HyFlex CM Research Articles

Phase transformation and metallurgical characterization of heat-treated nickel–titanium rotary instruments using differential scanning calorimetry, X-ray diffraction, and energy dispersive spectrometry

Objective: The present study aimed to evaluate the phase transformation behavior and elemental analysis of thermomechanical-treated nickel–titanium (NiTi) rotary instruments, TruNatomy (Dentsply Sirona), HyFlex CM (coltene, Whaledent), and Neoendo Flex (Orikam healthcare India), using differential scanning calorimetry (DSC), X-ray diffraction (XRD), and energy dispersive X-ray spectrometry. Materials and Methods: A total of 18 NiTi rotary instruments, TruNatomy, Hyflex CM, Neoendo Flex, taper. 04, size 25 (except TruNatomy, size 26) were selected and were divided into three groups (n = 6). Three NiTi files from each group were investigated for the DSC test (n = 3). The two segments of each sample were cut carefully by slow-speed water-cooling carborundum disc at 3 mm from the tip and then 4 mm from the previous section. The mass of the samples was measured on the electronic balance and samples that weighed 10–15 mg were loaded into a 40 µL aluminum crucible. The samples are then subjected first to a heating cycle from 0°C to 100°C and subsequently a cooling cycle from 100°C to 0°C in the differential scanning calorimeter (Mettler-Toledo, NIT Srinagar) at a rate of 10°C min−1. XRD (Make. Rigaku Japan, smart lab 3kW, NIT Srinagar.) was performed to verify the DSC results. The remaining two samples from each group (n = 2) were subjected to XRD analysis. The sample preparation for XRD analyses was done precisely with slow speed water cooled carborundum disc and samples were sectioned into three segments. Each segment was 5 mm long and grounded to obtain a uniform smooth plane. The data obtained from DSC and XRD were subjected to origin 8.5 software and graphs were obtained that depict the transformation temperature and phase composition, respectively. Alloy distribution and trace elements of the NiTi rotary instruments were done using energy dispersive spectrometry microanalysis. Results: The DSC results showed that the TruNatomy, Hyflex CM, and Neo Endo instruments had an Austenite finish (Af) temperature exceeding 37°C. The XRD graphs show the different intensity peaks that correspond to the various phases of NiTi rotary instruments. The TruNatomy is predominantly Austenite, Hyflex CM exists mainly in R-phase with a variable amount of austenite and martensite, while Neoendo flex endo mostly contains austenite phase. The elemental analysis revealed that all three file systems show Nickel and Titanium within their bulk structure in an equiatomic ratio. Conclusion: This study concluded that TruNatomy is predominantly martensite with a variable amount of austenite phase. There are differences in thermal transition temperature between the files.

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.

Comparison of hand, rotary, reciprocating and self-adjusting files in cleaning mesio-buccal canals of maxillary first molars.

The smear layer removal capability of different instrumentation techniques on the mesio-buccal root canals of maxillary first molars is of interest to dentists. Sixty extracted maxillary first molars with fully developed apices, curved root canals, and curvatures between 30 to 45 degrees were selected. The teeth were divided into four groups (n=15) based on the instrumentation technique used. The samples were analyzed using a thermal field emission scanning electron microscope to assess smear layer removal at the apical, middle, and coronal thirds of the canals. The Wave One file system showed superior performance in smear layer removal across all three regions of the canal compared to hand files, Hyflex CM rotary files and SAF.

Comparison of the Amount of Debris Extruded From the Apex During Retreatment Procedures Using Several File Systems and to Gauge the Effect of Same and Different Taper on the Debris Extrusion: An In Vitro Study.

To determine the amount of apical extrusion between various file systems during the retreatment procedure and to determine the effect of taper on the same. Seventy mandibular extracted premolars were taken, and preparation was performed using a Woodpecker file (Woodpecker Medical Instrument Co., Ltd., Guilin, China) (25/0.06). The gutta-percha (GP) was removed from each specimen with H file (#40/0.02) to simulate retreatment in seven groups (n = 10) using ProTaper Next (PTN;Dentsply, Maillefer, Ballaigues, Switzerland) (PTN) (30/0.07), Reciproc (25/0.08), Hyflex CM (30/0.06), Mtwo (30/0.05), Neoendo flex (30/0.04), Neoendo hybrid (30/0.04), and Flexicon file (30/0.06). The specimens were held with the help of a rubber stopper and put in the Eppendorf tube of volume 4 mL (pre-weighed before retreatment). The debris that was on the root surface of the specimen was washed with distilled water with 1 mL volume, kept in the oven, and then again weighed after 7 days. Apical extrusion was found in the following order: HYFLEX CM (LEAST) < FLEXICON < PROTAPER NEXT < RECIPROC < NEOENDO FLEX < NEOENDO HYBRID < MTWO (HIGHEST). W Hyflex CM and Flexicon files showed lesser extrusion of debris than others.

Comparative evaluation of cyclic fatigue resistance of thermomechanically treated NiTi rotary instruments in simulated curved canals with two different radii of curvature: An in vitro Study.

This study aimed to compare the effect of heat treatment on the cyclic fatigue resistance of three different nickel-titanium rotary file systems: TruNatomy, HyFlex CM, and NeoEndo flex in simulated curved canals at two different radii of curvatures. A total of 60 NiTi rotary files of three types were used, and the samples were divided into three groups TruNatomy, HyFlex CM, and NeoEndo flex. All the instruments were subjected to cyclic fatigue testing using a stainless steel custom-made canal model with a 60° angle of curvature and two radii of curvature 5 mm and 3 mm; the number of cycles to fracture and length of the fractured segment was measured. The separated instruments were subjected to fractographic analysis under scanning electron microscope. The number of cycles to failure to fracture a file at a 3 mm radius of curvature is significantly less as compared to a 5 mm radius of curvature (HCM > TRN > NE). Within the limitation of the present study, there was a positive correlation between the radius of curvature and fatigue life of NiTi files.

Effect of Coronal Flaring on Initial Apical File Size Estimation in Curved Canals Using Three Distinct Rotary Instruments: A Comparative In Vitro Study.

The initial size of a root canal is established by progressively introducing K-files according to the increase in the International Organization for Standardization (ISO) size in the apical region. The initial file-fit sensation is caused by coronal interferences rather than always occurring at the apex, as is commonly believed. Flaring the canal at its earliest stages enables the practitioner to accurately assess the size of the canal approaching the apex. This enables more informed judgments on the selection of the master apical file required for shaping and cleaning the apex. The aim of this in vitro study is to examine the impact of cervical flaring on the first estimation of apical file size using three distinct rotary instruments. Sixty-four extracted permanent maxillary first molars with a curvature of between 10⁰ and 20⁰ were chosen. Conventional access openings were made, and the precise length of the canal was determined, leaving it 1 mm short of the apex. The apical fit was deemed to have materialized when the largest file successfully reached the apex, and further progression beyond that depth was unattainable. An initial file that exhibited tactile resistance both before and following expansion at the designated working length (WL) was observed. The initial file that elicited a sensation of being securely attached was affixed using methacrylate into the root canal. A diamond sectioning disc was used to horizontally cut the apical 0.5 mm of the mesiobuccal root. This was done to expose the canal and the instrument at the WL. The uppermost portions were observed using a 3D optical profilometer, and digital photographs were captured for each sample. The occurrence of coronal interferences and the choice of instruments for flaring had a notable impact on the estimation of the initial apical file (IAF) size. The file size frequency was augmented following flaring using various rotary instruments, namely ProTaper, HyFlex CM, and Endoflare. Group 1, which did not undergo preflaring, exhibited the highest disparity of 257.3 ± 54.4. The variation was substantially different (p<0.01) from all the groups that underwent flaring. The use of HyFlex CM (group 3) for preflaring resulted in the smallest average difference (124.4 ± 29.6) between the maximum diameter of the canal at the apex and the diameter of the initial file used. Endoflare (group 4) exhibited the second lowest mean disparity (178.7 ± 46) between the maximum width of the apical root canal and the diameter of the IAF, with the ProTaper group (211 ± 43.5) following closely behind. Nevertheless, there was no statistically significant discrepancy observed in the average differences between groups 2 and 4 (ProTaper and Endoflare groups, respectively). Coronal preflaring significantly contributes to minimizingthe variation between the IAF and the diameter of the apical canal. Prior coronal expansion using rotary files enables a more precise identification of the IAF. The choice of equipment used for flaring affects the estimation of the IAF size.

Compare the Centering Ability, Canal Transportation and Root Canal Area Increase of XP Endoshaper, Hyflex CM and K3 XF File System by using Cone Beam: An Original Research

ABSTRACT Objective: Using cone beam computed tomography (CBCT), this study compared three rotary file systems—XP Endoshaper, Hyflex CM, and K3 XF—for centering, canal transportation, and root canal area growth. Materials and Methods: The rotating file system randomly separated 60 removed human mandibular molars into three groups (n = 20). Manufacturer-recommended root canal instrumentation was done. Specialized software examined pre- and post-instrumentation CBCT scans. Centering ability was measured by canal transportation and root canal area expansion at different levels from the apex. Results: The Hyflex CM file system had the best centering and the least canal transit at all levels (P &lt; 0.05). XP Endoshaper increased the root canal area the most (P &lt; 0.05). The K3 XF file system had average centering and canal transfer results. Conclusion: The Hyflex CM system centered well, whereas the XP Endoshaper system increased the root canal area the most. The clinical context and therapeutic goals should determine the rotating file system.

Comparative Evaluation of Apically Extruded Debris with Protaper Gold, Reciproc Blue and Hyflex CM Instruments.

Aim of study: The target of the present investigation was to compare the amount of apically extruded debris with three endodontic nickel -titanium instruments; ProTaper Gold, Reciproc Blue and Hyflex CM .&#x0D; Materials and Methods: 30 mandibular premolars were separated into three groups according to the instrumentation methods (n=10) for every system, Protaper Gold, Reciproc Blue and Hyflex CM. After change of each file 5ml of 2.5% NaOCl was used as an irrigating solution with a 30G side vented irrigating needle, the apically extruded debris was collected in pre weighed glass vials, the samples were takeout and incubated at 68Co for 5 days to remove the liquid. The tubes were measured again, and the contrast between the first and last weight was calculated to determine the weight of the debris. The data were statistically analysed using One-way ANOVA analyses followed by Post hoc Tukey LSD test.&#x0D; Result: Data obtained were statistically analyzed using One Way ANOVA and Post hoc Tukey LSD tests. All groups showed apical debris extrusion, The ProTaper Gold systems extruded more debris in comparison with other groups(0.0421)g, also the Protaper Gold group and Hyflex CM system showed statistically significant difference (p&lt;0.05).&#x0D; Conclusions: All experimental groups produced apically extruded debris .The Protaper Gold group associated with greater apically extruded debris than other groups. While the Hyflex CM group showed the least amount of apical extrusion

Shaping Ability of Different Rotary and Reciprocating File Systems in Simulated S-Shaped Root Canals.

This study aimed to examine the shaping ability of six rotary and reciprocating file systems, as well as hybrid techniques in simulated S-shaped root canals. A hundred and twenty S-shaped radiopaque thermosetting epoxy resin blocks were grouped according to the system used for biomechanical preparation. Six groups of 15 canals each were prepared using TruNatomy, Procodile, VDW Rotate, Hyflex CM, OneCurve, and WaveOne Gold, respectively. Two additional hybrid (Procodile/Hyflex CM and Procodile/TruNatomy) groups (n=15 each) were added after evaluating the results of individual systems. All canals were enlarged to 0.25 mm apically. Canal transportation, centering ability, diameter increase, and iatrogenic errors were assessed by superimposed pre-operative and post-operative images. AutoCAD was used for data analysis. All groups were statistically compared with analysis of variance and Tukey honest significant difference test (p<0.05). Hyflex CM resulted in the most conservative diameter increase in all thirds (coronal, middle, and apical; p<0.001). Procodile showed the best (p<0.001) centering ability in the coronal and middle thirds, while TruNatomy resulted in the least canal transportation and most centering preparation in the apical third (p<0.001). Hybridisation of Procodile and Hyflex CM produced the least canal transportation and best centering ability in the middle third (p<0.001). No instrument breakage occurred, and no ledge, elbow, or apical zip formation was observed during canal preparation. Hybridisation of Procodile and Hyflex CM showed remarkable results in preserving the canal diameter in all thirds and resulted in the least canal transportation and best centering ability in the middle third of the canal. However, when treatment cost and duration limit the clinical applicability of the hybrid technique, clinicians can use a single file system (Hyflex CM or TruNatomy) since it shows satisfactory results in all parameters when compared with a hybrid system.

An in vitro evaluation of dentinal microcrack formation during root canal preparations by three different nickel–titanium systems: ProTaper Gold, HyFlex CM, and Silk

Aim: This study aimed to compare the frequency of dentinal microcracks after root canal shaping with three different nickel–titanium (NiTi) systems, namely, ProTaper Gold (PG), HyFlex CM (HCM), and Silk. Methods: One hundred mandibular premolars with a single canal were chosen for this study. All specimens were decoronated and divided into four groups of 25 each. Teeth were mounted in the acrylic block with simulated periodontal ligaments. Group I served as a negative control Group, in which no treatment was performed. Biomechanical preparation was done in the Group II, using the Protaper gold file system. Group III, using the Hyflex CM file system and Group IV, using the Silk file system. Specimens were horizontally sectioned at 3, 6, and 9 mm from the apex using the low-speed diamond disc under water cooling. The slices were then viewed under a stereomicroscope at ×25 to determine the presence of cracks. The absence or presence of cracks was recorded, and the data were analyzed with a Chi-square test. The significance level was set at P &lt; 0.05. Results: Coronal section showed lesser crack formation in all three groups after biomechanical preparation. More number of dentinal microcracks were seen in the apical sections, followed by the middle and the coronal sections in Group II (PG), followed by Group IV (Silk), and Group III (HCM), respectively. Group II showed more microcracks at all three levels of the root canals when compared with Groups III and IV. Intergroup analysis showed no statistically significant difference in microcrack formation. Conclusion: Within the limitation of this in vitro study, it can be concluded that NiTi instruments may cause cracks on the root surface. HCM and Silk files tend to produce a less number of cracks as compared to PG instruments.

Accuracy of an Endodontic Rotary Motor with Integrated Apex Locator to Determine the Root Canal Length

Aim: The purpose of this study was to evaluate the efficacy to determine the root canal length, in vitro, of both the electronic apex locator (M2) and the autostop (AS - M3) functions of the Endus Duo Gnatus endodontic motor (Gnatus, São Paulo, SP, Brazil). Methods: Thirty extracted human single-rooted premolars had their root canal lengths (TLs) up to the apical foramen determined using the Endus Duo Gnatus in two ways: (1) In the stainless steel (SS) control group, the measurement was obtained using a stainless steel hand instrument with the electronic locator mode (M2 function) connected to a stainless-steel hand instrument (K-file #15). In the NiTi rotary instrument (NiTi RI) intervention group, the measurement was obtained during the instrumentation (M3 function) of the root canals with a nickel-titanium rotary instrument (Hyflex CM: Coltene Whaledent, Cuyahoga Falls, OH, USA), size 25/.06. The NiTi manually used instrument (NiTi MUI) Intervention group performed the measurement in locator mode using a Hyflex instrument, placed to true length manually. Statistical analysis was performed using ANOVA followed by the Tukey post-hoc test with a significance level of p &lt; 0.05. Results: The true mean length and standard deviation (SD) of the standardized root canals were 18.40 ± 2.14mm, while the mean lengths and standard deviations (SD) were 18.29 ± 1.89mm, 18.22 ± 1.85mm, and 17.24 ± 2.09mm for the SS, NiTi RI, and NiTi MUI groups, respectively. However, data from the NiTi MUI Intervention group indicated shorter root canal lengths when compared to the SS control group and the NiTi RI Intervention group values, and were significantly shorter than the true canal length (p &lt; 0.001). Conclusions: The use of the motor in NiTi RI Intervention group showed acceptable results. However, the NiTi MUI Intervention group resulted in unacceptable short measurements.

Phase transformation and mechanical properties of heat-treated nickel-titanium rotary endodontic instruments at room and body temperatures

BackgroundThe aim of this study was to evaluate the phase composition, phase transformation temperatures, bending property, and cyclic fatigue resistance of different heat-treated nickel-titanium (NiTi) rotary instruments with the same tip diameter and taper at room (RT; 25 ± 1 °C) and body (BT; 37 ± 1 °C) temperatures.MethodsFive heat-treated NiTi rotary instruments, HyFlex EDM (EDM), HyFlex CM (CM), Vortex Blue (VB), RE file CT (RE) and JIZAI, and a non-heat-treated NiTi rotary instrument (Mtwo) with a size 40, 0.04 taper were investigated. Temperature-dependent phase transformation was examined with differential scanning calorimetry (DSC). The bending loads of the instruments at RT and BT were evaluated using a cantilever-bending test. Cyclic fatigue resistance at RT and BT was measured using a dynamic test, during which the instruments were rotated in combination with a 2-mm back-and-forth motion in an artificial curved canal, and the number of cycles to failure (NCF) was determined. The results were analyzed using two-way repeated measures analysis of variance, a simple main effect test, and the Bonferroni test (α = 0.05).ResultsDSC results indicated that EDM and Mtwo were primarily composed of martensite/R-phase and austenite, respectively, while the other heat-treated instruments were composed of a mix of martensite/R-phase and austenite at the tested temperatures. Regardless of the temperature setting, the bending loads of heat-treated instruments were significantly lower than those of Mtwo (p < 0.05). EDM showed the lowest bending loads and highest NCF at both temperatures (p < 0.05). CM, VB, and JIZAI showed significantly higher bending loads at BT than at RT (p < 0.05). The NCF of all the heat-treated instruments, except VB, was lower at BT than at RT (p < 0.05). At BT, the NCF of CM, VB, RE, and JIZAI were not significantly higher than that of Mtwo (p > 0.05).ConclusionsHeat-treated NiTi instruments exhibited lower bending loads and higher NCF values than Mtwo. However, this tendency was less pronounced at BT than at RT, especially in the NCF values of instruments with a mixture of martensite/R-phase and austenite phases at the tested temperatures.

Intracanal removal and apical extrusion of filling material after retreatment using rotary or reciprocating instruments: A new approach using human cadavers.

This study compared intracanal removal of filling as well as the frequency and volume of extruded material after retreatment with either HyFlex or Reciproc instruments in mandibular teeth from cadavers. The root canals of 14 pairs of contralateral single-rooted teeth in mandibles of cadavers were instrumented with Reciproc R40 and filled using lateral compaction. The mandibles were scanned in a micro-computed tomographic (micro-CT) device before and after retreatment procedures. The contralateral teeth were assigned to two groups (n = 14) according to the retreatment protocol using either HyFlex or Reciproc instrument systems. In the HyFlex group, the HyFlex Remover instrument was worked 3 mm short of the working length (WL), followed by HyFlex CM 40.04 and 50.04 at the WL. In the Reciproc group, the R50 instrument was worked up at the coronal two thirds, followed by two more cycles until the WL was reached. Pre- and post-operative micro-CT images were analysed for extrusion and intracanal removal of filling material. After retreatment, extrusion of filling material occurred in 11 (78%) and 14 (100%) teeth from HyFlex and Reciproc groups respectively (p > .05). A similar volume of extruded material was observed after retreatment with both systems (p > .05). A significant decrease in the intracanal filling volume was verified after retreatment with both tested systems (p < .05). However, residual filling material was found in all root canals, regardless of the system. The amount of filling material removed (HyFlex = 80.8%; Reciproc = 65.9%) and the operation time was similar between systems (p > .05). A high frequency of filling material extrusion was observed after retreatment with the two systems in a cadaver model, with no significant difference between them. Both protocols obtained similar efficacy in filling material removal procedures, although none completely cleaned the canals.

Comparative evaluation of nickel titanium rotary instruments on canal transportation and centering ability in curved canals by using cone beam computed tomography: An in vitro study

The aim of this study was to compare canal transportation and centering ability of different nickle titanium systems using Cone beam computed tomography in curved canals. Ninety mandibular molars with angle of curvature ranging from 10°– 40° were randomly allocated into six experimental groups containing 15 teeth in each group. Preinstrumentation scans were taken with CBCT with constant exposure parameters before and after instrumentation. Six grouped specimens were instrumented with Wave One, Twisted File, Hyflex CM, K3XF, ProTaper Next, NeoNiTi file respectively. Post instrumentation the specimens were scanned by CBCT to obtain postoperative images. The amount of root canal transportation and centering ability of the instrument were determined. Statistical analysis on collected data was performed using One way analysis of ANOVA, and post-hoc Tukey test (p&amp;#60;0.0.5). K3XF group showed significantly higher transportation values in the apical third (2mm) than TF group (p=0.01) and Hyflex CM group (p=0.03). The coronal transportation values are higher than the apical values but with no significant difference between them (p&amp;#62;0.05). There was no significant difference in centering ratio values between the six groups (p&amp;#62;0.05) at any of the level.: All the file systems can be safely used, showing satisfactory preservation to the original canal shape with preference of TF files.

Impact of nickel-titanium instrument heat treatment on the precision of an inbuilt electronic apex locator and endodontic motor

Numerous nickel-titanium alloys have been designed by manufacturers, however there is little information on the precision of integrated EAL when utilized with various NiTi thermal processes to determine working length.An integrated EAL and endomotor assembly is utilized in this study to assess ex vivo the effects of different thermal processes on NiTi instruments.This study used 20 extracted human maxillary incisors. The visual approach was used to establish the working length (WL) control. WL was measured during cleaning and shaping using rotary files consisting of the Reciproc, Reciproc Blue, Wave One Gold, Twisted File Adaptive, and Hyflex CM systems using 0.25 diameter instrument size.Fisher's exact test and the Kruskal-Wallis statistic tests were used in the analysis of the information at hand.Heat treatment of NiTi rotary instruments has no significant impact on the EAL's accuracy (P &amp;#62; 0.051).The precision of WL estimation using an EAL incorporated with the endomotor was unaffected by the use of thermal processes.

Assessment of debris extrusion on using automated irrigation device with conventional needle irrigation – An ex vivo study

Introduction: Irrigation is an essential aspect of effective cleaning and disinfecting the root canal system. Debris tends to extrude in due course of instrumentation and irrigation. The present study aimed to assess the debris extrusion using an automated root canal irrigation device. Materials and Methods: Sixty-six intact maxillary premolars with double-rooted morphology undergoing extraction were collected. They were allocated into three groups – Group I: control (distilled water irrigation), Group II: conventional needle irrigation, and Group III: automated root canal irrigation (n = 22). Each specimen was then inserted into the Eppendorf tube for debris collection. The canals were then instrumented to 40 size 0.04 taper using HyFlex CM rotary file system. Experimental irrigation varied based on the specific group allocated. Finally, after the irrigation, the collected debris was weighed using the analytical balance. Results: A statistically significant difference (P &lt; 0.05) was elicited in the debris extrusion scores seen among different groups assessed. Conclusion: Debris extrusion was minimal with automated root canal irrigation device as compared to syringe needle irrigation.

Phase transformation behavior and mechanical properties of HyFlex EDM nickel-titanium endodontic rotary instrument: Evaluation at body temperature

Background/purposeTemperature-dependent phase compositional changes influence the mechanical properties of heat-treated nickel-titanium (NiTi) rotary instruments. This study evaluated the phase composition, bending properties, and cyclic fatigue resistance of HyFlex EDM NiTi rotary instruments against differently heat-treated and non-heat-treated NiTi instruments at body temperature (BT). Materials and methodsHyFlex EDM OneFile (EDM) instruments, heat-treated HyFlex CM (CM) and Twisted File (TF) instruments, and non-heat-treated K3 instruments (size #25/.08) were subjected to differential scanning calorimetry, and the martensitic, R-phase, and reverse transformation starting and finishing temperatures were determined. A cantilever bending test and a cyclic fatigue test were conducted at BT (37 °C ± 1.0 °C), and the bending load and number of cycles to failure (NCF) were recorded. Statistical analysis was performed using Kruskal–Wallis and Mann–Whitney U tests (α = 0.05). ResultsTF and K3 had reverse transformation finishing temperatures lower than BT, while those for EDM and CM were higher than BT. The bending loads at a 0.5 mm deflection were in the order of EDM < TF < CM < K3 (P < 0.05), and those at a 2.0 mm deflection were EDM < CM and TF < K3 (P < 0.05). EDM had the highest NCF among the four instruments (P < 0.05). ConclusionThe EDM instrument had a reverse transformation finishing temperature higher than BT indicating its martensite/R-phase composition at BT. The EDM instrument had superior flexibility and greater resistance to cyclic fatigue than the CM, TF, and K3 instruments at BT.

Impact of endodontic irrigants on surface roughness of various nickel-titanium rotary endodontic instruments

BackgroundThe aim of the current study is to assess the surface roughness of several recent nickel-titanium (Ni-Ti) rotary endodontic instruments, namely: Protaper next (PTN); Hyflex CM (CM); Hyflex EDM (EDM); WaveOne gold (WOG); and trunatomy (TN), before and after application of 5.25% sodium hypochlorite (NaOCl) irrigant solution.MethodsIn this in vitro study, five recently introduced rotary endodontic instruments of different metallurgical properties and designs were subjected to Atomic Force Microscopy (AFM) analysis, and then each file was rotated in 5.25% NaOCl for 15 min., with speed and torque according to manufacturer’s instructions. The instruments were then subjected to AFM analysis again. The surface roughness average (Sa) parameter was calculated. Data were analyzed by Paired T test, One-way ANOVA and Tukey tests.ResultsThere was a statistically significant decrease in the surface roughness of all rotary endodontic instruments after immersion in irrigants (P ≤ 0.05).ConclusionThe new TN and PTN instruments showed the least surface roughness. All tested Ni-Ti rotary endodontic instruments after irrigants exposure showed a varying increase in surface roughness.

Canal transportation and centering ability of HyFlex CM and TruNatomy rotary file systems in moderately curved root canals using CBCT: An in vitro study

ABSTRACT Aim: The objective of this study was to evaluate and compare canal transportation (CT) and centering ability (CA) in the curved canals prepared using HyFlex CM (HCM) and TruNatomy (TN) rotary file systems with the help of cone-beam computed tomography (CBCT). Materials and Methods: Forty extracted single-rooted mandibular premolars with 10°–30° of curvature were selected and divided into two groups. In Group 1, the canals were prepared with HCM files (Coltene Whaledent) and in Group 2 the canals were prepared with TN Prime rotary files (Dentsply Sirona). Pre- and postinstrumentation scans were performed at the same position using CBCT to evaluate CT and CA at three levels 3 mm, 6 mm, and 9 mm from the apex and were compared using CBCT software (On Demand 3D software). Statistical Analysis Used: The two groups were statistically analyzed with Mann–Whitney U-test. Results: There was no significant difference among the tested groups regarding the canal centering ratio (P &gt; 0.05). At 6- and 9-mm levels, there was no significant difference in CT among the two groups (P &gt; 0.05). However, at 3 mm from apex, there was a statistically significant difference (P = 0.006) with TN files exhibiting lesser CT. Conclusion: Both the file systems respected the canal anatomy, although in the apical third, TN files exhibited better results. Hence, this file system can be considered for instrumentation of canals with moderate apical curvatures. In regard to CA, no significant differences were found among the file systems.

Cleaning and Disinfecting Oval-Shaped Root Canals: Ex Vivo Evaluation of Three Rotary Instrumentation Systems with Passive Ultrasonic Irrigation.

Background and Objectives: Successful root canal treatment depends on the thorough removal of biofilms through chemomechanical preparation. This study aimed to investigate and compare the cleaning and disinfecting efficiency of oval-shaped root canals using XP-endo Shaper (XPS), ProTaper Next (PTN), and HyFlex CM (HCM) in combination with passive ultrasonic irrigation (PUI). Materials and Methods: Ninety extracted teeth were contaminated and randomly divided into three groups: XPS, PTN, and HCM. Each group was assigned to three subgroups: subgroup A (sterile saline), subgroup B (3% sodium hypochlorite and 17% ethylenediaminetetraacetic acid), and subgroup C (3% sodium hypochlorite, 17% ethylenediaminetetraacetic acid, and PUI). Bacterial sampling was conducted both from baseline samples and samples after chemomechanical preparation. Scanning electron microscopy (SEM) was used to evaluate the residue bacterial biofilms, hard tissue debris, and smear layers on the buccolingual walls of oval-shaped root canals. Results: When combined with sterile saline, XPS demonstrated a higher reduction of bacterial counts and was more effective in eradicating Enterococcus faecalis in the middle third of the canals compared to the other instruments (p < 0.05). Additionally, when used with antimicrobial irrigants, XPS was more effective in disinfecting the coronal third of the canals than the other instruments (p < 0.05). Furthermore, XPS reduced hard tissue debris more effectively in the middle third of canals than in the apical third (p < 0.05). Conclusions: XPS outperforms PTN and HCM in disinfecting oval-shaped root canals. Despite the fact that combining XPS and PUI improves cleaning and disinfecting, removing hard tissue debris from the critical apical area remains challenging.