bypassed, while in 5 cases, the instrument fragment remained inside the root canal. CONCLUSIONS: The use of Reciproc R25 instruments in root canal retreatments carried out by postgraduate students was associated with a low incidence of fractures.

Alargamento do forame como complemento no tratamento endodôntico para regeneração de uma lesão periapical extensa: relato de caso / Foraminal enlargement as a complement in the endodontic treatment for the regeneration of an extensive periapical lesion. A case report

Introdução: O alargamento do forame refere-se ao alargamento mecânico intencional do forame para reduzir a carga bacteriana em uma área afetada frequentemente por infecções endodônticas além do limite da constrição apical. Objetivo: O objetivo do presente relato de caso é apresentar a técnica de alargamento do forame de um dente com lesão periapical extensa, como complemento do tratamento endodôntico e alternativa precoce à microcirurgia periapical. Métodos: É apresentado o caso de um incisivo lateral superior endodonticamente tratado, com uma extensa lesão periapical associada. Devido à história clínica e radiográfica, tempo decorrido desde o tratamento endodôntico inicial e alta probabilidade de áreas de reabsorção apical com biofilme extrarradicular, o retratamento endodôntico com alargamento do forame foi indicado como primeira opção, adiando a indicação de cirurgia endodôntica de acordo com a evolução. Resultados: Na avaliação de acompanhamento de dois anos, por exame de imagem, observou-se evolução clínica favorável ao retratamento, com aumento total da densidade óssea. O procedimento cirúrgico endodôntico complementar foi descartado. Conclusão: O alargamento do forame é uma alternativa complementar viável em casos de periodontite apical de longa duração com suspeita de biofilme no nível do forame. Pode ser considerado uma opção antes da indicação de retratamento endodôntico cirúrgico (AU).

Introduction: Foraminal enlargement refers to intentional mechanical enlargement of the foramen to reduce the bacterial load in an area frequently affected by endodontic infections beyond the limits of the apical constriction. The objective of this case report is to present the foraminal enlargement technique of a tooth with an extensive periapical lesion as a complement in the endodontic treatment and an early alternative to periapical microsurgery. Materials and methods: The case is presented of an endodontically treated upper lateral incisor with an extensive associated periapical lesion. Due to the clinical and radiographic history, the time elapsed since the initial endodontic treatment, and the high probability of areas of apical resorption with extra-radicular biofilm, endodontic retreatment with foraminal enlargement was indicated as the first option, postponing the indication for endodontic surgery according to evolution. Results: In the follow-up appointment at 2 years, a favorable clinical imaging evolution of retreatment was observed, with a total increase in bone density. The complementary endodontic surgical procedure was discarded. Conclusion: Foraminal enlargement is a viable complementary alternative in cases of long-term apical periodontitis with suspicion of biofilm at the foramen level. It can be considered an option before the indication of surgical endodontic retreatment (AU).

Effect of Foraminal Enlargement on Postoperative Pain in Necrotic Single-Rooted Teeth: A Randomized Clinical Trial.

INTRODUCTION: The aim of this study was to evaluate pain perception, pain medication intake, and sealer extrusion after single-visit root canal treatment of asymptomatic teeth with or without foraminal enlargement. The correlation between sealer extrusion and pain was also investigated. METHODS: One hundred forty necrotic, single-rooted teeth were divided into 2 groups (n = 70): foraminal patency (FP), in which treatment was performed up to 1 mm short of the apex, and foraminal enlargement (FE), in which treatment was performed up to the apex. The canals were instrumented using WaveOne Gold files (Dentsply Maillefer, Ballaigues, Switzerland), irrigated with 2.5% sodium hypochlorite, and filled using the single-cone technique and AH Plus sealer (Dentsply Maillefer). A visual analog scale was used to record pain 24, 48, and 72 hours and 1 week postoperatively. The presence or absence of sealer extrusion was recorded. RESULTS: Pain levels were significantly higher for FE than FP at 24 hours (P < .05), namely 0.3 ± 0.9 versus 0.1 ± 0.1; no difference was found at 48 hours, namely 0.1 ± 0.5 versus 0.0 ± 0.0 (P > .05). No pain was reported 72 hours or 1 week postoperatively in either group. Although all patients requiring pain medication at 24 hours were from the FE group, the difference between FE and FP was not statistically significant with respect to this variable (P > .05). Nevertheless, the intake amount was significantly higher in FE than in FP at this time point (P < .05). Sealer extrusion occurred more frequently in FE than FP, namely 57.14 % versus 14.29% (P < .05). There was no association between pain and sealer extrusion (P > .05) or between pain and sex, age, or tooth type (P > .05). CONCLUSION: FE was related to higher pain levels 24 hours postoperatively and to higher rates of filling material extrusion; however, there was no association between filling material extrusion and postoperative pain.

Irrigant Agitation Techniques versus Passive Ultrasonic Irrigation for Removing Debris from Curved Root Canals: An Environmental Scanning Electron Microscopic Study.

Introduction: The aim of this study was to compare the efficacy of passive ultrasonic irrigation (PUI) versus mechanical agitation of the irrigant promoted by the EasyClean (EC) and XP-Endo Finisher (XP-F) systems in removing debris from root canal walls, using environmental scanning electron microscopy (ESEM). Methods and Materials: Twelve curved mesiobuccal canals of mandibular molars were prepared with the ProTaper Next system up to file X2 (25/0.06). The specimens were embedded in flasks containing silicone putty, sectioned lengthwise, and a 4-mm long groove was made on the canal wall of the buccal half of the specimen, extending from 2 mm up to 6 mm short of the apex. Five cross-sectional markings were made along this groove to establish standardized locations for imaging. The same specimens were used to prepare a negative control group (without debris), a positive control group (completely covered by debris), and 3 experimental groups according to the final irrigation protocol employed: PUI, EC or XP-F. ESEM images were obtained and evaluated by 3 examiners. The amount of debris observed on the images was classified according to a 4-category scoring system. The kappa test was used to assess inter-examiner agreement, and the Kruskal-Wallis and Dunn tests were used to compare the scores (P<0.05). Results: The scores attributed to the PUI, EC, and XP-F groups were statistically similar to those attributed to the negative control group (P>0.05). Conclusion: Based on this in-vitro study, the mechanical agitation of the irrigant promoted by EC and XP-F was as effective as using PUI to remove debris from the root canal walls.

Micro-computed Tomographic Assessment of Supplementary Cleaning Techniques for Removing Bioceramic Sealer and Gutta-percha in Oval Canals.

INTRODUCTION: The aim of this study was to conduct a micro-computed tomographic assessment of the effectiveness of 3 supplementary cleaning techniques in reducing the residual volume of gutta-percha and a bioceramic sealer after performing endodontic retreatment procedures in teeth with oval canals. METHODS: Thirty-six mandibular premolars were instrumented with the ProTaper Next system (instruments X1-X3; Dentsply Maillefer, Ballaigues, Switzerland) and filled with gutta-percha and Bio-C Sealer (Angelus, Londrina, PR, Brazil) using the single-cone technique. The teeth were reinstrumented with the Reciproc R40 instrument (VDW, Munich, Germany) and divided into 3 groups according to the supplementary cleaning technique used (n = 12): ultrasonic-assisted irrigation (UAI), EndoActivator (Dentsply Tulsa Dental Specialties, Tulsa, OK) irrigation (EAI), or the XP-endo Finisher R system (XPR; FKG Dentaire, La Chaux-de-Fonds, Switzerland). Micro-computed tomographic imaging was used to quantify the residual volume of filling material. One-way analysis of variance complemented by the Tukey test was used to perform the statistical analysis (P < .05). RESULTS: Significant reductions were obtained in the residual filling material after supplementary cleaning (P < .05). XPR (47.5%) led to significantly greater (P < .05) filling material removal than UAI (16.6%) or EAI (22.6%). The removal values of the 2 latter systems were not significantly different. CONCLUSIONS: XPR was more effective than UAI and EAI in removing filling material in mandibular premolars with oval canals. None of the tested supplementary cleaning techniques completely removed the residual filling material.

The Effectiveness of Three Irrigation Systems in the Enterococcus faecalis Reduction after Instrumentation with a Reciprocating Instrument.

OBJECTIVE: This study aimed to analyze the effectiveness of three irrigation systems: EndoActivator, passive ultrasonic irrigation (PUI), and Easy Clean in the reduction of Enterococcus faecalis, after instrumentation with the reciprocating system, through microbiological collection and culture method. MATERIALS AND METHODS: A total of 60 extracted human lower premolars were used and standardized at 16 mm in length. The teeth were accessed, contaminated with E. faecalis, and incubated for 21 days at 37°C. Initial collections (S1) were made with an absorbent paper cone to confirm the contamination; subsequently, instrumentation was performed with WaveOne Primary. The teeth were divided into four groups according to the final irrigation protocol (n = 15): group 1. EndoActivator; group 2, PUI; group 3, Easy Clean; and group 4, control group irrigated with saline solution sterile and without agitation. In the final irrigation, the agitation of the 17% ethylene amine tetra-acetic acid (EDTA) solutions was used, then 2.5% sodium hypochlorite (NaOCl); in both for this, three cycles of 20 seconds each. After the chemical-mechanical preparation and agitation of the irrigating solutions, the final collections (S2) for counting the colony-forming units (CFU/mL) occurred. RESULTS: The Kruskal-Wallis test revealed that all the agitation systems reduced by 100% and the control group by 65.7%. CONCLUSION: The control group presented a significantly higher amount of CFU/mL after the chemical-mechanical preparation than the other groups, which were similar to each other (p > 0.05).

Effect of ultrasonic cleaning on the bond strength of fiber posts in oval canals filled with a premixed bioceramic root canal sealer.

OBJECTIVE: This study aimed to evaluate the effect of ultrasonic cleaning of the intracanal post space on the bond strength of fiber posts in oval canals filled with a premixed bioceramic (Bio-C Sealer [BIOC]) root canal sealer. MATERIALS AND METHODS: Fifty premolars were endodontically prepared and divided into 5 groups (n = 10), based on the type of root canal filling material used and the post space cleaning protocol. A1: gutta-percha + AH Plus (AHP) and post space preparation with ultrasonic cleaning, A2: gutta-percha + BIOC and post space preparation with ultrasonic cleaning, B1: gutta-percha + AHP and post space preparation, B2: gutta-percha + BIOC and post space preparation, C: control group. Fiber posts were cemented with a self-adhesive luting material, and 1 mm thick slices were sectioned from the middle and cervical third to evaluate the remaining filling material microscopically. The samples were subjected to a push-out test to analyze the bond strength of the fiber post, and the results were analyzed with the Shapiro-Wilk, Bonferroni, Kruskal-Wallis, and Mann-Whitney tests (p < 0.05). Failure modes were evaluated using optical microscopy. RESULTS: The results showed that the fiber posts cemented in canals sealed with BIOC had lower bond strength than those sealed with AHP. The ultrasonic cleaning of the post space improved the bond strength of fiber posts in canals sealed with AHP, but not with BIOC. CONCLUSIONS: BIOC decreased the bond strength of fiber posts in oval canals, regardless of ultrasonic cleaning.

Can Irrigant Agitation Lead to the Formation of a Smear Layer?

INTRODUCTION: This study aimed to assess whether ultrasonic activation (UA) or the EasyClean (EC; BassiEndo, Belo Horizonte, BH, Brazil) or EDDY (ED; VDW, Munich, Germany) systems used to promote agitation of the irrigating solutions during the final irrigation step can lead to smear layer formation in the apical third of the root canal. METHODS: Thirteen premolars were instrumented with the Reciproc R40 file (VDW) and embedded in silicone, forming a closed irrigation/aspiration system. The teeth were cleaved, and 4 indentations were made on the inner buccal wall of the canal to standardize the observation sites. All the specimens were cleaned in an ultrasonic bath and evaluated under environmental scanning electron microscopy, thus constituting the control group. The same specimens were reassembled, submitted to final irrigation using UA or the ED or EC systems, and classified using a 4-level scoring system. The data were analyzed using the kappa, Pearson, and Kruskal-Wallis tests (P < .05). RESULTS: Smear layer formation occurred in all of the experimental groups and at all apical levels. At 3 and 4 mm, all of the experimental groups had significantly higher levels of smear layer formation than the control group. At 2 mm, the level of smear layer formation in the UA group was significantly higher than that of the control group, and there were no significant differences among the EC, ED, and control groups. At 1 mm, there were no significant differences between the ED and control groups, and the levels of smear layer formation in the EC and UA groups were significantly higher than that of the control group. There were no significant differences between the ED and EC groups at any of the apical levels. CONCLUSIONS: The smear layer formation occurred in all of the specimens submitted to final irrigation, irrespective of the technique used.

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

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.

Influence of foraminal enlargement on the apical extrusion of filling material: Volumetric analysis using micro-computed tomography.

The aim of this study was to compare the root canal instrumentation techniques that involve foraminal enlargement versus those not involving it, in regard to the apical extrusion of filling material, using micro-computed tomography (micro-CT). Twenty-two premolars with single canals were instrumented using the ProTaper Universal System and then randomly divided into two groups (n = 11): Group NFE, without foraminal enlargement, and Group FE, with foraminal enlargement. Instrumentation was performed up to 1 mm short of the apical foramen, and foraminal patency was maintained at each instrument change in both groups. Prior to obturation, the apical portion of the specimens was wrapped in adhesive paper to ensure complete separation between apex and extruded material. The canals were filled according to the continuous wave of condensation technique. The apically extruded material was collected and measured using micro-CT. Extrusion in Group FE was significantly higher than in Group NFE (0.928 mm3 vs. 0.148 mm3 ; P < 0.001).

Effect of immersion in sodium hypochlorite on the cyclic fatigue resistance of three rotary instruments.

CONTEXT: It is essential to know if the immersion in sodium hypochlorite (NaOCl) influences the cyclic fatigue resistance of nickel-titaniumm (NiTi) files. AIM: This study was aimed to evaluate the resistance to the cyclic fatigue of three NiTi systems, as well as the influence of 5.25% NaOCl on their resistance. METHODS: Files from the Sequence Rotary File (MK life, Porto Alegre, Brazil), ProTaper Next (PTN) (Dentsply, Maillefer, Baillagues, Switzerland), and HyFlex EDM (Coltène Whaledent, Allstatten, Switzerland) systems were tested and separated into Group 1)-without immersion in NaOCl solution and Group 2 and Group 3-immersed in 5.25% NaOCl solution, for 1 min, and 5 min, respectively. All instruments were submitted to the cyclic fatigue test. Images of the instruments were observed by scanning electron microscopy, to evaluate the type of defect presented on the fractured surface. The test performed for the analysis of two independent factors was a two-way analysis of variance. RESULTS: HyFlex EDM presented a greater number of cycles until fracture when compared to others (P < 0.001). The control group showed a greater number of cycles until fracture than the same instruments submitted to NaOCl (P < 0.001). Sequence instruments showed the lowest values of cycles until fracture (P < 0.001). There was no statistically significant difference between treatments (P = 0.998). PTN, showed intermediate values of fracture resistance when compared to the HyFlex EDM and sequence instruments (P < 0.001), but without intragroup differences (P = 0.437). CONCLUSIONS: Hyflex EDM instruments were the most resistant to cyclic fatigue.

Efficacy of passive ultrasonic irrigation, continuous ultrasonic irrigation versus irrigation with reciprocating activation device in penetration into main and simulated lateral canals.

CONTEXT: The use of chemicals solutions and means of activation is of utmost importance in endodontic treatment. AIMS: This study compared three activation techniques used in the final irrigation of the endodontic treatment. SUBJECTS AND METHODS: Eighty uniradicular teeth were instrumented with the Protaper Universal system up to F4 file. After decalcification, the teeth had artificial lateral canals created at 2, 4.5 and 6 mm from working length (WL). The groups were randomly divided into four groups (n = 20): control group (C), passive ultrasonic irrigation (PUI) group, continuous ultrasonic irrigation (CUI) group, and easy clean (EC) group. The penetration of the irrigant into the samples was evaluated using image observation using the Image J program. STATISTICAL ANALYSIS USED: The level of agreement among the observers was determined by the Cronbach's alpha test. The likelihood ratio test was used to evaluate possible differences between the groups and the Kendall's W statistic test to verify possible differences between the irrigant penetration levels in the lateral canals. The Fisher's exact test was applied to verify differences by the studied group considering the WL variables and lateral canals. RESULTS: The results showed no statistical difference in the penetration of the irrigator in the main canal when compared to the C, PUI, CUI, and EC groups (P > 0.05). CONCLUSIONS: The method using a positive syringe and needle pressure was not able to effectively carry the irrigator to the artificially made lateral canals, whereas PUI, CUI, and EC were equally efficient in this regard (P < 0.01).

Micro-computed Tomography versus the Cross-sectioning Method to Evaluate Dentin Defects Induced by Different Mechanized Instrumentation Techniques.

INTRODUCTION: The objective of this study was to compare the methods of micro-computed tomography (micro-CT) and cross-sectioning followed by stereomicroscopy in assessing dentinal defects after instrumentation with different mechanized systems. METHODS: Forty mesial roots of mandibular molars were scanned and divided into 4 groups (n = 10): Group R, Reciproc; Group PTN, ProTaper Next; Group WOG, WaveOne Gold; Group PDL, ProDesign Logic. After instrumentation, the roots were once again submitted to a micro-CT scan, and then sectioned at 3, 6, and 9 mm from the apex, and assessed for the presence of complete and incomplete dentinal defects under a stereomicroscope. The nonparametric Kruskal-Wallis, Friedman, and Wilcoxon tests were used in the statistical analysis. The study used a significance level of 5%. RESULTS: The total number of defects observed by cross-sectioning followed by stereomicroscopy was significantly higher than that observed by micro-CT, in all of the experimental groups (P ≤ .05). All of the defects identified in the postoperative period were already present in the corresponding preoperative period. There was no significant difference among the instrumentation systems as to the median numbers of defects, for either cross-sectioning followed by stereomicroscopy or micro-CT, at all the root levels (P > .05). In the micro-CT analysis, no significant difference was found between the median numbers of pre- and postinstrumentation defects, regardless of the instrumentation system (P > .05). CONCLUSION: None of the evaluated instrumentation systems led to the formation of new dentin defects. All of the defects identified in the stereomicroscopic analysis were already present before instrumentation, or were absent at both time points in the micro-CT analysis, indicating that the formation of new defects resulted from the sectioning procedure performed before stereomicroscopy and not from instrumentation.

Effectiveness of the ProTaper Next and Reciproc Systems in Removing Root Canal Filling Material with Sonic or Ultrasonic Irrigation: A Micro-computed Tomographic Study.

INTRODUCTION: The aim of this study was to evaluate the effectiveness of ProTaper Next (Dentsply Maillefer, Ballaigues, Switzerland) and Reciproc (VDW, Munich, Germany) systems in removing filling material from oval root canals using sonic or ultrasonic irrigation as additional cleaning methods. METHODS: Thirty-two human extracted mandibular premolars with oval canals were prepared using the ProTaper Universal system (Dentsply Maillefer) up to instrument F4 (40/.06) and then filled by the single-cone technique using Endofill sealer (Dentsply Maillefer). The teeth were randomly divided into 4 groups (n = 8) according to the instrumentation system and the additional cleaning method as follows: Reciproc 40 with ultrasonic activation, Reciproc 40 with sonic agitation, ProTaper Next (X2, X3, and X4) with ultrasonic activation, and ProTaper Next (X2, X3, and X4) with sonic agitation. All specimens were analyzed using micro-computed tomographic imaging before and after removal of the filling material and also after applying the additional cleaning methods. The data, in mm3 of remaining filling material, were analyzed by the Kruskal-Wallis, Dunn, and Mann-Whitney tests. RESULTS: None of the retreatment protocols completely removed the filling material from the root canals, and there was no significant difference between the instrumentation systems or between root thirds assessed in terms of the average volume of remaining filling material (P > .05). Likewise, no significant difference was observed between the additional cleaning methods in any of the root canal thirds assessed (P > .05). CONCLUSIONS: The ProTaper Next and Reciproc systems were equivalent with respect to effectiveness in removing filling material regardless of the additional cleaning method used. The additional cleaning methods were also equivalent and did not improve the removal of filling material significantly.

Avaliação da acurácia de quatro localizadores apicais durante o retratamento endodôntico / Evaluate the accuracy of four electronic apex locators during endodontic retreatment

Este estudo teve como objetivo avaliar a acurácia de quatro localizadores apicais eletrônicos durante o retratamento endodôntico. Quarenta pré-molares unirradiculares com apenas um canal, ápice completamente formado, foram divididos em quatro grupos e analisados: Grupo 1: Root ZX ll. Grupo 2: Mini Root. Grupo 3: Propex ll e Grupo 4: Mini Apex. Todos os elementos foram padronizados no comprimento de 22 mm, instrumentados com limas Wave One Primary (25.08), obturados e armazenados. Após um mês, foram desobturados com limas reciprocantes Wave One Primary (25.08) e, em seguida, montados em blocos de esponja vegetal, embebida em solução de cloreto de sódio a 0,9%. A acurácia eletrônica de cada elemento foi realizada, utilizando-se uma lima manual do tipo K#20, até que a mesma fosse ultrapassada pelo forame e recuada até o comprimento real do dente, onde, então, as medidas de cada elemento eram anotadas. Todas as medidas obtidas de cada grupo passaram por análise estatística. Não houve diferença estatisticamente significante entre os localizadores apicais eletrônicos analisados, quando utilizados durante o retratamento endodôntico, sendo possível concluir que, os quatro modelos de localizadores apicais analisados mostraram-se eficientes durante o retratamento endodôntico, dentro dos limites estabelecidos, não havendo diferença entre eles.

This study aimed to evaluate the accuracy of four electronic apex locators during endodontic retreatment. Forty single-rooted premolars, with a root canal, with fully formed apex, were divided into four groups and analyzed: Group 1: Root ZX II. Group 2: Mini Root. Group 3: Propex II and Group 4: Mini Apex. All elements have been standardized in the length of 22 mm, instrumented with Wave One Primary (25.08) files, sealed and stored. After a month, the desobturation with reciprocating Wave One Primaty (25.08) files off and then assembled into blocks vegetable sponge, soaked in 0.9% sodium chloride solution. Electronic accuracy of each element was performed using a manual file type K#20, until it was overtaken by the foramen and retracted to the actual length of the tooth, which then measures each element were noted. All measurements obtained from each group passed by statistical analysis. There was no statistically significant difference between the electronic apex locators analyzed when used during endodontic retreatment it is possible to conclude that the four models analyzed apex locators were effective during endodontic retreatment wirhin the established timits, there is no difference between them.

Comparative Analysis of Dentinal Erosion after Passive Ultrasonic Irrigation versus Irrigation with Reciprocating Activation: An Environmental Scanning Electron Study.

INTRODUCTION: The aim of this study was to assess ex vivo the erosive effects of passive ultrasonic irrigation versus irrigation with reciprocating activation on the dentinal surface of the root canal at 3 predetermined levels using environmental scanning electron microscopy. METHODS: Ten roots of mandibular premolars were prepared using the ProTaper Universal system (Dentsply Maillefer, Ballaigues, Switzerland). The specimens were embedded in flasks cleaved longitudinally, and indentations were made 3.0, 6.0, and 9.0 mm from the apex. The specimens in the control group (n = 10) were cleaned in an ultrasonic bath containing 2.5% sodium hypochlorite and 17% EDTA and then dried. Then, environmental scanning electron microscopic images were obtained at magnification × 800. The specimens were then reassembled in their flasks, and the NaOCl and EDTA solutions were activated according to the conditions established for the experimental groups (ie, the passive ultrasonic irrigation group [n = 5] and the EasyClean (Easy Equipamentos Odontológicos, Belo Horizonte, MG, Brazil) group, irrigation with reciprocating activation with the EasyClean instrument [n = 5]). The specimens of both experimental groups were analyzed in the same manner as in the control group. Analysis of the dentinal surface topography was conducted using the 3D Roughness Reconstruction program (Phenom-World BV, Eindhoven, the Netherlands) as a means for assessing erosion. The data were evaluated by means of the Kruskal-Wallis, Student-Newman-Keuls, and Mann-Whitney tests. RESULTS: In the EasyClean group, the degree of dentinal erosion at 3.0 mm was significantly higher than at 9.0 mm. In the other comparisons, there was no statistically significant difference (P < .05). CONCLUSIONS: The final irrigation techniques tested were equivalent in relation to the degree of erosion caused to the dentinal surface.