Evaluation of the Cyclic and Torsional Fatigue Resistance of Thermally Treated Hyflex CM versus Aurum Blue Nickel-titanium Rotary Instruments

Introduction: We aim to evaluate the cyclic and torsional fatigue resistance of two rotary instruments, Hyflex CM 25/0.06 (HCM) (Coletene-Whaledent, Allstetten, Switzerland) and Aurum Blue (AB) 25/0.06 (Meta-Biomed, Republic of Korea). Methods and Materials: Forty rotary instruments, HCM 25/0.06 and AB 25/0.06 (n=20 each) were used. The instruments were rotated in an artificial stainless steel canal with a 60° angle and a 5-mm radius of curvature (n=10) at body temperature (35°±1°C). The torsional test evaluated the torque and angle of rotation at failure of new instruments (n=10) in the portion 3 mm from the tip according to ISO 3630-1. The fractured surface of each fragment was observed by scanning electron microscopy. The data were analyzed using unpaired student’s t- test, and the level of significance was set at 5%. Results: AB 25/0.06 had significantly greater number of cycles to failure than HCM 25/0.06 (P<0.05). The torsional test showed there were no significant differences in the torsional strength and angular rotation to fracture between the groups (P>0.05). Conclusion: Based on this in vitro study, AB 25/0.06 instrument was more resistant to cyclic fatigue than the HCM 25/0.06 instrument, suggested that these instruments are safer than HCM 25/0.06 for the preparation of severely curved canals. However; there was no significant difference in the torsional properties of the two instruments then appear to have similar performance during constricted canal preparation

Micro-CT Assessment of Filling Removal Effectiveness in the Apical Third of Curved Canals with Different Types of Anatomy

Introduction: The aim of this study was to assess the effectiveness of filling removal material from the apical third of curved mesial root canals of mandibular molars. Reciprocating instrumentation followed by additional rotary instrumentation with instruments made of alloys with different heat treatments was evaluated. Materials and Methods: Thirty-six mesial roots of mandibular molars were divided into two groups: Group Class IV consisted of 16 roots with two independent canals, and Group Class II consisted of 20 roots with two canals that merged into one at their apical level. Each of these two groups were further divided into two subgroups, according to the additional rotary instrument used after the reciprocating instrumentation: Group RH and Group RM for Hyflex and Mtwo, respectively. After each procedural step, the roots were scanned by micro-tomography. After each step of filling removal, the Wilcoxon matched pair test and the Mann-Whitney test were used for the evaluation between groups. The significance level adopted was 5%. Results: Significant differences were observed between groups with different Class II and Class IV anatomies, regarding filling removal after Reciproc (P<0.05). After the use of an additional rotary instrumentation, no differences were observed between the two groups (P>0.05). Conclusions: In the apical third of mesial roots of mandibular molars with Class II anatomy, an additional rotary instrumentation was shown to be necessary for improving the removal of filling material after using the single-file reciprocating instrumentation technique

19th World Conference on Open Learning and Distance Education

Todos os trabalhos se desenvolveram no Austria Center Vienna, o mais moderno centro de congressos da capital austríaca, adjacente ao complexo das Nações Unidas, na margem esquerda do Danúbio, a menos de quinze minutos de metro do centro da cidade. Com mais de mil e trezentos participantes, na Conferência estiveram representados setenta e nove países, sendo trinta europeus, dezasseis asiáticos, quinze americanos, catorze africanos e quatro da zona do Pacífico. Em termos de representação individual, a Europa, com mais de 57% de presenças, foi a zona do globo mais visível. De salientar, contudo, a presença significativa de um elevado número de representantes de países em busca de desenvolvimento, de todos os continentes, da Letónia à Eslováquia, da Mongólia ao Vietname, da República Dominicana ao Equador, do Botswana à Tunísia, passando pelo Chade e pelo Togo

Effect of A Clinical-Replicable Cooling Protocol on the Cyclic Fatigue Resistance of Heat-Treated Nickel-Titanium Instruments

Introduction: The aim of this study was to evaluate the bending and cyclic fatigue resistance of Wave One Gold (WOG) and X1 Blue (X1B) instruments when tested at body temperature (36° ± 1°C) subjected or not to an alloy cooling protocol. Methods and Materials: Twenty instruments of each system (n=40) were selected and divided into two groups: body temperature (BT); body temperature with cooling protocol (CP). Cyclic fatigue test was performed until fracture in a custom stainless-steel device with water bath equipment to simulate body temperature. CP group instruments were subjected to 5 seconds of spray cooling at every 30 seconds. Time to fracture was recorded. Resistance to bending at 45o was evaluated using ten instruments of each system. Fractured surfaces were examined under scanning electron microscopy (SEM). Statistical analysis was performed using Student t test at 5% significance level. Results: WOG instruments had significantly less cyclic fatigue resistance compared to X1B instruments in BT (P=0.00001) and CP (P=0.0001) groups. Significantly increased resistance was observed in X1B instruments (P=0.0003) and in WOG (P=0.0003) when cooling protocol was applied. There were no significant differences between the values of resistance increase presented by the instruments after cooling (P>0.05). Bending test presented no statistically significant differences between the tested instruments (P>0.05). Both instruments in both groups showed typical features of cyclic fatigue behavior under SEM. Conclusions: Cooling protocol extended the cyclic fatigue resistance of both instruments

Divergence between confidence and knowledge of endodontists regarding non-odontogenic pain

This study aimed to assess the self-reported levels of confidence and knowledge related to non-odontogenic pain among a group of Brazilian endodontists. Methodology: A total of one hundred and forty-six endodontists affiliated with the Brazilian Society of Endodontics participated in the survey. The questionnaire, distributed via email or WhatsApp, contained inquiries designed to gauge self-perceived confidence and knowledge concerning non-odontogenic pain. The practitioners were categorized into four groups based on their self-reported familiarity with various orofacial pain types, classified as either sufficient or insufficient, and on their engagement in ongoing educational programs related to orofacial pain. Data were analyzed by Chi-Square Test and Fischer’s exact test (p<0.05). Results: Overall, self-reported confidence about non-odontogenic pain was high, especially for endodontists who considered their knowledge about orofacial pain sufficient, regardless of whether they had (71.1% - 97.8%) or not (35.7% - 96.4%) been continuously involved in education courses on orofacial pain. In general, self-reported knowledge about non-odontogenic pain was insufficient (0% - 42%), except in the question about how they would act in cases of pain that persists beyond the normal healing time after an endodontic procedure (70.6% - 81.9%). In general, endodontists are confident in their diagnosis and treatment of non-odontogenic pain. Nonetheless, this confidence did not correlate with a commensurate knowledge depth of. Thus, specialization courses in endodontics should highly consider training and qualifying these professionals in the diagnosis of non-odontogenic pain

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

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

Influence of radiopacifying agents on the solubility, pH and antimicrobial activity of portland cement

The aim of this study was to evaluate the interference of the radiopacifiers bismuth oxide (BO), bismuth carbonate (BC), bismuth subnitrate (BS), and zirconiun oxide (ZO) on the solubility, alkalinity and antimicrobial properties of white Portland cement (WPC). The substances were incorporated to PC, at a ratio of 1:4 (v/v) and subjected to a solubility test. To evaluate the pH, the cements were inserted into retrograde cavities prepared in simulated acrylic teeth and immediately immersed in deionized water. The pH of the solution was measured at 3, 24, 72 and 168 h. The antimicrobial activity was evaluated by a radial diffusion method against the microorganisms S. aureus (ATCC 25923), P. aeruginosa (ATCC 27853), E. faecalis (ATCC 29212) and C. albicans (ATCC 10231). The zone of microbial growth inhibition was measured after 24 h. The addition of BS and BC increased the solubility of the cement. The pH values demonstrated that all materials produced alkaline levels. At 3 h, BS showed lower pH than WPC (p<0.05). At 168 h, all materials showed similar pHs (p&gt;0.05). The materials did not present antimicrobial activity for S. aureus, P. aeruginosas and E. faecalis (p&gt;0.05). With regards to C. albicans, all materials formed an inhibition zone, mainly the mixture of WPC with ZO (p<0.05). The type of radiopacifier incorporated into WPC interfered with its physical and antimicrobial properties. ZO was found to be a viable radiopacifier that can be used with WPC

Laboratory study of tissue repair of resin-based endodontic sealers in critical surgical defects

Filling materials should be restricted to the root canal space. However, sometimes it is impossible to control the apical extrusion, in this case, the fate of the filling material and the result of the treatment will depend on its physicochemical properties and biocompatibility. Objective: To evaluate the tissue response and bone repair capacity of endodontic sealers that were implanted in the calvaria of Wistar rats, forming the groups (n=16): AH Plus and Sealer Plus, compared to the clot group. Methodology: On days 30 and 60, the animals were euthanized, the calvaria was removed and processed for hematoxylin-eosin, immunohistochemistry for collagen type I, Picrosirus red and microtomographic analysis. Data were subjected to ANOVA and Tuckey tests (p&lt;0.05). Results:At 30 days, all groups showed an intense inflammatory reaction (p&gt;0.05). At 60 days, the AH Plus and Sealer Plus maintained an intense inflammatory infiltrate compared to the clot group (p&lt;0.05). We observed immunopositive areas for type I collagen in all groups at 30 days and 60 days (p&gt;0.05). We observed more red collagen fibers for the Sealer Plus compared to the clot group at 30 days (p&lt;0.05). Considering the total fibers, the clot group at 30 days compared to 60 days after surgery showed an increase in the amount of matrix (p&lt;0.05). There were no statistical differences between groups for green and yellow fibers (p&gt;0.05). Regarding morphometric parameters, at 30 days, the newly formed bone volume and number of bone trabeculae were higher in the groups with sealers compared to the clot group (p&lt;0.05). At 60 days, AH Plus and Sealer Plus showed greater bone neoformation compared to the clot group (p&lt;0.05). Conclusions: Despite AH Plus and Sealer Plus induced an intense inflammatory reaction, they can be considered biocompatible materials, since they allowed bone repair