Rotary Nickel-titanium Research Articles

Nickel-Titanium Rotary Instruments: Development of the Single-File Systems.

Over the past two decades, the nickel–titanium (NiTi) rotary instruments have highly improved the quality of the cleaning and shaping of the root canals. The superelasticity and shape memory of these instruments reduce the possibility of the canal transportation along with saving the time for both the patients and the clinicians. Several commercial types of these instruments, produced by different manufacturers, have currently become available by modifying the characteristics of the wonder NiTi alloy and also the cross-sectional shapes, cutting edges, tapering and numbers and distances of the flutes of the instruments. Up to this date, five generations for NiTi rotary instruments have been described according to the time of introduction, properties, and method of application. The aim of this article is to review the evolution of these five generations of NiTi rotary instruments since their inception.

First Experience of Rotary Nickel Titanium Root Canal Instrumentation Performed by Undergraduate Students and General Dentists

First Experience of Rotary Nickel Titanium Root Canal Instrumentation Performed by Undergraduate Students and General Dentists

Endodontic treatment of canine teeth in a cynomolgus monkey ( Macaca fascicularis).

A case of bilateral superior canine tooth pulp necrosis in an 18-year-old male Macaca fascicularis is described . A skull computed tomography scan was performed to confirm the diagnostic suspicion. A successful bilateral endodontic treatment with coronotomy was performed using rotary nickel-titanium instruments. Post-operative dental radiographs confirmed the correct positioning of the sealant. A rapid and excellent clinical recovery was obtained after each surgery. This innovative approach may contribute to improving the quality of root canal treatments provided to non-human primates.

P.1.f.020 - Peripheral inflammation in fibromyalgia syndrome

This randomized clinical study compared the in vivo antibacterial efficacy of Reciproc Blue (RB), XP-endo Shaper (XP-S), and XP-endo Shaper associated with XP-endo Finisher (XP-F) systems in infected oval-shaped root canals with primary apical periodontitis.In this study, 28 human teeth with a single root and a single canal were randomly assigned to 2 groups according to the instrumentation technique: group 1, RB (n = 14) and group 2, XP-endo (XP-S and XP-F, n = 14). The single-rooted teeth were prepared by reciprocating and rotary nickel-titanium instruments with 5.25% sodium hypochlorite irrigation. Samples were collected from the canal at the baseline (S1), after chemomechanical preparation (S2), and after XP-F instrumentation (S3). The DNA extracts were subjected to quantitative analysis for total bacterial counts by quantitative real-time polymerase chain reaction. The data were analyzed using the analysis of variance test, and the level of significance was set at 5%.All samples tested positive for the presence of bacteria at baseline, and the bacterial counts substantially reduced after treatment procedures (P < .01). The results showed no statistical difference between RB and XP-S instrumentation with respect to the bacterial reduction (P > .05). A marked bacterial reduction was observed after the use of the XP-F instrument (P < .01).The XP-S and RB systems sharply reduced the bacterial load in oval-shaped root canals with primary apical periodontitis. XP-F used as a supplementary instrument to chemomechanical preparation promoted a significantly higher bacterial reduction.

Mechanical Properties of Various Heat-treated Nickel-titanium Rotary Instruments

AimThe purpose of this study was to compare the bending stiffness, cyclic fatigue, and torsional fracture resistances of heat-treated and conventional nickel-titanium rotary instruments. MethodsV-Taper 2 (VT2; #25/.08), V-Taper 2H (V2H; #25/.06), Hyflex CM (HCM; #25/.06), HyFlex EDM (HDM; #25/variable taper), and ProTaper Next X2 (PTN; #25/variable taper) were tested. The bending stiffness was measured with the customized device (AEndoS), and the files (n = 15) were fixed at 3 mm from the tip and bent at 45° with respect to their long axis. Cyclic fatigue resistance was tested by pecking and rotating instruments (n = 15) in artificial canal with a 7.8-mm radius and 35° angle of curvature until fracture. The ultimate torsional strength and toughness were estimated by using AEndoS. The file tip of 5 mm was fixed between resin blocks and driven clockwise at 20 rpm until fracture. The results were analyzed by using one-way analysis of variance and Duncan post hoc comparison. The fracture surfaces and longitudinal aspect of each group were examined under the scanning electron microscope. ResultsCM-wire instruments had lower bending stiffness than others. HDM showed the highest cyclic fatigue resistance, followed by VTH and HCM (P < .05). VT2 showed the highest ultimate strength, followed by HDM, VTH-PTN, and HCM. HDM and VT2 showed significantly higher toughness than VTH, HCM, and PTN (P < .05). Scanning electron microscope analysis showed typical fractographic features of cyclic fatigue and torsional fractures. ConclusionsCM-wire instruments showed higher flexibility and cyclic fatigue resistance than M-wire and conventional nickel-titanium instruments. Large cross-sectional area and conventional nickel-titanium showed high torsional resistance.

Endodontic Management of a Three Rooted Mandibular Third Molar with a Dilacerated Distal Root and Close Approximation to the Inferior Alveolar Canal: A Case Report

Aim: A thorough understanding of root and canal anatomical variations is essential for achieving successful endodontic treatment. Literature continues to demonstrate complex root and canal anatomical variations in mandibular third molars which are sometimes in close approximation to the inferior alveolar canal.&#x0D; Methodology: A 26-year-old male patient was referred for endodontic treatment of a three-rooted mandibular third molar with a dilacerated distal root and close approximation to the inferior alveolar canal. A cone beam computed tomography was performed to assess the root and canal anatomical variations together with the inferior alveolar canal. Conventional endodontic treatment was performed using a rotary nickel-titanium file system, and the canals were then obturated using a cold lateral condensation technique.&#x0D; Results: The endodontic treatment procedures were performed successfully and in the follow-up visit, the tooth was asymptomatic.&#x0D; Conclusions: Despite limited accessibility and challenges during root canal treatment procedures, retaining every functional component of the dental arch, including mandibular third molars, is an essential goal of contemporary dental practice. &#x0D; How to cite this article: Sharawy WW, Ahmed HMA. Endodontic management of a three rooted mandibular third molar with a dilacerated distal root and close approximation to the inferior alveolar canal: A case report. Int Dent Res 2017;7:42-45.

Influence of Continuous or Reciprocating Optimum Torque Reverse Motion on Cyclic Fatigue Resistance of Two Single-File Nickel-Titanium Rotary Instruments

Different single-file instruments and kinematics have been introduced on the market. It is important to know the cyclic fatigue performance of these instruments in these new kinematics such as reciprocation of Optimum Torque Reverse (OTR) motion. The aim of this study was to evaluate the resistance to cyclic fatigue of F6 SkyTaper and OneShape used in continuous rotation (proper rotation) or in reciprocating OTR motion.A total of forty-eight nickel-titanium files were tested. Twenty-four instruments of both brands were divided into two groups (n=12) on the basis of the motion tested: continuous rotation (group 1) or reciprocating OTR motion (group 2). Resistance to cyclic fatigue was determined by recording time to fracture (TtF) in a stainless steel artificial canal with a 60° angle of curvature and 5 mm radius of curvature. Data were analysed by two-way analysis of variance and post-hoc Bonferroni tests for multiple comparisons with P<0.05 as the level of significance.F6 SkyTaper showed higher TtF compared with OneShape, both in continuous and in OTR motion (P<0.0001). The two tested instruments showed higher cyclic fatigue resistance in reciprocating OTR motion than continuous rotation (P<0.0001).OTR motion significantly improves cyclic fatigue resistance of the tested instruments. In addition, F6 SkyTaper showed higher cyclic fatigue resistance than OneShape in both motions.

Influence of Continuous or Reciprocating Optimum Torque Reverse Motion on Cyclic Fatigue Resistance of Two Single-File Nickel-Titanium Rotary Instruments

Objective:Different single-file instruments and kinematics have been introduced on the market. It is important to know the cyclic fatigue performance of these instruments in these new kinematics such as reciprocation of Optimum Torque Reverse (OTR) motion. The aim of this study was to evaluate the resistance to cyclic fatigue of F6 SkyTaper and OneShape used in continuous rotation (proper rotation) or in reciprocating OTR motion.Methods:A total of forty-eight nickel-titanium files were tested. Twenty-four instruments of both brands were divided into two groups (n=12) on the basis of the motion tested: continuous rotation (group 1) or reciprocating OTR motion (group 2). Resistance to cyclic fatigue was determined by recording time to fracture (TtF) in a stainless steel artificial canal with a 60° angle of curvature and 5 mm radius of curvature. Data were analysed by two-way analysis of variance and post-hoc Bonferroni tests for multiple comparisons with P<0.05 as the level of significance.Results:F6 SkyTaper showed higher TtF compared with OneShape, both in continuous and in OTR motion (P<0.0001). The two tested instruments showed higher cyclic fatigue resistance in reciprocating OTR motion than continuous rotation (P<0.0001).Conclusion:OTR motion significantly improves cyclic fatigue resistance of the tested instruments. In addition, F6 SkyTaper showed higher cyclic fatigue resistance than OneShape in both motions.

Stress Generation during Pecking Motion of Rotary Nickel-titanium Instruments with Different Pecking Depth

IntroductionThe aim of this study was to evaluate the effect of different pecking depth on the stress generated by the screw-in forces of a rotating endodontic file in simulated canals. MethodsTwenty simulated resin blocks with a J-shaped curvature were used. Twenty OneG files (MicroMega, Besançon, France) were assigned for a screw-in test depending on the pecking depth in 2 groups (n = 10). The files were operated at 300 rpm, and the up and down speed was controlled at 1 mm/s stroke velocity and a 10-millisecond dwell time using a customized device. The distances (pecking depth) for the pecking motion were 2 mm or 4 mm for each group; “6 mm forward and 4 mm backward” and “6 mm forward and 2 mm backward” movements were applied, respectively, for the 2 pecking groups. During the operation, the positive and negative apical loads were recorded at a rate of 50 Hz using customized software attached to the device. The maximum negative apical load (screw-in force [SF]) was recorded, and the total energy during pecking motion until the file reached the working length (cumulative screw-in forces [CSFs]) was computed. The data were analyzed using an independent t test at a significance level of 95%. ResultsNo significant difference in SF was found between the 2 groups of pecking depths. However, the longer pecking depth (4-mm group) showed a significantly larger CSF compared with the shorter pecking depth group (P < .05). ConclusionsThe shorter pecking depth may generate lower overall stresses for the root dentin as well as the instrument.

Surface Changes of PathFile after Glide Path Preparation: An Ex Vivo and In Vivo Study

IntroductionThe aim of this study was to evaluate the changes in the surface profile of rotary nickel-titanium (NiTi) files designed to prepare a glide path and conventional stainless steel (SS) hand files when used in extremely narrow canals both in clinical and experimental conditions. MethodsThis ex vivo/in vivo study used either SS #10 K hand files or the PathFile system (Dentsply Maillefer, Ballaigues, Switzerland) to establish a glide path in maxillary molars with narrow root canals (defined as canals that bound a #8 K-file at the working length). After treatment, all files were cleaned and scanned using a noncontact laser profilometer. Changes to the surface profile (Ra cutting edge waviness = RaCEW) and roughness (Ra cutting edge roughness = RaCER) of the cutting edges and the surface roughness of the flute area (Sa flute roughness = SaFR) were analyzed. Results#10 K-files had significant increases in all types of measurements (RaCEW, RaCEW, and SaFR) after the preparation of second mesiobuccal canals compared with the control group (P < .05) in both studies. In the ex vivo study, the PathFile (P1) had no significant changes in the surface profile from baseline but had a significant increase in the surface roughness of the flute (SaFR) (P < .05). PathFiles that were used 3 times in vivo had a significant increase in roughness (flute and cutting edge) values across all PathFile sizes compared with control values. ConclusionsThis study showed that PathFiles had significantly less surface defects compared with SS files after the preparation of narrow canals, indicating their possible benefits when establishing a glide path in extremely narrow canals.

Assessment of Volumetric Distortion Artifact in Filled Root Canals Using Different Cone-beam Computed Tomographic Devices

IntroductionArtifacts in cone-beam computed tomographic (CBCT) imaging may compromise radiodiagnosis. Obturation materials for endodontic treatment may present with variable material density and thus also cause distinct artifact expression. The aim of this study was to assess the volume distortion artifact of root canal sealers using CBCT devices and micro-CT imaging as a reference. MethodsThirty single-root mandibular central incisors were used for this study. Teeth were prepared with EndoSequence rotary nickel-titanium files (Brasseler USA, Savannah, GA) and divided into 3 groups. Canals were obturated with gutta-percha and AH Plus root canal sealer (Dentsply Maillefer, Ballaigues, Switzerland) using single-cone filling techniques. Each tooth was scanned with different CBCT devices (ie, Promax 3D Max [Planmeca Inc, Roselle, IL], NewTom VGi evo [NewTom, Verona, Italy], and 3D Accuitomo 170 [J Morita, Kyoto, Japan]) with the same voxel size (0.2 mm3) and compared with micro-CT imaging as a reference standard. ResultsThe results showed a significant difference in terms of volume distortion between micro-CT and CBCT images (P < .05). There were also significant differences among CBCT devices. Promax 3D Max measurements showed significantly larger root canal volumes than the other CBCT machines (P < .05). However, NewTom VGi evo and 3D Accuitomo 170 showed similar results without any significant difference (P > .05). ConclusionsCBCT devices showed more volumetric distortion artifact than micro-CT imaging. The volume was variable for different CBCT devices while scanning at the same voxel size. However, to assess the effect of sealer materials on CBCT imaging, further studies should be conducted for different sealers.

Evaluation of Dentinal Crack Initiation after Root Canal Preparation Using three Different Nickel Titanium Rotary Instrument: An In Vitro Study

Evaluation of Dentinal Crack Initiation after Root Canal Preparation Using three Different Nickel Titanium Rotary Instrument: An <i>In Vitro</i> Study

EVALUATION OF ANTIBACTERIAL EFFECT OF DIODE LASER 980 NM, ENDOVAC AND PASSIVE ULTRASONIC IRRIGATION DURING FINAL IRRIGATION

Aim: The purpose of this study is to evaluate the antibacterial effect of Diode laser 980 nm, EndoVac and passive ultrasonic irrigation ex vivo. Methods: One hundred and five maxillary central incisors were standardized to 15mm in length. All samples were prepared using Protaper Universal rotary nickel titanium system till size # F4 then contaminated with E. faecalis. The irrigation protocol used was 2.5% sodium hypochlorite followed by 17% EDTA. Samples were randomly divided into 5 groups (n= 20) according to the irrigant activation method. LAI group, Diode laser 980nm. API group, EndoVac system. PUI group, passive ultrasonic activation. The positive control group, in which the irrigating solution was not activated and the negative control group in which the samples were not subjected to irrigation or activation. Residual bacteria were collected with sterile paper point, plated onto BHI media and incubated (37 °C, 48 h) to determine the colony-forming units (CFU mL-1). Data were analyzed using one-way ANOVA followed by performance of Tukey post hoc tests. Significance was set at p < 0.05. Scanning electron microscopy was used to investigate the changes in biofilm. Results: There was a statistically significant reduction in the mean numbers of colony-forming units among all groups. However, none of the activation methods was able to kill E. faecalis biofilm completely. The LAI group behaved most effectively among all groups.Conclusion: The adjunctive use of 980nm laser is an effective method for bacterial reduction after chemo-mechanical instrumentation of the root canal.

Root Canal Transportation and Centering Ability of Nickel-Titanium Rotary Instruments in Mandibular Premolars Assessed Using Cone-Beam Computed Tomography.

Introduction:The aim of this study was to evaluate, using cone-beam computed tomography (CBCT), transportation and centralization of different nickel-titanium (NiTi) rotary instruments.Methods: One hundred and twenty eight mandibular premolars were selected and instrumented using the following brands of NiTi files: WaveOne, WaveOne Gold, Reciproc, ProTaper Next, ProTaper Gold, Mtwo, BioRaCe and RaCe. CBCT imaging was performed before and after root canal preparation to obtain measurements of mesial and distal dentin walls and calculations of root canal transportation and centralization. A normal distribution of data was confirmed by the Kolmogorov-Smirnov and Levene tests, and results were assessed using the Kruskal-Wallis test. Statistical significance was set at 5%. Results:ProTaper Gold produced the lowest canal transportation values, and RaCe, the highest. ProTaper Gold files also showed the highest values for centering ability, whereas BioRaCe showed the lowest. No significant differences were found across the different instruments in terms of canal transportation and centering ability (P > 0.05).Conclusion: Based on the methodology employed, all instruments used for root canal preparation of mandibular premolars performed similarly with regard to canal transportation and centering ability.

Glide Path Enlargement of Mandibular Molar Canals by Using K-files, the ProGlider File, and G-Files: A Comparative Study of the Preparation Times

IntroductionThe preparation of a glide path before the introduction of rotary nickel-titanium instruments is a standard adjunct to ensure increased safety during root canal preparation. The aim of this study was to compare the mean preparation time of manual instrumentation with K-files, G-Files, and the ProGlider instrument to prepare a glide path in curved root canals. MethodsThe mesial canals of 90 mandibular molars (with curvature angles between 25° and 35°) were selected. The specimens were randomly divided into 3 groups with 30 canals each, and canal preparations were performed by an endodontist who used #10-15-20 stainless steel manual K-files (group KF), #10 stainless steel manual K-file followed by #12-17 G-File instruments (group GF), and #10 stainless steel manual K-file followed by #16 ProGlider instrument (group PG). The total time it took to prepare the glide paths was recorded with an electronic stopwatch. New instruments were used for each canal. ResultsGlide path enlargement with the PG group (27.9 ± 8.6 seconds) and GF group (41.9 ± 20.1 seconds) was shown to be statistically significantly faster than stainless steel KF group (74.9 ± 24.1 seconds) by using analysis of variance (P < .05). There was no statistically significant difference observed between the mean preparation times of the PG and GF groups (P < .05). ConclusionsGlide path preparation times with the rotary instrument groups were significantly faster than with stainless steel manual K-files.

Evaluation of surface characteristics of rotary nickel-titanium instruments produced by different manufacturing methods.

Instrument fracture is a serious concern in endodontic practice. The aim of this study was to investigate the surface quality of new and used rotary nickel-titanium (NiTi) instruments manufactured by the traditional grinding process and twisting methods. Total 16 instruments of two rotary NiTi systems were used in this study. Eight Twisted Files (TF) (SybronEndo, Orange, CA, USA) and 8 Mtwo (VDW, Munich, Germany) instruments were evaluated. New and used of 4 experimental groups were evaluated using an atomic force microscopy (AFM). New and used instruments were analyzed on 3 points along a 3 mm. section at the tip of the instrument. Quantitative measurements according to the topographical deviations were recorded. The data were statistically analyzed with paired samples t-test and independent samples t-test. Mean root mean square (RMS) values for new and used TF 25.06 files were 10.70 ± 2.80 nm and 21.58 ± 6.42 nm, respectively, and the difference between them was statistically significant (P < 0.05). Mean RMS values for new and used Mtwo 25.06 files were 24.16 ± 9.30 nm and 39.15 ± 16.20 nm respectively, the difference between them also was statistically significant (P < 0.05). According to the AFM analysis, instruments produced by twisting method (TF 25.06) had better surface quality than the instruments produced by traditional grinding process (Mtwo 25.06 files).

Comparison of canal transportation and centering ability of Twisted Files, HyFlex controlled memory, and Wave One using computed tomography scan: An in vitro study.

Aim:The aim of the present study was to compare the canal transportation and centering ability of three rotary nickel-titanium (NiTi) systems (Twisted Files [TF], HyFlex controlled memory [CM], and Wave One [WO]) in curved root canals using computed tomography (CT).Materials and Methods:Sixty freshly extracted single-rooted teeth having curved root canals with at least 25–35 degrees of curvature were selected. The teeth were randomly divided into three experimental groups of twenty each. After preparation with TF, HyFlex CM, and WO, all teeth were scanned using CT to determine the root canal shape. Pre- and post-instrumentation images were obtained at three levels, 3 mm apical, 9 mm middle, and 15 mm coronal above the apical foramen were compared using CT software. Amount of transportation and centering ability were assessed. The three groups were statistically compared with analysis of variance and post hoc Tukey's honestly significant difference test.Results:Least apical transportation and higher centering ability were seen in HyFlex CM file system in all the three sections followed by TF. WO file system showed maximum transportation.Conclusions:The canal preparation with HyFlex CM file system showed lesser transportation and better centering ability than TF, WO file system.

Fracture of rotary nickel titanium instruments

With the advent of rotary nickel titanium (NiTi) instruments, preparation of curved canals have become easy but chances of instrument separation have increased. Such an instrument separation can cause procedural problems in rendering endodontic therapy. There are various factors that cause separation of rotary NiTi instruments. These factors, various failure mechanisms and impact on the prognosis of instrument separation have to be well understood by the clinician.

Comparison of resistance to cyclic fatigue between two rotary nickel titanium systems

Comparison of resistance to cyclic fatigue between two rotary nickel titanium systems

Effect of Deep Cryogenic Treatment on Cyclic Fatigue of Endodontic Rotary Nickel Titanium Instruments.

Introduction:Cyclic fatigue is the common reason for breakage of rotary instruments. This study was conducted to evaluate the effect of cryogenic treatment (CT) in improving the resistance to cyclic fatigue of endodontic rotary instruments. Methods and Materials:In this in vitro study, 20 RaCe and 20 Mtwo files were randomly divided into two groups of negative control and CT. CT files were stored in liquid nitrogen at -196°C for 24 h, and then were gradually warmed to the room temperature. All files were used (at torques and speeds recommended by their manufacturers) in a simulated canal with a 45° curvature until breakage. The time to fail (TF) was recorded and used to calculate the number of cycle to fail (NCF). Groups were compared using independent-samples t-test. Results:Mean NCFs were 1248.2±68.1, 1281.6±78.6, 4126.0±179.2, and 4175.4±190.1 cycles, for the Mtwo-control, Mtwo-CT, RaCe-control, and RaCe-CT, respectively. The difference between the controls and their respective CT groups were not significant (P>0.3). The difference between the systems was significant. Conclusion:Deep CT did not improve resistance to cyclic fatigue of the evaluated rotary files.