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Introduction: The root curvature represents a challenge during the endodontic retreatment. Considering the different techniques to fill the root canals and the growing use of bioceramic sealers, this study aimed to evaluate the influence of the filling technique associated with a bioceramic sealer on the remaining filling material and the impact on the remaining dentin after the filling removal in the retreatment of curved mesial canals of mandibular molars., Methods: Eighteen curved mesial roots of mandibular molars with Vertucci type IV canals were prepared up to instrument 35/.05. Two groups were established according to the filling technique: single-cone (n=18) and continuous wave of condensation (n=18). Bio-C Sealer was used for both techniques. The filling was removed using the Reciproc Blue R25 instrument, and the repreparation was carried out using the Reciproc Blue R40 instrument. The samples were scanned by micro-CT before and after the filling removal and analyzed regarding the volume of the remaining filling material and dentin thickness for calculating transportation and centering ability. For statistical analysis, the data normality was checked, and parametric tests were used for normal distribution and non-parametric tests for non-normal distribution., Results: The remaining filling material was observed in both groups during retreatment, with no differences. Analyses of transportation and centering ability also indicated similarities between the two groups., Conclusion: Endodontic retreatment in curved mesial canals of mandibular molars filled with single-cone or continuous wave of condensation technique and bioceramic sealer was similar. The use of reciprocating instruments for filling removal and repreparation was efficient in curved mesial canals of mandibular molars, with no complications., (Copyright © 2025. Published by Elsevier Inc.)

Objectives: The aim of this study was to investigate the efficacy of three newly introduced rotary endodontic systems: Genius ProFlex (Medidenta), TruNatomy (Dentsply Maillefer), and ZenFlex (Kerr)., Methods: Forty-five mandibular molars with root canal curvatures <5° were utilized. Micro-computed tomography scans were performed pre- and post-preparation to assess apical transportation, centralization, percentage of dentin wear, and canal volume alterations. Eight instruments of each diameter underwent cyclic fatigue testing., Results: The percentage of dentin wear on mesial and distal walls showed no significant differences among ZenFlex, TruNatomy, and Genius ProFlex at 1, 2, 3, and 4 mm from the apical foramen and root canal orifice (p > 0.05). Centering ability varied in the mesiolingual canal (p < 0.05). No notable differences were observed in transportation (p > 0.05). Genius ProFlex demonstrated lower volumetric changes (p < 0.05). There were significant differences in cyclic fatigue, with higher values for Genius ProFlex and lower values for TruNatomy (p < 0.05)., Conclusions: The three nickel-titanium rotary instruments are safe and efficient for root canal preparation, with Genius ProFlex exhibiting superior cyclic fatigue resistance.

This study evaluated the shaping ability of HyFlex EDM and Rotate rotary systems in the preparation of S-Shaped mesial root canals of mandibular molars (n = 13). After root canal preparation with instruments HyFlex EDM and Rotate 0.25 and 0.40, the specimens were evaluated for root canal volume, volume increase, static voxels, accumulated hard tissue debris, centring ability and canal transportation. After 0.40 preparation, the Rotate group exhibited a greater increase in volume and less accumulated hard-tissue debris compared to the HyFlex group (p > 0.05). 0.40 preparation with Rotate instruments resulted in greater volume increases across all thirds and less debris in the apical third (p < 0.05). The Rotate group displayed greater transportation and lower centring ability in the apical third after 0.40 preparation (p < 0.05). HyFlex and Rotate demonstrated similar performance up to the 0.25 preparation, and while differences emerged after the 0.40 preparation, both systems provided safe preparation without procedural accidents., (© 2025 Australian Society of Endodontology Inc.)

Objective: This study investigated the associations among endodontic instruments, ultrasonic tips and various final irrigation protocols for removing intracanal and intratubular biofilms in long oval canals., Methodology: One hundred mandibular premolars inoculated with Enterococcus faecalis were divided into two groups: the control group (CG: n = 10), which received no treatment; and the test groups (n = 30), which included saline (SS), sodium hypochlorite (2.5% NaOCl) and chlorhexidine (2% CHX). The samples were prepared with Reciproc ® Blue 25/0.08, Flatsonic, Clearsonic and Reciproc Blue 40/0.06. Each test group was divided into three subgroups (n = 10): conventional irrigation (CI) with syringes and needles, passive ultrasonic irrigation (PUI) and continuous ultrasonic irrigation (CUI) with an Irrisonic tip. The root canals were examined using confocal laser scanning microscopy. Mann‒Whitney and Kruskal‒Wallis tests followed by Dunn post hoc tests (p < 0.05) were used for statistical analysis., Results: NaOCl and CHX were effective for intracanal and intratubular decontamination. Saline showed significant decontamination in the intratubular areas when CUI was used. The CI method was the least effective for intracanal decontamination., Conclusion: The use of Flatsonic and Clearsonic ultrasonic tips is promising for root canal disinfection., Clinical Relevance: The disinfection techniques in endodontic treatment focus on the removal of biofilms from long oval canals, which is crucial for effective cleaning during root canal procedures., Competing Interests: Declarations. Ethical approval: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Human teeth were used after Ethics Committee Approval (number: 50179321.9.0000.5417). Informed consent: Informed consent was obtained from all individual participants included in the study. Competing interests: The authors declare no competing interests., (© 2025. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: This study investigated the accuracy and reliability of apical limit control in endodontic retreatment using hybrid endodontic motors., Material and Methods: Thirty-six mesial canals of mandibular molars were accessed, and their apical foramina (AF) were standardized to 200 µm. Chemical-mechanical preparation was performed with WaveOne Gold instruments (#20/.07), followed by obturation with gutta-percha and AH Plus cement. After initial preparation, the teeth were divided into three groups (n = 12): Root ZX II (RZX), VDW Gold (VDW) and Tri Auto ZX2 (TRZX), all in rotary kinematics and with AF as the limit (0.0). Exposure was performed in the crown-down direction with ProTaper retreatment instruments using 2.5% NaOCl as an irrigation solution. Before using the instruments, the apexes of the teeth were immersed in alginate. With the auto-stop function activated, the hybrid instruments were calibrated to stop rotating when the desired apical limit was reached. The last instrument was fixed in the canal and a micro-computed tomography scan was performed to determine the distance between the instrument tip and the AF. Data were analyzed using the Kruskal-Wallis and Dunn tests ( P <0.05)., Results: No significant differences were found between the RZX (0.10 mm), Gold (0.13 mm) and TRZX (0.27 mm) devices; accuracy ranged from 91.70% (RZX and VDW) to 63.63% (TRZX). TRZX had the highest number of readings besides AF., Conclusions: It was concluded that all devices studied were efficient in maintaining the apical limit of instrumentation during endodontic retreatment when taken to the AF. Key words: Endodontics, Electronic odontometry, Endodontic retreatment., Competing Interests: The authors declare that they have no competing interests., (Copyright: © 2025 Medicina Oral S.L.)