Rotary File Systems Research Articles

Evaluation of the Root Canal Centering Ratio and Canal Transportation Associated With Three Rotary File Systems Using Cone Beam Computed Tomography (CBCT) Analysis

Evaluation of the Root Canal Centering Ratio and Canal Transportation Associated With Three Rotary File Systems Using Cone Beam Computed Tomography (CBCT) Analysis

Comparative evaluation of remaining dentin thickness and root canal transportation in curved canals with newer nickel–titanium single and multiple rotary file systems: A cone-beam computed tomography study

Abstract Context: The purpose of this study was to evaluate and compare the remaining dentin thickness and root canal transportation of WaveOne GOLD, XP-endo Shaper, and GenEndo file systems to assess their performance in curved canals using cone-beam computed tomography (CBCT) imaging. Materials and Methods: Seventy-five extracted maxillary first molars were selected with a curvature ranging between 15° and 30°. The samples were allocated into three groups (n = 25) and shaped using WaveOne GOLD, XP-endo Shaper, and GenEndo files. CBCT images were captured before and after instrumentation. Statistical Analysis: The remaining dentin thickness and root canal transportation were measured at 3, 5, and 7 mm from the apex in both mesiodistal and buccolingual directions. The data were statistically analyzed using one-way ANOVA followed by Tukey’s post hoc test. Results: GenEndo file system demonstrated greater preservation of remaining dentin thickness and resulted in less root canal transportation compared to the WaveOne GOLD and XP-endo Shaper systems across all three levels. Conclusions: GenEndo file system which comprises multiple files has removed less amount of dentin and canal transportation when compared to single file systems, i.e., WaveOne GOLD and XP-endo Shaper file systems.

Comparative evaluation of pediatric endodontic rotary file systems to bending and torsion tests: A finite element analysis

Background and objectiveThe introduction of Paediatric NiTi instruments has transformed the field of paediatric endodontics. However, no studies are available on the mechanical behaviour of these files, wherein Finite Element Analysis (FEA) was found to play a major role. The objective of this study is to evaluate the mechanical behavior of three commercially available pediatric endodontic rotary file systems to bending and torsion stress analysis test through Finite Element Analysis (FEA). MethodsA Finite Element Analysis study was performed on three commercially available pediatric endodontic rotary files (Pro AF baby, Kedo SG and Neoendo pedoflex) available for cleaning and shaping the narrow root canals of the deciduous teeth to bending and torsion tests with the boundary conditions according to ISO 3630-1 specifications. ResultsIn the bending analysis, Pro AF baby files were found to withstand the complete bending tests without yielding with a maximum von Mises stress of 1366 MPa, and Kedo SG, Neoendo Pedoflex file exhibited maximum von Mises stress of 2296 MPa, 1971 MPa. Under torsion tests Kedo SG exhibited maximum stress distribution, while Neoendo Pedoflex and Pro AF baby files exhibited similar stress distribution. ConclusionPro AF baby file effectively withstood the rigorous 45 -degree bending examination without experiencing yielding, while Kedo SG file exhibited higher flexibility. Under torsional resistance test, all the three instruments exhibited similar stress distribution under the yield limit. In summary, the mechanical behaviour (bending and torsion) of pediatric rotary file systems were influenced by design of the files.

Comparative Evaluation of Effectiveness of Rotary and Hand File Systems in Terms of Quality of Obturation and Instrumentation Time among Primary Teeth: A Systematic Review and Meta-analysis of Randomized Controlled Trials.

This systematic review and meta-analysis aimed to answer the following focused question: Are rotary file systems more effective than hand file systems in terms of the quality of obturation and instrumentation time among primary teeth? The inclusion criteria comprised studies that compared the effect on quality of obturation and instrumentation time among primary teeth after using rotary and hand file systems for biomechanical preparation of the root canals. This review was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. The searched databases included Medline (via PubMed), EBSCO, and Google Scholar. Articles published from January 2000 to December 2021, but only in English, were included. The search resulted in 8,003 published studies. After the removal of duplicate studies and full-text analysis, 9 studies were selected for systematic review, and 8 were selected for meta-analysis. Overall, the results demonstrated the promising effects of rotary file systems in reducing instrumentation time and improving obturation quality compared to hand files. Within the limitations of this review, it can be asserted that rotary file systems are superior to hand files in primary teeth for pulpectomy procedures. Rotary files, a more recent technique, are more efficient than traditional hand files in lowering the time required for instrumentation. Additionally, they provide superior obturation quality in primary molars, making them particularly beneficial for pediatric patients. Gala UP, Kalaskar R, Vinay V, et al. Comparative Evaluation of Effectiveness of Rotary and Hand File Systems in Terms of Quality of Obturation and Instrumentation Time among Primary Teeth: A Systematic Review and Meta-analysis of Randomized Controlled Trials. Int J Clin Pediatr Dent 2024;17(8):962-969.

Evaluation and Comparison of Dentin Thickness, Centering Ability, Canal Transportation, and Instrumentation Time of Pro AF Baby Gold and Pedoflex Files in Primary Root Canals Using a Cone Beam Computed Tomographic Analysis: An In Vitro Study.

Pediatric rotary systems have the advantage of improved canal centricity and conservative canal preparation with better obturation quality. Pro AF Baby Gold and Pedoflex files are two exclusive pediatric rotary file systems that were introduced in recent times. The aim of the present study is to compare and evaluate the dentine thickness, centering ability, canal transportation, and instrumentation time of Pro AF Baby Gold and Pedoflex files using cone beam computed tomography (CBCT). A total of 40 extracted human primary molar teeth with a minimum 7 mm root length were included in the study and randomly divided into two groups: group I, Pro AF Baby Gold; group II, Pedoflex files. Teeth were imaged preoperatively with CBCT, then root canal preparation was done in both groups with respective files, followed by postoperative CBCT imaging to evaluate the dentin thickness, centering ability, and canal transportation of both groups. Instrumentation time was noted using a stopwatch. There is a statistically significant difference in the instrumentation time; Pedoflex took a shorter time when compared to Pro AF Baby Gold files. Regarding canal transportation, there was no significant difference between the two files, with Pedoflex showing a better value than the other files. Regarding centering ability, there was no significant difference between the two files, with Pro AF Baby Gold having a better value than the other files (p < 0.001). From the findings of our present study, it was found that both systems were able to effectively shape curved root canals in terms of canal transportation and centering ability. Busi S, PJ N, Deoghare A, et al. Evaluation and Comparison of Dentin Thickness, Centering Ability, Canal Transportation, and Instrumentation Time of Pro AF Baby Gold and Pedoflex Files in Primary Root Canals Using a Cone Beam Computed Tomographic Analysis: An In Vitro Study. Int J Clin Pediatr Dent 2024;17(8):892-897.

To Compare and Evaluate Rotary and Manual Techniques in Biomechanical Preparation of Primary Molars to Know Their Effects in Terms of Cleaning and Shaping Efficacy.

The introduction of the rotary file system for children was a revolution in the field of pediatric endodontics. These files are cost-effective and help in consistent obturations with shorter instrumentation time. The present randomized controlled trial (RCT) was planned for a comparative evaluation of rotary and manual techniques in biomechanical preparation of primary molars to determine their effect in terms of cleaning and shaping efficacy, working time, quality of obturation, and postoperative pain. A randomized clinical trial study was conducted in 75 children aged 5-9 years requiring pulpectomy. Each tooth was randomly assigned to one of the three treatment groups: Kedo-S files, rotary K-Flex files, and hand instruments group. It was observed that Kedo-S files and rotary K-Flex files were more effective in cleaning and shaping of root canals compared to hand H/K files. The postbacterial count for hand files was higher compared to rotary files. Shorter working time was seen with rotary files (3.88-5.04 minutes) compared to hand files (15.68 minutes). Rotary files showed a reduced number of voids, with Kedo-S files in 92% of cases and rotary K-Flex files in 80% of cases. Apical seal and extent of fill were maximum with rotary files, having a grade C rating in 92% of cases. Kedo-S files and rotary K-Flex files showed a significant reduction in postoperative pain compared to hand files. The present study showed a significant reduction in bacterial count, working time, quality of obturation, and postoperative pain with rotary files. Moudgalya MS, Tyagi P, Tiwari S, et al. To Compare and Evaluate Rotary and Manual Techniques in Biomechanical Preparation of Primary Molars to Know Their Effects in Terms of Cleaning and Shaping Efficacy. Int J Clin Pediatr Dent 2024;17(8):864-870.

Evaluation of canal cleanliness of two rotary file systems with different taper systems: An in vitro scanning electron microscopic study

Evaluation of canal cleanliness of two rotary file systems with different taper systems: An in vitro scanning electron microscopic study

Comparative evaluation of clinical efficacy and volumetric changes in pulpectomized primary molars using hand K-file, ProTaper rotary file, and Kedo-SG blue file: an in-vitro cone beam computed tomography analysis.

The accomplishment of a successful pulpectomy depends on multiple factors that involve targeted removal of the causative irritants and soft and hard tissue debris by mechanical and chemical means. Compare and evaluate the efficacy of canal preparation and volumetric filling using conventional files and two rotary file systems using cone beam computed tomography (CBCT). Thirty freshly extracted human primary second molars were randomly divided into three groups of 10 teeth each. After access opening and working length determination, pre-operative volume analysis was done using CBCT. The canals were then instrumented by either hand K-files, ProTaper rotary files or Kedo-SG Blue rotary files. Post-operative volume analysis was performed using CBCT. All the canals were obturated using Metapex and scanned again using CBCT. Mean values of the pre- and post-operative canal volumes were analyzed using one-way Analysis of Variance (ANOVA). Inter- and intra-group volumetric changes were analyzed statistically using a post hoc test. The mean difference in volume after canal preparation and obturation was the highest in the Kedo-SG Blue group, followed by the ProTaper group and the least in the hand K group (p = 0.001). Inter-group comparison showed statistically significant differences between the hand K group and ProTaper group (p = 0.001), the ProTaper group and Kedo-SG Blue group (p = 0.001), and the hand-K group and Kedo-SG Blue group (p = 0.02). The volume of preparation and obturation was the highest using Kedo-SG Blue, followed by the ProTaper file systems.

A Comparative Evaluation of the Effect of Different Endodontic Irrigating Solutions on Microhardness of Root Canal Dentin: An in vitro Study.

During endodontic therapy, irrigation solutions applied in the root canal may affect the physicochemical properties of the dentinal wall, thereby changing its microhardness. This may adversely affect the sealing ability and adhesion of dental materials. Therefore, many studies have focused on the search for an ideal root canal irrigant that has a minimal effect on dentinal microhardness. This in vitro study was conducted to determine the changes in dentin microhardness after root canal irrigation with different endodontic irrigants. Ninety-five freshly extracted maxillary central incisor teeth with straight single canals were selected. These teeth were sectioned transversely at the level of the cementoenamel junction. The working length of each tooth was determined, and canal space was prepared by the HyFlex CM rotary file system. During instrumentation, normal saline was used for irrigation. Then, teeth were split longitudinally into two segments. According to the irrigating solution employed, samples were divided into five groups (n=19): normal saline (Group A), 3% sodium hypochlorite (Group B), 2% chlorhexidine (Group C), 5% calcium hypochlorite (Group D), and 0.2% nanochitosan (Group E).3 mL of the corresponding irrigating solution was administered for total15 minutes in each prepared sample. The Vickers micro-hardness tester was then used to assess micro-hardness. The data was analyzed using one-way analysis of variance (ANOVA). All tested irrigating solutions decreased the dentinal microhardness. Samples irrigated with 5% calcium hypochlorite demonstrated dentinal microhardness of 42.43±1.62, which is the lowest among all the tested groups, followed by nano chitosan, sodium hypochlorite, and chlorhexidine. Samples treated with control group (saline) demonstrated the maximum microhardness of dentin in the present study. Within the limitations of this research, it can be concluded that the tested novel irrigating solutions, 5% calcium hypochlorite and 0.2% nanochitosan, were more detrimental to radicular dentin microhardness when compared with conventional endodontic irrigants.

Apically extruded debris evaluation with the use of ProTaper Ultimate and TruNatomy files systems with and without glider preparation in primary tooth.

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

Comparison of cyclic fatigue resistance of four pediatric rotary file systems at body temperature: an in vitro study

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

Evaluation of the shaping ability of different rotary file systems in severely and abruptly curved root canals using cone beam computed tomography

BackgroundWhen selecting an instrument for canal preparation, it is important to consider several parameters that influence the shaping efficiency, including instrument design, metallurgy, and operating motion. This study aimed to evaluate the shaping ability of the ProTaper Next (PTN), WaveOne Gold (WOG), and XP-endo Rise Shaper (XPRS) rotary systems in severely and abruptly curved root canals using cone beam computed tomography (CBCT) and ImageJ software. Materials and MethodsForty-eight mesial root canals of the mandibular first molars were assigned equally to three groups: PTN, WOG, and XPRS. Using ImageJ software, CBCT images were acquired pre- and post-instrumentation to assess dentin removal, remaining dentin thickness (RDT), canal transportation, and centering ratio at the coronal, middle, and apical levels. Statistical analyses were conducted on all numerical data. ResultsAll rotary systems removed significantly more distocoronal dentin in the danger zone (DZ), than the mesiocoronal area. PTN removed significantly more dentin and caused less RDT than XPRS (p < 0.05). However, there were no significant differences between PTN-WOG and WOG-XPRS. In the DZ, the highest percentage of specimens with an RDT < 0.5 mm was observed when using PTN (50%), followed by WOG (31.3%), and XPRS (6.3%). Compared with PTN and WOG, XPRS demonstrated less coronal transportation. Among all rotary systems, there was no significant difference in apical transportation or centering ratio. ConclusionsBased on our observations, all rotary instruments exhibited a tendency to remove dentin in the DZ, but to different degrees. XPRS demonstrated better results in terms of coronal transportation and dentin thickness in the DZ. Comparable centering abilities and minimal apical transportation were demonstrated using all rotary instruments.

Evaluation of Volumetric Changes between Pediatric Rotary Files and Manual Files during Canal Preparation of Primary Mandibular Canine: A Nano-CT Analysis

Abstract Objective Pediatric endodontics has become popular due to advancements in cleaning, shaping, and irrigation systems, resulting in faster and effective removal of infected pulp, saving time, and creating a pathogen-free environment. The patented rotary file system, Kedo S, designed for primary teeth, introduced a single file generation for efficient pulp therapy. However, there are currently no studies assessing canal preparation in primary mandibular canine using nano-computed tomography (nano-CT). This study aims to evaluate the efficacy of rotary file systems (Kedo S plus, Kedo SG blue) against traditional hand files in root canal preparation of primary mandibular canines using nano-CT. Materials and Methods This in vitro study was performed in extracted primary mandibular canine based on certain inclusion and exclusion criteria. Samples were prepared and working length was determined before the preoperative scan using a high-resolution nano-CT device (SkyScan 2214, Bruker, Kontich, Belgium). A single well-experienced pediatric dentist prepared the canals using three file systems: Kedo S plus, Kedo SG blue, and hand K-files. A postoperative scan was performed similar to preoperative scan. Image reconstruction was performed with NRecon software for three-dimensional volumetric visualization and analysis of the root canals. Results Kedo S plus displayed significant alterations in volumetric, surface area, and instrumented areas postpreparation compared with Kedo SG blue and hand files. Statistical analysis revealed significant differences in volumetric and surface changes between Kedo S plus and hand files. Conclusion Rotary file systems, especially Kedo S plus, resulted in increased canal volume and surface area with minimal uninstrumented areas, showing promise for primary dentition root canal preparations. Further clinical assessments are warranted to validate these findings.

An in vitro comparative evaluation of efficiency of three rotary nickel-titanium file systems in terms of remaining dentin thickness using cone-beam computed tomography.

The objective of the present research was to assess and compare the residual dentin thickness after biomechanical preparation of teeth using three distinct rotary nickel-titanium (Ni-Ti) file systems. In the current experimental study, a total of 45 single-rooted teeth were selected for the analysis. The cementoenamel junction of each tooth was decoronated using a diamond disc. The teeth were randomly allocated to three groups, with each group representing a different rotary file system: Group 1: Hero GOLD (Micro Mega), Group 2: One Curve (Micro Mega), and Group 3: HyFlex electro-discharge machining (EDM) (Coltene-Whaledent, Altstatten, Switzerland). To evaluate the initial condition of the teeth, cone-beam computed tomography (CBCT) scans were conducted before the biomechanical preparation. The teeth were positioned on a modeling wax sheet, and the CBCT scans provided baseline measurements. The biomechanical preparation of the root canals followed the manufacturer's recommended guidelines for each file system. After the completion of the canal preparation, follow-up CBCT scans were conducted. The postprocedure CBCT scans were then compared with the initial scans to assess any changes in the residual thickness of dentin in the teeth. Post hoc Tukey analysis of variance tests was utilized to examine differences between the groups. A statistically significant result was defined as P = 0.05 or less for every test. The comparison of preinstrumentation and postinstrumentation CBCT images showed that the HyFlex EDM group removed less dentin clinically compared to the other two groups, i.e., Hero GOLD and One Curve. No significant statistical difference was found between Hero GOLD versus One Curve, One Curve versus HyFlex EDM, and Hero GOLD versus HyFlex EDM. Based on the results of this study, the HyFlex EDM file system exhibited superior cutting efficiency at various levels. Nonetheless, additional investigations are required to comprehensively assess the influence of Ni-Ti rotary file systems on the remaining dentin thickness.

A quantitative comparison of apically extruded debris during root canal preparation using NiTi full-sequence rotary and single-file rotary systems: An in vitro study

ABSTRACT Aim: The purpose of this study was to compare quantitatively the apically extruded debris during root canal preparation using NiTi full-sequence rotary and single-file rotary systems. Methods: Sixty extracted mandibular premolar teeth with single canals and similar lengths were used and divided into four groups. Groups A and B are NiTi full-sequence rotary systems and Groups C and D are single-file rotary systems. In Group A, the canals were prepared using V-Taper 2H file (up to 25/0.06), Group B: TruNatomy file (up to 26/0.04), Group C: OneShape file (25/0.06), and Group D: OneCurve file (25/0.04). The initial weight of each Eppendorf tube to be used was calculated using an analytical balance before instrumentation. After instrumentation, the tubes were then stored for 15 days in an incubator at 37°C. The Eppendorf tubes were weighed again to determine their final weight which contained the extruded debris. The data were statistically analyzed using a one-way ANOVA test and Tukey’s post hoc test. Results: The OneCurve single-file system resulted in statistically significant less debris extrusion than the OneShape single-file system, TruNatomy multifile system, and V-Taper 2H multifile system (P &lt; 0.001). Among the full-sequence rotary file systems, the TruNatomy rotary file system produced statistically significantly less debris extrusion than the V-Taper 2H rotary file system (P = 0.01). Conclusion: All the instrumentation systems caused apical extrusion of debris. OneCurve system showed least debris extrusion, followed by OneShape, TruNatomy, and V-Taper 2H systems. Thus, single-file rotary instruments performed better with the less extrusion of debris when compared to multifile rotary systems.

Comparing the impact of various sterilization methods on the cyclic fatigue resistance, bending strength, and torsional fatigue properties of NiTi rotary files

This study aimed to evaluate the influence of various sterilization techniques on the cyclic fatigue resistance, bending strength, and torsional fatigue resistance of Tornado Blue and Race Evo rotary endodontic file systems. Both the file systems underwent a series of 15 cycles of sterilization according to the following study groups: control group (G1; i.e., without treatment), chemical sterilization with 5.25% sodium hypochlorite (G2), dry heat sterilization (G3), glass beads sterilization (G4), and steam autoclaving (G5). Each group consisted of 8 samples (n = 8/group). Statistical analysis was performed using a two-way ANOVA and Tukey’s tests (p ≤ 0.05). Mean values for the number of cycles between both files were 1291 ± 52.79 rpm and 2095 ± 52.91 rpm for Tornado Blue and Race Evo, respectively. The torsional fatigue resistance was 8.00 ± 0.85 NCF and 10.70 ± 0.85 NCF and the bending strength was 486.94 ± 20.97 gf and 564.17 ± 20.97 gf for Tornado Blue and Race Evo, respectively. The results showed no significant difference in the mechanical properties followed by different sterilization protocols. However, a significant difference was observed in tested properties between the two file systems (p ≤ 0.05). The outcome is reassuring for clinicians that the essential process of routine sterilization at clinics seems safe with regards to mechanical integrity of the endodontic files.

Effectiveness of EndoActivator, PATS Vario system, and XP-endo Finisher files on smear layer removal under scanning electron microscope: A comparative study.

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

Comparative evaluation of remaining dentin thickness using single file, two file, and multiple rotary file system - An in vitro CBCT study.

Endodontic success hinges on a multifactorial interplay, with meticulous canal shaping, proper disinfection, and three-dimensional obturation being paramount. Among these factors, the amount of dentin remaining after instrumentation directly influences the biomechanical resilience and longevity of the tooth. This study aims to evaluate the impact of various rotary instrumentation systems, including single-file, two-file, and multiple-file configurations, on the remaining dentin thickness (RDT) following canal preparation. This was an in vitro study, original research article. Sixty mandibular premolar human extracted teeth were decoronated at the cementoenamel junction with a diamond disc. Samples were randomly assigned to three groups using a simple random sampling technique (n = 60). Group I - Single-file system (One Curve, MicroMega) (n = 20), Group II - Two-file systems (2Shape, MicroMega) (n = 20), and Group III - Multiple-file system (Hero Gold, MicroMega) (n = 20). Preoperative cone-beam computed tomography (CBCT) scans were obtained after the sample was mounted on a modeling wax sheet. The biomechanical preparation of canals followed the manufacturer's protocols for every system. Postoperative CBCT scans were obtained. Pre- and postoperative scans were compared at standardized depths (4 mm, 7 mm, and 11 mm) within the canals (coronal, middle, and apical thirds), allowing for a comprehensive assessment of RDT throughout the canal. According to one-way ANOVA, the highest mean was seen in Group I, followed by Group II and Group III. Hence, a statistically significant difference was found between all the groups. Post hoc Tukey's test was done for intergroup comparison. A single-file system preserved more dentin with less aggressive cutting compared to two-file and multiple-file systems.

An in vitro comparative evaluation of cyclic fatigue resistance of two rotary and two reciprocating file systems.

Root canal instrumentation is one of the important procedures for successful endodontic therapy. Unexpected fracture of files occurs during root canal instrumentation without any visible signs of deformation compromising the success of root canal treatment. The aim of the study was to evaluate and compare cyclic fatigue resistance (CFR) of rotary and reciprocating files in simulated canals with 45°, 60°, and 90° angle of curvature. The study design was an In vitro study. Sixty nickel-titanium files, 30 each of rotary and reciprocating files were selected and divided into four groups (n = 15) of Neoendo Flex, ProTaper Next, WaveOne Gold (WOG), and Reciproc Blue (RPB) files. Each group was further subdivided into three subgroups containing five samples each based on their use in simulated canals with 45°, 60°, and 90° angle of curvature. To simulate root canals with 45°, 60°, and 90° angle of curvature, three artificial canals were designed in a stainless steel metal block. Each file was autoclaved, immersed in 3% sodium hypochlorite (NaOCl), and coated with 17% ethylenediaminetetraacetic acid (EDTA). Each file was tested for CFR using a torque-controlled reduction handpiece by instrumenting in a simulated canal for 10 s until fracture. The cycle of autoclaving, exposure to NaOCl, EDTA, and testing of CFR for 10 s per canal as per groups and subgroups was repeated again and again until the respective file fracture. The time taken to file fracture was recorded using a digital chronometer. The time taken for each file fracture (in minutes) was multiplied by the number of rotations per minute to attain the number of cycles to failure (NCF). The obtained results were subjected to statistical analysis using one-way analysis of variance and independent t-test. One-way ANOVA test showed a statistically significant difference between the four groups, P < 0.001. Independent "t"-test between individual subgroups showed a statistically significant difference, as P < 0.05. WOG and RPB reciprocating file systems showed superior CFR, more especially in canals with abrupt 90° angle of curvature compared to both rotary file systems tested. Among rotary file systems tested, Neoendo Flex showed greater CFR than ProTaper Next.

Effect of Cross-Sectional Designs of Different Ni-Ti Files on Shaping Ability After Repeated Usage in Simulated Root Canals.

Background and Objective: The study aimed was to compare the effect of cross-sectional designs of five rotary systems (One Curve, 2Shape, K3-i File, E3 Azure, Neolix), on the shaping ability of the files in simulated resin blocks under controlled conditions with five repeated use. The shaping ability of the files includes the following variables: (1) Longitudinal sectional area difference, (2) Canal wall surface area difference, (3) Canal volume difference, (4) SMI (structure material index) difference, (5) Cross-sectional area difference. Methods: Five rotary file systems: (1) One Curve, (2) 2Shape, (3) K3-i File, (4) E3 Azure, (5) Neolix, were tested in simulated J-shaped root canal resin blocks with a 45˚ angle of curvature. 10 files from each system, each one of the 10 files were used to prepare 5 resin blocks, named R1-R2-R3-R4-R5. All the used files from the 5 systems had tip size 25 diameter, and taper (6%), and length (25 mm). The first 4 rotary systems were used with a fixed speed (350 rpm), and fixed torque (3 Ncm), except for the fifth system which was used with a speed of (500 rpm), and torque (4 Ncm), Following the manufactural recommendation of each system. All the 250 resin blocks were prepared for Glide Path with manual reamers size 10, and 15, with a fixed working length 16 mm, then all the 250 samples were prepared with a Proglider rotary file from Dentsply (size 16 taper 3%), then finally were prepared with Edge Files (USA), with size 20 and taper 6%, reaching to the step of master preparation with the selected files of the 5 systems. Using a customized device for preparation to ensure fixed vertical force and to exclude any lateral force, preparation was done with EDTA solution as irrigation, with a fixed no. of 4 strokes for the first 5 systems and 9 strokes for the Neolix, the time was controlled by using a Metronome, each stroke duration was 6 seconds. Results: In the first, second, third, and fourth variables a statistically non-significant difference (P &gt; 0.05) was found between One curve and 2Shape, a statistically significant difference (P &lt; 0.05) was found between One Curve, K3-i File, E3 Azure, and Neolix. About the fifth variable which is the Cross-sectional area difference: the study compared the difference between the cross-section area of the canal at the point D8, comparing the cross-section area before and after preparation using ANOVA test and Post hoc test, a statistically significant difference (P &lt; 0.05) was found between the Neolix and (2shape, K3 i-File, and E3 Azure). Conclusion: The cross-sectional design of the endodontic rotary instrument had an obvious effect on the shaping ability of the system. Keywords: Cross-sectional design, Shaping ability, Nickle Titanium rotary files (One Curve, 2Shape, K3-i File, E3 Azure, Neolix).