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Background/Aim. The most important moment in modern endodontics is the inclusion of rotating instruments made of nickel-titanium alloy in daily clinical work, which have supplanted stainless steel instruments due to their superior properties. The aim of this study was to investigate the influence of autoclave sterilization on cyclic fatigue (CF) in two types of rotating instruments produced by M-wire technology with different types of rotation. Methods. This research included two types of M-wire rotary instruments -- 48 ProTaper Next® instruments with full rotation and 48 WaveOne® Gold instruments with reciprocating rotation. Each of the two groups of instruments was divided into four additional groups of 12 instruments depending on the number of cycles of sterilization in the autoclave. The instruments were tested in an artificial canal with a 2 and 5 mm radius of curvature. Results. Statistically significantly higher resistance to CF was observed with WaveOne® Gold compared to ProTaper Next® (p < 0.001) instruments, both in the non-sterilized group and after their exposure to the first, third, and fifth cycle of sterilization. The third and fifth cycle of sterilization significantly reduced resistance to CF in the WaveOne® Gold (p < 0.001) group. There was no statistically significant difference in CF resistance between sterilized and non-sterilized instruments of the ProTaper Next® group. Conclusion. Sterilization in an autoclave for instruments based on M-wire technology did not increase resistance to CF. [ABSTRACT FROM AUTHOR]

Background/Aim. The clinical success of prosthetic rehabilitation that commences after the attained implant osseointegration is dependent on the influence of several factors, of which screw loosening is a frequent one, and it is highly related to inadequate tightening (torquing) using torque wrenches. Although the wrenches are initially calibrated by the manufacturer, it is of great importance to evaluate their function after usage for a certain period of time. The aim of this study was to evaluate the accuracy and repeatability of the performance of implant torque wrenches in delivering necessary torque values before and after one year of usage. Methods. Two types of wrenches were used in the study: the beam-type and the toggle-type. Four various brands of beam-type wrench were marked as Beam 1 - Beam 4, and three various brands of toggle-type wrench were marked as Toggle 1 - Toggle 3, according to their design. Torque values delivered by wrenches were measured and analyzed using the One-Sample t-test, Independent-Samples t-test, and Mann-Whitney U test. The Bland-Altman bias test was used as an index of accuracy, whereas Forkman's comparison of datasets coefficients of variation (CV) served as an index of repeatability. Results. All wrenches except new Beam 2 and Beam 3 showed differences between the average measured torque value and target torque value. Differences were found in the average measured values between all used and new wrenches. Higher bias was observed in Toggle 1, Toggle 2, and Toggle 3 brands, whereas lower bias was recorded between used and new Beam 1 and Beam 3 wrenches. When comparing the CV for used and new wrenches, Beam 1, Beam 4, Toggle 1, and Toggle 2 revealed differences, whereas the CV for Beam 2, Beam 3, and Toggle 3 did not differ significantly. Conclusion. Compared to toggle-type, the beam-type wrenches offer greater accuracy in achieving the target torque value. The torque deteriorates in all wrenches after aging/usage and is more prominent in toggle-type devices. [ABSTRACT FROM AUTHOR]

Background: Occlusal contacts can be stained and thereby visualised employing occlusal indicators. Qualitative and quantitative indicators are differentiated. The hybrid system OccluSense supposedly combines analogue contact marking and digital registration of contacts. The reliability and validity of its contact marking have not yet been validated. Objectives: The aim of this controlled randomised in‐vitro study was to examine the reliability and validity of analogue contact staining with OccluSense compared to Arti‐Fol and the reference standard Gnatho‐Film. Materials and Methods: An experimental apparatus was designed to simulate static occlusion. The occlusal contacts were stained 50 times with Gnatho‐Film to determine the average number and location of contacts registered. For comparison, the contacts were pre‐stained with Gnatho‐Film and then registered with Arti‐Fol or OccluSense 50 times each. Every staining was statistically evaluated and compared to Gnatho‐Film alone, regarding the number and location of contacts. Based on the observed characteristic staining behaviour of OccluSense, a modified evaluation strategy was developed for its colour markings (OccluSense (mod.)). Results: Both evaluations of OccluSense determine that the same number of contacts was registered in over 94% of all cases. Neither OccluSense nor Arti‐Fol stain the exact same number of contacts as Gnatho‐Film, but the modified evaluation OccluSense (mod.) did improve the results for validity. Conclusion: When employing the modified evaluation strategy, OccluSense staining achieves similar reliability and validity as the reference standard. Pre‐colouring of occlusal contacts with Gnatho‐Film and the modified evaluation strategy, might become standard for analysing occlusal contacts stained by OccluSense in the future. [ABSTRACT FROM AUTHOR]

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. 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%. 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. 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%. [ABSTRACT FROM AUTHOR]

Background: A number of mechanical decontamination methods have been proposed, however, there is no agreed-upon gold standard among them. This study aims to conduct a meta-analysis to assess the differences in the management of an inflammatory reaction around dental implants between air abrasion and mechanical decontamination. Methods: A comprehensive search strategy was employed, incorporating controlled vocabulary (MeSH) and free-text terms. This search was conducted by two reviewers to identify published systematic reviews. Three major electronic databases, namely, Medline via PubMed, the Cochrane database, and Embase, were searched up to May 2024. Results: Initially, 300 articles were identified. After conducting a comprehensive search and applying strict inclusion criteria, a total of 13 studies were deemed eligible for inclusion in the meta-analysis. The results showed that the mean difference in probing depth between air abrasion and other mechanical decontamination was 0.28 (95% confidence interval, −0.20 to 0.76). The mean difference in probing depth of air abrasion compared with other mechanical decontamination in maintenance purposes was 1.05 (95% confidence interval, 0.18 to 1.91). The mean difference in bleeding on probing between air abrasion and other mechanical decontamination was 0.51 (95% confidence interval, 0.07 to 0.95). The mean difference in alveolar bone loss between air abrasion and other mechanical decontamination was −0.14 (95% confidence interval, −0.77 to 0.48). The mean difference in alveolar bone loss for surgical approaches of air abrasion compared with other mechanical decontamination was 0.32 (95% confidence interval, 0.03 to 0.61). Conclusions: The findings of the study indicate that the use of air abrasion was just as effective as other mechanical decontamination methods in reducing probing depth and alveolar bone loss. The subgroup analysis showed that air abrasion was less effective in reducing probing depth in maintenance purposes. Additionally, air abrasion was less effective in reducing alveolar bone loss in surgical approaches. [ABSTRACT FROM AUTHOR]

Abstract Background Dynamic navigation for implant placement is becoming popular under the concept of top-down treatment. The purpose of this study is to verify the accuracy of a dynamic navigation system for implant placement. Methods Implant placement was performed on 38 patients using 50 implant fixtures. Patients in group C were treated using a conventional method, in which thermoplastic clips were fixed to the teeth, and patients in group M were treated using thermoplastic clips fixed to a mouthpiece attached to the teeth. The groups were compared to verify whether an accuracy difference existed. A treatment planning support program for dental implants was used to superimpose the postoperative computed tomography data on the preoperative implant design data to measure the entry point, apex point, and angular deviation. Results The accuracy of group C was 1.36 ± 0.51 mm for entry point, 1.30 ± 0.59 mm for apex point, and 3.20 ± 0.74° for angular deviation. The accuracy of group M was 1.06 ± 0.31 mm for the entry point, 1.02 ± 0.30 mm for the apex point, and 2.91 ± 0.97° for angular deviation. Significant differences were observed in the entry and apex points between the two groups. Conclusions The results indicate that group M exhibited better accuracy than group C, indicating that the stability of the thermoplastic clip is important for ensuring the accuracy of the dynamic navigation system. No previous studies have verified the accuracy of this system using the mouthpiece method, and additional data is required to confirm its accuracy for dental implant placement. The mouthpiece method improves the accuracy of implant placement and provides a safer implant treatment than the conventional method. Trial registration University hospital Medical Information Network Clinical Trials Registry (UMIN-CTR), Registration Number: UMIN000051949, URL: https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view_his.cgi on August 21, 2023.

Background: Dynamic navigation for implant placement is becoming popular under the concept of top-down treatment. The purpose of this study is to verify the accuracy of a dynamic navigation system for implant placement. Methods: Implant placement was performed on 38 patients using 50 implant fixtures. Patients in group C were treated using a conventional method, in which thermoplastic clips were fixed to the teeth, and patients in group M were treated using thermoplastic clips fixed to a mouthpiece attached to the teeth. The groups were compared to verify whether an accuracy difference existed. A treatment planning support program for dental implants was used to superimpose the postoperative computed tomography data on the preoperative implant design data to measure the entry point, apex point, and angular deviation. Results: The accuracy of group C was 1.36 ± 0.51 mm for entry point, 1.30 ± 0.59 mm for apex point, and 3.20 ± 0.74° for angular deviation. The accuracy of group M was 1.06 ± 0.31 mm for the entry point, 1.02 ± 0.30 mm for the apex point, and 2.91 ± 0.97° for angular deviation. Significant differences were observed in the entry and apex points between the two groups. Conclusions: The results indicate that group M exhibited better accuracy than group C, indicating that the stability of the thermoplastic clip is important for ensuring the accuracy of the dynamic navigation system. No previous studies have verified the accuracy of this system using the mouthpiece method, and additional data is required to confirm its accuracy for dental implant placement. The mouthpiece method improves the accuracy of implant placement and provides a safer implant treatment than the conventional method. Trial registration: University hospital Medical Information Network Clinical Trials Registry (UMIN-CTR), Registration Number: UMIN000051949, URL: https://center6.umin.ac.jp/cgi-open-bin/ctr%5fe/ctr%5fview%5fhis.cgi on August 21, 2023. [ABSTRACT FROM AUTHOR]

This comprehensive review explores the evolution, current state, and future directions of dental instruments, emphasizing innovations, standard practices, and the implications for clinical dentistry. Drawing from an extensive review of literature and patents, this paper categorizes dental instruments into diagnostic, restorative, surgical, endodontic, periodontal, orthodontic, and prosthodontic tools, detailing their specific applications and innovations in design and materials. Special attention is given to technological advancements that enhance functionality, improve durability, and increase patient comfort, including laser technology, CAD/CAM tools, and ergonomic designs aimed at preventing occupational injuries among dental professionals. The paper also addresses the critical importance of sterilization and maintenance protocols for dental instruments to ensure patient safety and prevent cross-contamination. Despite significant progress, challenges such as cost, complexity of maintenance, and adherence to sterilization protocols persist. Looking forward, the paper speculates on the impact of emerging technologies like 3D printing and nanotechnology on the future landscape of dental instrumentation. This review highlights the dynamic nature of dental instrument development and its critical role in advancing dental care, suggesting a need for ongoing research, innovation, and education to fully leverage these tools in clinical practi

Background: A number of mechanical decontamination methods have been proposed, however, there is no agreed-upon gold standard among them. This study aims to conduct a meta-analysis to assess the differences in the management of an inflammatory reaction around dental implants between air abrasion and mechanical decontamination. Methods: A comprehensive search strategy was employed, incorporating controlled vocabulary (MeSH) and free-text terms. This search was conducted by two reviewers to identify published systematic reviews. Three major electronic databases, namely, Medline via PubMed, the Cochrane database, and Embase, were searched up to May 2024. Results: Initially, 300 articles were identified. After conducting a comprehensive search and applying strict inclusion criteria, a total of 13 studies were deemed eligible for inclusion in the meta-analysis. The results showed that the mean difference in probing depth between air abrasion and other mechanical decontamination was 0.28 (95% confidence interval, −0.20 to 0.76). The mean difference in probing depth of air abrasion compared with other mechanical decontamination in maintenance purposes was 1.05 (95% confidence interval, 0.18 to 1.91). The mean difference in bleeding on probing between air abrasion and other mechanical decontamination was 0.51 (95% confidence interval, 0.07 to 0.95). The mean difference in alveolar bone loss between air abrasion and other mechanical decontamination was −0.14 (95% confidence interval, −0.77 to 0.48). The mean difference in alveolar bone loss for surgical approaches of air abrasion compared with other mechanical decontamination was 0.32 (95% confidence interval, 0.03 to 0.61). Conclusions: The findings of the study indicate that the use of air abrasion was just as effective as other mechanical decontamination methods in reducing probing depth and alveolar bone loss. The subgroup analysis showed that air abrasion was less effective in reducing probing depth in maintenance purposes. Additionally, air abrasion was less effective in reducing alveolar bone loss in surgical approaches.

Copyright of Dental Press Endodontics is the property of Dental Press International and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Most dental procedures that use handpieces, turbines, US scalers, airflow, and air abrasion tend to produce aerosols in which the patient’s oral fluids are also entrained, with consequences on the health of the medical staff and other patients. Oral fluids are highly contaminated with microorganisms. The aim of the study was to assess the degree of surface contamination in relation to certain variables of the aerosol-generating dental maneuvers. Material and methods: 2 operators performed 5 simulations of 10 min each for treatments with US scaler, turbine, and contra-angle with spray cooling system. The evaluation of the contaminated surfaces was carried out by measuring the colored surface, in cm, on the paper sheet that was placed on the mannequin, starting from the oral cavity of the mannequin. The measurements were made in all 4 directions (right, left, superior, inferior) to see which part of the operative field is more prone to contamination. Statistical analysis of the collected data was carried out using the SPSS 26.0. Result: Dental turbine operations will produce a significant number of aerosols, the most of them in the form of droplets, spanning regions up to 60 cm. US scaling produced less aerosols than the other activities, with the least contaminated surface. Statistics have proven that the observed differences are different (p=0.000). Conclusions: The surfaces were contaminated by all three aerosol-producing dental procedures at various and equivalent distances. The turbine produced a greater amount of aerosols, especially in the form of droplets, that exceeded the maximum contamination zone with an area of 1m

Decontamination of reusable medical devices is a key element of infection control in private practices. The aim of this study was to compare the effectiveness of the cleaning methods used in the dental office. Material and methods: The instruments taken from the dental office used during the treatment, consisting of manual and rotating endodontic needles and diamond burs were transferred to a container with detergent-disinfectant solution where from the office to the sterilization room. The initial evaluation of the armentarium is done in the sterilization room and the collected data were written in a file. After a period of 15 min. the armentarium was divided into 3 groups of 10 instruments each: group I – hand-cleaned instruments with a wire brush for 2 minutes under running water; – group II – instrument cleaning in the US bath for 15 min.; Group III – instrumentation initially cleaned in the US cleaning bath for 15 min., then manually for 2 min. Results: For the manually cleaned instrument the average value from 67.5 ± 25.85 to 10.36 ± 13.36; in US cleaning technique the average value decrease from 77.85 ± 22.16 to 8.57 ± 12.92 and in the combined cleaning (manual cleaning + US cleaning), the final value recorded being 86.92 ± 10.06, higher than the final average values obtained in the case of the other two groups. Conclusion: The most efficient method of cleaning the instrumentation is represented by the combination of manual cleaning with the US cleaning method (ultrasonic bath). Ultrasonic cleaning has proven to be more efficient than manual instrument cleaning, especially for diamond burs. Endodontic instruments have been cleaned more efficiently with manual cleaning than with US cleaning. It is necessary to carry out training courses to improve the level of knowledge on the need for proper processing of medical instruments to increase the safety of the medical act.

Objective: To investigate the opinions and attitudes of dental practitioners towards intracanal separation of endodontic instruments and to create awareness regarding the management of separated instruments Study Design: Cross-sectional survey Place and Duration of Study: Department of Operative Dentistry Armed Forces Institute of Dentistry, Rawalpindi Pakistan, from Mar to Apr 2021. Methodology: An online questionnaire was circulated among 374 dentists of private and public hospitals in Rawalpindi and Islamabad. The questionnaire consisted of close-ended questions related to demographic details, dentists' awareness of instrument separation, the frequency of separated instruments, the causes of separation, the management of separated instruments, and the retrieval strategies if used. Results: Out of 374 study participants, 307(82.1%) of the participants thought that operator-related factors such as improper or overuse of the instrument were considered the most common factors for instrument separation during root canal procedures. 205(54.8%) thought unwinding, defective flutes and shiny areas were the most common factors affecting instrument separation. 241(64.4%) of the instruments are separated during cleaning and shaping. 135(36.1%) K files and 119(31.8%) H files were separated in this survey. Conclusion: Most dentists of Rawalpindi and Islamabad face the problem of endodontic instrument separation during rootcanal preparation.

Objective: To compare the consistency of working length control in hand instrumentation and engine-driven rotary files Wave One by comparing their pre and post-instrumentation working lengths. Study Design: Quasi-experimental study. Place and Duration of Study: Armed Forces Institute of Dentistry, Rawalpindi Pakistan, from Jun to Dec 2019. Methodology: A total of 90 mandibular first molars were selected. Two groups were drawn with 45 mesio buccal canals each. The First-Group was prepared with manual K-files, whereas the second group had rotary instrumentation using the WaveOne system. Pre and post-preparation working lengths were noted. Results: The mean pre-operative (18.5±1.03mm) and post-operative (18.15±1.09mm) working lengths of manually prepared and WaveOne prepared canals (18.8±3.43mm and 18.7±3.25mm respectively) presented statistically significant loss of postoperative working lengths. The comparison of the two groups gives a statistically significant result in manual preparation, showing a greater loss of working length as compared to canals prepared with WaveOne rotary files. Conclusion: Manual instrumentation causes a greater loss of working length by straightening the canal more than enginedriven WaveOne rotary files postoperatively.

Abstract The aim of this study was to evaluate the root canal shaping effect of ProTaper Gold (PTG) versus ProTaper Next (PTN) instrumentation systems, and of a manual #15 K-type file (K15) versus the ProGlider (PG) mechanized instrument for glide path creation, in severely curved mesial canals. Twenty-four mandibular molars with two separate mesial canals were anatomically matched using computed tomographic scanning, and then divided into two groups (n=12) according to the glide path instrument used, either K15 or PG. In all teeth, the PTG system was used to prepare the mesiobuccal canal, and the PTN, the mesiolingual canal. The teeth were scanned by computed microtomography, before and after root canal preparation, and the values of the initial volume, final volume, volumetric variation, untouched walls, and canal transportation variables were determined. The data were analyzed using the two-way ANOVA test, and the Tukey test for multiple comparisons. There was no significant difference among the study groups regarding volumetric variation or root canal transportation, either in the cervical, middle or apical thirds, or in the entire root canal (p>0.05). In the apical third, the percentage of untouched walls was significantly higher in groups using K15 than in those using PG (p

Copyright of Turkiye Klinikleri Journal of Dental Sciences is the property of Turkiye Klinikleri and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Dental Press Endodontics is the property of Dental Press International and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objective: To compare the fatigue resistance of different heat-treated reciprocating instruments tested in a dynamic cyclic fatigue model. Methods: Forty-eight new instruments were inspected under magnification and selected for this study, and then divided as follows (n=12): X1 Blue (MK Life, Porto Alegre, RS, Brazil), Pro-R (MK Life), Reciproc (VDW, Munich, Germany), and Reciproc Blue (VDW). Artificial canals presenting a curvature of 60° angle and 5 mm radius were milled in zirconia. The block containing the artificial canals was mounted in a container filled with water kept at 37°C. A specially designed device was used to perform controlled axial movements while the instruments were activated inside the canals. Time to failure was recorded in seconds, and fragment lengths were measured (mm). Data were analyzed statistically with the significance level set at 5% (One-Way ANOVA and Tukey test). Results: Pro-R and Reciproc Blue instruments presented the highest fatigue resistance, being significantly different from the other tested files (p<0.05). Reciproc presented intermediate results, significantly different X1 Blue (p<0.05). The fractographic analysis showed typical features of cyclic fatigue for all instruments. Conclusion: Pro-R and Reciproc Blue instruments are more resistant to dynamic cyclic fatigue than the Reciproc and X1 Blue. [ABSTRACT FROM AUTHOR]

Objective: This study aims to evaluate the centering ability and canal transportation of the ProTaper Next, One Curve, and TruNatomy instruments in curved root canals. Methods: Forty-five curved mesiobuccal canals of human mandibular molar teeth were selected, randomly divided into 3 groups, and prepared using the ProTaper Next, One Curve, and TruNatomy files. Cone Beam Computed Tomography images of the cross-sectional planes at 1 mm, 3 mm, 5 mm, and 7 mm from the apical foramen were determined before and after the preparation. For each specified millimeter canal transportation and centering ability were measured. Statistical analysis was performed and compared all groups. Results: No significant differences were observed between the groups or root canal levels in both canal transportation and centering ability (p > 0.05). Conclusion: The TruNatomy system demonstrated comparable results with both predecessor ProTaper Next and One Curve single-file systems. [ABSTRACT FROM AUTHOR]

This study compared the accumulated hard‐tissue debris (AHTD) after preparation with WaveOne Gold (WOG) to XP‐endo Shaper (XPS), without and with a supplementary step using XP‐endo Finisher (XPF) using clinically applicable irrigation. Twenty‐four mesial roots with two canals and single foramen were micro‐CT‐scanned and matched. Scans were also taken after preparation with WOG or XPS, and after XPF. Irrigation with 2.5% NaOCl (total: 17 ml per canal) and 17% EDTA (2.5 ml per canal) was performed using a 30ga Max‐I‐Probe needle placed up to the working length. Morphological parameters were calculated and compared within and among groups. XPF significantly reduced unprepared area within XPS and WOG groups, and AHTD within WOG (p < 0.05). There were no significant differences between WOG and XPS after preparation and after XPF (p > 0.05). In conclusion, WOG and XPS produced a similar volume of AHTD, but the supplementary step with XPF decreased the AHTD in the WOG group. [ABSTRACT FROM AUTHOR]

Background/Aim. There is no standard protocol for cleaning and disinfection of used endodontic instruments before their sterilization and reuse. The aim of this study was to determine the efficiency of the different methods of removing biological debris from different types of used hand stainless steel endodontic instruments. Methods. A total of 120 hand stainless steel endodontic instruments: KerrTM reamers, KerrTM files, and HedströmTM files, each forty ISO 25, used for root canal treatment on extracted teeth, were analyzed. The used instruments were divided into four groups based on different decontamination protocols. The evaluation of the efficiency of the cleaning methods was based on the evaluation of the amount of stained organic residues on the instruments (Van Gieson staining). Samples were analyzed by stereomicroscopy (x40). Statistical analysis was performed using the Mann-Whitney U test for the KerrTM reamers and HedströmTM files, while the One-Way ANOVA/Bonferroni test was used for the KerrTM files, at a significance level of 5 % (a = 0 .05). Results. Residual biological debris was observed on 93.3% of all the samples taken. The thermal disinfectant cleaning method showed the lowest contamination values for all types of instruments. The method of mechanical cleaning showed that the mean value of maximum biologic contamination (MBC) was 58.5% for the KerrTM reamers and 56.2% for KerrTM files, while for HedströmTM files, the highest MBC (50.2%) was shown by the ultrasonic method of cleaning. Conclusion. The use of a thermal disinfectant was the most efficient cleaning method for all three types of hand endodontic instruments. [ABSTRACT FROM AUTHOR]

Rotary cutting instruments (RCIs) are sterilized routinely. The authors aimed to analyze the structural integrity, presence of dirt, and microbial contamination of RCIs used in clinical practice after processing. Eighty-four RCIs (42 carbide burs, 42 diamond burs) were divided into baseline, control, and test groups. The RCIs were evaluated by means of scanning electron microscopy and microbiological analysis. Evaluation criteria included presence of structural damage, dirt, biofilm, and isolated cells and their phenotypic profile. The carbide burs from all groups and diamond burs from the test groups had structural damage. Dirt was observed in the baseline and test groups. Three bacterial species were isolated from 4 RCIs (9.52%). An isolated cell was observed from 1 carbide bur. Biofilm was observed on 3 RCIs (7.14%). RCIs should not be subjected to multiple uses; after the first clinical use they accumulate structural damage and dirt that hampers the cleaning step, causing failure in the sterilization process. The presence of microorganisms and structural damage on the RCIs confirmed that they are not amenable to processing, a fact that characterizes them as a single-use health care product. [ABSTRACT FROM AUTHOR]

This randomized clinical trial aimed to compare postoperative pain after the use of 2different irrigation activation techniques: passive ultrasonic irrigation and the EasyClean device. Sixty-six single-rooted teeth diagnosed with asymptomatic pulp necrosis and apical periodontitis were randomly assigned to 2experimental groups (n = 33), which differed in the irrigation activation technique. Postoperative pain levels were assessed after 24, 48, and 72 hours using a verbal rating scale; the ibuprofen intake amount was recorded at the same time intervals. Data were analyzed using Student's t-test, Mann–Whitney U and Fisher's exact tests, with a significance level of 5%. Postoperative pain levels and analgesic intake frequency were not significantly different across the 2irrigation activation techniques (P >.05). The frequencies obtained in relation to the prevalence of postoperative pain were 3.1-25.8% for all participants of the 2studied groups. The irrigation activation techniques of passive ultrasonic irrigation and the EasyClean device were found to be equivalent in terms of postoperative pain and analgesic intake. [ABSTRACT FROM AUTHOR]

The introduction of nickel‐titanium (NiTi) mechanical instruments dramatically changed clinical endodontics over the last few decades. Before NiTi, it was necessary to use more instruments to create an ideal root canal shape, and many approaches, sequences and techniques were developed over the years. Recently, NiTi endodontic instruments have undergone a series of changes brought about by modifications in design, surface treatments, and thermal treatments to improve their root canal preparation outcomes and reduce associated canal preparation risks during root canal treatment. Heat treatment is one of the most fundamental approaches to improving the fatigue resistance and flexibility of NiTi endodontic instruments. In addition, new kinematics have been developed to offer greater safety and efficiency. This narrative review describes the general properties and manufacturing of NiTi instruments, and the mechanical system evolution of NiTi instruments. [ABSTRACT FROM AUTHOR]

Background/Aim. Diabetes mellitus is a common metabolic disease-causing high mortality and morbidity worldwide. So, physicians need to identify this condition early to implement prevention strategies. The study aimed to test the concept of a novel periodontal device that can be attached to a glucose monitoring device as an innovative tool to screen for periodontitis and diabetes mellitus simultaneously during a routine dental examination. Therefore, correlation of blood glucose between the conventional finger-prick blood glucose (FPBG) and gingival crevicular blood glucose (GCBG) method, along with estimation of patient's pain perception by visual analogue scale (VAS). Methods. A crosssectional comparative study was conducted among 250 participants whose GCBG and FPBG were estimated. VAS score scale was recorded for each patient immediately after the procedure. Results. The mean GCBG value was 151.19 ± 42.64 mg/dL, while mean FPBG was 150.48 ± 42.95 mg/dL, showing a high Pearson's correlation (r=0.9932; p< 0.00001). Mann-Whitney U for VAS score between both the groups showed a statistically significant difference (p < 0.00001). Conclusion. The GCBG method was well tolerated by patients, and highly correlated with peripheral blood glucose levels. The proposed concept of the novel periodontal device appeared to be a feasible option for examining periodontium and screening diabetes simultaneously in dental clinics.

Background/Aim. During retreatment, filling material and debris may extrude and trigger an inflammatory reaction of periapical tissues. Resilon™ has not been investigated in terms of solvent use and influence on apical extrusion during retreatment. The aim of the study was to evaluate the amount of apically extruded debris during Resilon™ removal using ProTaper (PT), Twisted File (TF), and Hedstrom instruments, with and without solvent. Methods. In total, 72 extracted teeth with single canals were used. Canals were prepared with PT Universal (F2) and filled with Resilon™ and RealSeal sealer before being assigned randomly to 6 groups (n = 12 in each group). Retreatment in Groups 1–3 was done with PT, TF, or Hedstrom instruments, without solvent. In Groups 4–6, the same instruments were used with chloroform. Apically extruded debris was collected in a simulated periapical environment and assessed visually. Additionally, the time required for retreatment was recorded. Data were analyzed statistically using the Mann-Whitney U test, with a significance level of 0.05. Results. There were no significant differences in apical extrusion debris between groups (p > 0.05) regarding solvent use. Rotary instruments, without solvent, were associated with significantly less debris extrusion when compared with hand files (p < 0.05). When solvent was used, rotary instruments caused a higher degree of extruded material, which was similar to the results of hand instruments. Conclusion. The use of rotary instruments without solvent resulted in a lower degree extrusion of Resilon ™ material compared to hand instruments, while greater caution is advised in the presence of solvent when rotary instruments are used to remove this material.

Background and Aim: Maintaining the original shape and path of the canal is among the most important criteria for optimal root canal preparation. The aim of this study was to compare the centering ability of F6 SkyTaper and RaCe rotary files in mesiobuccal canals of mandibular molars. Materials and Methods: In this experimental study, 30 mesiobuccal canals of extracted human mandibular molars with 25-30-degree curvature were randomly divided into two experimental groups (n=15) of RaCe and F6 SkyTaper. After mounting of the teeth in a putty mold, the distance between the canal walls and the outer surface of the roots in mesial and distal aspects was measured. The measurements were made at 1, 3 and 7 mm from the apex. Initial glide path in the canals was achieved using a # 15 K-file. Then, the canals in group A were prepared by RaCe rotary file #25/6% while the canals in group B were prepared by F6 Sky Taper rotary file #25/6%. Measurements were repeated and the difference between the two measurements was calculated and compared with the Mann-Whitney U test. Results: The mean centering ability was 0.72 ± 0.62 in the RaCe group and 0.95 ± 1.39 in F6 SkyTaper group. the centrality was better in F6 SkyTaper group (it was closer to 1) but the difference was not statistically significant (P=0.4). Conclusion: Both RaCe and F6 SkyTaper rotary systems partially offset the centrality of the root canal system.

Abstract The goal of this review is to present a detailed and comprehensive description of the published work from the past decade regarding methods of improved material, geometric design, and additional functions in root canal files. The main improved methods of files and the most common technologies were further addressed, underlining their advantages and main limitations. Online databases (the Derwent Innovations Index) were consulted on this topic. Published work from 2010 to 2022 was collected and analyzed the relevant papers were chosen for inclusion in this review. The patent map classified the latest phase of the root canal files based on the analysis of the number of patents. The performance of the root canal files, such as materials. Directly affects the quality of the root canal therapy. We provided a thorough review of advances in the field of root canal files. In particular, three categories of improved methods were examined and compared, including material-based methods, geometry-based methods, and those based on additional functions. To understand this state of the art of different improved methods of root canal files, we conducted a literature analysis and a series of comparisons between different methods. The features and limitations of each method of root canal files were further discussed. Finally, we identified promising research directions in advancing the methods for the improved performance of root canal files. There is no perfect technology for all material/geometric design/additional functions, capable alone of fulfilling all the specificity and necessities of every patient. Although it is very promising, the material of the files remains understudied, and further work is required to make material science a pervasive technology in root canal therapy, and contribute to endodontic and periapical diseases by assisting in the subsequent development of root canal files.

Objectives: The current study aimed to assess the cyclic fatigue resistance of two nickel-titanium (NiTi) rotary files after immersion in 5% sodium hypochlorite (NaOCl) and Deconex. Materials and Methods: In this in vitro study, 90 new M3 Pro Gold size 25.06 and size F2 SP1 files were tested. Forty-five files of the same brand were randomly distributed into three groups (n=15) and submitted to the following immersion protocol for 5 minutes at room temperature: no immersion (control group), immersion in 5% NaOCl, and immersion in Deconex. The cyclic fatigue resistance of the files was then measured in a custom-made tester. Two-way ANOVA was applied to compare the cyclic fatigue resistance of SP1 and M3 NiTi rotary files based on the type of disinfectant solution. Post-hoc LSD test was used for pairwise comparisons and P<0.05 was considered significant. Results: Two-way ANOVA indicated a significant difference in the mean cyclic fatigue resistance of M3 and SP1 NiTi rotary files. The M3 files immersed in NaOCL displayed the lowest and the SP1 files immersed in Deconex showed the maximum cyclic fatigue resistance. The effect of type of disinfectant solution (P<0.001) and type of NiTi file (P<0.001) on cyclic fatigue resistance was statistically significant. Conclusions: The cyclic fatigue resistance of NiTi rotary instruments can be affected by immersion in disinfectants, and the specific type of file and disinfectant used will ultimately determine the extent of this impact. [ABSTRACT FROM AUTHOR]

The nickel–titanium (NiTi) instruments' geometry plays an important role in their performance and behavior. The present assessment intends to validate and test the applicability of a 3D surface scanning method using a high-resolution laboratory-based optical scanner to create reliable virtual models of NiTi instruments. Sixteen instruments were scanned using a 12-megapixel optical 3D scanner, and methodological validation was performed by comparing quantitative and qualitative measurements of specific dimensions and identifying some geometric features of the 3D models with images obtained through scanning electron microscopy. Additionally, the reproducibility of the method was assessed by calculating 2D and 3D parameters of three different instruments twice. The quality of the 3D models created by two different optical scanners and a micro-CT device was compared. The 3D surface scanning method using the high-resolution laboratory-based optical scanner allowed for the creation of reliable and precise virtual models of different NiTi instruments with discrepancies varying from 0.0002 to 0.0182 mm. The reproducibility of measurements performed with this method was high, and the acquired virtual models were adequate for use in in silico experiments, as well as for commercial or educational purposes. The quality of the 3D model obtained using the high-resolution optical scanner was superior to that acquired by micro-CT technology. The ability to superimpose virtual models of scanned instruments and apply them in Finite Element Analysis and educational purposes was also demonstrated. [ABSTRACT FROM AUTHOR]

Copyright of Brazilian Dental Science is the property of Brazilian Dental Science Journal-ICT-UNESP and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introduction: the in vitro study compared the dynamic cyclic fatigue resistance of 3 reciprocating NiTi files with heat treatment. Methods: we distributed 30 new endodontic files in three groups. The endodontic files selected for this experiment were: AF Blue R3 25/06 (AFB) (Fanta Dental, Shanghai, China), X1 Blue File 25/06 (X1B) (MK Life, Porto Alegre, RS, Brazil), and Reciproc Blue 08/25 (RB) (VDW, Munich, Germany. We measured the time to file fractureand the length of the fractured fragment. ANOVA analysis was used, followed by the Tukey test for multiple comparisons, with a significance level of 5% (P < 0.05). Results: the mean time in seconds until the file fractured was 170.7 ±15.1 for AFB files, 110.4 ±26.8 for X1B, and 163.3 ±22.9 for RB files. This difference was statistically significant when comparing X1B to AFB (p: 0.000) and X1B to RB (p: 0.000). However, there are no statistically significant differences between RB and AFB (p:0.739). Conclussions: this study found that RB and AFB files exhibit similar resistance to cyclic fatigue.

Aim: This study assessed the ability of Reciproc R25 instruments in maintaining the original profile of root canal anatomy in simulated curved canals (SCC) after multiple uses. The bending resistance of R25 before and after each use was evaluated. Materials and methods: Fifty SCC manufactured in clear resin blocks and ten R25 instruments were used. Each instrument prepared five SCC with four reuses, without intermediate sterilization. The flexibility of each instrument was determined by 45-degree bending tests before and after reuse. Colour stereomicroscopic images from each block were taken at the same position before and after instrumentation. All image processing and data analysis were performed with Fiji program. Evaluation of canal transportation was obtained for straight and curved canal regions. Univariate analysis of variance and Tukey's test were used (P < 0.05). Results: No significant difference was observed in bending resistance before and after multiple uses (P > 0.05). There was no difference in canal transportation resulting from utilizing R25 instruments after five multiple uses (P > 0.05). However, canal transportation was more severe in curved canal portions than straight portions (P < 0.05). Conclusions: Bending resistance and the final shape obtained in plastic blocks following R25 instrument use did not vary significantly between the first and the fifth use. [ABSTRACT FROM AUTHOR]

ObjectivesThe purpose of this study was to evaluate the effect of different ambient temperatures on cyclic fatigue (CF) life of two NiTi rotary systems and correlate the results with martensitic transformation temperatures.Materials and methodsHeat-treated NiTi Vortex Blue (VB) and EdgeSequel Sapphire (SP) instruments (tip sizes no. 20, 25, 30, 35, 40) were tested for CF resistance at room and body temperature (n = 20 each group) in a simulated canal (angle of curvature 60°; radius 3 mm; center from instrument tip 4.5 mm) with a motor controlled by an electric circuit. Mean half-life, beta and eta Weibull parameters were determined and compared. Two further instruments of each brand were subjected to differential scanning calorimetry (DSC).ResultsTemperature had an effect on fatigue behavior: all instruments lasted significantly longer at room than at body temperature. All VB significantly outlasted those of SP at body temperature; while smaller diameters of VB (size no. 20) were also significantly more resistant than SP when tested at room temperature; SP with larger diameters (sizes no. 30, no. 35, and no. 40) lasted significantly longer than VB did.ConclusionsImmersion in water at body temperature was associated with a marked decrease in the fatigue life of all rotary instruments tested. VB instruments were significantly more CF resistant at body temperature and showed the highest predictability in terms of fracture resistance.Clinical relevanceRotary instruments manufactured with different post-machining heat treatment responded differently to changed ambient temperatures. DSC assessment of martensitic conversion temperatures helps to predict the behavior of nickel titanium rotaries in different environments.

Objectives: The current study aimed to assess the cyclic fatigue resistance of two nickel-titanium (NiTi) rotary files after immersion in 5% sodium hypochlorite (NaOCl) and Deconex. Materials and Methods: In this in vitro study, 90 new M3 Pro Gold size 25.06 and size F2 SP1 files were tested. Forty-five files of the same brand were randomly distributed into three groups (n=15) and submitted to the following immersion protocol for 5 minutes at room temperature: no immersion (control group), immersion in 5% NaOCl, and immersion in Deconex. The cyclic fatigue resistance of the files was then measured in a custom-made tester. Two-way ANOVA was applied to compare the cyclic fatigue resistance of SP1 and M3 NiTi rotary files based on the type of disinfectant solution. Post-hoc LSD test was used for pairwise comparisons and P

This study aimed to compare the intracanal lateral force and cutting efficiency associated with two engine-driven nickel-titanium (NiTi) systems during root canal shaping. Bovine single-rooted teeth models were assembled to a custom-made splitting force measuring platform while being endodontically treated with rotary (ProTaper Gold [PTG]) or reciprocal systems (WaveOne Gold [WOG]) by two clinicians. The cutting efficiency test was run for each group by a free-falling endomotor on dentin discs for 3 min. The resulting force, files, and stroke force peaks were recorded. Data were analyzed by the Shapiro-Wilk test and ANOVA. Statistical significance was set at alpha = 0.05. Intracanal lateral forces (p < 0.01), cutting efficiency (p < 0.01), and time efficiency (p < 0.01) were significantly different between the NiTi groups. The maximum lateral splitting force was detected using the PTG shaping full-length file (S1) and during the WOG final stroke. Thus, caution is advised when reciprocating single-file systems approach the apical third or when using a large taper and wide-diameter rotatory instruments. The WOG had significantly less maximum horizontal splitting force and significantly greater cutting efficiency but less time efficiency than the PTG system. [ABSTRACT FROM AUTHOR]

The Nickel-Titanium (NiTi) alloy was developed by the metallurgist William Buehler, and it has since been introduced into various fields of knowledge due to its properties of super elasticity and shape memory effect. The introduction of NiTi revolutionized endodontics as it enhanced safety in the biomechanical preparation of curved root canals, even in larger diameters. Its utilization offered advantages over stainless steel files. This study aimed to conduct a literature review of the advancements in the mechanical properties of the NiTi alloy used in the manufacturing of endodontic instruments. The bibliographical research was conducted from the electronic search of articles indexed in English in electronic databases (PubMed, Scopus, and Web of Science) without time restrictions. Articles were identified by crossing the following descriptors: NiTi, Nitinol, and Endodontics. The initial endodontic instruments made of NiTi were austenitic, and, therefore, less flexible. The incorporation of new manufacturing methods, such as electropolishing and heat treatments allowed the creation of instruments with higher amounts of martensitic phase, resulting in greater flexibility and enhanced fracture resistance and ensuring safety in treating curved canals. The introduction of NiTi in the manufacturing of endodontic instruments is associated with an improved safety and efficiency in biomechanical preparation compared to stainless steel files. Heat treatments enabled the production of more flexible and fracture-resistant instruments for curved canal preparation. [ABSTRACT FROM AUTHOR]

Copyright of Revista Facultad de Odontología Universidad de Antioquia is the property of Universidad de Antioquia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista ADM is the property of Asociacion Dental Mexicana and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The goal of this review is to present a detailed and comprehensive description of the published work from the past decade regarding methods of improved material, geometric design, and additional functions in root canal files. The main improved methods of files and the most common technologies were further addressed, underlining their advantages and main limitations. Online databases (the Derwent Innovations Index) were consulted on this topic. Published work from 2010 to 2022 was collected and analyzed the relevant papers were chosen for inclusion in this review. The patent map classified the latest phase of the root canal files based on the analysis of the number of patents. The performance of the root canal files, such as materials. Directly affects the quality of the root canal therapy. We provided a thorough review of advances in the field of root canal files. In particular, three categories of improved methods were examined and compared, including material-based methods, geometry-based methods, and those based on additional functions. To understand this state of the art of different improved methods of root canal files, we conducted a literature analysis and a series of comparisons between different methods. The features and limitations of each method of root canal files were further discussed. Finally, we identified promising research directions in advancing the methods for the improved performance of root canal files. There is no perfect technology for all material/geometric design/additional functions, capable alone of fulfilling all the specificity and necessities of every patient. Although it is very promising, the material of the files remains understudied, and further work is required to make material science a pervasive technology in root canal therapy, and contribute to endodontic and periapical diseases by assisting in the subsequent development of root canal files. [ABSTRACT FROM AUTHOR]

Objectives: This study aimed to evaluate the effects of root canal irrigation on maximum operative torque and vertical force of Wave One Gold Primary (WOG), Reciproc Blue R25 (RB) and Protaper Next X2 (PTN) endodontic rotary instruments during simulated root canal preparation in the presence and absence of a surfactant “benzalkonium chloride”. Material and methods: A custom-made automated irrigation and torque/force analyzing device connected with endomotor was used for the study. Acrylic resin blocks with simulated curved root canals of 35° were randomly assigned to 6 groups for each file. The following irrigants were used during simulated root canal preparation with continuous rotation or reciprocation motion with pecking mode: 5% NaOCl and 5% NaOCl with 0.084% benzalkonium chloride. Maximum torque and vertical force values of files were recorded during preparation. Results: BAC addition to NaOCl did not significantly affect maximum torque values of instruments (p>0.05). WOG generated lowest torque value compared with PTN and RCB in both groups (p

Objective: To compare the effectiveness of reciprocating instruments in removing gutta-percha and bioactive-based (BioRoot RCS and MTA Fillapex) and epoxy resin-based (AH Plus) sealers from root canals based on filling residues and the time required for root canal revision. Material and methods: Root canals of 90 teeth were instrumented with Reciproc R40. All root canals were obturated using the single-cone technique with Reciproc R40 gutta-percha and with one of the selected sealers. Samples with oval, straight canals were used and randomly divided into three groups: (i) filled with AH Plus sealer and gutta-percha (n=30); (ii) filled with MTA Fillapex and gutta-percha (n=30); (iii) filled with BioRoot RCS and gutta-percha (n=30). Each group was divided into two subgroups (n=15) according to the retreatment instrument used (Reciproc M-Wire R25/R40 or Reciproc blue RB25/RB40). Root canals were longitudinally split and analyzed with a stereomicroscope at 15 × magnifications in the coronal, middle, and apical third. Computational analyses were performed with the Image J software. Data were compared using the Kruskal-Wallis test and Mann-Whitney U test. Results: While no statistically significant differences in the residual material surface were found for Reciproc Blue, Reciproc M-Wire showed significantly higher residual material surface for AH Plus and MTA Fillapex compared to BioRoot RCS. For AH plus. Residual material surface was significantly lower for Reciproc Blue than for Reciproc M-Wire. In contrast, BioRoot RCS showed a significantly higher residual material surface for Reciproc Blue. Conclusions: Calcium silicate-containing sealers were more retrievable compared to AH Plus, with fewer sealer remnants and shorter retreatment time. Retreatment with Reciproc M-Wire instruments was superior to Reciproc blue instruments in retreatment of BioRoot RCS. However, none of the sealers were removed completely.

Objective: Effective tools and methods are applied during root canal retreatment to eliminate root canal obturation materials and preserve the initial root canal anatomy. The present study compared the efficacy of Reciproc, Neoniti, ProTaper, and Hedstrom files in the retreatment of curved root canals. Material and methods: In the present in vitro study, 100 root canals with 25‒45º curvatures were used. After the samples were initially prepared and examined by CBCT, the root canals were obturated with gutta-percha and randomly assigned to four groups (n=25). A retreatment was carried out in each group with NeoNiTi, ProTaper, Reciproc, and Hedstrom files. CBCT examinations were carried out again under the same conditions. The samples were evaluated at 3-, 6-, and 9-mm distances from the apex on the first and the second CBCT image for root canal transportation and remaining gutta-percha in the root canals. The time required for retreating each canal in each sample was recorded. One-way ANOVA and corresponding non-parametric tests were applied for data analysis. Results: The root canal transportation in the NeoNiTi group was lower than that in the other groups and significantly different from the ProTaper group (P0.05). Conclusion: Despite the fact that the NeoNiTi file produced less transportation than other file systems evaluated in the retreatment of curved root canals, all the files were very effective at the clinically acceptable levels.

Aims: The goal of this study was to analyze the bacterial microleakage following two methods (heat vs. rotary) of postspace preparation after two-time intervals (immediate vs. 1 week later). Setting and Design: In vitro-comparative study. Materials and Methods: Eighty-two single-rooted teeth were decoronated at the cementoenamel junction. Root canals were prepared using rotary files. After root canal obturation, specimens were randomly allocated to 4 experimental groups based on the method of postspace preparation (heat or peeso reamer) and time interval (immediate or 1 week later) (n = 18). Group 1: Peeso reamer-immediate, Group 2: Heat-immediate, Group 3: Peeso reamer-1 week later, Group 4: Heat-1 week later. 10 specimens were considered as positive and negative controls (n = 5 each). Custom-made dual-chamber devices were used to appraise the bacterial microleakage for 60 days. Statistical Analysis Used: Data were analyzed with Chi-Square and Log-Rank tests and Cox regression. Results: All through the experimental period, there was no significant difference (P = 0.41) between the studied groups. Groups 2 and 4 had the highest microleakage and the lowest survival rate (55.56% ± 11.71%). Group 1 showed the lowest microleakage and the highest survival rate (77.8% ± 9.80%). Conclusions: The applied techniques for postspace preparation and the time intervals (neither independently nor simultaneously) showed no significant difference in the field of bacterial leakage.

Introduction: Endodontic instrument separation is one of the iatrogenic errors which may affect the outcome of treatment. The present in vitro study was aimed to investigate the effect of different cross-sectional designs of separated nickel–titanium (Ni-Ti) rotary files on apical microleakage. Materials and Methods: A total of 48 mandibular premolar roots were selected. The samples were randomly assigned to four experimental groups including Mtwo (n = 10), HERO Shaper (n = 10), RaCe (n = 10), and FlexMaster (n = 10) as well as positive (n = 4) and negative (n = 4) control groups. Ni-Ti rotary instruments with the same size and taper (0.06, #30) were separated in the apical region after complete cleaning and shaping, and the remaining root canal was obturated with gutta-percha and AH-26 sealer. The bacterial microleakage of each group was assessed through Enterococcus faecalis for 60 days. Survival analysis was done by SPSS 22. Results: There were no statistically significant differences between the studied groups in terms of the time of microleakage (P = 0.955). Conclusion: The separated Ni-Ti rotary instruments with different cross-sectional designs had no impact on apical microleakage.