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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. [ABSTRACT FROM AUTHOR]

Introduction: Success in endodontics depends on canal preparation, disinfection, and obturation. Cleaning and shaping play a pivotal role in successful endodontic therapy. An important factor in preventing procedural mishaps and further complications is the quantity of dentine removed during instrumentation because the fracture resistance of the root is directly influenced by the amount of dentine that remains after instrumentation. Aim: To evaluate and compare the remaining dentine thickness of the root canal after instrumentation with three different rotary file systems using Cone Beam Computed Tomography (CBCT) imaging. Materials and Methods: Thirty permanent extracted, single-rooted teeth were collected. The samples were decoronated at the level of the Cementoenamel Junction (CEJ). A pre-instrumentation CBCT scan was taken. Access opening and working length were determined. The samples were randomly assigned to three groups: Group I - Edge Endo X7, Group II- Hero Gold, Group III - Neo-endo flex files. Biomechanical preparation was carried out using the respective files. To evaluate the remaining dentine thickness, a comparison was made with the pre-instrumentation CBCT scan. Statistical analysis was performed using One-way ANOVA. Results: Upon inter-group comparison of the pre-instrumentation group, no significant difference (p≥0.05) was observed. Post-instrumentation, it was noted that the remaining dentine thickness in Group I (p≤0.05) at the apical third was significantly less than in Group II (p=0.007) and Group III (p=0.042). Maximum preservation of dentine was seen with Hero gold files, whereas the minimum preservation of dentine was seen with Edge Endo X7. Conclusion: Hero gold files exhibited less removal of dentine apically, whereas Edge Endo X7 showed more removal of dentine apically.

Introduction: Success in endodontics depends on canal preparation, disinfection, and obturation. Cleaning and shaping play a pivotal role in successful endodontic therapy. An important factor in preventing procedural mishaps and further complications is the quantity of dentine removed during instrumentation because the fracture resistance of the root is directly influenced by the amount of dentine that remains after instrumentation. Aim: To evaluate and compare the remaining dentine thickness of the root canal after instrumentation with three different rotary file systems using Cone Beam Computed Tomography (CBCT) imaging. Materials and Methods: Thirty permanent extracted, singlerooted teeth were collected. The samples were decoronated at the level of the Cementoenamel Junction (CEJ). A preinstrumentation CBCT scan was taken. Access opening and working length were determined. The samples were randomly assigned to three groups: Group I - Edge Endo X7, Group II-Hero Gold, Group III - Neo-endo flex files. Biomechanical preparation was carried out using the respective files. To evaluate the remaining dentine thickness, a comparison was made with the pre-instrumentation CBCT scan. Statistical analysis was performed using One-way ANOVA. Results: Upon inter-group comparison of the pre-instrumentation group, no significant difference (p=0.05) was observed. Postinstrumentation, it was noted that the remaining dentine thickness in Group I (p=0.05) at the apical third was significantly less than in Group II (p=0.007) and Group III (p=0.042). Maximum preservation of dentine was seen with Hero gold files, whereas the minimum preservation of dentine was seen with Edge Endo X7. Conclusion: Hero gold files exhibited less removal of dentine apically, whereas Edge Endo X7 showed more removal of dentine apically. [ABSTRACT FROM AUTHOR]

Raid Abdullah Almnea,1 Sadun Mohammad Al Ageel Albeaji,2 Ahmed Ali Alelyani,3 Dalia AlHarith,4 Abdulmajeed Saeed Alshahrani,1 Ahmed Abdullah Al Malwi,5 Mohammed A Alobaid,6 Mohammed M Al Moaleem7 1Department of Restorative Dentistry, Division of Endodontics, College of Dentistry, Najran University, Najran, Saudi Arabia; 2Consultant Endodontics, Dental Center, Hafar al Batin, Saudi Arabia; 3Restorative Department, Endodontic Division, College of Dentistry, Najran University, Najran, Saudi Arabia; 4Department of Restorative Dentistry, Riyadh Elm University, Riyadh, Saudi Arabia; 5‏Department of Restorative Dentistry, Division of Endodontics, College of Dentistry, King Khalid University, Abha, Saudi Arabia; 6Restorative Dental Science Department & Department of Dental Education, College of Dentistry, King Khalid University, Abha, Saudi Arabia; 7Department of Prosthetic Dental Science, College of Dentistry, Jazan University, Jazan, 45142, Saudi ArabiaCorrespondence: Mohammed M Al Moaleem, Department of Prosthetic Dental Science, College of Dentistry, Jazan University, Jazan, 45142, Saudi Arabia, Tel +966-550599553, Email malmoaleem@jazanu.edu.saBackground: This simulated study of 30 severely curved L-shaped root canals aimed to compare preparation time, aberrations, width measurements, and fractured files of three nickel–titanium (Ni–Ti) files, namely, ProTaper, ProTaper Next (PTN), and WaveOne (WO).Methods: Thirty simulated L-curved root canals of resin blocks were randomly divided into three groups. The canals were prepared to a tip size of 25 using ProTaper, PTN, and WO rotary file systems. Pre- and post-operative views for each sample were captured by a professional camera at a standardized distance and position. Blue India ink was injected into the pre-operative canals, and red India ink was injected into the post-operative canals to give a clear superimposition image. Five points were assessed through the halfway of the canal to the orifice (area between the beginning of curvature and apical end point). Preparation time, aberrations, width measurements, and fractured files were recorded and analyzed.Results: Mean preparation time was longest in ProTaper (4.89± 0.68 minutes). PTN and WO were the fastest in preparing the canals (about 3 minutes). A statistically significant difference was found between WO and ProTaper & PTN and ProTaper (p=0.000), while the difference was non-significant (p > 0.05) between WO and PTN. Nine aberrations consisting of three zips, one ledge and one outer widening were related to ProTaper, while WO recorded a ledge and fractured file, but for PTN system, it verified an outer widening and ledge. Only one WO file fractured, with no deformation observed in the other instruments. No significance was recorded among the width measurements in the different levels.Conclusion: ProTaper next achieved faster cutting than the ProTaper and WO file systems. PTN maintained the best apical termination position and produced the least canal aberration, followed by WO and ProTaper.Keywords: simulated canal, rotary system, preparation time, canal aberrations, nickel–titanium files, dental pulp cavity, root canal therapy

Background: Effective endodontic instrumentation aims to remove microorganisms, debris, and tissue from the root canal while maintaining dentinal integrity. This study compares dentinal defect incidence following canal preparation with different hand files, nickel-titanium rotary files, and reciprocating files. Materials and Methods: Eighty single-rooted mandibular premolars with mature apices were collected. Four groups (n = 20) were established based on canal patency establishment, canal preparation technique, irrigation solution, and final irrigation. After root sectioning at 3 mm, 6 mm, and 9 mm from the apex, slices were examined under a stereomicroscope, and dentinal defects were recorded. A second examiner reviewed the images. Results: The results showed significant difference of P = 0.031 among Hand files vs. Rotary ProTaper files: In Hand files vs. Reciprocating WaveOne files significant difference was P = 0.048, and for rotary ProTaper files vs. Reciprocating WaveOne files: No significant difference (P = 0.643). Dentinal defect counts were similar at 3 mm, 6 mm, and 9 mm. Statistically significant variation was observed between hand files and rotary files, as well as hand files and reciprocating files. Conclusion: Both rotary and reciprocating files showed a statistically significant increase in dentinal defect incidence compared to hand files. However, clinical implications should be considered cautiously. Instrumentation technique selection should be based on clinical context, operator experience, and patient factors. Further clinical studies are needed for validation.

Background: Effective endodontic instrumentation aims to remove microorganisms, debris, and tissue from the root canal while maintaining dentinal integrity. This study compares dentinal defect incidence following canal preparation with different hand files, nickel-titanium rotary files, and reciprocating files. Materials and Methods: Eighty single-rooted mandibular premolars with mature apices were collected. Four groups (n = 20) were established based on canal patency establishment, canal preparation technique, irrigation solution, and final irrigation. After root sectioning at 3 mm, 6 mm, and 9 mm from the apex, slices were examined under a stereomicroscope, and dentinal defects were recorded. A second examiner reviewed the images. Results: The results showed significant difference of P = 0.031 among Hand files vs. Rotary ProTaper files: In Hand files vs. Reciprocating WaveOne files significant difference was P = 0.048, and for rotary ProTaper files vs. Reciprocating WaveOne files: No significant difference (P = 0.643). Dentinal defect counts were similar at 3 mm, 6 mm, and 9 mm. Statistically significant variation was observed between hand files and rotary files, as well as hand files and reciprocating files. Conclusion: Both rotary and reciprocating files showed a statistically significant increase in dentinal defect incidence compared to hand files. However, clinical implications should be considered cautiously. Instrumentation technique selection should be based on clinical context, operator experience, and patient factors. Further clinical studies are needed for validation. [ABSTRACT FROM AUTHOR]

This study evaluated surface wear and resistance to fracture of reciprocating and novel rotary instruments after use in curved canals. Twenty new instruments (n = 5/each group): Reciproc Blue, WaveOne Gold, XP‐endo Shaper (XPS) and TruNatomy were used twice for the instrumentation of simulated curved canals in plastic blocks. The instrumentation was performed according to the manufacturer's instructions at body temperature. Surface roughness was evaluated, using a profilometer, before instrumentation and twice after the instrumentation. Instruments were, then, subjected to a cyclic fatigue test to evaluate the time to failure. Differences were assessed using ANOVA and post hoc tests (α = 0.05). The XPS instruments showed significantly higher values of roughness compared with TruNatomy at every stage, especially after the second use (p < 0.008). Reciprocating instruments showed superior cyclic fatigue resistance compared with novel rotary instruments (p < 0.05). TruNatomy showed minimal surface roughness, and XPS exhibited significantly higher surface roughness. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the effect from usage and autoclaving on torsional fracture resistance of heat-treated nickel-titanium rotary instruments. ProTaper Gold F2 (PG) and TruNatomy Prime (TN) were selected. For group-N, new files were tested to make a baseline torsional resistance. For group-U, files underwent instrumentation in a J-shaped canal block, and files were tested. For group-S, files underwent instrumentation as in the group-U and followed by autoclave sterilization then were tested. Maximum torsional strength and distortion angel until fracture were measured using a customized device and toughness was calculated. Statistical analysis was conducted at the significance level of 95%. The topographic appearances of torsional fracture fragments were examined under scanning electron microscopy. PG showed significantly higher torsional strength after usage and sterilization; however, TN had reduced torsional strength (p < 0.05). PG showed significantly higher torsional strength in group-S than subgroup-N, while TN showed significantly lower torsional strength in group-U than group-N (p < 0.05). Regardless of the test conditions, PG showed significantly higher torsional strength and toughness than TN while TN had bigger distortion angle than PG (p < 0.05). The mechanical loads from usage and heat application during sterilization may result in alteration of torsional resistances according to geometry and alloy characteristics.

Aims: We aimed to investigate the effect of instrument length on the torsional resistance and bending property of three nickel–titanium files, namely ProTaper Gold (PTG), ProTaper Next (PTN), and HyFlex CM (HCM) using finite element analysis. Materials and Methods: Three-dimensional models of each aforementioned system were created using the computer-assisted design (CAD) software SolidWorks® 2016 (Dassault Systèmes, SolidWorks Corp., Concord, MA, U. S.). Then, all models were imported to the ANSYS® Workbench 16 (Canonsburg, PA, U. S.) where the simulation was computed. The boundary conditions used to simulate the behavior of the endodontic instruments were in compliance with the ISO 3630 1 specification standards. Results: It was observed that in bending test, HCM model exhibited load of 510.35 MPa with displacement of 6.05 mm, followed by PTG model (465.48 MPa) and 11.21 mm displacement, then PTN file model (440.74 MPa) and 10.30 mm displacement, whereas in torsional test the rigidity curve for HCM file (1.9673 N mm/Radian) lies much below PTG (6.4615 N mm/Radian) which clearly shows that HCM is flexible as compared to PTG and PTN. Conclusion: Considering the high flexibility of the HCM file, it can be effectively used in severely curved root canals and PTG and PTN files in moderately curved root canals. It was also recommended that HCM files should not be kept in canals for a longer time because stresses might reach to ultimate level quickly which can cause fracture.

Aim: The aim of this ex vivo study was to compare the amount of debris extruded during retreatment using stainless steel hand files (Hedstroem files) and R-Endo Nickel Titanium rotary instruments. Methodology: Eighty single-rooted freshly extracted human mandibular premolars were divided into two groups consisting of 40 teeth each. Retreatment was performed with R-Endo (Micro-Mega, Besançon, France) and Hedstroem files (Dentsply, Maillefer, Ballaigeus, Switzerland). The experimental teeth were obturated with lateral condensation technique. Then, 1.5-mL Eppendorf tubes were used to collecting the material that was extruded during preparation by subtracting post-instrumentation weight from pre-instrumentation weight. Results: There were significant differences in the amount of debris extruded between the groups (p<0.001). The amount of apical extrusion in the R-Endo group was determined to be less than in the hand instrumentation group. Conclusion: Within the limitations of this study, it might be concluded that all tested instruments resulted in apical extrusion of debris. During endodontic retreatment procedures, the hand files extruded a significantly higher amount of debris than the R-Endo. [ABSTRACT FROM AUTHOR]

Aim: Testing whether two sealant systems (cold laterally compacted gutta-percha and Obtura II) can be used with extraction across two apically separated rotational nickel-titanium files was the primary objective of this study (RACE and K3). Materials and Methods: Both the positive and negative control teeth were randomly distributed among 62 mandibular premolars to create two groups of 30 each. Following the RACE and K3 approaches, four subgroups were created from the roots. Subgroups A1, B1, and A2, B2 (n = 10 each) were formed in the apical thirds of the canal at 3 mm from the tip. There was no division of instruments between groups A3, B3, B4, and A4. When it came to obturation, the Obtura II method was used for A2, A4, B2, B4, and A1, A3. A dye extraction process was employed to determine whether the specimens had been obliterated. Analysis of variance (ANOVA), Student t test (two-tailed, independent), and Leven's test were used to ascertain the values for each of the study groups. Results: Group A1 had a substantially lower leakage rate than group B1. Groups A2, B2 and A3, B3 had no statistically significant differences. Group A4 had a substantially lower leakage rate than group B4. Conclusion: Even when the cracked NiTi rotary system was not present, Obtura II-obturated groups had less leakage than the lateral condensation approach. [ABSTRACT FROM AUTHOR]

Aims: We aimed to investigate the effect of instrument length on the torsional resistance and bending property of three nickel–titanium files, namely ProTaper Gold (PTG), ProTaper Next (PTN), and HyFlex CM (HCM) using finite element analysis. Materials and Methods: Three-dimensional models of each aforementioned system were created using the computer-assisted design (CAD) software SolidWorks® 2016 (Dassault Systèmes, SolidWorks Corp., Concord, MA, U. S.). Then, all models were imported to the ANSYS® Workbench 16 (Canonsburg, PA, U. S.) where the simulation was computed. The boundary conditions used to simulate the behavior of the endodontic instruments were in compliance with the ISO 3630 1 specification standards. Results: It was observed that in bending test, HCM model exhibited load of 510.35 MPa with displacement of 6.05 mm, followed by PTG model (465.48 MPa) and 11.21 mm displacement, then PTN file model (440.74 MPa) and 10.30 mm displacement, whereas in torsional test the rigidity curve for HCM file (1.9673 N mm/Radian) lies much below PTG (6.4615 N mm/Radian) which clearly shows that HCM is flexible as compared to PTG and PTN. Conclusion: Considering the high flexibility of the HCM file, it can be effectively used in severely curved root canals and PTG and PTN files in moderately curved root canals. It was also recommended that HCM files should not be kept in canals for a longer time because stresses might reach to ultimate level quickly which can cause fracture. [ABSTRACT FROM AUTHOR]

Aim of the Study: Need for our study was to evaluate a comparison between canal preparation ability of nickel–titanium (NiTi) hand files with step-back manual technique, of NiTi files installed on a reciprocating hand piece and of Wave-One files utilizing noninvasive cone-beam computed tomography (CBCT) technique. Materials and Methods: Thirty extracted intact single-rooted human mandibular premolars were used in the study, segregated in three sets of 10 specimens each, where canal instrumentation was done by different methods using NiTi in step-back technique, using reciprocating hand piece with NiTi files and using primary file with the use of Wave-One reciprocating system. Later, evaluation of centering ability was conducted using the references through CBCT images. Results: Hand NiTi files showed even less canal centering ability as compared to other two sets. Mesiodistal diameter at 9 mm length of the prepared canal was 1.06 and later was 0.98, which shows excessive preparation in case of Set I versus Set II. In case of comparison between Set III and Set I, mesiodistal diameter at 9 mm length of the prepared canal was 0.99, and later was 1.06, depicting better canal shaping ability with Wave-One file. Conclusion: The use of hand NiTi files installed on a reciprocating hand piece would be economically beneficial producing the similar results as that of wave one without any deviation from the original canal anatomy.

The study aimed to compare the extent of dentinal microcracks in the radicular dentin using hand K files and various types of rotary nickel-titanium (NiTi) file systems. Forty mandibular incisor teeth (human) were grouped for the study. The root apices were closed, and the canals were straight (

Aim of the Study: Need for our study was to evaluate a comparison between canal preparation ability of nickel-titanium (NiTi) hand files with step-back manual technique, of NiTi files installed on a reciprocating hand piece and of Wave-One files utilizing noninvasive cone-beam computed tomography (CBCT) technique. Materials and Methods: Thirty extracted intact single-rooted human mandibular premolars were used in the study, segregated in three sets of 10 specimens each, where canal instrumentation was done by different methods using NiTi in step-back technique, using reciprocating hand piece with NiTi files and using primary file with the use of Wave-One reciprocating system. Later, evaluation of centering ability was conducted using the references through CBCT images. Results: Hand NiTi files showed even less canal centering ability as compared to other two sets. Mesiodistal diameter at 9 mm length of the prepared canal was 1.06 and later was 0.98, which shows excessive preparation in case of Set I versus Set II. In case of comparison between Set III and Set I, mesiodistal diameter at 9 mm length of the prepared canal was 0.99, and later was 1.06, depicting better canal shaping ability with Wave-One file. Conclusion: The use of hand NiTi files installed on a reciprocating hand piece would be economically beneficial producing the similar results as that of wave one without any deviation from the original canal anatomy. [ABSTRACT FROM AUTHOR]

This clinical study was aimed to evaluate apical transportation and centering ability of WaveOne, OneShape files and Tornado rotary system using Cone-beam computed tomography (CBCT). Lower molars with a curving angle of buccal canals extending from 15°-45° in 24 patients were arbitrarily divided into three groups (n=8) rendering to the rotary systems used: Group 1, Tornado system, Group 2, WaveOne rotary system, and Group 3, OneShape rotary system. CBCT was used as a diagnostic method to evaluate centering ratio and canal transportation at 2, 5 and 8 mm from apical foramen. One-way analysis of variance and post hoc Tukey tests were used for statistical analysis at p≤0.05. No statistically significant difference in the magnitude of transportation and centering ability was found at all tested levels (P>0.05). WaveOne and OneShape nickel-titanium files and Tornado stainless-steel file conserved the original canal curvature with no significant variance. [ABSTRACT FROM AUTHOR]

The study aimed to compare the extent of dentinal microcracks in the radicular dentin using hand K files and various types of rotary nickel-titanium (NiTi) file systems. Forty mandibular incisor teeth (human) were grouped for the study. The root apices were closed, and the canals were straight (<5°). The samples were divided into four groups (n = 10). Group 1—Hand K file system (SybronEndo, SA), Group 2—XP-endo Shaper (FKG Dentaire, La Chaux-de-Fonds, Switzerland), Groups 3—Neoendoflex file (Neoendo, Orikam, India), and Group 4—Hero Shaper files (Micro-Mega, Becacon, France). Sectioning was done at 3, 6, and 9 mm from the apex, perpendicular to the long axis using a diamond disc under water coolant. The cut samples were then observed through a scanning electron microscope at ×50 enlargement. The control group showed no microcracks except one sample in the coronal third, which was less significant. The difference in the amount of crack detected on comparing the different groups was significant. In the experimental groups, XP-endo Shaper group showed significantly less number of cracks than the Neoendo flex, and Hero Shaper groups. Within the limitations of this study, all the system, except hand K files, produced remarkable dentinal microcracks. Least cracks were seen in canals instrumented with XP-endo Shaper. It can also be noted that single file system causes less number of microcracks. [ABSTRACT FROM AUTHOR]

In modern dentistry, reliable endodontic treatment is increasingly important. Many procedures have been developed in recent years in order to improve the treatment possibilities. For instance, the laser-supported disinfection of root dentin has brought a major advance. Whatever technique is applied for infection control and the achievement of a tight root canal seal, the indispensable basis for successful endodontic treatment is a dependable root canal preparation. In general, root canal preparation means accessing the root canal system and performing shaping and cleaning of the canals. Nowadays, it is recommended to shape and clean with a combination of chemical and mechanical methods. Another important part is the disinfection protocol using various irrigations, medication, and ultrasonic or laser devices. To use these methods, it is necessary to obtain access to the root canal system and perform a mechanical root canal enlargement. This article presents the preparation of an ideal access cavity and the general working principle of mechanical root canal treatment with nickel-titanium instruments and the crown-down technique. Finally, guidelines for safe working conditions with the presented technique are given. [ABSTRACT FROM AUTHOR]

Abstract: Aim: To evaluate the resistance to cyclic fatigue of ProTaper Next (PTN; Dentsply Sirona, Ballaigues, Switzerland), Revo‐S (Micro‐Mega, Besançon, France), Mtwo (Sweden & Martina, Padova, Italy), Twisted Files (TF, SybronEndo, Orange, CA, USA) and EndoWave (J Morita Corporation, Osaka, Japan) used in continuous rotation or in reciprocation of Optimum Torque Reverse motion (OTR). Methodology: A total of 120 nickel‐titanium files were tested. Twenty‐four instruments for each brand were divided into two groups (n = 12) on the basis of the motion tested: continuous rotation (Group 1) or reciprocation of OTR motion (Group 2). Resistance to cyclic fatigue was determined by recording time to fracture (TtF) in a stainless steel artificial canal with a 60° angle of curvature and 5 mm radius of curvature. The TtF data were analysed by using two‐way analysis of variance ( anova) and Bonferroni's post hoc tests at 0.05. Results: Mtwo and TF had significantly higher TtF when compared with all other instruments, both in continuous rotation and in reciprocation of OTR motion (P < 0.0001 and P < 0.05, respectively). No difference was observed between Mtwo and TF (P > 0.05), in both motions. PTN was associated with higher cyclic fatigue resistance than Revo‐S and EndoWave, both in continuous rotation and in reciprocation of OTR motions (P < 0.0001). No difference was observed between Revo‐S and EndoWave, in both motions (P > 0.05). Reciprocating OTR motion improved TtF of all instruments (P < 0.0001). Conclusions: Reciprocation of OTR motion improved significantly cyclic fatigue resistance of all instruments tested compared with continuous rotation. Mtwo and TF had significantly higher cyclic fatigue than the other instruments, in both continuous rotation and reciprocation of OTR motion. [ABSTRACT FROM AUTHOR]

Background: Premature loss of primary teeth results in space loss, thus affecting the integrity of the oral tissues. According to the American Academy of Pediatric Dentistry, the treatment for a carious primary molar with pulpal involvement is pulpectomy. The success of this procedure depends on the elimination of bacteria, the most common being Enterococcus faecalis (E. faecalis) , by cleaning and shaping the root canals with rotary or hand instrumentation., Aims and Objectives: Evaluating and comparing the cleaning efficacy and obturation quality using Kedo-SH hand files and rotary Kedo-SG (blue) and Pro AF Baby Gold files in primary molar teeth., Materials and Methods: A total of 51 extracted primary molar teeth were selected and divided into three equal groups. Group I, the control group, was instrumented with Kedo-SH hand files. Groups II and III were instrumented with Kedo-SG (blue) and Pro AF Baby Gold files, respectively. Baseline data and postinstrumentation data were sent for microbiological analysis to check microbial levels of bacteria E. faecalis . Obturation quality was then scored using Barrieshi-Nusair criteria and the T-scoring system by Robia., Results: Associating obturating length between each group, maximum samples in group I showed adequate fill. Relating to density, maximum samples in group III showed no voids present in the obturation. Distribution of the T-scoring system shows maximum samples in group III having all three qualities of ideal obturation. On comparing microbiological analysis among the groups, group I showed higher colony counts of E. faecalis compared to groups II and III., Conclusion: In the present study, rotary instrumentation in the canals showed more consistent results than hand instrumentation. Among the rotary files, Pro AF Baby Gold files show a greater reduction in E. faecalis , with a good obturation quality. Thus, the use of nickel-titanium (Ni-Ti) files is a good option for root canal instrumentation in primary teeth., How to Cite This Article: Shanker K, Patil SB. Evaluation of the Efficiency to Remove the Infected Dentin via Enterococcus faecalis Bacterial Count and to Adequately Shape the Canal Using Hand Kedo-SH Files, Rotary Kedo-SG (Blue) and Pro AF Baby Gold Files in Primary Molars: An In Vitro Study. Int J Clin Pediatr Dent 2023;16(S-2):S142-S148., Competing Interests: Source of support: Nil Conflict of interest: None, (Copyright © 2023; The Author(s).)

Introduction The aims of this study were to determine the flexibility of ProFile Vortex (VX) and Vortex Blue (VB) files (Dentsply Tulsa Dental Specialties, Tulsa, OK) and then to evaluate and compare their fatigue resistance in artificial single curvature and 2 different artificial double curvature canals. Methods Flexibility of the files (size 25/.04) in bending was assessed according to ISO 3630-1. Both files were subjected to fatigue tests inside artificial canals with a single curvature (group 1: 60° curvature, 5-mm radius) and with 2 different double curvatures (group 2: first [coronal] curve of 60° curvature and 5-mm radius and the second one [apical] of 30° curvature and 2-mm radius and group 3: first curve of 60° curvature and 5-mm radius and the second one of 60° curvature and 2-mm radius). The number of cycles to fracture (NCF) was recorded, and the fracture surface of all fragments was examined with a scanning electron microscope. Results The bending load was significantly lower for VB files than VX files ( P < .05), and the 2 types of files followed different trajectories in identical canals. In group 1, the 2 files had significantly higher NCF than in groups 2 and 3 ( P < .05). Both files had significantly higher NCF in group 2 than in group 3 ( P < .05). In group 1, VB files had fatigue resistance superior to VX files ( P < .05), whereas in groups 2 and 3 their fatigue resistance was not statistically different from each other. The crack initiation of a vast majority of files that fractured in double curvature canals (groups 2 and 3) was localized on either 1 of 2 of the 3 cutting edges. Conclusions Double curvature canals represent a much more stressful and challenging anatomy than single curvature canals, and, in them, fatigue resistance may be affected by the degrees and the radii of curvatures as well as by the bending properties of the files. [ABSTRACT FROM AUTHOR]

Introduction: This clinical study was conducted to compare the effectiveness of single-file reciprocating systems and rotary systems in removing endotoxins and cultivable bacteria in endodontic retreatment. Methods: Thirty endodontically treated teeth with post-treatment apical periodontitis were selected. The specimens were divided into three groups according to the system used: WaveOne ( n = 10), Reciproc instrument ( n = 10), and ProTaper Universal Retreatment system ( n = 10). Samples were collected before and after chemomechanical preparation. The irrigation was performed by using 2.5 % sodium hypochlorite. A chromogenic limulus amebocyte lysate assay test was used to quantify endotoxins. Culture techniques were used to determine bacterial colony-forming unit counts. Results: At baseline, endotoxins and cultivable bacteria were recovered from 100 % of the root canal samples in a median value of 5.84 EU/mL and 4.98 × 10 CFU/mL, respectively. After CMP, no differences were found in the median percentage values of endotoxin reduction achieved with reciprocating systems-WaveOne [94.11 %] and Reciproc [93.29 %] and with rotary systems-ProTaper [94.98 %] ( P > 0.05). Both single-file reciprocating systems [WaveOne (98.27 %) and Reciproc (99.54 %)] and rotary system [ProTaper (98.73 %)] were effective in reducing bacterial load ( P > 0.05). Moreover, no differences were found among the systems tested. Conclusions: The Reciproc and WaveOne reciprocating systems were as effective as the ProTaper system for removal of endotoxins and bacteria in endodontic retreatment. Clinical relevance: All systems tested were effective to remove cultivable bacteria and endotoxin in endodontic retreatment. As no differences among systems were observed, it is possible to suggest that clinicians should choose the preferred technique to perform endodontic. [ABSTRACT FROM AUTHOR]

New files (ProTaper Next/HyFlex/OneShape) are made from novel nickeltitanium (NiTi) alloys/treatments. The purpose of this study was to compare the cyclic fatigue resistance of these new instruments with that of Revo-S instruments. Four groups of 20 NiTi endodontic instruments were tested in steel canals with a 3 mm radius and a 60° angle of curvature. The cyclic fatigue of the following NiTi instruments with a tip size 25 and 0.06 taper that were manufactured with different alloys was tested: ProTaper Next X2 (M-Wire), OneShape (conventional NiTi), Revo-S Shaping Universal (conventional NiTi) and HyFlex 25/0.6 (controlled memory NiTi wire). A one-way ANOVA and post-hoc Tukey's test (α = 0.05) revealed that the HyFlex files had the highest fatigue resistance and the Revo-S had the least fatigue resistance among the groups (P < 0.001). [ABSTRACT FROM AUTHOR]

Objectives: The purpose of this study was to compare root canal preparation in curved canals in molar teeth with the rotary NiTi Mtwo and ProTaper systems in terms of canal shape and smear layer. Materials and Methods: Mesiobuccal canals of 60 molar teeth with angles of curvature between 25 and 35 degrees were prepared with a torque controlled low speed engine; 30 canals for each system. Each individual instrument was used to prepare four root canals and the time required for preparation was recorded. Standardized radiographs were taken before and following instrumentation and used to determine changes in canal curvature. Results: There was no significant difference in preparation time between the two systems. No instruments separated during use. The Mtwo system gave a statistically smaller change in canal curvature and thus was better for maintaining the original shape of the root canal, with less transportation (P less than 0.05). The greatest difference was seen for maxillary molar teeth. When prepared root canals were examined by SEM there was no difference between the two systems at the coronal, middle or apical thirds. Conclusion: Overall, the results of this study suggest that Mtwo instruments are preferable for situations where canals are curved, particularly for maxillary molars.

Aim To compare the cyclic fatigue resistance of Pro- Taper Next files (PTN; Dentsply Maillefer, Ballaigues, Switzerland) with Twisted Files (TF; SybronEndo, Orange, CA, USA), HyFlex CM (HF; ColténeEndo/ Whaledent, Inc, Cuyahoga Falls, OH, USA) and Pro- Taper Universal (PT; Dentsply Maillefer). Methodology Size 25, .06 taper for PTN X2, TF, HF and PT F1 size 20, .07 taper were rotated in simulated canals until failure, and the number of cycles to failure (NCF) was recorded to evaluate their cyclic fatigue resistance. A scanning electron microscope was used to characterize the topographic features of the fracture surfaces of broken files. The data of the NCF and fragment length values were analysed statistically using one-way analysis of variance and Tukey post hoc tests. Statistical significance level was set at P < 0.05. Results Twisted Files had a significantly higher resistance to cyclic fatigue than the other instruments (P < 0.05). No significant difference was found in NCF between PTN and HF (P > 0.05); however, there was a significant difference (P < 0.05) of both these systems with PT, which exhibited the lowest mean NCF. The ranking in the NCF values was: TF > PTN > HF > PT. The fracture cross-sections of all brands revealed similar fractographic features, including crack origins, fatigue zone and an overload fast fracture zone. Conclusions The new ProTaper Next had greater resistance to cyclic fatigue compared with ProTaper and HyFlex CM but not the Twisted Files. [ABSTRACT FROM AUTHOR]

Introduction The purpose of this study was to compare the torsional resistance, flexibility, and surface microhardness of ProTaper Next files (PTN) with Twisted Files (TF) and RaCe (RC). Methods A metal block with a cubical hole was used to evaluate the torsional resistance. Five millimeters of the tip of each file was securely held in place by filling the mold with a resin composite, and the files were driven clockwise at 300 rpm. The number of load applications before fracture was recorded for each file. A scanning electron microscope was used to characterize the topographic features of the fracture surfaces of the broken files. The files were tested for bending resistance by using cantilever-bending test. Vickers microhardness was measured on the cross section of instruments with 300-g load and 15-second dwell time. Torsional resistance data were analyzed by using the nonparametric Kruskal-Wallis and Mann-Whitney U tests. Bending resistance and microhardness data were analyzed by using analysis of variance and Tukey tests. Results PTN showed the highest torsional resistance and microhardness, followed by RC ( P < .05). The fracture cross sections of all brands showed dimpling near the center of fracture surface. The ranking in the bending resistance values was as follows: RC > PTN > TF. Conclusions PTN improved its resistance to torsional stresses and wear compared with TF and RC. TF showed improved flexibility compared with other tested brands. [ABSTRACT FROM AUTHOR]

Introduction This study investigated the surface, fractured structure, and physicochemical properties related to cyclic fatigue in various nickel-titanium (NiTi) files. Methods Among a total of 10 groups of NiTi files, conventional NiTi files (ProFile [Dentsply Maillefer, Ballaigues, Switzerland] and K3 [SybronEndo, Orange, CA]) and new-generation NiTi files (ProFile Vortex [PV; Tulsa Dental Specialties, Tulsa, OK], Vortex Blue [VB; Tulsa Dental Specialties], and K3 XF [XF; SybronEndo, Orange, CA]) with the same tip diameter (ISO size 25) and 2 types of taper (0.04 and 0.06) were used in this study. Scanning electron microscopy of the file surface structure, differential scanning calorimetry, and cyclic fatigue resistance tests were conducted. Results Many mechanical grooves were recognized on the file surface. The surface in the ProFile group was extremely smooth compared with that observed for the other files. Many shallow hollows besides mechanical grooves were noted on the surface in the XF group. A smooth curve was observed in the ProFile, K3, and PV groups. Defined peaks in differential scanning calorimetry were observed in the VB and XF groups. The 0.04 taper files exhibited a statistically higher number of cycles to fracture than the 0.06 taper files in all groups ( P < .05). Cracks along the mechanical grooves were observed in the NiTi files, with the exception of the XF group. The start of cracking was detected at U-shape sites in the ProFile group, the cutting edge in the PV and VB groups, and radial islands in the K3 and XF groups. Conclusions The present findings suggest that new-generation NiTi files are not necessarily improved compared with conventional files. [ABSTRACT FROM AUTHOR]

Introduction The purpose of this study was to compare the cyclic fatigue resistance of coronal flaring instruments. Methods Three groups of nickel-titanium (NiTi) endodontic coronal flaring instruments were tested in steel canals with a 3-mm curvature radius and 60° (n = 18) and 45° of curvature (n = 18). The cyclic fatigue of the following NiTi instruments was tested: ProTaper Sx (Dentsply Maillefer, Ballaigues, Switzerland), HyFlex 25.08 (Coltene-Whaledent, Allstetten, Switzerland), and Revo-S SC1 (Micro-Mega, Besancon, France). The length and diameter of the fractured fragment and the total area of the fractured surface of each instrument were measured. The data were then statistically analyzed using a 1-way analysis of variance and the post hoc Tukey test (α = .05). Results At the 60° of curvature, Revo-S had the highest fatigue resistance, HyFlex had the second highest fatigue resistance, and ProTaper Universal had the least fatigue resistance. At the 45° of curvature, the Revo-S and HyFlex showed superior cyclic fatigue resistance compared with the ProTaper. The length of the fracture fragment of the ProTaper instrument was longer than that of the other groups at the 60° of curvature. At the 45° of curvature, the length of the fracture fragment of the ProTaper and HyFlex instruments was longer than that of Revo-S. The mean diameter and surface area of the HyFlex instruments in the fractured part was higher than that of other groups at both angles of curvature. Conclusions The Revo-S SC1 and HyFlex 25.08 instruments showed better cyclic fatigue resistance than the ProTaper Sx instrument. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: The purpose of this study was to evaluate and compare the cyclic fatigue resistance of RaCe (FKG Dentaire, La Chaux-de-Fonds, Switzerland) and Mtwo (VDW, Munich, Germany) rotary files in continuous rotation and reciprocating motion. Methods: A total of 60 new rotary Mtwo and RaCe files (ISO size = 25, taper = 0.06, length = 25 mm) were selected and randomly divided into 4 groups (n = 15 each): Mtc (Mtwo NiTi files in continuous rotation), Rc (RaCe NiTi files in continuous rotation), Mtr (Mtwo NiTi files in reciprocating motion), and Rr (RaCe NiTi files in reciprocating motion). A cyclic fatigue testing device was fabricated with a 60° angle of curvature and a 5-mm radius. All instruments were rotated or reciprocated until fracture occurred. The time taken for each instrument to fracture and the length of the broken fragments were recorded. All the fractured files were analyzed under a scanning electron microscope to detect the mode of fracture. The Kolmogorov-Smirnov test was used to assess the normality of samples distribution, and statistical analysis was performed using the independent sample t test. Results: The time taken for the instruments of the Mtr and Rr groups to fail under cyclic loading was significantly longer compared with the Mtc and Rc groups (P < .001). Scanning electron microscopic observations showed that the instruments of all groups had undergone a ductile mode of fracture. The length of the fractured segments was between 5 and 6 mm, which was not statistically significant among the experimental groups. Conclusions: Mtwo and RaCe rotary instruments showed a significantly higher cyclic fatigue resistance in reciprocating motion compared with continuous rotation motion. [Copyright &y& Elsevier]

Introduction In recent years, with the advances in counterfeiting methods, counterfeit products have reached the dental market. The purpose of this study was to compare the cyclic fatigue resistance of original and counterfeit rotary root canal instruments. Materials and methods The cyclic fatigue of original and counterfeit ProTaper F2 endodontic instruments was tested (n = 20) in 3 mm radius steel canals with a 60° angle of curvature. The number of cycles to fracture (NCF) was calculated, and the data were subjected to the Student's t-test (α = 0.05). Results The original instruments showed better cyclic fatigue resistance than the counterfeit ones (p < .001). The mean NCF was 483 ± 84 for the original files and 186 ± 86 for the counterfeit files. Conclusions The cyclic fatigue resistance of the counterfeit instruments was very low. As a result, clinicians should be careful not to purchase counterfeit products. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: The maximum removal of root canal filling material is essential for successful endodontic retreatment. The purpose of this study was to assess the efficacy of 2 reciprocating systems (Reciproc [VDW, Munich, Germany] and WaveOne [Dentsply Maillefer, Ballaigues, Switzerland]) compared with a nickel-titanium (NiTi) rotary system (ProTaper Universal Retreatment [Dentsply Maillefer]) in the removal of root canal filling material. Methods: Sixty root canals of extracted human maxillary incisors were prepared using the NiTi ProTaper rotary system with the complementary use of a #40 K-type file and then obturated. The specimens were divided into 3 groups (n = 20) according to the system used for filling removal: group 1: instrument R25 of the Reciproc system, group 2: primary instrument of the WaveOne system, and group 3: NiTi rotary instruments of the ProTaper Universal Retreatment system. The teeth were cleaved longitudinally and photographed under a dental operating microscope with 5 × magnification. Images were transferred to a computer, and residual filling material was quantified using Image Tool software (University of Texas Health Science Center, San Antonio, TX). Results were compared using 1-way analysis of variance (P < .05). Results: All teeth examined had filling remnants within the canal. No statistically significant difference (P > .05) in residual filling material was observed among the groups, with 4.30% in group 1, 2.98% in group 2, and 3.14% in group 3. Conclusions: The Reciproc and WaveOne reciprocating systems were as effective as the ProTaper Universal retreatment system for gutta-percha and sealer removal. [Copyright &y& Elsevier]

Aim: The study was designed to investigate the sealing ability of two obturation systems (cold laterally compacted gutta percha and Obtura II) over different apically separated rotary nickel-titanium files (RACE and K3 system) using dye extraction method. Materials and Methods: Sixty-two mandibular premolars were divided into 2 groups of 30 teeth each, and 2 teeth served as negative controls. In Groups A and B, roots were prepared using RACE and K3 system, respectively, and were further subdivided into 4 subgroups. In subgroups A1, B1 and A2, B2 (n = 10 each), files were separated at 3 mm from the tip in apical 3rd of the canal. In subgroups A3, B3 and A4, B4 (n = 5), instruments were not separated. Subgroups A1, A3, B1, B3 and A2, A4, B2, B4 were obturated by lateral condensation method and Obtura II techniques, respectively. The sealing ability of the obturated specimens were tested using dye extraction method. The values for each group were recorded and analysis of variance (ANOVA), Student "†" test (two-tailed, independent), and Leven's test were performed. Results: Group A1 showed significantly less leakage than B1. No statistical significant difference between Groups A2 and B2 and Groups A3 and B3, respectively, were observed. Group A4 showed significantly less leakage than B4. Conclusion: Groups obturated with Obtura II showed less leakage than the lateral condensation technique irrespective of presence or absence of fractured NiTi rotary system. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: Effective removal of gutta-percha in endodontic retreatment is a significant factor to ensure a favorable outcome from failed procedures. The purpose of this study was to evaluate the efficacy of a nickel-titanium rotary instrument system with or without a solvent versus stainless steel hand files for gutta-percha removal. Methods: Forty extracted human maxillary anterior teeth were prepared and filled. They were divided into 4 groups: Gates-Glidden and K-files, Gates-Glidden and K-files with chloroform, ProTaper Universal rotary retreatment system, and ProTaper Universal rotary retreatment system with chloroform. The operating time was recorded. The teeth were longitudinally sectioned and photographed. The images were analyzed and the filling remnants were quantified by using the IMAGE TOOL software. Results: With Kruskall-Wallis test, statistical analysis showed that there was no significant difference between the techniques in regard to the amount of the endodontic filling remnants (P < .05); however, the ProTaper Universal rotary retreatment system was faster than the hand files (P < .05). Conclusions: All of the techniques proved helpful for the removal of endodontic filling material, and they were similar in material remaining after retreatment, but the ProTaper Universal rotary retreatment system without chloroform was faster. [Copyright &y& Elsevier]

Abstract: The purpose of this in vitro study was to compare the torsional stress and cyclic fatigue characteristics of ProFile GT (Dentsply Tulsa Dental, Tulsa, OK) and ProFile GT Series X (Dentsply Tulsa Dental). Files of 0.04 and 0.06 taper, 25 mm in length, and ISO sizes of 20 and 30 tips were compared (n = 25 per test group). Torque stress resistance was evaluated by measuring the torque in gram-centimeters (g-cm) and angle of deflection (degrees of rotation) required for instrument separation with use of a torsiometer instrument. Cyclic fatigue was determined by recording the time until breakage of a file rotating in a simulated canal with an applied 45° or 60° curve. The files were operated in a cyclic fatigue instrument that simulated clinical rotary file usage with a constant cyclical axial motion. There was no statistical difference (p > 0.05) when comparing the torque (g-cm) required to induce a torsional failure of ProFile GT and ProFile GT Series X files of identical file sizes. The angle of deflection (degrees of rotation) of ProFile GT was significantly greater (p ≤ 0.001) before separation than ProFile GT Series X for all file sizes tested except 20/.04 (p > 0.05). There was no statistical difference (p > 0.05) in cyclic fatigue failure for ProFile GT and ProFile GT Series X in a canal with a curvature of 45°. In the 60° canal curvature, ProFile GT was found to be significantly more resistant (p = 0.005) to fracture because of cyclic fatigue than ProFile GT Series X for file size 30/.06 and significant (p ≤ 0.001) for files sizes 20/.06 and 30/.04. There was no difference (p > 0.05) in cyclic fatigue resistance in the 60° canal for ProFile GT and ProFile GT Series X for file size 20/.04. [Copyright &y& Elsevier]

Abstract: The purpose of this study was to evaluate the efficiency of FlexMaster, ProTaper, and RaCe rotary instruments compared with Hedström files for removal of gutta-percha during retreatment. Sixty mandibular premolars with one single straight canal were instrumented with K-type files and filled using cold lateral compaction and sealer. The teeth were randomly divided into four groups of 15 specimens each. After repreparation with Gates Glidden burs and the test instruments the specimens were cleared. The area of remaining gutta-percha/sealer on the root canal wall was measured from two directions. The RaCe group showed significantly less residual obturation material than FlexMaster and Hedström group (p < 0.05; closed test procedure). There was no difference between ProTaper and all other instruments (p > 0.05). ProTaper and RaCe instruments required significantly less time for retreatment than FlexMaster and Hedström files (p < 0.05). One RaCe file, two ProTaper, and two FlexMaster instruments separated. RaCe cleaned obturated canals more effectively than hand files and FlexMaster files. [Copyright &y& Elsevier]

Abstract Aim The purpose of this study was to compare the efficacy in vitro of gutta-percha removal from obturated root canals using ProFiles. Methodology Forty-eight human root canals with curvatures ranging between 25 and 45° were instrumented by a standardized method to an apical ISO size 30 and 0.04 taper. They were obturated with vertically condensed gutta-percha. Retreatment was performed with the following techniques: K-Flexofiles with chloroform; Hedstrom files with chloroform; ProFiles 0.04 taper with chloroform; ProFiles 0.04 taper alone. The time for each method was measured. A microfocal macroradiographic technique was used to evaluate the amount of debris remaining within the root canals after the retreatment procedure. Roots were divided into apical, middle and coronal parts and scored on a scale of 0 (no debris) to 3 (>50% of walls covered with debris) by trained observers on two separate occasions. Results The scores for debris remaining within root canals for K-Flexofiles with chloroform and ProFiles with chloroform were the lowest and not significantly different at all three levels of the roots examined (P > 0.05), and Hedstrom files with chloroform and ProFiles with chloroform were not significantly different in the apical part. In general, coronal parts were cleaner than apical parts. The difference in scores at the three levels between ProFiles with chloroform and ProFiles alone were each significant (P < 0.01). Instrumentation using ProFiles with chloroform (mean 6.42 min) was significantly faster than using hand files (mean 11.67 min) (P < 0.01). Conclusion The results indicated that ProFiles or hand files with chloroform produced similarly clean canals, but that ProFiles were faster. [ABSTRACT FROM AUTHOR]

AbstractAim The purpose of this study was to quantify the amount of remaining gutta-percha/sealer on the walls of root canals when two engine-driven instruments (Quantec and ProFile) and two hand instruments (K-file and Hedström file) were used to remove these materials. The amount of apically extruded debris and the time required for treatment were also recorded. Methodology One hundred extracted mandibular premolars were prepared using a modified step-back, flare technique and obturated with the lateral condensation technique. After repreparation with the test instruments, the specimens were cut transversally at the cervical, middle and apical thirds with steel discs and the three sections were split longitudinally. The amount of residual debris on the canal walls in each section was examined using a stereomicroscope. Results In all groups the cervical and middle thirds showed no debris. In the apical third, obturating material was observed in some specimens. No statistically significant difference was found between the two groups for incidence of debris, although the Hedström group showed a greater number of samples with remaining gutta-percha/sealer. When analysing dirty specimens only, there was a statistically significant difference between the four groups (P < 0.01) with the Hedström group having significantly less length of canal wall with remaining obturation material than the Quantec group. There was no significant difference amongst the groups for weight of extruded debris. However, there was a significant difference amongst the groups for mean treatment time with the Hedström file group requiring significantly less time than the Quantec group (P < 0.001); no significant differences were found between the other groups. Six instruments fractured in the Quantec group, four in the ProFile group, two in the Hedström group and two in the K-type group. Conclusions The results showed that overall, all instruments may leave filling... [ABSTRACT FROM AUTHOR]

Aim: This in vitro study aims to detect the dentinal defects associated with different irrigants during biomechanical preparation using rotary nickel-titanium (Ni-Ti) files (Hyflex CM)., Materials and Methods: For the study, 120 extracted mandibular incisors were taken. Depending on the irrigant used, teeth were divided into six groups ( n = 20). In Group 1, teeth were not biomechanically prepared considered as, control group. In Group 2, Group 3, Group 4, Group 5, and Group 6, biomechanical preparation was with Hyflex CM rotary Ni-Ti files using saline, 3% sodium hypochlorite (NaOCl), 17% ethylenediaminetetraacetic acid (EDTA), SmearClear, and 2% chlorhexidine (CHX), respectively, as irrigant. IsoMet Saw was used to section samples at 3, 6, and 9 mm from the apex perpendicular to the long axis of tooth. Segments were seen at 30x magnification under a digital stereomicroscope., Statistical Analysis: Statistical analysis was done using two-tailed t -test., Results: Maximum number of dentinal defects was seen with 17% EDTA, followed by 3% NaOCl, SmearClear, and 2% CHX., Conclusions: Irrigation with 17% EDTA causes more dentinal defects as compared to irrigation with 3% NaOCl, SmearClear, and 2% CHX., Competing Interests: There are no conflicts of interest., (Copyright: © 2022 Journal of Conservative Dentistry.)

The purpose of this study was to assess the effect of dry-heat or autoclave sterilization on the resistance to fracture in torque and angular deflection and the resistance to bending of K-type files made of nickel-titanium (Nitiflex, Naviflex), titanium (Microtitane) or stainless steel (Flexofile, Flex-R). Ten K-type files of each sort, from size 25 to 40, were tested, according to ANSI/ADA specification 28 (1988) and ISO specification 3630 (1992). Sterilization with dry heat and autoclave slightly decreased the flexibility of files made of stainless steel and nickel-titanium for most of the sizes, although the values obtained satisfied ISO specifications. The files made of titanium showed an increased flexibility after sterilization with autoclave (sizes 30 and 35) and dry heat (sizes 30, 35 and 40). Resistance to fracture varied amongst the five groups of files tested as follows: it decreased in some sizes of stainless-steel instruments, decreased in all sizes of titanium files assessed by the torsional moment, and either increased or decreased in some sizes of nickel-titanium files. All files tested, however, satisfied relevant standards for angular deflection after being subjected to sterilization with an autoclave or dry heat. [ABSTRACT FROM AUTHOR]

The aim of this study was to examine the cutting patterns of recently introduced nickel-titanium endodontic files and compare them with similarly shaped stainless steel filed using both balanced-force and stepback techniques. Simulated canals were constructed in resin blocks with 40° curvature. Fifty blocks were prepared by a balanced-force technique 25 wîth Nitiflex (Maillefer) and 25 with Flexofiles (Maillefer) to a master apical file size 40. Fifty blocks were prepared by a stepback technique: 25 with Nitiflex and 25 with Flexofiles to a master apical file size 30. Composite prints were made of pre-and post-instrumentation canals using a computerized imaging system. The amount of material removed from the inner and outer canal curvatures was measured at right levels in the apical 11 mm of the canal. The results were analysed by Kruskal-Wallis ANOVA. Using the balanced-force technique. Nitiflex files removed less material on the outer curve apically and less on the inner curve mid-canal (P<0.05), while Flexofiles caused more apical transportation. In the stepback technique, the Nitiflex files removed more material from the outer curve apically (P<0.05); the Flexofiles removed more material along the entire inner curve (P<0.05), and maintained canal curvature better than Nitiflex files. It appeared preferable to use Nitiflex files in a balanced-force technique, and Flexofiles in a filing technique as stainless steel files can be precurved. [ABSTRACT FROM AUTHOR]

Objectives: To evaluate the fracture incidence of Reciproc R25 instruments (VDW) used during non-surgical root canal retreatments performed by students in a postgraduate endodontic program., Materials and Methods: From the analysis of clinical record cards and periapical radiographs of root canal retreatments performed by postgraduate students using the Reciproc R25, a total of 1,016 teeth (2,544 root canals) were selected. The instruments were discarded after a single use. The general incidence of instrument fractures and its frequency was analyzed considering the group of teeth and the root thirds where the fractures occurred. Statistical analysis was performed using the χ 2 test ( p < 0.01)., Results: Seven instruments were separated during the procedures. The percentage of fracture in relation to the number of instrumented canals was 0.27% and 0.68% in relation to the number of instrumented teeth. Four fractures occurred in maxillary molars, 1 in a mandibular molar, 1 in a mandibular premolar and 1 in a maxillary incisor. A greater number of fractures was observed in molars when compared with the number of fractures observed in the other dental groups ( p < 0.01). Considering all of the instrument fractures, 71.43% were located in the apical third and 28.57% in the middle third ( p < 0.01). One instrument fragment was removed, one bypassed, while in 5 cases, the instrument fragment remained inside the root canal., Conclusions: The use of Reciproc R25 instruments in root canal retreatments carried out by postgraduate students was associated with a low incidence of fractures., Competing Interests: Conflict of Interest: No potential conflict of interest relevant to this article was reported., (Copyright © 2021. The Korean Academy of Conservative Dentistry.)

Abstract: Introduction: A new nickel-titanium (NiTi) rotary file called the ProFile Vortex (PV; Denstply, Tulsa Dental Specialties, Tulsa, OK) has recently been released for endodontic use. The purpose of this study was to compare cyclic fatigue resistance of the new size 30 PV files with size 30 files of other popular brands. Other files tested include Twisted File (TF; Sybron Dental Specialties, Orange, CA), ProFile (PF; Denstply Tulsa Dental Specialties, Tulsa, OK), GTX (GTX, Denstply Tulsa Dental Specialties), and EndoSequence (ES; Brasseler, Savannah, GA). Methods: Size 30 files with a constant .06-mm/mm taper were rotated at manufacturer-recommended speed and torque settings in a simulated canal until failure. Results: Significant differences were found between the various brands of files. The differences between file brands may be because of a different manufacturing process or differences in file design. Conclusions: Based on a simulated canal model, the PV, TF, and GTX files appear to offer greater cyclic fatigue resistance than ES and PF files. [Copyright &y& Elsevier]