Continuous Rotation Motion Research Articles

Incidence and Intensity of Pain Following Endodontic Treatment by Different Instrumentation Techniques in Teeth With Periapical Lesion.

This study was carried out to compare the effectiveness of hand and rotary instrumentation techniques on postoperative pain in asymptomatic necrotic premolars with periapical lesions and instrumented by a modified step-back technique using a K file, crown down by continuous rotary motion technique using ProTaper Universal (Dentsply Mailefer, Ballaigues, Switzerland), and with the reciprocation technique using WaveOne (Dentsply Sirona, Charlotte, NC, USA). For this study, 66 premolars with single roots and canals were chosen. The procedure was completed in a single visit. Following access opening, the working length was initially determined using an apex locator and then confirmed after inserting K file #10 by radiograph. The canal was cleaned and shaped using a grouping system. After the masterapical preparation, the canal was dried by paper point and obturated with gutta-percha and AH plus sealer, an epoxide-amine resin pulp canal sealer. In order to confirm the obturation, a radiograph was taken. After that, a permanentrestoration material was used to seal the access cavity. Following that, patients to whom the visual analog scale (VAS) had already been explained were contacted by phone at six, 12, 24, and 48 hours. In this study, compared to a stainless steel instrumentation technique, WaveOne instrumentation caused more noticeable pain. The results of the current study showed that, on average, postoperative pain scores decreased over the course of the 12to 48-hour period, reaching a minimum or a maximum at 48 hours (p<0.01). Postoperative pain was produced by all instrumentation methods used in the study. In comparison to ProTaper and WaveOne, instrumentation using the modified step-back technique with K files caused less pain, especially over the course of a 24-hour period.

On the flow dynamics of wall-mounted low-aspect-ratio rotating cylinders

The flow physics and vortical features attributed to a low-aspect-ratio circular cylinder cantilevered on a laminar boundary layer plate and rotated about its respective axial coordinate were investigated experimentally using Stereo Particle Image Velocimetry. The investigation documents the three-dimensional spatial evolution of on-body dynamics to deep-wake phenomena. In disseminating the more salient global characteristics of the resultant flowfield, the analysis focuses on the particular case of an aspect ratio of 1 driven in continuous rotary motion at a speed ratio of 3. The two key findings are (i) vortex source: a wall-normal swirl develops and reorients into a streamwise vortex at the cylinder's mid-diameter location due to the heavy influence of the incoming boundary layer, local fluid entrainment, and proximity to the wall. (ii) Enhanced downwash: in return, the streamwise vortex primarily drives the production of additional downwash in the wake, which appends to the downwash generated by the cylinder's free end. A two-dimensional planar particle image velocimetry campaign in service of a parametric survey reveals the sensitivity of streamwise vortex production and downwash to rotational rate and cylinder height relative to boundary layer thickness. The streamwise vortex production tends to deteriorate when the cylinder is immersed in the boundary layer due to reduced downwash.

The Effects of Two Instrumentation Techniques for VDW.Rotate Instruments on the Apical Extrusion of Debris and Irrigants: An In Vitro Study

Objectives: This study compared the amount of apically extruded debris and irrigant using VDW.ROTATE instruments with different kinematics (continuous rotation and reciprocation motion) and the ProTaper Gold system. Methods: Sixty extracted mandibular premolar teeth were selected. The teeth were prepared for the agar gel model. The roots were randomly divided into three groups (n=20). In two groups, the root canals were instrumented using the following movement kinematics: VDW.ROTATE reciprocation motion and continuous rotation. In the other group, root canals were prepared with ProTaper Gold. Apically extruded debris and irrigant during instrumentation were collected into preweighed Eppendorf tubes and were assessed with an electronic balance. All procedures were performed in a 35oC hot water bath. The data were analyzed using the Shapiro–Wilk and Kruskal–Wallis tests at a 5% significance level. Results: ROTATE-Reciprocation extruded the least amount of debris, but this finding was not significant when compared with the amount of debris and irrigant extruded by the ProTaper Gold and ROTATE-Rotation (p&gt;.05). Conclusion: All instrumentation kinematics were associated with apical debris and irrigant extrusion. Movement kinematics did not affect the amount of apically extruded debris and irrigants when using VDW.ROTATE instruments.

Effect of Sodium Hypochlorite Irrigation with and Without Surfactant on Maximum Operative Torque and Vertical Force of Nickel-Titanium Endodontic Instruments.

ObjectivesThis study aimed to evaluate the effects of root canal irrigation on maximum operative torque and vertical force of Wave One Gold Primary (WOG), Reciproc Blue R25 (RB) and Protaper Next X2 (PTN) endodontic rotary instruments during simulated root canal preparation in the presence and absence of a surfactant “benzalkonium chloride”.Material and MethodsA custom-made automated irrigation and torque/force analyzing device connected with endomotor was used for the study. Acrylic resin blocks with simulated curved root canals of 35° were randomly assigned to 6 groups for each file. The following irrigants were used during simulated root canal preparation with continuous rotation or reciprocation motion with pecking mode: 5% NaOCl and 5% NaOCl with 0.84% benzalkonium chloride. Maximum torque and vertical force values ​​of files were recorded during preparation.ResultsBAC addition to NaOCl did not significantly affect maximum torque values of instruments (p>0.05). WOG generated lowest torque value compared with PTN and RCB in both groups (p<0. 05). RB generated higher vertical force compared with WOG and PTN instruments in NaOCl+BAC group. The surface modifier decreased the maximum force value of WOG instrument (p<0.05).DiscussionSurfactan addition to NaOCl had no negative effects on maximum torque and force of the instruments.

Construction and Evaluation of a Vertical Motorized Feed Mixer

In order to reduce the overall cost of poultry production by small scale farmers, a motorized feed mixer was modified, fabricated and evaluated. The mixer consists of an outer drum, an inner mixing chamber and an auger. All these components were vertically oriented for mixing operation. There was a hopper located at the base of the mixer for loading the materials and a chute for the discharging of mixed products. It was modified to work through a central rotating auger fixed on a shaft that carries a pulley of diameter 185 mm. The rotational motion was transmitted from a motor through a V-belt to the pulley shaft. A 5-0 hp electric motor with 1440 rpm was used to drive the machine. Mixing was achieved as the auger conveyed the feed materials from the bottom to the top, in a continuous rotational motion. The mixer was evaluated using a whole corn kernel (WCK) at 15.35 % (d.b) and small pieces of coloured paper (CP) of 5x5 mm² as tracers in ground maize as base materials. The auger pitch was reduced from 90.0 mm to 85.0 mm to increase the number of pitches from 10 to 12. This modification increased the throughput capacity of the mixer from 50.0 kg to 70.0 kg. The mixed material was delivered through the delivery chute after mixing. Mixing time values evaluated were 2.0, 4.0, 6.0, 8.0 and 10.0 mins. The test results showed that maximum mixing occurred at 6.0 mins for coloured paper and 8.0 mins for whole kernel corn.

Patient discomfort levels during instrumentation procedure using nickel-titanium files with different kinetic movements.

This study evaluated the perceived vibration, noise and discomfort levels associated with two nickel-titanium file systems with different kinetics; reciprocating motion (REC) using WaveOne Gold and continuous rotation motion (CON) using ProTaper NEXT. Forty roots with two canals from maxillary premolar and molar of 40 patients were included. Root canals were instrumented using each system for each canal. Patients were surveyed about the vibration, noise and discomfort experienced using visual analogue scale, and their preference. The responses were statistically analysed using Wilcoxon Signed-Rank test, Mann-Whitney U test and Spearman's rank correlation test at the 95% of significance level. The vibration, noise and discomfort experienced were significantly greater in REC than CON (P < 0.05). In REC, male subjects reported significantly higher vibration than female (P < 0.05). Majority respondents (72.5%) preferred the CON method. The perceived vibration, noise and discomfort were less apparent from the CON than the REC.

Retreatment of Experimental Carrier-Based Obturators with the Remover NiTi Instrument: Evaluation of Apical Extrusion and Effects of New Kinematics.

The objective of this study is to evaluate the retreatment time and weight of apically extruded debris yielded by two different kinematics during the removal of different root canal filling materials. Forty straight single-rooted extracted teeth were instrumented with HyFlex CM files and obturated with two different techniques: 25.04 HyFlex experimental carrier-based obturators (Coltène/Whaledent, Altstätten, Switzerland) (group 1) or 25.04 single gutta-percha cones (Roeko Coltène/Whaledent, Altstätten, Switzerland) (group 2) and Guttaflow Bioseal as the sealer. Samples were divided into four subgroups (n = 10) according to the used kinematics for the removal of root canal filling materials: continuous rotation (A) or retreatment motion (B) with a Remover and HyFlex EDM Nickel-Titanium instruments activated with a CanalPro Jeni micromotor (Coltène/Whaledent, Altstätten, Switzerland). Time for retreatment was digitally recorded, and debris extruded from the apex was collected in Eppendorf tubes and weighted with an analytical balance. Data on retreatment time and apical extrusion were statistically analyzed with the Kruskal–Wallis test (p < 0.05). Working length was achieved in all the retreated samples. The removal of root filling material resulted significantly faster with the Jeni mode (p < 0.001), and the difference was significant for the removal of both filling materials (p < 0.05). No significant differences on debris extrusion between single cone and experimental obturators groups were noted (p > 0.05), and no significant differences between kinematics (continuous rotation vs. Jeni motion) were observed (p > 0.05). All the tested retreatment strategies lead to an extrusion of material from the apex, and the weight of apically extruded debris was similar. The use of the innovative CanalPro Jeni kinematics accelerates the time for the removal of root filling materials.

Continuous rotational motion in birefringent particles using two near-orthogonally polarized optical tweezers beams at different wavelengths with low ellipticity

Continuous yaw (in-plane) rotation of an optically trapped birefringent particle is conventionally achieved by illuminating with light of high ellipticity. This ellipticity has to be high enough to make the tilt of the washboard potential bypass the confining effect of the corrugation. Here by using a novel technique, we generate continuous rotations of a 3 µm sized spherical birefringent particle with ellipticity lower than that permissible with a single optical tweezers beam. We use two lasers, near-orthogonally polarized, with similar intensities at wavelengths of 1064 and 975 nm to obtain continuous rotations, just by making one of the beams elliptically polarized, but well lower than that permissible by the washboard potential. The maximum rotation frequency we achieve with the present configuration is 5 Hz which can be increased by simultaneously increasing the two laser intensities.

Failure Analysis of the Short Drive Shaft in a Screw Press Machine

The screw press is a type of machine press used for extracting crude palm oil from the oil palm’s mesocarp, where its short driveshaft, a mechanical component for transmitting torque and rotation, is often found to be susceptible to failure. Since the initial damage to the short driveshafts in the shaft keyway area is associated with the frequent incidence of shaft failure, this research aimed to discover the root cause of this failure and how to prevent it using visual inspection and stress analysis methods as well as those of the fractography, metallography, chemical composition, and hardness tests. Using the descriptive method to analyse the collected data, the visual inspection and the fractography results of the research indicated that the fatigue crack failure of the short drive shaft in the palm oil screw press machine was caused by the fatigue crack initiation that was safe from stress concentration in its keyway areas. This crack initiation was followed by crack propagation as indicated in beach mark forms. Finally, the ductile fracture observed on the shaft surface was found to have resulted from the continuous rotational motion and the loading and unloading effect of the central shaft driving system.

Influence of rotational speed on torque/force generation and shaping ability during root canal instrumentation of extracted teeth with continuous rotation and optimum torque reverse motion.

To evaluate how different rotational speeds affect the torque/force generation and shaping ability of rotary root canal instrumentation using JIZAI (MANI, Utsunomiya, Japan) nickel-titanium instruments in continuous rotation and optimum torque reverse (OTR) motion. Mesial root canals of extracted mandibular molars were instrumented up to size 25, 0.04 taper using JIZAI instruments, and anatomically matched canals were selected based on geometric features of the canal [canal volume (mm3 ), surface area (mm2 ), length, 15°-20° curvature and radius of curvature (4-8mm)] after micro-computed tomographic scanning. An automated root canal instrumentation and torque/force analysing device was programmed to permit a simulated pecking motion (2s downward and 1s upward at 50mmmin-1 ). The selected canals were prepared with size 25, 0.06 taper JIZAI instruments using continuous rotation or OTR motion and further subdivided according to the rotational speed (300 or 500rpm, n=10 each). Real-time clockwise/counterclockwise torque and downward/upward force were recorded using a custom-made torque/force analysing device. Then, the registered pre- and post-operative micro-computed tomographic datasets were examined to evaluate the canal volume changes and centring ratios at 1, 3, 5 and 7mm from the apical foramen. Data were analysed using two-way analysis of variance or the Kruskal-Wallis test and Mann-Whitney U test with Bonferroni correction (α=5%). Maximum upward force and clockwise torque were significantly smaller in 500rpm groups than in 300rpm groups (P<.05); however, no significant difference was found between continuous rotation and OTR motion (P>.05). OTR motion developed higher maximum counterclockwise torque than continuous rotation (P<.05). Maximum downward force, canal volume changes and centring ratios were not significantly different among all groups (P>.05). There was no file fracture in any of the groups. Under laboratory conditions using JIZAI instruments, a rotational speed of 500rpm generated significantly lower maximum screw-in forces and torque values than rotational speed of 300rpm. Continuous rotation and OTR motion performed similarly in shaping the canals.

Optimum glide path motion is safer than continuous rotation of files in glide path preparation

This study evaluated the resistance to flexural fatigue and torsional strength of files for glide path preparation in continuous rotation or Optimum Glide Path motion (OGP). ScoutRace 15.02 and ProGlider 16.02 files were used in a dynamic testing device during preparation of simulating curved root canals (40-degree curvature and 5mm radius). For the torsional test, a machine was used to test torsion measured maximum torsional strength (N.cm). Two-way anova and Tukey's multiple comparisons test were used for statistical analysis. Files in OGP motion had a statistically better resistance to flexural fatigue (P<0.05). ProGlider files took longer time to failure than ScoutRace files only when OGP was used (P<0.05). The torsional test revealed that OGP produced significantly less torsional stress than rotary motions for both types of glide path files (P<0.05) In conclusion, OGP motion increased substantially the mechanical safety of endodontic glide path files.

Root Microcracks Formation during Root Canal Instrumentation Using Reciprocating and Rotary Files

The aim of this study was to compare the formation of dentinal cracks with nickel-titanium (NiTi) instruments working in continuous rotation and reciprocating motion. One hundred sixty extracted human mandibular first molars were selected for the study. The mesial roots were resected and mounted in resin blocks with simulated periodontal ligaments. Those teeth were randomly assigned to five groups (n = 32 teeth/group). The first one was treated with K-files and served as control group, and the remaining 128 teeth were divided into 4 groups depending on the root canal preparation technique. Group 2 samples were prepared by sequential ProTaper Universal (PTU), group 3 samples with rotary ProTaper Universal (RPTU), group 4 achieved by the One Shape (OS), and group 5 with the WaveOne (WO) primary files. Roots were then horizontally sectioned at 3, 6, and 9 mm from the apex, and the slices were then observed under a stereomicroscope at ×40 magnification to determine the presence of internal dentinal microcracks. The presence or absence of dentinal defaults was recorded and the statistical analysis was performed by Pearson Chi-square test. The significance level was set at p < 0.05. The study was made in the oral biology and biotechnology research laboratory of the faculty of medical dentistry of Rabat, Morocco. No dentinal defect was seen with the stainless steel hand file (group 1). The manual PTU (group 2), the RPTU (group 3), the OS (group 4), and the WO (group 5) in reciprocating motion caused cracks in 15.6%, 12.4%, 21.9%, and 6.2% of samples, respectively. The highest percentage of dentinal defect was showed in group 4 but without significant difference with the other group (p > 0.05). Dentinal cracks are produced indifferently of motion kinematics. Within the limits of this study and the current literature, such incidence is less with instruments working in reciprocating motion compared with those working in continuous rotation. Manual and rotary NiTi sequential systems showed fewer microcracks than the single file system working by continuous rotation motion.

INCIDENCE OF DENTINAL DEFECTS AFTER ROOT CANAL PREPARATION USING HYFLEX EDM and MPRO FILES

INTRODUCTION: The use of motor-driven nickel-titanium (Ni-Ti) files in root canal preparation have numerous advantages. However, it might lead to dentinal crack formation which greatly affects the endodontic treatment prognosis. Therefore, new Ni-Ti files are developed with different heat treatments to enhance file flexibility, thus reduce stress concentration during root canal preparation. AIM OF THE STUDY: To compare the incidence of dentinal defects produced by two motor-driven Ni-Ti systems; Hyflex EDM and MPro files using stereomicroscopic analysis. MATERIALS AND METHODS: This study was conducted on thirty mesio-buccal root canals of human mandibular molars. All teeth were examined under a stereomicroscope to exclude any dentinal defects before instrumentation followed by decoronation and sectioning of distal roots. The root canals were randomly divided into three equal groups according to the file system used. Group I: Hyflex EDM files with continuous rotation motion. Group II: MPro files with continuous rotation motion, ending the preparation till tip size 25 in both groups. Group III: unprepared canals (negative control). All roots were sectioned at 3, 6, 9 mm from the apex using a precision cutter device. Stereomicroscope analysis was performed in all sections. Data were statistically analyzed. RESULTS: All groups (including the control group) showed no dentinal defects with no statistically significant differences between the test groups and the control group at all levels. CONCLUSIONS: The new generations of heat-treated rotary files could produce root canal preparation with less dentinal defects owing to their enhanced physical and mechanical properties.

Comparison of Torque, Screw-in Force, and Shaping Ability of Glide Path Instruments in Continuous Rotation and Optimum Glide Path Motion

IntroductionThis study aimed to analyze torque/force generation and transportation in double-curved canals instrumented with 3 types of glide path files using optimum glide path (OGP) motion in comparison with continuous rotation. MethodsSixty simulated double-curved canals were prepared with #10/0.05 or #15/0.03 HyFlex EDM Glidepath files (Coltene/Whaledent, Altstätten, Switzerland) or a #13/0.04 prototype MANI Glidepath file (Tochigi, Japan) using OGP motion or continuous rotation (n = 10 each). Canals were sequentially prepared to 20 mm and 22 mm (full working length) using automated root canal instrumentation and a torque/force analyzing device. Transportation was calculated at 1–9 mm from the apex. Data were compared using 2-way analysis of variance followed by a post hoc simple main effect test with Bonferroni correction and a Kruskal-Wallis test (α = 5%). ResultsAll #10/0.05 instruments fractured. In the 22-mm preparation, the OGP motion resulted in lower clockwise torque and screw-in force than did continuous rotation (P < .05). In the 20-mm preparation, #15/0.03 instruments recorded a lower screw-in force for OGP motion than for continuous rotation (P < .05). Comparing the 2 preparation phases, OGP motion generated no significant differences; however, continuous rotation developed higher clockwise torque and screw-in force in the 22-mm preparation than in the 20-mm preparation (P < .05). There was no significant difference among the tested groups for transportation values. ConclusionsCompared with continuous rotation, OGP motion generated less screw-in force, lower clockwise torque, and similar transportation. The #15/0.03 HyFlex EDM instrument and the #13/0.04 prototype MANI instrument performed similarly well.

Assessment of cyclic fatigue resistance of Protaper Next and WaveOne Gold in different kinematics

BackgroundThe purpose of the current study was to inspect and compare the influence of applying continuous rotation and reciprocation motions on the cyclic fatigue resistance of Protaper Next (PTN) file (X2) and WaveOne Gold (WOG) Primary file in simulated canals. Twenty Protaper Next files(X2) and 20 WaveOne Gold Primary files were included in this study. A cyclic fatigue testing device was employed to test the cyclic resistance of each file in different motions. The testing device has an artificial custom-made stainless-steel canal with a 60° angle of curvature and a 2-mm radius of curvature. The files were randomly divided into 4 groups; group 1: PTN in continuous rotation, group 2: PTN in reciprocation, group 3: WOG in continuous rotation and group 4: WOG in reciprocation. All the instruments were rotated until fracture occurred, and the time to fracture was recorded in seconds using a digital chronometer. The number of cycles to fracture (NCF) was calculated. The data were analyzed statistically (p < .05).ResultsResults represented that when using either continuous rotation motion or reciprocating motion, WOG files showed a significantly longer time until failure than PTN files (p < 0.001). The time till fracture increased significantly, when using both types of files with a reciprocating filing motion.ConclusionWithin the confinement of this study, WOG file in reciprocation showed higher cyclic fatigue resistance than PTN in both continuous rotation and reciprocating motion. The reciprocating motion enhances both files behavior in terms of cyclic fatigue resistance.

Effect of different kinematics and operational temperature on cyclic fatigue resistance of rotary NiTi systems

BackgroundThe aim of this study was to compare the effect of different kinematics and operational temperature on cyclic fatigue resistance of Protaper Next, WaveOne Gold, and Twisted File Adaptive files in a static model.MethodologyAn artificial canal, made of stainless steel with an inner diameter of 1.5 mm, a 60° angle of curvature, and a curvature radius of 2 mm, was used for the cyclic fatigue test immersed in a water bath for temperature adjustment (37 °C and 20 °C). A total of 120 files were divided into three groups according to the type of motion continuous rotation motion (CRM), adaptive motion (AM), and reciprocation motion (RM). Each group was further subdivided into two subgroups according to the operational temperature (37 °C and 20 °C), All instruments were operated until fracture occurred, and the time to fracture was recorded in seconds. Mean number of cycles to failure and standard deviations were calculated for each group, and data were analyzed statistically using two-way ANOVA followed by Tukey’s post hoc test (P ≤ 0.05).ResultsThe continuous rotation motion exhibited significantly lower cyclic fatigue resistance than reciprocating or adaptive motion (p ≤ 0.001) at 37 °C and 20 °C.ConclusionsCyclic fatigue resistance of NiTi files was affected by the motion used during root canal preparation. Reciprocation motion and adaptive motion resulted in extended fatigue. The operational temperature affects the cyclic fatigue resistance of the twisted file.

Ex-Vivo Comparison of Torsional Stress on Nickel-Titanium Instruments Activated by Continuous Rotation or Adaptive Motion.

This study aimed to evaluate the effect of adaptive motion applied to conventional nickel-titanium (NiTi) rotary instruments on torsional stress generation during shaping procedure. One hundred and twenty mesio-buccal canals of molars were randomly assigned to two groups according to the kinetics; adaptive motion (AD) and continuous rotation (CR). Each group was divided into four subgroups (n = 15) according to the NiTi instrument systems: HyFlex EDM, One Curve, Twisted File Adaptive, and ProTaper Next. A glide path was established with PathFile #1, for each file group being used with either of the kinetic movements. During the instrumentation with the designated motion and file system, the generated torque was measured via the control unit and acquisition module. Based on the acquired data, the maximum and total torque were calculated. The data were statistically analyzed using Kruskal–Wallis and Mann–Whitney tests at a significance level of 95%. The maximum and total torque generated by all instruments were significantly reduced by the adaptive motion (p < 0.05). In the CR group, HyFlex EDM generated the highest maximum and total stress. In the AD group, HyFlex EDM showed the highest maximum torsional stress, and One Curve showed the highest total torsional stress (p < 0.05). The TF Adaptive instrument with adaptive movement produced the lowest maximum and total torsional stress (p < 0.05). Under the conditions of this study, the use of adaptive motion would be useful to reduce the torsional stress of instrument and root dentin. The reduction of torsional stress through adaptive motion may enhance the durability of instruments and reduce the potential risk of dentinal cracks.

Apical Debris Extrusion and Root Canal Cleanliness Using Several Rotary Nickel Titanium Files with Different Kinematics In Round and Oval Canals.

Aim: this study was conducted to evaluate and compare the amount of apically extruded debris and canal wall cleanliness using different Ni-Ti instruments (ProTaper file F2, Twisted File 25 and Reciproc R 25) used in continuous rotation and reciprocating motion, in round and oval root canals. Materials and methods: One hundred twenty extracted single rooted teeth were divided into two groups according to the cross section; 60 round and 60 oval cross section. Each group was subdivided into three subgroups according to the file system (20 ProTaper, 20 Twisted File and 20 Reciproc). Each subgroup was further divided into two divisions according to the motion used (10 rotation and 10 reciprocation). Teeth were mounted in glass vials through holes in the rubber stoppers. The glass vials were weighed before instrumentation. Root canal preparation was performed according to its assigned system according to the manufacturer's instructions, and distilled water was used as root canal irrigant. After instrumentation, the amount of apically extruded debris was evaluated by weighing the samples on the microbalance. Thereafter, roots were longitudinally divided for evaluation of smear layer by Scanning Electron Microscope SEM. The data were tabulated and subjected to statistical analysis. Results: Reciprocating motion extruded more debris than continuous rotation motion. SEM examination revealed greater amount of smear layer in the oval cross section canal than round cross section canal.

Droplet‐Based Self‐Propelled Miniboat

AbstractSelf‐propelled autonomous devices have huge application prospects in the field of environmental protection and energy. Nonetheless, the requirement of special chemicals or external electric and thermal energy limits their practical application. Here, a green self‐propelling method based on Laplace pressure originated from water droplets is reported. First, a triangle‐shaped miniboat composed of a superhydrophobic plate with an inclined superhydrophilic pore is fabricated. Water droplets put on superhydrophilic pore pass through the pore and form a jellyfish‐like jet, which further propels the miniboat to move spontaneously and directionally. The propelling distance, propelling time, and instantaneous propelling velocity of the miniboat is greatly affected by the pore size and the initial water droplet volume. Then, two types of devices are designed and installed on the miniboat to successively provide small water droplets from the reservoir or rain to realize the continuous and long‐distance self‐propelled motion. Moreover, a spindle‐shaped miniboat with two or four symmetrical and inclined pores is designed. Under propelling by the torque, the spontaneous and continuous rotation motion is also achieved. This finding will open a new avenue for a wide range of applications ranging from a detecting minirobot on the water surface to a power generation device from rain.

Influence of glide path size and operating kinetics on time to reach working length and fracture resistance of Twisted File adaptive and Endostar E3 nickel-titanium file systems.

ObjectivesThis study investigated the influence of glide path size and operating kinetics on the time to reach the working length and the fracture resistance of Twisted File (TF) and Endostar E3 files.Materials and MethodsA total of 120 mandibular single-rooted premolars were selected. Two methods of kinetic motion (TF adaptive and continuous rotary motion) and file systems (TF and Endostar E3) were employed. The files were used in root canals prepared to apical glide path sizes of 15, 20, and 25. The time taken to reach the working length and the number of canals used before the instrument deformed or fractured were noted. Fractured instruments were examined with scanning electron microscopy.ResultsThe TF system took significantly more time to reach the working length than the Endostar E3 system. Both systems required significantly more time to reach the working length at the size 15 glide path than at sizes 20 and 25. A greater number of TFs than Endostar E3 files exhibited deformation, and a higher incidence of instrument deformation was observed in adaptive than in continuous rotary motion; more deformation was also observed with the size 15 glide path. One TF was fractured while undergoing adaptive motion.ConclusionsNo significant difference was observed between continuous rotary and adaptive motion. The TF system and adaptive motion were associated with a higher incidence of deformation and fracture. Apical glide path sizes of 20 and 25 required significantly less time to reach the working length than size 15.