Energy Consumption of ProTaper Next X1 after Glide Path with PathFiles and ProGlider

Introduction

Instrument failure caused by excessive torsional stress can be controlled by creating a manual or mechanical glide path. The ProGlider single-file system (Dentsply Maillefer, Ballaigues, Switzerland) was recently introduced to perform a mechanical glide path. This study was designed to compare the effect of a glide path performed with PathFiles (Dentsply Maillefer) and ProGlider on torque, time, and pecking motion required for ProTaper Next X1 (Dentsply Maillefer) to reach the full working length in simulated root canals.

Methods

Forty Endo Training Blocks (Dentsply Maillefer) were used. Twenty were prepared with a mechanical glide path using PathFiles 1 and 2 (the PathFile group), and 20 were prepared with a mechanical glide path using a ProGlider single file (the ProGlider group). All samples were shaped with ProTaper Next X1 driven by an endodontic motor connected to a digital wattmeter. The required torque for root canal instrumentation was analyzed by evaluating the electrical power consumption of the endodontic engine. Electric power consumption (mW/h), elapsed time (seconds), and number of pecking motions required to reach the full working length with ProTaper Next X1 were calculated. Differences among groups were analyzed with the parametric Student t test for independent data (P < .05).

Results

Elapsed time and electric power consumption were significantly different between groups (P = .0001 for both). ProGlider appears to perform more efficiently than PathFiles in decreasing electric power consumption of ProTaper Next X1 to reach the full working length.

Conclusions

This study confirmed the ability of ProGlider to reduce stress in ProTaper Next X1 during shaping through a glide path and preliminary middle and coronal preflaring.     

Evaluation of a New Nickel-Titanium System to Create the Glide Path in Root Canal Preparation of Curved Canals

Introduction

Nickel-titanium rotary instruments recently have been introduced with the purpose of creating an initial glide path. The purpose of this study was to compare the maintenance of canal anatomy, the occurrence of apical transportation, and the working time observed using mechanised instrumentation with the new G-File rotary system (Micro-Mega, Besançon Cedex, France) with those observed using instrumentation with the PathFile system (Dentsply Maillefer, Ballaigues, Switzerland) and manual instrumentation with K-type files (Micro-Mega) to create a glide path in curved root canals.

Methods

The mesial canals of 45 mandibular molars (with curvature angles between 25° and 35°) were selected. The specimens were randomly divided into 3 groups with 15 canals each, and canal preparations were performed by an endodontist using #12-17 G-File rotary instruments (group GF), #13-16-19 PathFile rotary instruments (group PF), and #10-15-20 K-type stainless steel manual files (group M). A digital double radiographic technique was used to determine apical transportation and the change in the angle of curvature. The working time was also calculated.

Results

No statistically significant differences in the angle of canal curvature and apical transportation were found between the groups. However, concerning the working time, specimens from the group who underwent canal preparation using #12-17 G-File rotary instruments achieved significantly lower mean values when compared with the other 2 groups, whereas the group who underwent canal preparation using the #10-15-20 K-type stainless steel manual files had the highest values.

Conclusions

The G-File rotary instruments, the PathFile system, and the manual instruments did not have any influence on the occurrence of apical transportation nor did they produce a change in the angle of canal curvature. The G-File instruments seemed to be the most rapid system in creating a safe glide path.     

Comparative Study of Different Novel Nickel-Titanium Rotary Systems for Root Canal Preparation in Severely Curved Root Canals

Introduction

We compared the effects of 6 different rotary systems on transportation, canal curvature, centering ratio, surface area, and volumetric changes of curved mesial root canals of mandibular molar via cone-beam computed tomographic (CBCT) imaging.

Methods

Mesiobuccal root canals of 120 mandibular first molars with an angle of curvature ranging from 20°–40° were divided into 6 groups of 20 canals. Based on CBCT images taken before instrumentation, the groups were balanced with respect to the angle and radius of canal curvature. Root canals were shaped with the following systems with an apical size of 25: OneShape (OS) (MicroMega, Besancon, France), ProTaper Universal (PU) F2 (Dentsply Maillefer, Ballaigues, Switzerland), ProTaper Next X2 (Dentsply Maillefer), Reciproc (R) R25 (VDW, Munich, Germany), Twisted File Adaptive (TFA) SM2 (SybronEndo, Orange, CA), and WaveOne primary (Dentsply Tulsa Dental Specialties, Tulsa, OK). After root canal preparation, changes were assessed with CBCT imaging. The significance level was set at P = .05.

Results

The R system removed a significantly higher amount of dentin than the OS, PU, and TFA systems (P < .05). There was no significant difference among the 6 groups in transportation, canal curvature, changes of surface area, and centering ratio after instrumentation.

Conclusions

The 6 different file systems straightened root canal curvature similarly and produced similar canal transportation in the preparation of mesial canals of mandibular molars. R instrumentation exhibited superior performance compared with the OS, TFA, and PU systems with respect to volumetric change.     

Incidence of Apical Crack Initiation and Propagation during the Removal of Root Canal Filling Material with ProTaper and Mtwo Rotary Nickel-Titanium Retreatment Instruments and Hand Files

Introduction

The aim of this study was to determine the incidence of crack initiation and propagation in apical root dentin after retreatment procedures performed by using 2 rotary retreatment systems and hand files with additional instrumentation.

Methods

Eighty extracted mandibular premolars with single canals were selected. One millimeter from the apex of each tooth was ground perpendicular to the long axis of the tooth, and the apical surface was polished. Twenty teeth served as the control group, and no preparation was performed. The remaining 60 teeth were prepared to size 35 with rotary files and filled with gutta-percha and AH Plus sealer. Specimens were then divided into 3 groups (n = 20), and retreatment procedures were performed with the following devices and techniques: ProTaper Universal retreatment files, Mtwo retreatment files, and hand files. After retreatment, the additional instrumentation was performed by using size 40 ProTaper, Mtwo, and hand files. Digital images of the apical root surface were recorded before preparation, after instrumentation, after filling, after retreatment, and after additional instrumentation. The images were then inspected for the presence of any new apical cracks and propagation. Data were analyzed with the logistic regression and Fisher exact tests.

Results

All experimental groups caused crack initiation and propagation after use of retreatment instruments. The ProTaper and Mtwo retreatment groups caused greater crack initiation and propagation than the hand instrument group (P < .05) after retreatment. Additional instrumentation with ProTaper and Mtwo instruments after the use of retreatment instruments caused crack initiation and propagation, whereas hand files caused neither crack initiation nor propagation (P < .05).

Conclusions

This study showed that retreatment procedures and additional instrumentation after the use of retreatment files may cause crack initiation and propagation in apical dentin.     

Evaluation of Root Canal Transportation,Centering Ratio,and Remaining Dentin Thickness Associated with ProTaper Next Instruments with and without Glide Path

IntroductionThe purpose of this study was to evaluate and compare the volume of removed dentin, transportation, and centering ability of ProTaper Next (PTN) system with and without glide path preparation by using cone-beam computed tomography (CBCT) imaging.MethodsSixty mesiobuccal canals of mandibular first molars with curvatures of 25°−35° were divided into 3 experimental groups (n = 20) according to the instrumentation technique as follows: group PG/PTN (glide path was created with ProGlider [PG]) and canals were shaped with PTN system), group PF/PTN (glide path was created with PathFile [PF]) and canals were shaped with PTN system), and group PTN (glide path was not performed and canals were shaped with PTN system only). Canals were scanned before and after instrumentation by using CBCT scanner to evaluate root canal transportation and centering ratio at 3, 5, and 7 mm from the apex and volumetric changes. Data were statistically analyzed, and the significance level was set at P < .05.ResultsThere was no significant difference among the tested groups regarding the volume of removed dentin and centering ratio (P > .05). At 3-mm and 5-mm levels, the PG/PTN group showed a significantly lower mean transportation value among the groups (P < .05). However, at 7-mm level, there was no significant difference in canal transportation among the groups (P > .05).ConclusionsPG/PTN instrumentation method revealed better performance with fewer canal aberrations when compared with instrumentation performed with PF/PTN or PTN only.     

Effects of ProTaper Universal,ProTaper Next,and HyFlex Instruments on Crack Formation in Dentin

Introduction

The aim of the present study was to investigate the incidence of cracks in root dentin after root canal preparation with ProTaper Next (Dentsply Maillefer, Ballaigues, Switzerland), HyFlex (Coltene-Whaledent, Allstetten, Switzerland), and ProTaper Universal (Dentsply Maillefer) rotary instruments.

Methods

One-hundred mandibular premolars were selected. Twenty-five teeth were left unprepared and served as a negative control; another 25 teeth were instrumented with the ProTaper Universal system up to size F4 as a positive control, and the remaining 50 teeth were shaped with the following experimental groups with an apical size 40 file: ProTaper Next X4 and HyFlex 40/0.4. After root canal preparation, all of the roots were sectioned perpendicular to the long axis at 2, 4, 6, and 8 mm from the apex, and the sections were then observed under a stereomicroscope. The absence/presence of cracks was recorded, and the data were analyzed with a chi-square test. The significance level was set at P = .05.

Results

No cracks were observed in the negative control group. Vertical root fractures were not observed in any of the groups. The ProTaper Next and HyFlex instruments caused fewer cracks (28%) than the ProTaper Universal instrument (56%) (P < .05). However, there were no significant differences in crack formation between the ProTaper Next and HyFlex groups (P > .05).

Conclusions

Within the limitations of this in vitro study, all of the instrumentation systems used in this study created cracks in the root dentin. The ProTaper Next and HyFlex instruments tended to cause fewer dentinal cracks compared with the ProTaper Universal instrument.     

Assessment of Dentinal Damage during Canal Preparation Using Reciprocating and Rotary Files

Introduction

The role of motion kinematics in creating dentinal damage during instrumentation is not very clear. The purpose of this study was to compare the formation of dentinal cracks with instruments working in continuous rotation and reciprocating motion.

Methods

One hundred twenty extracted human mandibular premolars were selected for the study. Thirty teeth served as controls, and the remaining 90 teeth were divided into 3 groups depending on the root canal preparation technique. Group 1 samples were treated with WaveOne primary files (Dentsply Maillefer, Ballaigues, Switzerland), group 2 samples with single F2 ProTaper (Dentsply Maillefer) working in reciprocating motion, and group 3 samples were prepared with sequential ProTaper (Dentsply Maillefer) until F2 working in continuous rotation motion. Roots were then sectioned at 3, 6, and 9 mm from the apex, and the cut surface was observed under a stereomicroscope for the presence of dentinal microcracks.

Results

The control group and WaveOne, single F2 ProTaper in reciprocating motion, and continuous ProTaper groups caused cracks in 0%, 15%, 26%, and 53% of samples, respectively. A statistically significant difference was found between 2 reciprocating file groups (WaveOne and single F2 ProTaper in reciprocating motion) and the continuous rotation group (ProTaper) (P < .05). However, no significant difference was found among the 2 reciprocating file groups (P > .05).

Conclusions

Dentinal cracks are produced irrespective 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.     

Reciprocating Versus Rotary Systems for Root Filling Removal: Assessment of the Apically Extruded Material

Introduction

This study was designed to quantitatively evaluate the amount of apically extruded debris by comparing the ProTaper Universal Retreatment system (Dentsply Maillefer, Ballaigues, Switzerland) with 2 reciprocating single-file systems (Reciproc [VDW, Munich, Germany] and WaveOne [Dentsply Maillefer]) during endodontic retreatment.

Methods

Forty-five mandibular premolars with a single canal were prepared with the ProTaper Universal system and then obturated. The specimens were divided into 3 groups (n = 15) according to the system used for filling removal: ProTaper Universal Retreatment system associated with the ProTaper Universal system (until file F4 40/0.06]), Reciproc system (Reciproc R40 [40/0.06]), and WaveOne system (WaveOne Large [40/0.08]). Sodium hypochlorite was used as an irrigant, and the apically extruded debris was collected in glass vials and then dried. The mean weight of debris was assessed with a microbalance and statistically analyzed using 1-way analysis of variance and post hoc Tukey multiple comparison tests (P < .05).

Results

The ProTaper Universal Retreatment system produced significantly more debris compared with the Reciproc and WaveOne systems (P < .01). The reciprocating systems showed no significant difference between them (P > .05).

Conclusions

Under the conditions of the present study, all systems caused apical debris extrusion. Reciprocating systems were associated with less debris extrusion when compared with a conventional rotary retreatment system.     

Shaping Ability of Three Nickel-Titanium Endodontic File Systems in Simulated S-shaped Root Canals

Introduction

The purpose of this study was to determine the shaping ability of 3 nickel-titanium (NiTi) endodontic file systems by measuring canal transportation.

Methods

Seventy-two S-shaped canals in resin blocks were randomly allocated into 3 groups (n = 24): the Self-Adjusting File (SAF; ReDent Nova, Ra’anana, Israel) group, the Typhoon group (Typhoon rotary files with Controlled Memory Wire; DS Dental, Johnson City, TN), and the Vortex group (ProFile Vortex rotary files with M-Wire NiTi; Dentsply Tulsa Dental Specialties, Tulsa, OK). Blocks were secured in a jig for imaging standardization and instrumentation stabilization. Gates Glidden and PathFile drills (25 mm/.02 taper) were used to prepare the glide paths. For the Typhoon and Vortex groups (25 mm/.04 taper), canals were flooded with sterile water and instrumented using a crown-down technique from sizes 40 to 20/.04 and then apically enlarged to size 30/.04. The SAF group (25 mm) was instrumented with constant sterile water irrigation in a light-pecking, transline motion. Pre- and postinstrumentation images were taken at 40× magnification and layered, and canal transportation was measured.

Results

After adjusting for the level and canal wall side, the mean transportation was significantly higher for the Typhoon (P < .001) and Vortex (P = .005) groups compared with the SAF group. Additionally, the mean transportation was significantly higher for the Typhoon group versus the Vortex group (P < .001).

Conclusions

Under the conditions of this study, SAFs showed less canal transportation than ProFile Vortex and Typhoon files in simulated S-shaped root canals.     

Root Canal Preparation of Mandibular Molars with 3 Nickel-Titanium Rotary Instruments: A Micro–Computed Tomographic Study

Introduction

The aim of this study was to describe the canal shaping properties of ProTaper Next (PTN; Dentsply Maillefer, Ballaigues, Switzerland), ProTaper Universal (PTU; Dentsply Tulsa Dental Specialties, Johnson City, TN), and WaveOne (Dentsply Maillefer) nickel-titanium instruments in mandibular first molars by using micro–computed tomographic (micro-CT) scanning.

Methods

A total of 36 maxillary first molars with 2 separate mesial canals and 1 distal canal were selected and scanned preoperatively and postoperatively by using micro-CT scanning with a voxel size of 30 μm. Canals were prepared with PTU, PTN, and WaveOne systems under hypochlorite irrigation. The volume of the untreated canal; the volume of dentin removed after preparation; the amount of the uninstrumented area; and the transportation to the coronal, middle, and apical thirds of canals were measured. The preparation time and instrument failure were also recorded.

Results

Instrumentation of canals increased their volume and surface area. The distal canals had a significantly higher proportion of unprepared surfaces than mesial canals (P < .05). The PTN system produced less transportation than the WaveOne and PTU systems in the apical third of the mesial canals (P < .05). There was no significant difference on apical transportation in distal canals among the 3 instrument systems. Instrumentation with WaveOne was significantly faster than with the other 2 instruments (P < .05).

Conclusions

The PTN, PTU, and WaveOne instruments shaped root canals in mandibular first molars in vitro without significant shaping errors. The curved canals prepared using PTN had less apical transportation than the canals prepared using WaveOne and PTU.     

Assessment of Apically Extruded Debris Produced by the Self-Adjusting File System

Introduction

This study was designed to quantitatively evaluate the amount of apically extruded debris by the Self-Adjusting-File system (SAF; ReDent-Nova, Ra’anana, Israel). Hand and rotary instruments were used as references for comparison.

Methods

Sixty mesial roots of mandibular molars were randomly assigned to 3 groups (n = 20). The root canals were instrumented with hand files using a crown-down technique. The ProTaper (Dentsply Maillefer, Ballaigues, Switzerland) and SAF systems were used according to the manufacturers' instructions. Sodium hypochlorite was used as an irrigant, and the apically extruded debris was collected in preweighted glass vials and dried afterward. The mean weight of debris was assessed with a microbalance and statistically analyzed using 1-way analysis of variance and the post hoc Tukey multiple comparison test.

Results

Hand file instrumentation produced significantly more debris compared with the ProTaper and SAF systems (P < .05). The ProTaper system produced significantly more debris compared with the SAF system (P < .05).

Conclusions

Under the conditions of this study, all systems caused apical debris extrusion. SAF instrumentation was associated with less debris extrusion compared with the use of hand and rotary files.     

In Vitro Comparison in a Manikin Model: Increasing Apical Enlargement with K3 and K3XF Rotary Instruments

Introduction

The aim of the study was to compare the K3 and K3XF systems (SybronEndo, Glendora, CA) after 1 and 2 uses by evaluating apical transportation, working length loss, and working time in a manikin model.

Methods

Mesial canals of 40 extracted first mandibular molars were instrumented. Radiographs taken after instrumentation with #25, #30, #35, and #40 files were superimposed on the preoperative image in both mesiodistal and buccolingual angulations. AutoCAD (Autodesk Inc, San Rafael, CA) was used to measure working length loss and apical transportation at 0, 0.5, and 1 mm from the working length (WL). The working time was measured. Group comparison was analyzed using post hoc Tukey honestly significant difference tests (P < .05).

Results

No significant differences were found in apical transportation, working length loss between K3 and K3XF systems, or between the number of uses. Significant differences were found when canal enlargement was performed to a #35–40 (P < .05). K3 instrumentation performed significantly faster (29.6 ± 15.4) than with the K3XF system (40.2 ± 17.7) (P < .05). No differences were observed in working time when comparing the number of uses.

Conclusions

K3 and R-phase K3XF rotary systems shaped curved root canals safely with minimal apical transportation, even up to a 40/04 file.     

Evaluation of Root and Canal Morphology of Maxillary Permanent First Molars in a North American Population by Cone-beam Computed Tomography

Introduction

The purpose of this study was to evaluate the number of roots and canal morphology of maxillary permanent first molars in a North American population.

Methods

Three hundred seventeen cases with bilateral maxillary first molars were included. All images from cone-beam computed tomography were carefully reviewed by 2 endodontists. Frequency of number of roots, presence of an additional mesiobuccal canal (MB2), and Vertucci canal type for each root were tabulated. Age, gender, and ethnicity differences were calculated with the χ² test. The intra-rater reliability was assessed by using the Cohen kappa statistic.

Results

The fused root rate was 0.9%. The occurrence of 3-rooted maxillary first molars differed between left and right sides (P = .03). MB2 occurrence only showed statistically significant differences among age groups (P = .005). In the mesiobuccal roots, the most common Vertucci classifications of canal types were type IV (2-2, 41.9%), type I (1, 28.3%), and type II (2-1, 26.3%). There was a statistically significant difference in Vertucci classification of canal type among 5 ethnic groups (African American, Asian, Hispanic, Other, and Non-Hispanic white, P < .001).

Conclusions

Cone-beam computed tomography facilitates the identification of root and canal configuration. The information gained about the tooth anatomy and canal morphology before treatment could potentially facilitate root canal therapy.     

Influence of Single-file Endodontics on Apical Transportation in Curved Root Canals: An Ex Vivo Micro–Computed Tomographic Study

Introduction

More information regarding the ability of single files to maintain the original canal position is required before adopting a single-file approach to cleaning and shaping. This study compares apical transportation in curved root canals when instrumenting with a single WaveOne (WO) file (Dentsply Tulsa Dental Specialties, Tulsa, OK) in a reciprocating motion with that incurred when using a sequence of Twisted Files (TFs; SybronEndo, Orange, CA) in a continuous rotating motion.

Methods

Forty mesial canals of mandibular molars were evenly allocated into 2 balanced groups (n = 20) with a 17-mm average canal length and 20° average curvature. Canals were accessed in a conventional manner and instrumentation was completed with a single WO file or a series of TFs. The canals were instrumented according to the manufacturers' protocol. Apical transportation was assessed on a comparison of the pre- and postinstrumentation micro–computed tomographic scans at 1-, 2-, 3-, 4-, and 5-mm sections. One-way analysis of variance was performed to assess if a significant difference between systems exists.

Results

No significant difference (P > .05) was found between the WO and TF groups. Transportation in the mesial direction was of greater magnitude than distal transportation for both files systems. The mean transportation in the mesial direction was 100.1 ± 8.8 μm (WO group) and 101.0 ± 10.9 μm (TF group) (P = .5), whereas distal transportation was found to be 80.9 ± 14.6 μm (WO group) and 60.3 ± 11.0 μm (TF group) (P = .3).

Conclusions

The results suggest that no difference exists between the WO file system and the conventional multifile TF system when considering apical transportation in curved canals.     

Morphologic Micro–Computed Tomography Analysis of Mandibular Premolars with Three Root Canals

Introduction

This study aimed to describe the anatomy of mandibular premolars with type IX canal configuration by using micro–computed tomography.

Methods

Mandibular premolars with radicular grooves (n = 105) were scanned, and 16 teeth with type IX configuration were selected. Number and location of canals, distances between anatomic landmarks, occurrence of apical delta, root canal fusion, and furcation canals, as well as 2-dimensional (area, perimeter, roundness, major and minor diameters) and 3-dimensional (volume, surface area, and structure model index) analysis were performed. Data were statistically compared by using analysis of variance and Kruskal-Wallis tests (α = 0.05).

Results

Overall, specimens had 1 root with a main canal that divided into mesiobuccal, distobuccal, and lingual canals at the furcation level. Mean length of the teeth was 22.9 ± 2.06 mm, and the configuration of the pulp chamber was mostly triangle-shaped. Mean distances from the furcation to the apex and cementoenamel junction were 9.14 ± 2.07 and 5.59 ± 2.19 mm, respectively. Apical delta, root canal fusion, and furcation canals were present in 4, 5, and 10 specimens, respectively. No statistical differences were found in the 2-dimensional and 3-dimensional analyses between root canals (P > .05).

Conclusions

Type IX configuration of the root canal system was found in 16 of 105 mandibular premolars with radicular grooves. Most of the specimens had a triangle-shaped pulp chamber. Within this anatomic configuration, complexities of the root canal systems such as the presence of furcation canals, fusion of canals, oval-shaped canals in the apical third, small orifices at the pulp chamber level, and apical delta were also observed.     

Infection in a Complex Network of Apical Ramifications as the Cause of Persistent Apical Periodontitis: A Case Report

Introduction

This article reports a case of persistent apical periodontitis lesion in a mesiobuccal root of a maxillary molar subjected to single-visit endodontic treatment.

Methods

The treatment protocol followed endodontic standards including using nickel-titanium instruments with working length ending 0.5-mm short of the apex, establishment and maintenance of apical foramen patency, irrigation with 5% NaOCl, smear layer removal, a final rinse with and ultrasonic agitation of chlorhexidine, and filling by the vertical compaction technique. Even so, the lesion in the mesiobuccal root became larger in size after follow-up examination at 1 year 6 months, and periradicular surgery was performed. Radiographic control after 11 months showed that periradicular healing was almost complete. The root apex and the lesion were analyzed histologically and histobacteriologically.

Results

The lesion was diagnosed as a “pocket cyst,” and no bacteria were noted extraradicularly. The cause of continued disease was a heavy bacterial biofilm infection located in an intricate network of apical ramifications. Bacteria were also observed on the walls of one of the mesiobuccal canals packed between the obturation material and the root canal wall.

Conclusions

This case report reinforces the need for treating the infected root canal as a complex system that possesses anatomic intricacies in which bacteria can spread and remain unaffected by treatment procedures.     

Shaping Ability of WaveOne Primary Reciprocating Files and ProTaper System Used in Continuous and Reciprocating Motion

Introduction

The purpose of this study was to compare the shaping effects of Wave One (Dentsply Maillefer, Ballaigues, Switzerland) and full-sequence ProTaper nickel-titanium (NiTi) files (Dentsply Maillefer) used in reciprocating and conventional movements in a simulated canal.

Methods

Seventy-five S-shaped canals in resin blocks were randomly allocated to 3 groups (n = 25): WaveOne (group 1), full sequence of ProTaper Universal files in conventional movements (group 2), and full sequence of ProTaper Universal files in reciprocating movements (group 3). Preoperative and postoperative photographs of the simulated canals were taken under standardized conditions, after which they were accurately superimposed. Two methods were adopted to evaluate the shaping ability of the 3 approaches: measuring the differences in apical and coronal curvature modifications and measuring the amount of resin removed for both curvatures on the right and left sides of the simulated canals. Differences in canal curvature modifications and in the amount of resin removed were analyzed using 1-way analysis of variance (P < .0001) followed by a Tukey-Kramer multiple comparison post hoc test and mixed-effects linear model (P < .05), respectively.

Methods

Group 3 maintained better coronal and apical canal curvature and less straightening of the simulated canals with respect to groups 1 and 2.

Conclusions

When preparing S-shaped canals, full-sequence ProTaper Universal NiTi files used in a reciprocating motion exhibited better shaping effects than full-sequence ProTaper Universal NiTi files used in a conventional motion and WaveOne.     

Shaping Ability of the Conventional Nickel-Titanium and Reciprocating Nickel-Titanium File Systems: A Comparative Study Using Micro–Computed Tomography

Introduction

This study used micro–computed tomographic imaging to compare the shaping ability of Mtwo (VDW, Munich, Germany), a conventional nickel-titanium file system, and Reciproc (VDW), a reciprocating file system morphologically similar to Mtwo.

Methods

Root canal shaping was performed on the mesiobuccal and distobuccal canals of extracted maxillary molars. In the RR group (n = 15), Reciproc was used in a reciprocating motion (150° counterclockwise/30° clockwise, 300 rpm); in the MR group, Mtwo was used in a reciprocating motion (150° clockwise/30° counterclockwise, 300 rpm); and in the MC group, Mtwo was used in a continuous rotating motion (300 rpm). Micro–computed tomographic images taken before and after canal shaping were used to analyze canal volume change and the degree of transportation at the cervical, middle, and apical levels. The time required for canal shaping was recorded. Afterward, each file was analyzed using scanning electron microscopy.

Results

No statistically significant differences were found among the 3 groups in the time for canal shaping or canal volume change (P > .05). Transportation values of the RR and MR groups were not significantly different at any level. However, the transportation value of the MC group was significantly higher than both the RR and MR groups at the cervical and apical levels (P < .05). In the scanning electron microscopic analysis, file deformation was observed for 1 file in group RR (1/15), 3 files in group MR (3/15), and 5 files in group MC (5/15).

Conclusions

In terms of shaping ability, Mtwo used in a reciprocating motion was not significantly different from the Reciproc system.     

Root Canal Shaping Using Nickel Titanium,M-Wire,and Gold Wire: A Micro–computed Tomographic Comparative Study of One Shape,ProTaper Next,and WaveOne Gold Instruments in Maxillary First Molars

Introduction

The aim of this study was to evaluate the root canal shaping effect of instruments manufactured from nickel titanium, M-Wire, and Gold wire with different glide path preparation techniques.

Dentinal Damage and Fracture Resistance of Oval Roots Prepared with Single-file Systems Using Different Kinematics

Introduction

Vertical root fracture is a common finding in endodontically treated teeth, notably oval roots. The aim of the present study was to determine the effect of instrumentation kinematics and the material of instrument construction of single-file systems on dentin walls and fracture resistance of oval roots.

Methods

Sixty-five roots with oval canals were allocated into a control group (n = 5) and 3 experimental groups of 20 roots each. Group WO was instrumented with the WaveOne primary file (Dentsply Maillefer, Baillagues, Switzerland), group PT-Rec was prepared with F2 ProTaper files (Dentsply Maillefer, Baillagues, Switzerland) used in a reciprocating motion, and group PT-Rot was prepared with F2 ProTaper files used in a rotation motion. For crack evaluation, half of the samples (n = 30) were embedded in acrylic resin, and the blocks were sectioned at 3, 6, and 9 mm from the apex. The sections were examined under a stereomicroscope and scored for crack presence. The other half of the specimens (n = 30) were obturated using lateral condensation of gutta-percha and AdSeal sealer (Meta Biomed Co, Ltd, Chungbuk, Korea). The specimens were then subjected to a load of 1 mm/min to determine the force required to fracture the roots.

Results

WaveOne instruments induced the least amount of cracks and exhibited greatest resistance to fracture compared with ProTaper F2 files whether used in reciprocating or rotating motions.

Conclusions

The alloy from which the material is manufactured is a more important factor determining the dentin damaging potential of single-file instruments than the motion of instrumentation.