Investigation of four nickel titanium endodontic instruments, with cyclic fatigue resistance, scanning electron microscopy, and energy dispersive x-ray spectroscopy.

The aim of this study was to compare of four different nickel-titanium (Ni-Ti) endodontic files and evaluate in terms of cyclic fatigue resistance and metallurgical properties. Four different type Ni-Ti root canal files Protaper Next X2 (PTN) (Dentsply Maillefer, Ballaigues, Switzerland), One Curve (OC) #25.06 (Micro Mega, Besancon, France), EndoPlus Flex Plus Gold X2 (EPG) (Turkuaz Dental, Denizli, Turkey), and EndoPlus Flex Plus Blue #25.06 (EPB) (Turkuaz Dental, Denizli, Turkey) files were tested for cyclic fatigue resistance (n = 20). During experiments artificial zirconia block canal was used. The artificial canal designed with curvature 60° and 5-mm radius. The number of cyclic to fracture (NCF) was noted. Fractured length (FL) parts of Ni-Ti files were recorded to assessment of fracture volumetric point. All fractured surfaces of Ni-Ti files were assessed by scanning electron microscope (SEM) to confirm the type of fractures. Descriptive evaluation become accomplished for the fundamental composition of units with the aid of using energy-dispersive x-ray spectroscopy (EDX). NCF data were evaluated via Bonferroni test with post hoc multiple comparison method. OC showed the highest NCF values (p < .05). The standardization of the study was confirmed as the FL of files was statistically similar in length (p > .05). SEM analysis confirmed that all scanned samples were fractured due to cyclic fatigue. EDX analysis confirmed that EPB established the poorest Ni content file. RESEARCH HIGHLIGHTS: The cyclic fatigue-related failure of One Curve was significantly more resistant than Protaper Next and EndoPlus files. Scanning electron microscopy images showed that One Curve and Protaper Next have round tips Energy dispersive x-ray spectroscopy showed that all four endodontic instruments mainly have Nickel and Titanium elements.

Comparative evaluation of the effects of different torque settings on dentinal crack formation using single- and multi-file system: An in vitro study.

Context: To improve efficiency, biomechanical preparation in root canal treatment is shifting from manual SS to nickel-titanium (NiTi) rotary devices. While multi-file NiTi systems entail crack and fracture issues, modern single-file systems address these concerns. Aims: The aim of this study was to evaluate and compare the effects of different torque settings on dentinal crack formation using single-file systems (SFS) (One Curve [OC]) and multi-file systems (ProTaper Next [PTN]) at different levels of the tooth. Subjects and Methods: The study was conducted on 45 freshly extracted human mandibular premolars divided into groups: OC at minimal and maximal torque, PTN at minimal and maximal torque, and a control group. After canal preparation, teeth were horizontally sectioned at 3, 6, and 9 mm from the apex, and then examined for cracks using a stereomicroscope. Statistical Analysis Used: This was analyzed using Chi-square test. Results: PTN group: Highest crack rates at the middle (55.6%) and apical (77.8%) thirds with maximum torque; OC group: Highest rates at the middle (22.2%) with minimal torque and apical (11.1%) with maximum torque. Conclusions: Maximal torque settings had more incidence of cracks compared to minimal torque settings. It can be stated that SFS (OC) produced less cracks compared to multi-file system (PTN) at both minimal and maximal torque settings.

Comparative Evaluation of Efficiency of Different Endodontic File Systems; Protaper Universal, MTWO, Protaper Next, Trunatomy, I-Race in Terms of Remaining Dentin Thickness: An In vitro CBCT Analysis.

Introduction: The longevity of an endodontically treated tooth depends on fracture resistance by preserving more remaining dentin thickness. The aim of this study is to determine which file system preserves more remaining dentin thickness. Materials and Methods: Protaper universal, M-two, Protaper Next, Trunatomy, I-Race and mandibular first premolar. The removed dentin thickness during instrumentation of each file system was noted by taking the difference of RDT of pre-instrumentation and post-instrumentation with the aid of CBCT. Results and Discussion: TRN [Group-4] shows the least aggressive cutting with maximal preservation of remaining dentin thickness at 3 mm and 6 mm from the apex at both mesiodistal and buccolingual dimensions. M-two [Group-2] shows maximum removed dentin thickness at 3 mm from the apex both mesiodistal dimension and buccolingual dimension. PTU [Group-1] shows maximum removed dentin thickness at 6 mm from the apex at mesiodistal dimension. M-two [Group-2] shows maximum removed dentin thickness at 6 mm from the apex at the buccolingual dimension. Conclusion: In this study, it is concluded that the Trunatomy file system preserves more remaining dentin thickness both mesiodistally and buccolingually both 3 mm and 6 mm from the apex.

Shaping ability of three instrumentation system in moderately curved canals: A micro-CT study.

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

Fracture Strength of Tooth Roots Following Canal Preparation by Three Rotary File Systems: An In Vitro Study.

BACKGROUND: Since the beginning of modern endodontics, there have been many concepts, strategies, and techniques for root canal preparation. A mind-boggling variety of files have developed for negotiating and shaping them throughout the years. Today's most secure, most effective, and simplest file system combines the most reliable design elements of the past with the latest technological advances to create the most effective file system. So, the need for the study is to evaluate the fracture strength of tooth roots following canal preparation by three rotary file systems: ProTaper Universal file system (Dentsply, USA), ProTaper Next file system (Dentsply Sirona USA), and Neolix A1 nickel-titanium (NiTi) file system (Orikam Healthcare India Pvt Ltd., New Delhi, India). METHOD: Ninety human mandibular molars were selected for the study. Inclusion criteria include human mandibular first and second molars and teeth removed for routine clinical reasons, and intact apices were selected, excluding cases with root surface caries, root surface fissures, teeth with immature root apex, mesial canal fusion, extremely short roots, thin roots, or curved roots. All teeth were preserved in a solution of 10% neutral buffered formalin for two weeks and then transferred to distilled water for examination. The teeth were randomly divided into three groups. Access cavities were created, and working lengths were determined. Groups 1, 2, and 3 underwent shaping using ProTaper Universal, ProTaper Next, and Neolix A1 (NiTi) file systems, respectively, following guidelines. Canals were irrigated with sodium hypochlorite and ethylenediaminetetraacetic acid (EDTA) and were obturated up to the mid-root region with AH Plus sealer. To facilitate fracture testing, obturation was performed to distribute the load from the spreader to the canal wall. The EndoSequence and Quick-Fill obturation system were utilized to fill the apical half of the canal with gutta-percha material. After obturation, the distal root of each tooth was cut, while the mesial root was securely positioned in a putty material. A universal testing machine was employed for the fracture tests, operating at a cross-head speed of 1 mm/min. The machine was equipped with a D11 hand spreader tip, which was inserted into the root canal to make contact with the gutta-percha. Gradual force was applied to the root canal until a fracture occurred, at which point the force application was stopped. The amount of force required to cause the fracture was measured in newtons. Data were collected and recorded using IBM SPSS Statistics for Windows, Version 17.0 (Released 2008; IBM Corp., Armonk, New York, United States) and then transferred to Microsoft Excel for analysis. Descriptive statistics, mean, and standard deviation were used for continuous data. The fracture resistance of dental roots treated with three types of files was compared using a one-way ANOVA. Graphs were generated using Excel and Word. A significance level of p<0.01 was chosen. RESULT: ANOVA indicated significant differences in mean fracture resistance: Neolix A1 (NiTi) (95.3 N) > NEXT (91.0 N) > universal (86.6 N), with a p-value of 0.004 (<0.001), confirming statistical significance. CONCLUSION: The study concludes that the canal instrumented with Neolix A1 (NiTi) exhibits higher fracture resistance after canal instrumentation compared to ProTaper Next and ProTaper Universal.

Comparative evaluation of hand and rotary file systems on dentinal microcrack formation during pulpectomy procedure in primary teeth: an in vitro study.

PURPOSE: Pulpectomy can be used for the management of deep dentinal carious lesions in primary teeth which can be restored. Mechanical preparation of root canals can be performed using hand or NiTi rotary files. However, this may cause dentinal stress and consequently dentinal microcracks. Hence, the aim was comparative evaluation of hand and rotary file systems on dentinal microcrack formation during pulpectomy procedure in primary teeth. METHODS: 60 extracted primary molar teeth were selected comprising of 80 root canals. Simple random sampling was used to divide root canals into four groups (n = 20): Group A-Hedstrom file, Group B-Pro AF Baby Gold rotary, Group C-ProTaper Next rotary, and Group D-unprepared group. Assessment was conducted on presence or absence of microcracks using Chi square test (p < 0.05). RESULTS: The total number of microcracks in Group A: one (5%), Group B: four (20%), Group C: nine (45%) and Group D: zero (0%) which was statistically significant (p = 0.002). At cervical third, the number of microcracks seen with Group A: one (5%), Group B: zero (0%), Group C: five (25%) and Group D: zero (0%) (p = 0.005). At the middle third, the number of microcracks seen in Group A: zero (0%), Group B: four (20%), Group C: four (20%) and Group D: zero (0%) (p = 0.029). CONCLUSION: The study concluded that dentinal microcracks are formed with both hand and rotary file systems in primary teeth. ProTaper Next showed significantly higher number of microcracks, followed by ProAF Baby Gold and H files.

Life span of Neoendo Flex and ProTaper Next rotary files with reciprocating motion in single-rooted teeth.

Background: Cleaning and shaping represent a vital step in the endodontic procedure. In routine endodontic therapy, the fracture of nickel-titanium (NiTi) instruments is a procedural problem creating a major obstacle to therapy. Aim: This study examines the life span of one Neoendo Flex and ProTaper Next (PTN) rotary file using reciprocating motion and compares the time required by both file systems for canal preparation. Materials and Methods: One hundred maxillary permanent central incisors were selected. In that, fifty teeth are utilized in a reciprocating motion (RM) with the PTN file (n = 25) and Neoendo Flex file (n = 25). To check fractured resistance and the overall root canal preparation time, fifty more teeth are employed in continuous motion (CM) with canals prepared using PTN (n = 25) and Neoendo Flex (n = 25). All canals are prepared following the sequence of respective files. Later, the fracture mechanism of the files was inspected using a scanning electron microscope. Results: In an RM motion, both PTN and Neoendo Flex files can be used in a minimum of 25 canals in single-rooted teeth. Statistical analysis using the Mann-Whitney U-test showed no significant difference in total time taken by PTN and Neoendo Flex in both motions. Conclusion: Within the limitation of this study, the RM was found to be better than CM with less incidence of instrument fracture.

Apical extrusion of debris when using OneCurve, ProTaper Next and TruNatomy in curved canals.

BACKGROUND: The extrusion of apical debris is related to various factors, and may be affected by variations in technique or instrumentation system. Although the extrusion cannot be completely prevented, it is crucial to minimize the amount of extruded material. OBJECTIVES: The present study aimed to compare apical debris extrusion by the novel TruNatomy (TRN), OneCurve (OC) and ProTaper Next (PTN) instruments in curved root canals. MATERIAL AND METHODS: A total of 60 multi-rooted human mandibular molar teeth with moderate and severe curvature were selected and randomly divided into 3 groups. The root canals were prepared with the OC, TRN and PTN files. For collecting the debris extruded through the apical foramen, Eppendorf tubes were used. After the vaporizing period, the tubes were re-weighed, and the amount of the extruded debris was calculated by subtracting the initial weight from the final weight. Statistical analysis was performed with the Shapiro-Wilk and Kruskal-Wallis tests. The statistical significance level was set at p < 0.05. RESULTS: The least amount of debris was extruded with TRN and the greatest with PTN, but the difference between the groups was not significant (p = 0.257). CONCLUSIONS: All instrumentation systems were associated with debris extrusion. The tested file systems presented similar results in terms of apical debris extrusion in curved canals. The novel TRN system demonstrated promising results, comparable to OC and PTN.

Impact of cooling on shaping ability of thermally treated files in canal models with double curvature.

Background: This study compared the ability of thermally treated files in shaping simulated canals with double curvature. Fifty-six canals were enlarged to a final size of 25 with ProTaper Next (PTN) or ZenFlex (ZF). Materials: Half of the samples were shaped with cooled files (n = 14 each). The amount of removed resin was measured and canal deviation was determined at eight levels. Shaping time and maximum shaping torque values were also recorded. Data were statistically analyzed using analysis of variance and LSD, Kruskal-Wallis, and chi-square tests at a 0.05 significance level. Results: Compared to PTN and cooled PTN, ZF and cooled ZF required lesser time to shape the canals. The maximum torques were found comparable between the groups. All the groups generated negligible deviations at every canal level evaluated and maintained the canal geometry. Although not significant, the cooled PTN and ZF files exhibited lesser canal deviations than their counterparts. Conclusion: All groups demonstrated similar shaping ability whilst maintaining the original curvature of the canal in simulated canals with double curvature. However, ZF groups were able to shape the canals faster than PTN groups. There was a trend that cooled files made lesser canal deviations compared to their counterparts.

Comparison of single and multiple file rotary endodontic instruments for debris and irrigant extrusion: An in vitro study.

Aim: The aim of this study was to assess and compare the quantity of apically debris which was extruded apically by TruNatomy (TN), ProTaper Next (PTN), HyFlex electric discharge machining (EDM), and HyFlex controlled memory (CM), following root canal preparation. Materials and Methods: Sixty extracted single-canal mandibular premolars were used. The root canal preparation was done with TN, HyFlex EDM, PTN, or HyFlex CM files. The preweight debris, which was extruded apically, was collected in the Eppendorf tube and later on incubated at 670°C for 3 days and weighed again to record the extruded debris. Results: The result showed that there was a significant reduction in debris extrusion by TN system, followed by PTN system, HyFlex EDM, and maximum extrusion in HyFlex CM (P < 0.05). Between the PTN and TN groups as well as between the HyFlex EDM and HyFlex CM groups, statistically significant difference was not observed (P > 0.05). Conclusion: Apical debris extrusion is the inherent nature of the all file systems. Nevertheless, the TN file system produced substantially minimum debris extrusion among other systems compared in the study.

Comparative Evaluation of Dentinal Defects After Root Canal Preparation Using Various Nickel Titanium Files: An In Vitro Study.

AIM: This study set out to compare the damage done to dentin by three distinct titanium file brands - the Hyflex EDM, the ProTaper Next, and the Waveone Gold Nickel - in order to draw conclusions about which one is the most effective. MATERIALS AND METHODS: Forty-first premolars in the mandible with straight canals and single roots were instrumented using Hyflex EDM, Waveone Gold, and Protaper Next. Dentinal flaws after endodontic treatment were studied by sectioning specimens using a hard tissue microtome and analyzing them under a stereomicroscope. RESULTS: There was no discernible variation between the groups in the coronal third (p=0.312) or apical third (p=0.076). Hyflex EDM and Protaper Next differed significantly in the middle portion of the tape (p=0.016). The Hyflex EDM sample had the fewest cracks. There was no statistically significant difference between Hyflex EDM and Waveone Gold; however, Hyflex EDM had fewer fractures in the middle third of the sample than Waveone Gold did. CONCLUSION: Electric discharge machining (EDM) files made from Hyflex proved to be far superior to their Protaper Next and Waveone Gold counterparts as they induced the fewest cracks in the middle third of the root dentin.

Comparison of Postoperative Pain After the Utilization of Different File Systems in Single Visit Endodontics.

Purpose: This prospective single-blind, parallel-group, randomized clinical trial was aimed to compare the effect of three different rotary instrumentation systems ProTaper Next (PTN), Self-Adjusting File (SAF) and XP-endo Shaper (XPS) on postoperative pain and analgesic intakes. Patients and Methods: A total of 159 molars diagnosed with symptomatic irreversible pulpitis were randomly divided into three study groups according to the instrumentation techniques: PTN (n = 54), SAF (n = 52), and XPS (n = 53). The preoperative pain scores were taken before the onset of treatment in the groups. After a single appointment for root canal treatment, the patients were asked to rate the level of their pain according to the Visual Analog Scale (VAS) of 100 mm at 6, 24, 48, and 72-hour post-treatment intervals. Ibuprofen was prescribed to be taken while experiencing pain; patients were requested to note the number of pills consumed at intervals after treatment. Results: The patients in SAF and XPS groups had lower mean VAS scores than the PTN group at 24-, 48-, and 72-hour intervals (p < 0.05). The most common analgesic intake was optimally seen in the PTN group at a 6-hour interval. All shaping procedures caused postoperative pain, whose intensity decreased with time. Conclusion: The SAF and XPS groups had a lesser intensity of pain as well as minimum analgesic intakes as compared to the PTN group. All instrumentation systems moderately caused pain, and the PTN group experienced the highest pain among others.

Canal Transportation and Centring Ratio of Paediatric vs Regular Files in Primary Teeth.

BACKGROUND: During mechanical preparation of the primary root canal, the original anatomy of the tooth should be preserved and the instrument should be perfectly balanced centrally into the canal space for reducing the probability of canal transportation. The aim of this research was to compare canal transportation and canal centring ability in primary root canals using ProTaper Next (Dentsply Mailfair,), AF baby (Fanta), and Kidzo Elephant (Endostar, Poldent Sp.) files. MATERIALS AND METHODS: Eighteen root canals were randomly divided into 3 experimental groups (n = 6 in each group). Instrumentation was performed using ProTaper Next, Fanta AF baby, and Kidzo Elephant files in groups 1, 2, and 3, respectively. During the instrumentation procedure, the irrigation of 2 mL of 1.5% sodium hypochlorite between each file was done, followed by 5 mL of 17% ethylenediaminetetraacetic acid as a final irrigating solution. Cone-beam computed tomography images were obtained before and after instrumentation. Each group was evaluated for transportation and centring ratios. RESULTS: On comparing all the tested groups within each root canal level canal transportation, the results revealed a statistically nonsignificant difference in the buccolingual direction (P > 0.05). Meanwhile, in the mesiodistal direction, group 1 showed a statistically highly significant difference compared to groups 2 and 3 at the cervical level (P < .01). However, in both middle and apical root canal levels, there was a statistically nonsignificant difference amongst all groups (P > 0.05). Regarding the centring ability comparison of the 3 groups within each root canal level, there was a statistically nonsignificant difference amongst all groups (P > 0.05) in both buccolingual and mesiodistal directions. CONCLUSIONS: The ProTaper Next regular rotary file and the paediatric rotary files showed no difference in canal transportation and centring ability in the buccolingual direction, while in the mesiodistal direction at the cervical root canal level, the ProTaper Next showed high transportation liability.

Quantitative Evaluation of Apically Extruded Debris during Biomechanical Preparation using Hand K-File, Protaper Next, and Waveone - An In Vitro Study.

Background: The instrumentation technique which produces least amount of apically extruded debris is desirable to use in biomechanical preparation of root canal. Aim: To quantitatively evaluate apically extruded debris during instrumentation with hand K-file, ProTaper Next, and WaveOne. Materials and Methods: Forty-five extracted human single-rooted mandibular premolars with straight, single canal and single apical foramen were selected after radiographic evaluation and divided equally into three groups. Cleaning and shaping was done using hand K-files in step-back technique, ProTaper Next, and WaveOne single-file system. Debris extruded apically was collected into Eppendorf tubes and stored in an incubator at 37°C temperature for 5 days for drying. Weight of dry debris was measured using electronic microbalance with an accuracy of 10-5 g. Statistical Analysis: Student's t-test, with P value < 0.05 is statistically significant. Results: Statistically significant (P < 0.05) amount of debris was extruded by all three instrumentation systems: hand K-file- 1.9220 mg, ProTaper Next- 1.4940 mg, and WaveOne- 0.9940 mg. Least amount of debris produced by WaveOne was statistically significant (P < 0.05) when compared with the other two systems. Conclusion: The WaveOne reciprocating system extruded least amount of debris in comparison to hand K-file and ProTaper Next.

Comparative Evaluation of Fracture Resistance of Endodontically Treated Bicuspids Instrumented With Hand Files, TruNatomy, ProTaper Next, ProTaper Gold, and WaveOne - An In vitro Study.

Aim: The study aims to compare and evaluate the fracture resistance of endodontically treated bicuspids instrumented with Hand Files, TruNatomy (TRN), ProTaper Next (PTN), ProTaper Gold (PTG), and WaveOne (WO). Materials and Methods: In total, 45 extracted single-rooted human premolar teeth were selected and sectioned at or below the cementoenamel junction to obtain roots 15 mm long. The samples were divided into four experimental groups and one control group (n = 9): instrumentation with nickel-titanium (NiTi) Hand Files (control group), instrumentation with TRN files, instrumentation with PTN files, instrumentation with PTG files, and instrumentation with WO files. The samples were obturated by lateral compaction technique using gutta-percha points and AH Plus sealer. A vertical load was applied to the tooth using the universal testing machine (Tecsol-TSI-BDS-2Kn-Sr No. 170710) for the fracture resistance test. Statistical analysis was performed. Results: The study reported that teeth instrumented with NiTi hand files exhibited the highest fracture resistance when compared to all the rotary and reciprocating file systems. Among rotary and reciprocating instruments, root prepared with TRN files showed the most significant resistance to fracture compared with PTN, PTG, and WO files. Conclusion: Within the limitations of this study, it can be concluded that minimally invasive instrumentation of the system preserves more pericervical dentin, which may increase the resistance to fracture. Results of this study and other studies support the use of minimally tapered instruments to improve the fracture resistance of endodontically treated teeth.

Comparison of the fracture resistance of the teeth prepared with ProTaper Universal, ProTaper Next, and ProTaper Gold rotary files.

OBJECTIVES: Root canal preparation can lead to cracks on the roots by creating stresses on the root canal walls, which decreases the fracture resistance of the tooth. The present study compared the fracture resistance of the teeth prepared by the ProTaper Universal (PTU), ProTaper Next (PTN), and ProTaper Gold (PTG) rotary file systems. MATERIALS AND METHODS: Fifty-six single-canal premolar teeth were sectioned 14 mm from the root apex. The roots were standardized based on the buccolingual and mesiodistal diameter and randomly assigned to three experimental (n = 14) and one control group (n = 14). The teeth in three experimental groups were instrumented with PTU, PTN, and PTG rotary files. The roots in the control group were not instrumented. A vertical force was applied to each root in a universal testing machine until the root fractured. The data were statistically analyzed by one-way analysis of variance. RESULTS: There was no significant difference in the fracture resistance of the teeth between the control, PTU, PTN, and PTG groups (p = .115). CONCLUSIONS: Root canal preparation with ProTaper files manufactured with conventional NiTi (PTU) and heat-treated alloys (PTN and PTG) did not affect the fracture resistance of teeth.

Comparison of postoperative pain after the use of different nickel titanium instrumentation systems: a randomized clinical trial.

Purpose: Postoperative pain is a common complication in endodontics contributed by multiple etiological factors, which consist canal preparation instruments and kinematics. The aim of this randomized clinical trial compare the postoperative pain in terms of intensity and incidence after the use of different nickel titanium (NiTi) file systems. Patients and methods: In this randomized clinical trial (NCT03791762), a total of 150 patients were root canal treated by 2 experienced endodontists according to a standardised protocol. The subjects were randomly assigned to 1 of the 3 groups according to preparation instrument used: ProTaper Next (Dentsply Sirona, Ballaigues, Switzerland), Reciproc Blue (VDW, Munich, Germany) and WaveOne Gold (Dentsply Sirona). Following preparation the teeth underwent standardized root canal treatment procedures in a single visit. The patients were contacted to gather information about the incidence of pain and intensity at 6th, 12th, 18th, 24th, 48th, and 72nd hours postoperatively. The data were analysed using chi-square, one-way analysis of variance and post hoc Tukey tests and logistic regression analysis with 5% significance threshold. Results: No significant difference was found among preparation groups in relation to the intensity of postoperative pain. The incidence of postoperative pain was significantly linked with the preoperative pain presence with odds ratio values ranging between 2.06 and 4.08 irrespective of the preparation technique (P<0.05). Conclusion: The effects of reciprocating and the continuous rotary systems on the intensity and incidence of postoperative pain were found to be similar.

Influence of Optimum Torque Reverse Motion on Dentinal Cracks after Root Canal Preparation with Two Nickel-Titanium Rotary Systems.

Objectives: This study was aimed to evaluate the cause-effect relationship between canal preparation with ProTaper Next (PTN) and ProTaper Gold (PTG) using optimum torque reverse (OTR) motion or continuous rotation and dentinal crack formation. Materials and Methods: Fifty distobuccal roots of human maxillary first molars were divided into five groups; Group I: PTG Full rotation, Group II: PTG in OTR, Group III: PTN Full rotation, Group IV: PTN in OTR, Group V: unprepared (control group). After mechanical preparation, the distobuccal roots were sectioned horizontally at 3, 6, and 9 mm from the apex. Images were captured using a stereomicroscope at 25X to determine the presence or absence of dentinal cracks. Friedman test was used to compare between root sections followed by Wilcoxon signed-rank test for pairwise comparison. Kruskal-Wallis test was used to compare between tested rotary systems followed by pairwise comparison with Dunn Bonferroni correction (α = 0.05). Results: Crack development was significantly higher in PTG using OTR motion 36.7% followed by PTN using OTR 33.3%, while the control group showed no cracks. PTG and PTN with full rotation showed crack development with 23.3% and 13.3%, respectively. Conclusions: The type of motion kinematics used during mechanical preparation have an impact on dentinal crack formation. Nickel-titanium instruments with larger taper tend to induce more cracks.

A comparative evaluation of remaining dentin thickness following biomechanical preparation of teeth using different rotary file systems: An in vitro study.

Aim: The aim of the study is to compare and evaluate the remaining dentin thickness following biomechanical preparation of teeth using different rotary file systems. Materials and Methodology: Sixty noncarious mandibular premolar teeth were collected and decoronated at the level of cementoenamel junction with a diamond disc. All specimens were randomly divided into 5 experimental groups - ProTaper Next (Dentsply Mallifer), Mtwo (VDW, Antaeus, Munich, Germany), RaCe (FKG, La Chaux-de-Fonds, Switzerland), Hyflex electro-discharge machining (EDM) (Coltene-Whaledent, Allstetten, Switzerland), NeoNiTi (Neolix, France) and 1 control group of 10 teeth each. After mounting the samples on a modeling wax sheet, preoperative cone-beam computed tomography (CBCT) scans were taken. Biomechanical preparation of canals was done following the assigned protocol of manufacturers. Postoperative CBCT scans were taken and comparison was carried out with preoperative scans. Statistical Analysis Used: Difference among the groups was analyzed by post hoc Turkey and analysis of variance tests. A P < 0.05 was considered statistically significant for all tests. Results: A comparison of preinstrumentation and postinstrumentation CBCT images revealed ProTaper Next group to remove more dentin at 7 mm as opposed to other groups in mesiodistal direction. However, no statistical difference was evident between ProTaper Next, MTwo, Race, Hyflex EDM, NeoNiTi file systems at 3 mm, 5 mm, and 7 mm in buccolingual direction. A statistically nonsignificant difference was evident between MTwo, Race, Hyflex EDM, NeoNiTi file systems at 3 mm, 5 mm, and 7 mm in both mesiodistal and buccolingual direction. Conclusion: Race file system performed better and removed lesser dentin in both buccolingual and mesiodistal directions. More dentin was removed at the coronal in mesiodistal direction with the use of ProTaper Next, and significant difference was seen between Protaper Next group and other groups in the study.

Effect of Different Downward Loads on Canal Centering Ability, Vertical Force, and Torque Generation during Nickel-Titanium Rotary Instrumentation.

This study aimed to examine how downward loads influence the torque/force and shaping outcome of ProTaper NEXT (PTN) rotary instrumentation. PTN X1, X2, and X3 were used to prepare J-shaped resin canals employing a load-controlled automated instrumentation and torque/force measuring device. Depending on the torque values, the handpiece was programmed to move as follows: up and down; downward at a preset downward load of 1 N, 2 N or 3 N (Group 1N, 2N, and 3N, respectively; each n = 10); or upward. The torque/force values and instrumentation time were recorded, and the canal centering ratio was calculated. The results were analyzed using a two-way or one-way analysis of variance and the Tukey test (α = 0.05). At the apex level, Group 3N exhibited the least canal deviation among the three groups (p < 0.05). The downward force was Group 3N > Group 2N > Group 1N (p < 0.05). The upward force, representing the screw-in force, was Group 3N > Group 1N (p < 0.05). The total instrumentation time was Group 1N > Group 3N (p < 0.05). In conclusion, increasing the downward load during PTN rotary instrumentation improved the canal centering ability, reduced the instrumentation time, and increased the upward force.