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Background: Root canal retreatment is necessary when initial treatment fails. Nickel-titanium systems help remove filling materials; however, some methods can cause canal content extrusion, resulting in inflammation and delayed healing. This study aimed to examine the impact of different preparation techniques and endodontic file systems on apical debris volume to limit material dispersion to periradicular tissues., Methods: Ninety extracted maxillary incisors were evaluated. Simulated apical root resorption was created by removing the apical 2 mm of the root. The teeth were divided into two groups: one filled with a single cone and the other with cold lateral compaction (CLC). Each group was further divided into three subgroups (n = 15 each): Subgroup 1 used Reciproc R25 for removal and R50 for final preparation; Subgroup 2 used ProTaper Universal Retreatment (PTUR) files D1, D2, and D3 for removal and ProTaper Next X5 for finalization; and Subgroup 3 used VDW.Rotate Retreatment (VDW.RotateR) for removal and VDW.Rotate 50.04 for completion. Debris from retreatment was collected in pre-weighed tubes to determine the amount. The apical extrusion data underwent a two-way analysis of variance., Results: The Reciproc group had a mean extruded debris weight of 0.54 ± 0.24 mg, higher than the PTUR (0.28 ± 0.15 mg) and VDW.RotateR (0.39 ± 0.29 mg) groups (p < 0.05). The single-cone technique (SCT) resulted in a mean debris weight of 0.34 ± 0.23 mg, lower than the CLC technique, which had a mean of 0.46 ± 0.27 mg (p < 0.05). SCT had a shorter retreatment duration (111.12 ± 33.46 s) compared to CLC (176.26 ± 52.26 s) (p < 0.05)., Conclusion: The Reciproc file system and the CLC obturation technique resulted in greater apical debris extrusion than the other methods. SCT was quicker than CLC. The Reciproc groups are more susceptible to apex extrusion during retreatment., (© 2024. The Author(s).)

Information regarding the influence of resorption and glide paths on debris extrusion in primary teeth is lacking. Therefore, we evaluated debris extrusion with and without resorption and with and without the use of a path file in primary molar teeth prepared with ProTaper Ultimate (PTU) Prime and TruNatomy (TRN) Prime rotary file systems. Forty resorbed and forty non-resorbed primary molar teeth were collected. Both groups were divided into four subgroups (n = 10). The Eppendorf tubes were weighed pre-debris. The distal canals of the teeth were prepared with PTU Prime and TRN Prime file systems, with and without the use of path files. The debris-filled tubes were weighed, and the weight of only the extruded debris was calculated by subtraction. The data were analyzed using a three-way analysis of variance (ANOVA) test. The presence of tooth resorption significantly increased debris extrusion, and the use of a path file significantly decreased debris extrusion ( p < 0.001). The binary and ternary interactions of the three evaluated parameters among the groups showed no significant differences in terms of the amount of debris extruded ( p > 0.05). While debris extrusion was observed in all groups, the use of a glide path file in primary teeth before the preparation process resulted in less debris extrusion., Competing Interests: The authors declare no conflict of interest., (©2024 The Author(s). Published by MRE Press.)

The accomplishment of a successful pulpectomy depends on multiple factors that involve targeted removal of the causative irritants and soft and hard tissue debris by mechanical and chemical means. Compare and evaluate the efficacy of canal preparation and volumetric filling using conventional files and two rotary file systems using cone beam computed tomography (CBCT). Thirty freshly extracted human primary second molars were randomly divided into three groups of 10 teeth each. After access opening and working length determination, pre-operative volume analysis was done using CBCT. The canals were then instrumented by either hand K-files, ProTaper rotary files or Kedo-SG Blue rotary files. Post-operative volume analysis was performed using CBCT. All the canals were obturated using Metapex and scanned again using CBCT. Mean values of the pre- and post-operative canal volumes were analyzed using one-way Analysis of Variance (ANOVA). Inter- and intra-group volumetric changes were analyzed statistically using a post hoc test. The mean difference in volume after canal preparation and obturation was the highest in the Kedo-SG Blue group, followed by the ProTaper group and the least in the hand K group ( p = 0.001). Inter-group comparison showed statistically significant differences between the hand K group and ProTaper group ( p = 0.001), the ProTaper group and Kedo-SG Blue group ( p = 0.001), and the hand-K group and Kedo-SG Blue group ( p = 0.02). The volume of preparation and obturation was the highest using Kedo-SG Blue, followed by the ProTaper file systems., Competing Interests: The author declares no conflict of interest., (©2024 The Author(s). Published by MRE Press.)

Nickel-titanium (NiTi) instruments offer many advantages during endodontic instrumentation; however, the fracture risk within the canal remains a concern. Manufacturers continuously develop and introduce instruments to the market with supposedly enhanced cyclic fatigue resistance and increased flexibility, achieved through different proprietary manufacturing processes, the details of which have not been made public. In recent years, two rotary systems specially designed for deciduous teeth have been commercially available, but information about their performance is lacking. This investigation aimed to identify which manufacturing process provides better cyclic fatigue resistance: the AF-H Wire technology used in the AF baby rotary files (AF-f) or the CM-Wire technology used in the i3 Gold deciduous teeth rotary files (i3G-f). Forty rotary International Organization for Standardization (ISO) 25/04 files were tested in artificial canals with a standard geometry of 60° angle and 2.5 mm radius until fracture. The number of cycles to fracture was calculated, and the length of the fragments was measured. A scanning electron microscope (SEM) was used to examine the fracture surfaces and fragments. Energy dispersive spectroscopy (EDS) was used to determine the percentage weight of NiTi in each file. The statistical analysis (Mann-Whitney test) showed that the cyclic fatigue resistance of the AF-f was significantly higher ( p < 0.0001) than that of the i3G-f. Additionally, there was a significant difference ( p = 0.0419) in the length of the fractured fragments. All instruments showed one or more types of manufacturing defects and presented similar NiTi percentages by weight. The manufacturing process is critical to cyclic fatigue resistance, and there seems to be responsible for the difference in cyclic fatigue resistance between these similar instruments., Competing Interests: The authors declare no conflict of interest., (©2024 The Author(s). Published by MRE Press.)

Introduction: Curved mesial roots can be challenging for different stages of endodontic treatment. Preparation aims to enlarge, clean, and shape the root canal system, and hundreds of systems are available to carry it out. Aiming to maintain pericervical dentin, minimally invasive preparation was proposed, and with it, instruments with lower tapers emerged. This study aimed to evaluate the increase in canal volume, the centering ability of the instruments, and root canal transportation of two different rotary systems with lower tapers., Methods: Eighteen curved mesial roots of extracted mandibular molars were scanned by micro-CT at 3 moments: initial and after the 2 stages of endodontic preparation. The canals were prepared using TruNatomy (TN) and ProDesign Logic 2 (PDL2) instruments up to sizes 25.04 and 26.04, respectively, and after 36.03 and 35.05, respectively. The data were analyzed using parametric and nonparametric tests with a significance level of 5%., Results: TN and PDL2 systems showed no difference regarding the increase in the volume of the canals with the first instruments, but after preparation with a diameter size of 35 or 36, there was a difference (P < .01) between the systems in the cervical and middle thirds., Conclusion: Both systems shaped the mesial canals of mandibular molars while keeping low transportation and good centering ability in enlargements up to diameter size 35 or 36 with tapers of 3 or 5%., (Copyright © 2024 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: This study aimed to evaluate the dynamic cyclic fatigue resistance of Reciproc Blue files subjected to brushing motion., Methods: Twenty Reciproc Blue files (R25, VDW, Munich, Germany) were employed for chemical-mechanical preparation in root canals of 3D printed replicas of mandibular molars. The instruments were divided into two groups (n = 10): Group brushing motion, instrumentation with brushing motions; Group without brushing motion , instrumentation without brushing motions. Subsequently, the same instruments underwent cyclic fatigue testing using artificial canals consisting of a stainless-steel plate and an apical segment with a 45° curvature. Data regarding the time to fracture, number of cycles to fracture, and length of the fractured fragment were collected and subjected to statistical analysis using the t-test or Mann-Whitney test, with a significance level of 5%. Additionally, the fractured fragments were examined under a scanning electron microscope., Results: No statistical differences were observed between the groups in terms of time to fracture (P < .05), number of cycles to fracture (P < .05) and length of the fractured fragment (P < .05)., Conclusion: The brushing motion did not affect the dynamic cyclic fatigue resistance of Reciproc Blue files., (Copyright © 2024 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Aim: To describe the management of the palato-mesiobuccal (PMB) canal in maxillary second molars with fused roots using conventional techniques., Summary: Root canal treatment success hinges upon effectively addressing the intricate and variable anatomy of molar teeth. Failure to do so can lead to persistent infections and treatment failure. Recent advancements in imaging technologies have provided unparalleled insights into dental anatomy, especially in molars. Among these discoveries is the PMB canal, a unique anatomical variant recently reported for the first time in Endodontic literature. This canal, found in maxillary second molars with fused roots and originating from the coronal third of the palatal canal while traversing towards the mesiobuccal root presents challenges in clinical management due to its location. This article is the first to showcase the management of the PMB canal using conventional techniques. In the first case, a 38-year-old male patient presented with asymptomatic irreversible pulpitis in the maxillary second right molar. Following thorough instrumentation and irrigation, the presence of the PMB canal was discovered during root canal preparation. The canal was managed using rotary instruments and obturated successfully, resulting in a symptom-free tooth at an 8-year follow-up. The second case illustrates a similar scenario in a 23-year-old female patient presenting with symptomatic irreversible pulpitis in tooth 17. The PMB canal was identified during treatment and managed using rotary nickel-titanium instruments, leading to a favourable outcome at a 9-year follow-up., Key Learning Points: In fused roots of maxillary second molars, a PMB canal might be expected. Exploration of the buccal wall of the palatal canal under magnification after shaping procedures can reveal the PMB canal orifice in fused roots. Small tapers are suggested for the enlargement of the PMB canal. Continuous bleeding spots in the palatal canal might indicate a possible PMB canal orifice in vital cases. The use of an apex locator is suggested for the differential diagnosis of the PMB canal orifice from a perforation site., (© 2024 British Endodontic Society. Published by John Wiley & Sons Ltd.)

Aim: This study was twofold: (i) it aimed to investigate the morphometric changes of three temperature-sensitive nickel-titanium (NiTi) instruments at different temperatures, and (ii) to conduct an in vivo real-time analysis of intracanal temperature changes., Methods: Changes in the shape and length of XP-Endo Shaper, XP-Endo Finisher, and XP-Endo Finisher-R were evaluated in real time whilst heated in a temperature-controlled water bath from 22 to 45°C. Instruments were fixed to a laminated water-resistant 1 mm graph paper attached to a stone block. Instruments were imaged whilst subjected to increasing temperature using a digital camera attached to an operating microscope. From recorded videos, still frames were extracted at 10-s intervals and changes in the length and shape of each instrument were measured and changes were plotted against time. Moreover, the intracanal temperature of distal roots of lower molars was measured in vivo for patients attending the clinic for non-surgical root canal treatments. The temperature was measured using a K-type thermocouple probe inserted into the mid-root level after irrigating the canal with a solution set at room temperature (22°C) or heated to 45°C. The intraoral and intracanal temperatures were recorded using a video camera for 180 s at 5-s intervals to plot the change in the intraoral and intracanal temperature, after both irrigation solution temperatures, with time., Results: The shape transformation of XP-Endo Shaper began at 31.5 ± 2.0°C and reached its optimal transformation at 35.1 ± 1.0°C. For the Finisher and Finisher-R, shape transformations began at 29.2 ± 1.9 and 26.9 ± 2.2°C reaching the optimal transformation at 33.9 ± 1.4 and 32.7 ± 1.7°C, respectively. The average decreases in lengths of XP-Endo Shaper, Finisher, and Finisher-R after full transformation were 0.43 ± 0.23, 1.07 ± 0.22, and 1.15 ± 0.22 mm, respectively. The intracanal temperature reached 32.9 ± 0.8 and 33.2 ± 1.0°C after 3 min of application of irrigation solutions set at 22 or 45°C, respectively., Conclusion: The tested instruments exhibited diverse changes in their shapes and lengths at varying temperatures. Despite the temperature of the irrigation solution, the intracanal temperature consistently remained lower than the intracanal temperature once equilibrium was reached. This highlights the importance of considering the temperature of irrigation solution during in vitro testing of endodontic instruments., (© 2024 British Endodontic Society. Published by John Wiley & Sons Ltd.)

Introduction: The aim of this study was to evaluate changes in geometry following root canal preparation using R-Motion instruments with different apical sizes and tapers., Methods: Fifty-four mesial canals of mandibular molars with single curvature of angles ranging between 20° and 30° were stratified into 3 groups according to their internal anatomy (R-Motion 25/.06, 30/.04, Reciproc Blue) (n = 18 per group). Micro-computed tomography was used to standardize the samples before instrumentation and, after instrumentation, to assess canal transportation, changes in canal volume and centering ability. Canals were irrigated with 17% EDTA and sodium hypochlorite, and the final rinse included subsonic agitation of these solutions. Measurements were analyzed automatically using the Dragonfly software (Come, Montreal, Canada) and were confirmed by a technician and an endodontist, based on a previously validated methodology. The results were analyzed using the Kruskal-Wallis's and Mann-Whitney's tests. The level of statistical significance was set at 5%., Results: Significant differences were found in the coronal third for canal transportation, with Reciproc Blue R25 having greater values compared with both R-Motion instruments (P < .05) and greater changes in volume when compared with R-Motion 30/.04 (P < .05)., Conclusions: R-Motion of apical size and taper 25/.06 and 30/.04 were associated with similar changes in geometry following root canal preparation in curved mesial canals of mandibular molars, whereas Reciproc Blue was associated with greater canal transportation in the coronal root third., (Copyright © 2024 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Background: The screw-in effect is a tendency of a nickel-titanium (NiTi) rotary endodontic file to be pulled into the canal, which can result in a sudden increase in stress leading to instrument fracture, and over-instrumentation beyond the apex. To reduce screw-in force, repeated up-and-down movements are recommended to distribute flexural stress during instrumentation, especially in curved and constricted canals. However, there is no consensus on the optimal number of repetitions. Therefore, this study aimed to examine how repeated up-and-down movements at the working length affect torque/force generation, surface defects, and canal shaping ability of JIZAI and TruNatomy instruments., Methods: An original automated root canal instrumentation device was used to prepare canals and to record torque/force changes. The mesial roots of human mandibular molars with approximately 30˚ of canal curvature were selected through geometric matching using micro-computed tomography. The samples were divided into three groups according to the number of up-and-down movements at the working length (1, 3, and 6 times; n = 24 each) and subdivided according to the instruments: JIZAI (#13/0.04 taper, #25/0.04 taper, and #35/0.04 taper) or TruNatomy (#17/0.02 taper, #26/0.04 taper, and #36/0.03 tape) (n = 12 each). The design, surface defects, phase transformation temperatures, nickel-titanium ratios, torque, force, shaping ability, and surface deformation were evaluated. Data were analyzed with the Kruskal-Wallis and Dunn's tests (α = 0.05)., Results: The instruments had different designs and phase transformation temperatures. The 3 and 6 up-and-down movements resulted in a smaller upward force compared to 1 movement (p < 0.05). TruNatomy generated significantly less maximum torque, force, and surface wear than JIZAI (p < 0.05). However, TruNatomy exhibited a larger canal deviation (p < 0.05). No statistical differences in shaping ability were detected between different up-and-down movements., Conclusions: Under laboratory conditions with JIZAI and TruNatomy, a single up-and-down movement at the working length increased the screw-in force of subsequent instruments in severely curved canals in the single-length instrumentation technique. A single up-and-down movement generated more surface defects on the file when using JIZAI. TruNatomy resulted in less stress generation during instrumentation, while JIZAI better maintained the curvature of root canals., (© 2024. The Author(s).)

Background: The aim of this study was to compare the cyclic fatigue resistance (CFR) of the newly developed pediatric nickel-titanium (NiTi) rotary file systems for root canal preparation of primary teeth., Methods: Eighty pediatric NiTi rotary file systems files were used in this study, including 20 EasyInSmile X-Baby (25/0.04), 20 Scope miniScope (25/0.04), 20 EndoArt Pedo Gold (25/0.04), and 20 EndoArt Pedo Blue (25/0.04) files. Static CFR tests; performed on a custom-made stainless steel block with an inner diameter of 1.5 mm, an angle of curvature of 60° and a curved artificial canal with a radius of curvature of 5 mm. The test system was filled with distilled water and the temperature was kept constant at 35 ± 1 °C. The files were rotated in the simulated canal until fracture occurred. The number of cycles to failure (NCF) data was recorded, and all the fracture surfaces of the files were evaluated using scanning electron microscopy (SEM). One-way ANOVA and Tukey tests were used for statistical analysis of the data, and the significance level was set at p < 0.05., Results: EndoArt Pedo Blue showed the highest NCF values (2668.10 ± 755.26), while the miniScope showed the lowest NCF values (453.65 ± 72.51), with a statistically significant difference between all the tested file systems (p < 0.05). There was no statistical difference in terms of fractured fragment lengths among all tested files (p > 0.05)., Conclusion: The EndoArt Pedo Blue file system showed the best CFR performance among the four file systems specifically designed for primary teeth., (© 2024. The Author(s).)

Objective: The aim of this in vitro study was to assess the stress distribution of novel endodontic rotary files of different cross sections and metallurgy against the root canal wall at three different levels by using finite element analysis., Methods: A total of 60 novel NiTi rotary files were included in this study after being scanned for any surface deformities using a scanning electron microscope. The scanned files were assigned into 4 groups of 15 samples each based on their metallurgy and design: Group A-TruNatomy, Group B-XP-endo Shaper, Group C-F360, and Group D-2shape files. ANSYS® 15 Workbench finite element software (Canonsburg, Pennsylvania, United States) was used to numerically analyse the stress created by computer-aided models of these instruments on the dentinal wall of a simulated root canal to test the mechanical behaviour of these files. All data were analysed using one-way ANOVA with post hoc Tukey analysis, the Shapiro Wilk test, and Levene's test. The significance level was set at 5%., Results: XP-endo Shaper files employed minimal stress on the surface of dentine during instrumentation, and F360 files exerted maximum stress on the dentinal wall. However, no statistically significant difference was found among the groups in relation to the amount of stress produced at the distinct levels of the root canal wall (p>0.05)., Conclusion: There was no discernible difference in stress generation among the four groups in the current investigation. Therefore, it can be inferred that the upgrade in design and metallurgy of rotary files has the potential to downgrade the stress during the shaping of the canal and the menace of instrument breakage during their clinical usage.

This is a series of 7 cases in which the operator penetrated lateral canals with instruments. Two teeth presented with irreversible pulpitis, 4 with necrotic pulps, and 1 with previous treatment. Except for the teeth with pulpitis, all the others were associated with apical periodontitis. The main root canal was always relatively straight, with the lateral canals at the middle third of the root. Suggestive images of lateral canal presence were seen on periapical radiographs in five cases. The clinician introduced intentionally small hand instruments in the lateral canal in 5 cases, while the penetration was fortuitous in the others. The lateral canals were obturated in all cases. Follow-up examination was possible in five cases, all of them showed evidence of successful clinical and radiographic outcomes. Introducing files into lateral canals may permit some preparation and penetration of irrigant solution, favoring disinfection and, consequently, enhancing the treatment outcome. (EEJ-2023-05-063).

Background: To evaluate the accuracy of the electronic apex locators (EALs), and Cone-Beam Computed Tomography (CBCT) scanning, both in working length (WL) determination and in the detection of root canal perforations in retreatment cases., Methods: Sixty human mandibular premolars were selected. After crown removal partially and canal access, root canals were instrumented and irrigated. The obturation process utilized gutta-percha and sealer with warm vertical compaction. Two groups were distinguished: one without perforation (Group 1) and the other with an apical third perforation (Group 2). Retreatment included filling removal, apical preparation, and irrigation. Actual working lengths (AWL) were determined using a stereomicroscope. CBCT images were used to measure CBCT working length (CWL), with adjustments for optimal views. Propex II and Dentaport ZX were used to measure electronic working length (EWL). Differences between EWL and AWL, as well as CWL, were analyzed to gauge accuracy. Data underwent Two-way ANOVA analysis. Measurements within ± 0.5 and ± 1 mm tolerance ranges were deemed successful for each device, followed by applying the Pearson Chi-square test., Results: The study reveals no significant inter-group variations in device performance (p > .05). Dentaport ZX missed detecting perforation in two Group 2 (apical perforation) cases. For ± 1 mm tolerance, Propex II displayed the highest success in Group 2 (apical perforation)., Conclusion: This study demonstrates the comparable performance of Propex II, Dentaport ZX, and CBCT in endodontic retreatment, providing insights into diagnostic reliability., (© 2024. The Author(s).)

Background: This study aimed to investigate the perspectives, preferences, and clinical experiences regarding using electronic apex locator and apex locator integrated instrumentation of dentists and endodontists., Methods: A web-based questionnaire consisting of 3 parts and 23 closed-ended questions to achieve the objective of the study was carried out in ethical conditions between August and October 2023. The first part of survey included demographic information, while the second part was about evaluating electronic apex locator usage. In the last part, only participants' use of apex locator-integrated instrumentation was evaluated. Data were analyzed at a significance level of p < 0.05., Results: A total of 297 clinicians, including 59 endodontists and 34 endodontic residents/Ph.D. students participated in the questionnaire. Endodontists and endodontic residents/Ph.D. students perform statistically significantly more root canal treatments per week on average (p = 0.001). For the working length determination method (multiple option question), 78.5% of participants use an electronic apex locator and 39.7% apex locator-integrated engines. However, the preference rate for electronic apex determination technique was generally 95.6%, with the full rate confirmation of endodontists and endodontic residents/Ph.D. students (100%). A total of 21 endodontists out of 59 prefer apex locator integrated engine-driven instrumentation. Although many of these specialized clinicians use this technique, they stated that they measure electronic working length passively for confirmation of the working length before (90.5%) and after the preparation (66.7%)., Conclusions: Dentists, as well as endodontists, are skeptical about apex locator-integrated engine-driven instrumentation. Using this technique as a supporter rather than a primary way for preparation within safe limits may give safer results in terms of treatment outcomes., (© 2024. The Author(s).)

The aim of this study is to evaluate the effect of different irrigation activation methods on root canal sealer penetration in teeth with simulated internal root resorption (IRR) and calcium hydroxide (CH) applied using a confocal laser scanning microscope (CLSM). 60 incisors with a single root and a single canal were included in the study. IRR cavities were created in the middle third of the root canal, and CH was placed. The samples were randomly divided into 4 groups (n = 15) according to the irrigation activation method to be tested: standard needle irrigation (SNI), sonic activation (EDDY), photon-induced photoacoustic flow (PIPS), and shock wave enhanced emission photoacoustic flow (SWEEPS). After irrigation activation applications, the root canals were obturated. Sections of 1.0 ± 0.1 mm were taken from the apical, middle, and coronal regions of each sample. The penetration area (µm 2 ) and maximum penetration depth (µm) of the root canal sealer were examined by CLSM and analyzed using ImageJ software. Statistical analysis was performed with a one-way ANOVA and post-hoc Tukey test at the P < 0.05 significance level. Among all irrigation activation methods tested, both the penetration area and maximum penetration depth of the root canal sealer were greater in the coronal region than in the apical region (p < 0.05). In the IRR region, there was no difference in terms of maximum penetration depth between PIPS and SWEEPS (p > 0.05), it was highest in SWEEPS (p < 0.05). PIPS and SWEEPS were better than other irrigation activation methods in the penetration of root canal sealer in the resorption areas of teeth with IRR., (© 2024. The Author(s), under exclusive licence to Springer-Verlag London Ltd., part of Springer Nature.)

BACKGROUND This systematic review of the literature aimed to identify published studies and evaluate them on the quality of root canal fillings (RCF) and procedural errors with rotary systems for in vivo studies prepared for different clinical settings. MATERIAL AND METHODS A full literature exploration was conducted in Clarivate Analytics' Web of Science, Elsevier's Scopus, Embase, and PubMed for studies published between January 2020 and March 2024. A manual search was also performed by reviewing the references of selected papers. The following keywords were used: quality of root canal filling(s) OR quality of root canal obturation, root canal obturation OR endodontic treatment, clinical setting (academic, private, governmental), AND/OR procedural errors and rotary instrumentation. RESULTS Sixteen clinical studies were included in this review. The acceptance percentages for obturation length, density, and taper were 76.3%, 74.7%, and 82.5%, respectively, indicating significantly high, good ratios. The overall RCF recorded showed that 68.2% of root canal obturations were considered acceptable. Acceptable rates remained higher than unacceptable rates in academic, hospital, and private settings, and percentages ranged from 65.2% to 93.0%. Only 5 studies reported procedural errors, namely, ledge formation, separated instruments, apical perforation, transportation, lateral perforation, and root/foramen perforation. CONCLUSIONS Using rotary instruments for different root canal treatment steps as instrumentation and obturations is highly recommended. Among different clinical setting and practice, these instruments resulted in a good and acceptable RCF, overall quality performed by those instruments, and few procedural errors.

Numerous systematic reviews (SRs) have produced conflicting findings on engine-driven nickel-titanium reciprocating instruments (reciprocating instruments) since Yared's seminal study 15 years ago. This umbrella review analysed SRs examining the clinical and laboratory evidence regarding reciprocating instruments for root canal treatment. SRs that evaluated qualitatively and/or quantitatively the outcomes postoperative pain, oral health-related quality of life (OHRQoL), shaping ability, debris extrusion, microbial load, endotoxins reduction, cyclic fatigue, file fracture, dentinal cracks and root canal filling removal were included. The AMSTAR 2 tool was used to evaluate SRs quality, while the ROBIS tool to assess risk of bias (RoB). Forty SRs were included. The SRs revealed predominantly 'high' RoB and 'critically low' quality. Most focused on technical outcomes, exhibiting significant methodological and statistical heterogeneity. Findings suggest comparable efficacy between reciprocating and rotary instruments. However, due to the scarcity of high-quality evidence, future well-designed studies and reviews considering core outcome measures are needed., (© 2024 The Author(s). Australian Endodontic Journal published by John Wiley & Sons Australia, Ltd on behalf of Australian Society of Endodontology Inc.)

This study assessed the ability of Twisted File Adaptive (TFA), TruNatomy (TRN) and VDW.Rotate (VR) instruments activated by continuous rotation (CR) and adaptive motion (AM) to shape curved root canals. Thirty mandibular molars with two separate mesial canals 20°-40° curved were collected and scanned using micro-computed tomography (μCT). The canals were then randomly assigned into six groups (n = 10): TRN, VR or TFA instruments activated by CR or AM. TRN groups 17.02, 20.04 and 26.04; VR groups 15.04, 20.05 and 25.06; TFA groups were shaped consecutively using 15K-file, 20.04 and 25.06. After they were shaped, the canals were scanned again. The volume of removed dentin, canal transportation and centring ratio were calculated μCT images. All data were analysed using the Kruskal-Wallis test or one-way analysis of variance (p < 0.05). With both kinematics, the TRN instrument removed the least amount of dentin, the VR-CR and the TFA-AM removed the most (p < 0.05). The transportation and centring ratios among all groups were similar (p > 0.05). The volume of dentin removed, the diameter or design features of the instruments and different kinematics did not affect the centring ratio and the amount of transportation and remained within safe limits. All three instruments activated by either kinematics were found to have similar effectiveness in shaping curved root canals., (© 2024 Australian Society of Endodontology Inc.)

Objectives: The aim of this research was to compare the penetration ability of calcium silicate-based sealers (iRoot SP and TotalFill BC HiFlow) and an epoxy resin-based sealer (AH Plus) into the lateral canals using the single-cone (SC) or continuous wave compaction (CW) obturation techniques., Methods: Ninety single-rooted human teeth received canal instrumentation and diaphanisation before artificial lateral canals were created at 3 different root levels. The specimens were randomly allocated into 6 groups based on the combination of obturation technique and sealer used. Radiographic and photographic measurements evaluated the percentage of sealer penetration. Statistical analysis was performed to compare the penetration ability amongst different types of sealers, obturation methods, and root levels., Results: Although TotalFill BC HiFlow sealer combined with the CW technique demonstrated greater sealer penetration at the coronal level (P < .05), the overall penetration ability of iRoot SP, TotalFill BC HiFlow, and AH Plus was not significantly different. The deepest sealer penetration was observed at the apical root level., Conclusions: All sealers showed similar penetration abilities into the lateral canals using the SC or CW techniques in vitro. Calcium silicate-based sealers have comparable penetration ability into lateral canals compared to epoxy resin-based sealers using SC or CW obturation techniques., Competing Interests: Conflict of interest None disclosed., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

This study assessed canal preparation effects on disinfection and dentin preservation. Thirty mandibular incisors were paired into two experimental groups (n = 10). Following contamination, the initial microbial sample was collected. Instruments 30/0.03 (Group 1) and 30/0.05 (Group 2) were employed and a second sample was obtained. Canals were enlarged using instruments 40/0.03 and 40/0.05, respectively, and a third sample was collected. Final irrigation was performed, and sample S4 obtained. A final scan evaluated volume, surface area, unprepared areas, removed dentin and dentin thickness. Data were analysed using Student t-test, Mann-Whitney, Kruskal-Wallis and Dunn tests. A significant difference was observed between S1 and other time points (p < 0.05). Comparison between groups showed no differences in bacterial loads and in the percentage of microbial reduction (p > 0.05). Group 2 exhibited greater reduction in dentin thickness than group 1 in the mesial aspect of the root (p < 0.05). Instrument 30/0.03 might provide effective disinfection and safety during mandibular incisors canal preparation., (© 2024 Australian Society of Endodontology Inc.)

Introduction: To compare the stress produced on the walls of simulated canals by rotary instruments with varied tip and taper sizes., Methods: Ninety isotropic transparent blocks, each containing a 60-degree curved canal, were distributed into 18 groups (n = 5) based on the instrument tip (sizes 10, 15, 20, 25, 30, and 35) and taper (sizes 0.02, 0.04, and 0.06). The blocks were fixed in a circular polariscope setup for dark field analysis. A digital camera was employed to capture the real-time birefringence patterns generated by each instrument. Digital image frames, corresponding to the instrument reaching the end of each canal third, were extracted and evaluated by 2 independent observers for the stress generation on canal walls. The data analysis employed a semi-quantitative scale ranging from 0 to 5. Cohen's Kappa coefficient test was used to determine the inter-observer agreement while the results were compared using Kruskal-Wallis test followed by an all-pairwise posthoc procedure (α = 5%)., Results: Inter-observer agreement was 0.95. A significant influence of the tip size on stress was observed across the coronal (P = .011), middle (P = .006), and apical (P = .026) thirds. In contrast, taper size did not affect the stress induced at the coronal (P = .509), middle (P = .958), or apical (P = .493) thirds. The variations in tip and taper sizes did not result in a significant stress differences among the thirds (P = .181)., Conclusions: The stress significantly increased across all canal thirds with larger tip sizes of rotary instruments, whereas the taper sizes did not influence the stress when compared to the canal thirds., (Copyright © 2024 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

This study aimed to evaluate the feasibility of preclinical training, specifically in root canal preparation, using a virtual educational system equipped with an operating microscope. Ten postgraduate general dentistry trainees and practitioners undergoing postgraduate training in endodontics participated. The telesimulation course included three steps: theory, demonstration of practical work by the teacher and lastly practical training by the participants. The digital environment including the dental microscope was presented, and the feedback was collected with a questionnaire. The majority of participants considered that the online video conference format allowed them to acquire theoretical content but also practical knowledge and skills, owing to the contribution of the operating microscope. The technical feasibility of endodontic telesimulation was demonstrated. The operating microscope has a potential role in distance education, enabling teaching to occur synchronously and collaboratively. This allows learners to interact with each other and demonstrators in real time., (© 2024 Australian Society of Endodontology Inc.)

Introduction: Nickel-titanium rotary endodontic files have been commercially available for decades, but more recent innovations have introduced heat-treated and surface-treated files. This study investigated the corrosion properties of various nickel-titanium files in normal saline and sodium hypochlorite (NaOCl)., Methods: Ten different file brands of size 40 with a 0.04 taper were subjected to electrochemical testing in 0.9% NaCl (saline) and 5.25% NaOCl at room temperature. The Open Circuit Potential (OCP) was observed for 1 hour followed by a cyclic polarization test from -300 to 700 mV and back to -300 mV (vs OCP). Nonparametric ANOVA and a pairwise comparison (P < .05) were used for statistical analysis of the OCP at 1 hour and the corrosion current (Icorr) obtained via the cyclic polarization test., Results: Significant differences (P < .05) were found between files with respect to OCP and Icorr in both solutions. Nine files exhibited significantly greater (P < .05) Icorrs in NaOCl than in saline. Conversely, pitting corrosion was observed in the saline solution but not NaOCl. Weak and/or moderate correlations existed between OCP and Icorr measures in the 2 solutions., Conclusion: Significant differences in electrochemical properties were observed among the 10 brands of files. Overall, there was not a clear trend between conventional, heat-treated, or surface-treated files among OCP or Icorr in either solution., (Copyright © 2024 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Objective: This is the first study evaluating the impact of different pecking motion depths on dynamic cyclic fatigue resistance of different endodontic instruments., Methods: Four nickel-titanium systems (Hyflex EDM OneFile 25/. ∼; Rotate 25/0.6; Mtwo 25/0.6; Reciproc Blue R25) were tested. Forty instruments from each group were subjected to 4 different pecking movements to evaluate their cyclic fatigue resistance. The distances for the pecking motion were 3-mm forward and backward, 1-mm (3-mm forward and 2-mm backward), 2-mm (4-mm forward and 2-mm backward), and 3-mm (5-mm forward and 2-mm backward). Speeds were 100 and 200 mm/min for the descending and ascending motion, respectively. The times to fracture (TtF) in seconds were recorded for each instrument. Data were statistically analysed by using 2-way ANOVA and Bonferroni multiple comparison post hoc test (P < .05)., Results: All instruments had a significant increase in cyclic fatigue resistance during the forward dynamic motion compared with the axial continuous. Overall, the heat-treated instruments reported higher fatigue strength than the untreated files (P < .05). Reciproc Blue and Hyflex EDM showed higher TtF in the forward movements of 1-/2-mm and 2-mm (P < .05), respectively while Mtwo 25.06 and Rotate 25.06 in the forward movement of 3-mm (P < .05)., Conclusions: Within the limits of this in vitro study, the pecking motion depths had varying impacts on the cyclic fatigue resistance of instruments. Reciproc Blue and Hyflex EDM performed significantly better with pecking motions of 1-and 2-mm. Improving endodontic instrument durability through specific pecking depths has the potential for improving clinical performance and reducing instrument failures., Competing Interests: Conflict of interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Objectives: This ex vivo study aimed to evaluate the influence of different filling techniques on the filling removal from oval root canals filled with bioceramic sealer., Methods: Thirty-six mandibular incisors with single oval canals were filled with bioceramic sealer following the techniques (n = 12): single-cone, modified McSpadden, or continuous wave of condensation, and scanned by micro-computed tomography (micro-CT). The filling was removed using the Clearsonic ultrasound tip and Reciproc system up to the R40 instrument, and the working time was recorded. The teeth were scanned again by micro-CT. Percentage of remnant volume (mm³) of the filling material, dentin thickness, and root canal transportation were measured. The data was analyzed using parametric and non-parametric tests with a significance level of 5%., Results: It took more time to remove the filling material using the continuous wave of condensation technique (p < 0.05), followed by the modified McSpadden and single-cone techniques. There was no difference (p > 0.05) when comparing the percentage of remaining filling material among the three groups, nor did it among the segments of each tooth. There was also no difference in the analysis of dentin thickness and transportation when comparing the groups (p > 0.05)., Conclusions: The filling technique did not influence the amount of remaining filling material, dentin thickness, and transportation. The working time was longer with thermoplastic filling techniques., Clinical Relevance: Endodontic retreatment in teeth filled with bioceramic sealers increases with their use. Several techniques are used to fill the root canals, thus, it is important to know whether the filling technique influences the non-surgical endodontic retreatment., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Cleaning and shaping the root canal system are essential steps for performing successful endodontic therapy, and are challenging procedures in the apical region. This study aimed to conduct an ex vivo assessment of the debridement ability of the WaveOne Gold (Medium 35/.06) and TruNatomy (Medium 36/.03) systems in the apical third of round root canals of mandibular premolars. Forty-eight teeth, extracted for orthodontic or periodontal reasons, were divided into three groups (n=16), as follows: Group C, control (without instrumentation or irrigation); Group WOG, instrumentation with WaveOne Gold; Group TN, instrumentation with TruNatomy. A total of 40 mL of 2.5% sodium hypochlorite and 5 mL of 17% ethylenediamine tetraacetic acid were used per root canal in all the groups. Ten 0.5-μm serial cross-sections per specimen were obtained every 0.2 mm from a 2-mm segment of the apical region, extending from 1 to 3 mm short of the root apex. The sections were stained with hematoxylin-eosin and analyzed under a digital microscope (100x). The percentages of unprepared walls and remaining debris were quantified using ImageJ software. Generalized linear models were used to analyze the results (α=5%). Groups WOG and TN had significantly lower percentages of unprepared walls and remaining debris than Group C (p<0.05). There was no significant difference between groups WOG and TN for either of the variables studied (p>0.05). Instrumentation with the WaveOne Gold Medium and TruNatomy Medium instruments was associated with equivalent percentages of unprepared walls and remaining debris in the apical third of round canals of mandibular premolars.

Background: This is a triple-blinded, prospective split-mouth clinical trial. It is important to shed light on the effect of different apical preparation sizes regarding postoperative pain within the same patient with the same pulpal histological status. The aim is to compare and evaluate the severity of postoperative pain following apical enlargement with two different sizes after the IBF using the visual analogue scale., Methods: Fifty "teeth" in 25 patients were assigned into two equal groups (25 per group) using E3 Azure rotary files; Group A was prepared two sizes greater than the Initial binding file (IBF) (the largest K file to bind at the actual working length) mesial canals, which were enlarged to 35#/0.04 and 40#/0.04 for the distal canals. Group B was prepared in three sizes larger than the IBF: 40#/0.04 for mesial canals and 45#/0.04 for the distal canals. On a modified VAS form, patients were questioned to indicate the degree of their pain and assisted in narrating their pain intensity during the following periods: 12, 24, and 72 h, and after a week. VAS data were non-parametric and analyzed using the signed-rank test for intergroup comparisons, Freidman's test, and the Nemenyi post hoc test for intragroup comparisons. The significance level was set at p < 0.05., Results: showed that regardless of measurement time, enlargement of apical preparation was significantly associated with higher pain scores (p < 0.001). Within both groups, there was a significant reduction of measured pain score with time, with values measured after 12 and 24 h being significantly higher than values measured at other intervals (p < 0.001) and with values measured after three days being significantly higher than 1-week value (p < 0.001)., Conclusion: The size of apical preparation had a significant effect on postoperative pain., Trial Registration Number & Date: NCT05847738, 08/05/2023., (© 2024. The Author(s).)

Objective: Although apex locators are generally effective tools for determining root canal working length, they may produce inaccurate results in some cases. The present study aimed to evaluate the efficacy of ultrasonography as an alternative method for measuring root canal length., Materials and Methods: Forty-seven anterior teeth with apical lesions were selected for the study. Initially, an electronic apex locator was used to measure the working length. Subsequently, ultrasonography was employed to visualize the root apex and determine the working length. During ultrasound imaging, a K-file No. 15 was inserted into the root canal until its tip was visible on the ultrasound monitor. Measurements obtained from both methods were compared using an independent sample t-test. Correlations were assessed with the Pearson correlation coefficient, and agreement was determined using the Bland‒Altman plot., Results: The mean working canal length was 19.9 mm for the apex locator and 20.6 mm for the ultrasonography-guided method. No significant differences were observed between the data obtained using the apex locator method and the data obtained using the ultrasonography guidance method. Furthermore, a high level of agreement was identified between the two techniques., Conclusion: Ultrasonography can be used to visualize the apex effectively and determine canal length, especially when canal length determination is uncertain for various reasons., (© 2024. The Author(s).)

Both root canal sealer-based and supplementary protocols may influence removal of filling material during endodontic retreatment. Mesial root canals of extracted mandibular molars were prepared using HyFlex EDM 25/.08, and filled with a calcium silicate sealer (Bio-C Sealer), or an epoxy resin (AH Plus), using the single cone technique (n = 12). Retreatment was performed using ProDesign Logic (PDL) RT and PDL 35/.05. The specimens were randomly divided into two experimental groups (n = 12), and the sealers were distributed similarly. A supplementary protocol was performed with PDL 50/.01 or XP-endo Finisher. Root canal transportation and volume, in addition to the remaining filling material percentage were evaluated using high-resolution (5 µm voxel size) micro-CT. Statistical analysis was performed using t-tests (α = 0.05). Root canals filled with AH Plus presented high residual filling material (p < 0.05). Both protocols decreased residual volume of filling material in the apical third (p < 0.05). PDL 50/.01 increased the apical root canal volume (p < 0.05). No difference was observed between the systems regarding canal transportation (p > 0.05). In conclusion, AH Plus is more difficult to remove from the apical third than Bio-C Sealer. PDL 50/.01 and XP-endo Finisher enabled greater removal of filling materials in the apical third, in the retreatment of curved root canals, without promoting apical transport.

Context: The smear layer may harbor many bacteria; hence, alternative methods are used to disrupt and remove biofilm., Aim: The aim of the study was to compare the effectiveness of EndoActivator, PATS Vario System, and XP-endo Finisher files on smear layer removal using a scanning electron microscope., Subjects and Methods: Sixty single-rooted extracted premolars with Vertucci Type 1 configuration were decoronated and divided into four groups. The groups were instrumented with the rotary ProTaper file system. All specimens were flushed with 1 ml of 3% sodium hypochlorite. Group 1 was irrigated with a conventional needle and syringe. In Group 2, the irrigant was activated with an EndoActivator. In Group 3, the irrigant was activated with PATS Vario system, and in Group 4, XP-endo Finisher files were used after biomechanical preparation to remove debris and smear layer. All specimens were finally rinsed with 3 ml of 3% sodium hypochlorite. The teeth underwent longitudinal splitting and grooving in the coronal, middle, and apical thirds, and then, the samples were taken for scanning electron microscopy to evaluate the amount of smear layer removal in each third., Results: The middle and coronal thirds Showed that almost similar efficacy to remove smear layer in both Group II and Group III. At the apical third, Group III showed comparatively better results than Group I, II, and IV, respectively., Conclusion: Equal amount of smear layer was seen with EndoActivator and PATS Vario system when used as sonic irrigation devices., (Copyright © 2024 Copyright: © 2024 Journal of Indian Society of Pedodontics and Preventive Dentistry.)

Background: The dentinal debris produced during root canal preparation can be extruded through the apical foramen, which may cause undesired consequences, such as the postoperative inflammation of periapical tissues., Objectives: The aim of the present in vitro study was to evaluate the effect of glide path preparation on apical debris extrusion for the Reciproc®, WaveOne Gold® and One Curve file systems., Material and Methods: A total of 72 mandibular incisors were divided into 6 groups according to the nickel-titanium (NiTi) system used and glide path preparation: group Rp - Reciproc; group Rp-O - Reciproc after glide path preparation; group WG - WaveOne Gold; group WG-O - WaveOne Gold after glide path preparation; group OC - One Curve; and group OC-O - One Curve after glide path preparation. The preand post-instrumentation weight of Eppendorf tubes was measured. The pre-weight was subtracted from the post-weight to calculate the amount of apically extruded debris. The data was analyzed using the one-way analysis of variance (ANOVA) with the statistical program PASW Statistics for Windows, v.18.0., Results: No statistically significant differences were found between the single-NiTi file systems with different kinematics in terms of apical debris extrusion, with or without glide path preparation (p > 0.05)., Conclusions: The amount of apically extruded debris was not affected by the kinematics of different single-NiTi file systems. Moreover, creating a glide path had no effect on the apically extruded debris in straight root canals.

Introduction: In an effort to enhance the quality of mechanized endodontic instruments, various thermal treatment methods, and design modifications have been suggested. However, upon evaluation, these endodontic instruments may exhibit microscopic irregularities. The objective of this in vitro study was to analyze the cutting capacity, surface finish, and mechanical properties of Nickel-Titanium 25/.04 Rotate (VDW GmbH, Munich, Germany) and LOGIC 2 (Easy Equipamentos Odontológicos, Belo Horizonte, MG, Brazil) rotary instruments., Methodology: Twenty rotary instruments were divided into 2 groups: GR, the group with ROTATE instruments (n = 10); and GL2, the group with LOGIC 2 instruments (n = 10). They were evaluated for roughness, using a profilometer, for bending resistance, buckling resistance, and cutting capacity using a universal testing machine, as well as for torsional strength (torque and angular deflection) using a torquemeter. The instruments were visualized before and after the mechanical tests through scanning electron microscopy., Results: GR showed better surface finish in terms of roughness, greater cutting capacity, and greater angular deflection than GL2 (P < .05). However, GL2 showed better flexibility than GR (P < .05). GL2 and GR did not show statistically significant differences in terms of buckling and torque (P > .05)., Conclusion: The ROTATE and LOGIC 2 rotary instruments differed in their surface finish, cutting capacity, and mechanical properties, except for their buckling resistance and required fracture torque., (Copyright © 2024 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

We aimed to evaluate the screw-in force, torque generation, and performance of three nickel-titanium (NiTi) glide-path files with different rotational kinetics. ProTaper Ultimate Slider (PULS) and HyFlex EDM Glide-path (HEDG) files were used for canal shaping with constant rotation (CON) or the alternative rotation technique (ART). In the ART mode, the NiTi file was periodically rotated at a speed of 1.5 times faster than that in the CON mode. WaveOne Gold Glider was used with reciprocating motion (WOGG&#95;RCP). Sixty J-shaped resin blocks were assigned to five groups: PULS&#95;CON, PULS&#95;ART, HEDG&#95;CON, HEDG&#95;ART, and WOGG&#95;RCP (n = 12). Glide-path preparation was performed using an automated pecking device. During glide-path preparation, the screw-in force and clockwise and counterclockwise torques were recorded and the number of pecking motions required to reach the working length was determined. The centering ratio was calculated after glide-path preparation using stereomicroscopic images. Data were analyzed using one-way analysis of variance with the Games-Howell post hoc test and the Kruskal-Wallis test with Bonferroni correction. PULS&#95;ART generated a lower maximum screw-in force than PULS&#95;CON. The average number of pecking motions required to reach the working length by HEDG&#95;ART was lower than that by HEDG&#95;CON. The mean centering ratios of PULS&#95;CON and HEDG&#95;CON were - 0.04 and - 0.06, respectively, while those of PULS&#95;ART, HEDG&#95;ART, and WOGG&#95;RCP were 0.09, 0.01, and 0.08, respectively. The ART mode reduced the screw-in force of PULS and enabled faster glide-path preparation with the HEDG file., (© 2023. The Author(s), under exclusive licence to The Society of The Nippon Dental University.)

Introduction: The purpose of this study was to evaluate the effect of side flattening of cutting flutes on the cyclic resistance and torsional resistance of nickel-titanium files., Methods: Both novel flattened Platinum V.EU (PL) and standard nonflattened CC Premium V.EU (CC) rotaries were tested. For cyclic fatigue tests, all the files were rotated in an artificial root canal with a curvature of 45° and a radius of 6.06 mm at 300 rpm (n = 15 in each group). The number of cycles to failure (NCF) was calculated. For torsional tests, the files were rotated at 2 rpm clockwise until fracture occurred. The maximum torque value at fracture was measured and the toughness and distortion angle were computed. Subsequently, 5 fragments were randomly selected in each experiment, the cross-section and longitudinal direction of the fragments were photographed using a scanning electron microscope. An unpaired t-test was performed at a significance level of 95%., Results: There was a statistically significant difference in NCF between CC and PL (P < .05). CC showed higher NCF than PL. There was no statistically significant difference between CC and PL with regards to the parameters related to torsional resistance (distortion angle, ultimate strength, and toughness) (P > .05)., Conclusion: Within the limitations of this study, side flattening of the file did not improve cyclic resistance or torsional resistance of the files. As side flattening may reduce a file's cyclic resistance, such files should be used with caution in clinical practice., (Copyright © 2024 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Aim: To analyse the effect of ultrasonic irrigant activation (UIA) and the GentleWave (GW) multisonic irrigation (GW) with minimal instrumentation on the root canal microbial diversity in an ex vivo model that used extracted molars with a history of pulp necrosis., Methodology: Twenty-three mandibular molars were prepared ex vivo for collection of superficial (surface control), pre-treatment and post-treatment samples 24 h after extraction. Samples were divided into two groups: UIA using 6% NaOCl (n = 11) and GW group (n = 12). All samples were processed using quantitative real-time polymerase chain reaction (qPCR) and 16S rRNA next-generation sequencing to measure microbial diversity before and after the antimicrobial treatment. For qPCR, a t-test (α = .05) was used to compare the log10 reduction. The Chao1 and Shannon indices evaluated alpha diversity. Differences in community composition (beta diversity) were evaluated by analysis of similarity (ANOSIM). Kruskal-Wallis test with Bonferroni corrections was performed to evaluate the differences in abundances genera in the samples., Results: Quantitative real-time polymerase chain reaction revealed an estimated 1.6 and 2.6 log10 reduction for UIA and GW groups respectively (p = .048). An average of 5 ± 4 and 3 ± 5 operational taxonomic units (OTUs) were found in surface's samples in the UIA and GW group respectively. These values were significantly lower (p < .001) compared to the number of preoperative OTUs in those groups (155 ± 79 and 187 ± 121). In assessing beta diversity, there were no significant differences found in pre-treatment samples (R = .090, p = .070 ANOSIM with Bonferroni corrections). Also, no significant differences in community composition were observed in post-treatment samples (R = -.05, p = .829). After treatment, there was a significant reduction of Eubacterium using conventional treatment with UIA and a significant reduction of Prevotella using minimal instrumentation with GW irrigation (p = .007 and p = .002 respectively)., Conclusion: Quantitative PCR analysis revealed a significant reduction in microbial load for GW group. Overall, diversity changes were similar between UIA and GW irrigation in this ex vivo model that used extracted teeth with a history of pulp necrosis. OTUs obtained from the surface sample were negligible and did not affect the statistical outcome of the study., (© 2023 The Authors. International Endodontic Journal published by John Wiley & Sons Ltd on behalf of British Endodontic Society.)

The aim of this study is to evaluate the effect of various disinfection protocols on the cutting efficiency and chemical composition of ProTaper, Twisted File, Twisted File Adaptive, and Hedström files. Four experimental groups (n = 10) were presoaked in either enzymatic solution or 1% sodium hypochlorite for 30 min, followed by either 5 or 15 min of ultrasonic cleaning and then autoclaved. Resin-simulated canals with a single curvature of 38-40° were prepared by each instrument system. Cutting efficiency of each instrument was analyzed by subtracting the final weight from the initial weight of the resin blocks. Chemical compositions were studied by field emission scanning electron microscopy and X-ray energy-dispersive spectrometry. The cutting efficiency of Hedström, ProTaper, and Twisted File instruments decreased compared to their control groups (p < 0.05) whereas it did not change for Twisted File Adaptive. More corrosion was detected with longer ultrasonication time. No difference was observed regarding the pre-soaking media. Disinfection protocols exerted a significant overall effect on the performance of Hedström, ProTaper, and Twisted File instruments. Corrosion, microcracks, and crevices were evident on all tested instruments after disinfection protocols applied. All disinfection protocols, regardless of the pre-soaking media used or the ultrasonic cleaning time applied, have some effect on the cutting efficiency and the surface characteristics of the files., (© 2024. The Author(s), under exclusive licence to The Society of The Nippon Dental University.)

Aim: To compare the efficacy of Enterococcus faecalis biofilm removal using the GentleWave System (GWS) (Sonendo Inc, CA) on non-instrumented versus minimally instrumented root canal systems., Methodology: Thirty-four mandibular molars were autoclaved and allocated to four groups: Negative control (n = 5); positive control (n = 5); Group 1: non-instrumentation + GWS (NI + GWS) (n = 12); and Group 2: minimal instrumentation + GWS (MI + GWS) (n = 12). Of 34 samples, 24 samples with Vertucci type 2 configuration within the mesial root of each sample were allocated to Groups 1 and 2 and then matched based on the working length and root canal configuration. After inoculation of samples with E. faecalis for 3 weeks, the GWS was used on Group 1 without any instrumentation and Group 2 after instrumentation of mesial canals until size 20/06v. CFU and SEM analysis were used., Results: Log 10 (CFU/mL) from the positive control, and Group 1 and 2 were 7.41 ± 0.53, 3.41 ± 1.54, and 3.21 ± 1.54, respectively. Both groups showed a statistically significant difference in the reduction of viable E. faecalis cells compared to the positive control (Group 1 [p = .0001] and Group 2 [p < .0001]), whilst showing no significant difference between the two tested groups (p < .05)., Conclusion: The use of GWS on the non-instrumented root canal system could be an effective disinfection protocol in removing the biofilm without dentin debris formation., (© 2024 The Authors. International Endodontic Journal published by John Wiley & Sons Ltd on behalf of British Endodontic Society.)

Objectives: This study compared, retrospectively, the incidence of clinical errors and effects on treatment outcomes, when students were exposed to two different instrumentation techniques: a hybrid rotary technique (HYB), consisting of both hand instrumentation with hand stainless steel and Ni-Ti files plus the use of a rotary system (Vortex Blue, Dentsply Sirona), versus a full reciprocation instrumentation technique (WaveOne Gold [WOG], Dentsply Sirona)., Methods: A total of 368 endodontic cases (n = 184) in anterior and premolar teeth, completed by dental students at the University of Michigan School of Dentistry from 2013 to 2022, were used for the study. The groups were evaluated by two calibrated clinicians, observing the incidence of clinical errors: file separations, over-instrumentation, ledges and transportations. Treatment outcomes were also observed. Data were analyzed statistically by Fisher's exact test and Mann-Whitney U test (p < 0.05)., Results: No significant difference in file separations, ledges, and transportation was observed between the two groups. However, the WOG Group experienced significantly more over-instrumentation than HYB group, although this did not significantly affect tooth survival or periapical index (PAI). Cases with PAI scores of 5 were found to have significantly less tooth survival compared to the other PAI scores., Conclusions: It can be concluded that both techniques in our study are well suited to advancing the endodontic dental education of students and novice operators, anticipating relatively successful outcomes of tooth survival, as long as the cases selected are less severe in progression preoperatively., (© 2024 The Authors. Journal of Dental Education published by Wiley Periodicals LLC on behalf of American Dental Education Association.)

Introduction: This ex vivo study evaluated the accuracy of the Electronic Apex Locator (EAL) and Automatic Apical Stop (AAS) functions of the E-Connect S+ and Morita Tri Auto ZX2+ cordless apex locators in determining patency length., Methods: Sixty-four human teeth with a single root were randomly allocated into E-connect or Morita groups (n = 32). The canals were accessed and preflared, after which a size 15 K-file was inserted into the canal to the major foramen and recorded as the actual length (AL). Matched measurements were taken using the AAS and EAL functions and visually confirmed with confocal microscopy. The variance between canal length (mm), the persons correlation (ρ) between function and AL, and the accuracy (%) of the canal length relative to the AL (Δmm) between devices and functions were assessed., Results: Regardless of device or function, all measurements were within 1±Δmm and correlated strongly (ρ > 0.97) with the AL. When considering a more stringent clinically acceptable range of 0.5±Δmm from the AL, all devices and functions demonstrated similar accuracy levels (84%-94%). However, at lower tolerance ranges, the E-connect device with the EAL function exhibited the highest accuracy. On average, all devices and functions stopped short of the AL (mean Δmm>0)., Conclusion: The E-Connect S+ and Morita Tri Auto ZX2+ apex locators provided reliable accuracy in determining the position of the major foramen. These findings demonstrate a high level of reproducibility in canal length measurements using both cordless endodontic handpieces, regardless of whether the EAL or AAS functions were employed., (Copyright © 2024 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

The aim of the study was to evaluate the ability of a modified passive deflation needle to reduce the apical voids during the intra-canal iRoot SP sealer injection. A modified passive deflation injection needle was designed. Forty 20°-curved and twenty S-shaped single-canal resin block models were allocated into six groups. Each group was mechanically prepared to #25/04 or #25/06 file; then the root canals were injected with iRoot SP sealer using a modified needle or a normal plastic needle. Radiographs were taken to measure the length of apical void in each specimen. Similarly, twenty single-canal extracted premolars were collected and randomly divided into four groups. Each group was prepared to #25/04 or #25/06 file; then the root canals were injected with iRoot SP sealer using a modified needle or a normal plastic needle. Roots were then scanned using micro-computed tomography (micro-CT), and the volume of voids in root canals was analyzed and compared among groups. Statistical analysis demonstrated that the length and the volumetric percentage of voids were much lower in the modified needle group in both resin block root canal models and extract teeth than the normal plastic needle group (P < 0.05). The modified passive deflation needle can efficiently reduce apical voids during the intra-canal iRoot SP sealer injection., (© 2024. The Author(s), under exclusive licence to The Society of The Nippon Dental University.)

Introduction: The aim of this study was to investigate the feasibility of a real-time three-dimensional dynamic navigation system (3D-DNS) for post space preparation (PSP) in root canal-treated teeth and to compare the accuracy and efficiency of 3D-DNS to freehand (FH) for PSP., Methods: Fifty-four maxillary molars were divided into two groups: 3D-DNS (n = 27) and FH group (n = 27). Cone beam computed tomography (CBCT) scans were taken preoperatively and postoperatively. The drilling path for the PSP was virtually planned in the preoperative CBCT scan in the X-guide software (X-Nav Technologies, Lansdale, PA). For the 3D-DNS group, the PSP drilling was conducted under dynamic navigation. The 3D deviations and angular deflections were calculated. The residual dentin thickness (RDT) was determined after PSP. The operation time and the total number of mishaps were recorded. Shapiro-Wilk, t-test or Mann-Whitney rank sum, weighted Cohen's kappa, and Fisher exact tests were used (P < .05)., Results: The PSP was completed in all samples (54/54). The 3D-DNS was more accurate than the FH, with significantly fewer 3D deviations and angular deflections (all, P < .05). The 3D-DNS required less operating time than the FH (P < .05). For the 3D-DNS, no teeth had RDT < 1 mm, whereas 6/27 in the FH showed RDT < 1 mm after the PSP. There was no difference in the total number of mishaps (P > .05)., Conclusion: Within the limitations of this in vitro study, the 3D-DNS is feasible for PSP. The 3D-DNS improved the accuracy and efficiency of PSP. The dynamic navigation system can potentially become a safe and reliable technology for PSP., (Copyright © 2024 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Background: Eccentric instruments have been proposed as more effective and less time-consuming for endodontic instrumentation., Aim: To compare biomechanical outcomes of different instrumentation systems and time undertaken for instrumentation in resin prototypes., Design: Sixty standardized prototypes of mandibular second primary molars were instrumented according to the following systems: K-files, ProTaper Next (PTN), XP-endo Shaper (XPS), XP-endo Finisher (XPF), XP-Clean (XPC), and Sequence Baby File (SBF; n = 10/each). Irrigation was performed with saline with simultaneous aspiration, and time spent was recorded. The prototypes were micro-CT-scanned before and after the instrumentation, and image sets were reconstructed and registered. Non-instrumented areas, accumulated debris, removed root material volume, and canal transportation were quantified. Data were analyzed through ANOVA, the Kruskal-Wallis test, and the Wilcoxon signed-rank test (α = 5%)., Results: K-files and SBF resulted in more instrumentation time (p < .05). SBF, XPC and PTN removed less root dentine (p < .05), but PTN left more untouched areas (p < .05). Accumulated debris were lower for XPC and SBF (p < .05). Canal transportation was similar among the groups., Conclusion: Rotary systems reduced instrumentation time, whereas SBF and XPC resulted in more conservative instrumentation, with less debris accumulation and non-instrumented areas. A dedicated paediatric endodontic system (SBF) outperformed eccentric instruments in terms of effectiveness., (© 2023 BSPD, IAPD and John Wiley & Sons Ltd.)

Background: Paediatric rotary file systems have recently been developed for primary teeth use., Aim: To study the cleaning efficacies of two paediatric rotary endodontic files, the Prime Pedo TM , and the Kedo-SG Blue TM against the standard H files., Design: This in vitro study included 54 freshly extracted primary molars, which were randomised into three groups (n = 18 each) and were prepared using either Kedo-SG Blue TM , Prime Pedo TM or hand H files after injecting methylene blue dye into the canals. Pre- and post-operative cone beam computerised tomography (CBCT) was performed to assess change in root canal volumes. Methylene blue dye removal from canals was assessed using stereomicroscopy, and canal cleanliness was examined by scanning electron microscopy (SEM)., Results: Both Prime Pedo TM and Kedo-SG Blue TM files reduced significantly less dentine when compared with conventional hand filing with Prime Pedo TM removing the least amount of dentine. No significant difference was found in median SEM scores among the groups in the cervical, middle and apical thirds of the roots. Stereomicroscopic assessment of root canal cleanliness using dye removal technique shows a statistically significant difference existing between Kedo-SG Blue TM and hand H files groups., Conclusion: Prime Pedo TM removed the least amount of dentine. Kedo-SG Blue TM performed significantly better than conventional hand filing with H files when the root canal cleanliness was assessed., (© 2023 BSPD, IAPD and John Wiley & Sons Ltd.)

Introduction: This systematic review aimed to compare reciprocating with continuous rotary instrumentation kinematics, by means of microcomputed tomography evaluations, in extracted human permanent teeth with moderate and severe canal curvatures., Methods: The research protocol was registered in the International Prospective Register of Systematic Reviews and given the reference number CRD42023404035. An electronic search was undertaken in MEDLINE (PubMed), EBSCO, Scopus, Web of Science databases until December 2021. Manual screening of issues in endodontic journals and references of relevant articles were assessed individually. The risk of bias (RoB) of the included articles was evaluated with the QUIN tool (Quality Assessment Tool for In Vitro Studies)., Results: Among 1640 retrieved articles, 49 were included in the qualitative synthesis. Fifteen articles had low RoB, 33 articles had medium RoB, and only 1 study was at high RoB. Continuous rotary systems had better centering ability in both moderate and severe canal curvatures and resulted in less apical transportation in severely curved root canals. None of the kinematic systems was capable of instrumenting the entire canal surface area. Reciprocating kinematics systems tended to provide higher increase in surface area of severely curved canals and produced fewer dentinal microcracks in moderately curved canals., Conclusions: The evidence presented in this review suggests that continuous rotary system seems to be better than reciprocating system in solving the major issues encountered during root canal instrumentation of extracted teeth with moderate and severe curvatures., (Copyright © 2024 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

This study aims to compare the shaping ability of three systems using micro-computed tomography (micro-CT). Moderately-curved mesial canals of 36 mandibular molars were assigned to three groups (n = 24); Protaper Next (PTN, 0.25, 0.06), WaveOne Gold (WOG, 0.25, 0.07), TruNatomy (TRN, 0.25, 0.04), and instrumentation was performed. Pre- and post-micro-CT scans were obtained. Canal volume and surface, structure model index (SMI), centroid shift, canal transportation, and untouched canal were analyzed. One-way ANOVA and Student's t-test were used for statistics. There was no difference in SMI, centroid shift, and centering ability between the study groups (p > .05). Removed dentin and canal surface changes were lower in TRN, while untouched dentin walls were higher (p < .05). Cross-sections became more rounded (p < .05), but not significant between groups (p > .05). Considering the removed dentin by TRN, it can be used in critical dentin thickness, such as the danger zone (DZ). PTN, WOG, and WOG kept the original canal course similarly. Untouched dentin by TRN (41%) was wider than PTN and WOG, consequently, meticulous irrigation is recommended. TRN, which provides a controlled increase in canal volume, can be used in thin dentin such as the DZ, however, its use should be supported by copious irrigation and brushing considering the rate of untouched dentin walls. RESEARCH HIGHLIGHTS: TRN presented a higher untouched dentin wall compared to PTN and WOG. Canal volume and surface changes were the lowest in the TRN group. The centering abilities were similar in PTN, WOG, and TRN., (© 2024 The Author(s). Microscopy Research and Technique published by Wiley Periodicals LLC.)

Objective: This systematic review aims to comparatively analyse the amount of dentin removal by free hand and static guided endodontics with dynamic navigation system (DNS) in endodontic access cavity preparation., Methods: The systematic review was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines. Based on the structured PICO framework of "Comparative evaluation of dynamic navigation system (I) to freehand (C) and static guided endodontics (C) in endodontic access cavity preparation on the preservation of tooth structure (O) when assessed on permanent human teeth (P)", the keywords were formulated and the articles were retrieved from three databases namely PubMed, Scopus and Embase, based on the keywords from the time of inception of DNS till June 2023. The risk of bias assessment was done using a modified Joanne Briggs Institute checklist, which evaluated domains such as randomisation, sample size, image acquisition using CBCT, angulation, accuracy and time taken. As the data was heterogenous, a quantitative meta-analysis was not performed., Results: Initially, 174 articles were retrieved from the three databases, 30 duplicates were removed, after title check 108 articles were excluded and following abstract check only 10 articles qualified for full text analysis. On reviewing the 10 full text articles, 5 articles were excluded and the remaining 5 articles were subjected to the risk of bias analysis which showed that 2 articles displayed low risk of bias and three articles showed high risk of bias. The RoB analysis revealed that only 2 studies evaluated the preservation of dentin in terms of accuracy, angulation and time taken proving the increased precision with minimal loss of tooth structure using DNS. In both the studies, DNS proved to be superior to free hand technique in terms of precision, accuracy and efficiency in locating the canals during access cavity preparation with maximal preservation of tooth structure., Conclusion: With the minimal literature evidences, the present systematic review highlights maximal preservation of dentin using DNS. However, further invitro and invivo studies comparing the free hand, static guided endodontics to DNS must be carried out for its translation into clinical practice., Clinical Significance: Dynamic navigation system provides maximal preservation of dentin during access cavity preparation., (© 2024. The Author(s).)

Purpose: The fatigue resistance of mechanical nickel-titanium files was tested by phase-locked infrared flaw detection method, in order to timely detect instrument wear, providing reference for clinical safe use and timely abandonment of nickel-titanium files., Methods: Twenty sets of mechanical nickel-titanium files were selected from Reciproc-Blue(RB), MTWO and S3 respectively, and resin simulated root canals with 60° and 90° bending were prepared, which were divided into 6 subgroups. The fatigue value after use, the number of uses before breaking and the length of fracture of file 25# of each group of files were recorded and compared with SPSS 26.0 software package., Results: With the increase of the times of use, the fatigue value of the three kinds of files increased gradually. Among the two types of curved root canals, the number of uses before fracture in RB group was significantly increased compared with that in MTWO group and S3 group (P＜0.05). The number of uses of the three kinds of files in the 90° curved root canal were significantly less than in the corresponding groups in the 60° curved root canal(P＜0.05). There was no significant difference in the length of fracture among the three kinds of files(P＞0.05)., Conclusions: Phase-locked infrared flaw detection method can be used for non-destructive testing and quantitative analysis of the fatigue degree of nickel-titanium files.

Aim: To evaluate the influence of different preparation tapers on the reduction in planktonic bacteria and biofilms of Enterococcus faecalis and Candida albicans in the apical third (4 mm) of the mesial roots of mandibular molars, correlating decontamination with canal shape., Methodology: After microtomography analysis for morphological standardization of the canals, 48 mandibular molar roots, each containing two canals (96 canals), were contaminated with E. faecalis and C. albicans and divided into four groups (n = 11) for canal instrumentation using ProDesign Logic 2 files with different tapers G (.03): # 25.03; G (.04): # 25.04; G (.05): # 25.05; and G (.06): # 25.06 and irrigation with 2.5% sodium hypochlorite. Four roots were examined under a scanning electron microscope (SEM) to qualitatively assess biofilm formation. Eight roots were used as the negative control group (samples were not contaminated). Bacteriological samples were taken exclusively from the apical third of the roots before and after chemical-mechanical preparation and bacterial counts were determined (CFU/mL). The final micro-CT scan was used to quantify the volume variation and unprepared canal area in the apical third. Statistical analysis was performed using the Kruskal-Wallis, Student-Newman-Keuls and Wilcoxon tests for analysis of microbiological data. anova and the Tukey or Games-Howell test were used for analysis of micro-CT data and Spearman's test for correlations (α = 5%)., Results: All groups showed a significant reduction in bacteria (p < .05), with no statistically significant difference between groups. There was no significant difference in per cent volume increase between groups. The unprepared area (Δ%) was affected by the file used (p = .026) and was significantly lower for G (.06) compared to G (.03). There was no statistically significant correlation among bacterial reduction, volume and unprepared area (p > .05)., Conclusion: The different preparation tapers influenced root canal shaping in the apical third but did not improve decontamination in this region., (© 2024 British Endodontic Society. Published by John Wiley & Sons Ltd.)