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Objectives: This study aimed to evaluate the efficacy of three methods in root canal retreatment to remove the filling material in the root canals., Methods: Ninety tooth roots filled by gutta percha or plasticized material ( n =45, each) were randomly divided into three groups ( n =15). WaveOne (WaveOne group), 1 # P drill+WaveOne (1 # P+WaveOne group), and ultrasound P5 working end ET25+ProTaper Universal (P5+ProTaper Universal group) were used to remove the root canal filling material and prepare for root canal. The operating time of each canal was recorded and the percentage of residual filling material area was measured on the root canal wall of the mesial and distal dissected root section. The degree of deviation of the root canal after operation was measured for the root samples filled by gutta percha., Results: The type of root filling material and the method of root canal retreatment had no significant effect on the percentage of residual area of the filling material ( P >0.05). However, the remaining filling material area of apical 1/3 of the root canal was significantly higher than that of cervical 1/3 of the root canal ( P <0.05). The average operating times for removing gutta-percha or plasticized material in the W and 1 # P+WaveOne groups were significantly less than that in the P5+ProTaper Universal group ( P =0.000). The root canal retreatment methods had no significant effect on the curvature of the root canal ( P =0.650)., Conclusions: WaveOne single file's cleaning ability and center positioning ability were similar to those of ProTaper Universal. Moreover, WaveOne can be independently used for most root canals without a pathway when removing the root canal fillings, thereby simplifying the process of root canal retreatment.

Background: Root canal treatment in primary teeth is quite difficult and time-consuming, especially canal preparation. Pain is the most common negative outcome following root canal treatment, occurring hours or days after treatment. It is an unpleasant experience for both the patient and the dentist., Objectives: The objective of this study was to assess the severity and duration of pain following the endodontic treatment of primary molars with the use of rotary and reciprocating preparation systems compared to the traditional manual method., Material and Methods: The research sample consisted of 157 asymptomatic primary lower second molars with non-vital pulp that were indicated for root canal treatment. The patients were randomly divided into 3 groups: in the 1st group, the molars (n = 52) were prepared using the manual method; in the 2nd group (n = 53), a reciprocating automated preparation system (WaveOne®) was used; and in the 3rd group (n = 52), a rotary preparation system (ProTaper Next®) was used. Pain assessment was carried out after 6, 12, 24, 48, and 72 h, and after 1 week, using a four-face facial pain scale., Results: The manual method provided a higher pain score through 6, 12 and 24 h (p < 0.05) as compared to the 2 automated preparation systems. The intensity of pain did not vary between the 2 machine preparation systems after 6, 12 , 24, and 48 h (p > 0.05). There were no differences between the 3 methods after 72 h and after 1 week (p > 0.05)., Conclusions: The manual method caused more pain than the other 2 preparation systems, but there was no difference between the 2 automated methods. Automated root canal preparation systems could be used to reduce the intensity of postoperative pain after the endodontic treatment of primary teeth.

Objectives: To determine the effect of the location of the canal curvature on the fatigue resistance of WaveOne (WO), WaveOne Gold (WOG), Reciproc (Rec), and Reciproc Blue (RecB) files, and to examine the phase transformation behaviors of the reciprocating file systems., Material and Methods: The instruments were subjected to fatigue testing in five artificial canals with a curvature of 60° angle and a 3-mm radius. The location of the curvature was unique for each canal. Each file was inserted 16 mm into the canal and operated until fracture occurred. The time to fracture was recorded and the length of the fragment was measured. Differential scanning calorimetry was used to characterize the thermal behavior of the files. The number of cycles to failure was analyzed using two-way analysis of variance and the post hoc Tukey test. The Kruskal-Wallis test was used to compare the mean fragment lengths between groups., Results: The instruments had significantly lower fatigue resistance in canals with curvatures in the middle and coronal canals compared with those with apical curvatures (p < 0.05). At all tested curvature locations, RecB had superior fatigue resistance compared with WO and Rec (p < 0.05). There were no significant differences between WOG and Rec in canals with curvatures in the middle and coronal canals. The DSC thermograms for RecB exhibit a single exothermic peak during cooling but double endothermic peaks during heating indicating that a two-step phase transformation from martensite to R-phase to austenite takes place., Conclusions: The reciprocating instruments experience decreased cyclic fatigue resistance when operated in canals with coronal- and middle-third curvatures when compared with curvatures in the apical-third. Instrumenting coronally positioned curvatures with reciprocating files needs to be performed with caution., Clinical Relevance: The location of the root canal's curvature influences the fracture resistance of rotary files that are used with reciprocating movements. Therefore, caution needs to be exercised when using reciprocating instruments in canals with coronal or middle curvatures.

Background: Under axial loading, there is stress concentration around the cervical areas especially in the premolars because of their location in the arch., Aim: To evaluate and compare flexural fracture resistance of mandibular premolars after instrumentation with ProTaper ® Universal, ProTaper Next ® , OneShape ® , and WaveOne ® endodontic file systems., Methods: Seventy-five mandibular premolar teeth with single straight canals were divided into five different groups (n = 15): Group A: Control, Group B: ProTaper Universal (PTU), Group C: ProTaper Next (PTN), Group D: OneShape, Group E: WaveOne. The teeth were instrumented as per the manufacturer's instructions. After obturation and core placement, the teeth were placed in a customized jig mounted on a universal testing machine where force was applied at 45° on the buccal cusp and the force required to fracture the teeth was noted., Results: Amongst all the instrumented groups, WaveOne showed the highest resistance to fracture (1065.56 ± 175.05) and the control group was 1104.13 ± 188.42. All groups showed a significant difference in the fracture load values with the control group. However, there was a statistically significant (P < 0.05) difference seen with WaveOne vs PTU and WaveOne vs OneShape., Conclusions: Root canals instrumented with reciprocating motion have better flexural fracture resistance than continuous rotary motion. Mandibular premolars when instrumented with ProTaper Universal and OneShape endodontic files showed similar fracture resistance, proving that dentin removal does not depend on the number of files used., Competing Interests: None

Introduction: This study evaluated and compared the shaping ability of the WaveOne Gold (Dentsply/Tulsa Dental Specialties, Tulsa, OK), TRUShape 3D Conforming File (Dentsply/Tulsa Dental Specialties), EdgeCoil (EdgeEndo, Albuquerque, NM), and XP-3D Shaper (Brasseler USA, Savannah, GA) endodontic file systems on oval-shaped canals using micro-computed tomographic (micro-CT) technology., Methods: Thirty-two oval-shaped, single-canal extracted human teeth were decoronated 1 mm coronal to the cementoenamel junction and scanned via a micro-CT scanner (μCT100; Scanco Medical, Bassersdorf, Switzerland). Teeth were divided into 4 groups (n = 8) and instrumented according to the manufacturer's instructions. Coregistered images, before and after root canal preparation, were evaluated for morphometric measurements of the surface area, volume, structure model index (SMI), conicity, and percent of walls untouched using the manufacturer's evaluation software (IPL Register, Scanco Medical). Data were statistically compared between groups using 1-way analysis of variance and within groups using a paired sample t test., Results: Instrumentation with all file types increased the surface area, volume, and conicity between and within groups. There was no statistically significant difference between the groups for any of the rotary instruments used (P < .05)., Conclusions: Instrumentation of oval-shaped canals with WaveOne Gold, TRUShape, EdgeCoil, and XP-3D Shaper rotary endodontic instruments similarly increase the volume, surface area, and conicity. None of the file systems were capable of contacting all of the surface area in any canal., (Copyright © 2019 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: The goal of this study was to compare the cyclic fatigue resistance of 5 heat-treated nickel-titanium files in reciprocating movement with the same tip size and different cross sections., Methods: Five groups (WaveOne [Dentsply, Ballaigues, Switzerland], WaveOne GOLD [Dentsply], RECIPROC [VDW, Munich, Germany], RECIPROC BLUE [VDW GmbH, Munich, Germany], and TF [Sybron Endo, Glendora, CA] Adaptive) of 24 files each of the rotary files were examined. Cyclic fatigue resistance was compared between groups by determining the time needed to fracture and the number of cycles to failure in a cyclic fatigue testing device with 2 different curvatures, the first with a 5-mm radius of curvature and a 60° angle and the second with a double curvature, coronal curvature of 60° angle and a radius of 5 mm, and an apical curvature of 70° angle and a 2-mm radius. Scanning electron microscopic evaluation was performed at the fracture sites to investigate the types of fracture., Results: RECIPROC BLUE group had a higher mean time to fracture followed by RECIPROC and WaveOne GOLD for both single and double curvature. WaveOne had a higher mean time to fracture in a single curvature canal than TF Adaptive, whereas the opposite was true for a double curvature canal. Both RECIPROC groups were significantly greater in cyclic fatigue resistance in comparison with all other groups (P < .05). WaveOne GOLD was significantly greater than the WaveOne and TF Adaptive groups (P < .05)., Conclusions: RECIPROC BLUE files exhibited significantly greater cyclic fatigue resistance compared with other files tested in an S-shaped artificial canal., (Copyright © 2019 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

This study aimed to compare the surface topographies and nanoscale profiles of intact and used WaveOne, WaveOne Gold, Reciproc, and Reciproc blue nickel-titanium (NiTi) instruments. Sixteen NiTi instruments were evaluated; four from each one of WaveOne (25/0.08), WaveOne Gold (25/0.07), Reciproc (25/0.08), and Reciproc blue (25/0.08) files. Each instrument was used to prepare four curved canals. A three-dimensional nanoscale surface profiler was used to assess instrument surfaces before and after root canal instrumentation. The data were analyzed with one-way analysis of variance using SPSS 21.0 software and set significance at P < 0.05. There were significant differences in surface topography between NiTi instruments. Intact WaveOne and WaveOne Gold instruments had the highest values, followed by the Reciproc and Reciproc blue instruments (P < 0.05). Used WaveOne and WaveOne Gold instruments had the highest values, followed by Reciproc and Reciproc blue instruments (P < 0.05). Some indications of microcracks in qualitatively intact Reciproc blue files were observed, and minor surface cracks in used WaveOne Gold instruments were also observed. Used WaveOne, Reciproc, and Reciproc blue instruments exhibited cracks and microcavities. WaveOne Gold and Reciproc blue instruments had significantly higher levels of surface distortion after root canal instrumentation, and WaveOne exhibited the lowest level of surface deformation. Each of the Reciprocating instruments was safely used to prepare four canals without incident. The three-dimensional stylus profiler provided valuable assessments of the surface topographies of NiTi instruments.

Aim: To assess the fracture incidence of instruments from single-file reciprocating systems when used by students in an endodontic graduate programme., Methodology: Dental records and periapical radiographs of patients treated by students on an endodontic graduate programme using reciprocating systems were assessed. Data on tooth type, number of treated root canals, number of fractured instruments, fragment size, angle, radius, arc length and position of root canal curvature where fractures occurred were tabulated for analysis. The risk of fracture was calculated for each group of teeth, root canal and root thirds, whilst the incidence of fractures reported for the reciprocating systems was compared using the chi-squared test at 5% significance level., Results: Overall, 2056 root canals (826 teeth) from 810 patients were included. The incidence of fractured files from single-file reciprocating systems in relation to a number of instrumented canals was 0.92%. Fracture rates of 0.84% and 0.93% were found in 830 and 1226 root canals instrumented with WaveOne and Reciproc systems, respectively. No significant differences were observed between the systems. The highest fracture rate was 52.6% in the mesiobuccal root of mandibular molars. The central angle, radius and arc length of the curvature of root canals where the instruments fractured ranged from 58° to 84°, from 1.7 to 7.2 mm and from 2.4 to 7.6 mm, respectively., Conclusion: The use of WaveOne and Reciproc single-file reciprocating systems in an endodontic graduate programme was associated with a low incidence of instrument fractures., (© 2018 International Endodontic Journal. Published by John Wiley & Sons Ltd.)

Introduction: The purpose of this study was to compare canal transportation and the centering ability of Reciproc (VDW, Munich, Germany), WaveOne (Dentsply Maillefer, Ballaigues, Switzerland), and EdgeFile (EdgeEndo, Albuquerque, NM) rotary systems using cone-beam computed tomographic imaging., Methods: Ninety mesiobuccal mandibular first molar uncalcified canals with at least a 19-mm length, a canal curvature of 15°-30° (the Schneider method), and a mature apex were selected. Canals were randomly divided into 3 groups of 30 teeth, and canal preparation with the Reciproc, WaveOne, and EdgeFile systems was performed according to the manufacturers' instructions. Cone-beam computed tomographic images were taken before and after instrumentation in the same position. Apical transportation was calculated in the distances of 2, 3, and 4 mm from the apex. Kruskal-Wallis and Mann-Whitney U tests were used to statistically analyze the data., Results: The mean canal transportation was significantly lower with EdgeFile (P < .001) followed by the WaveOne rotary system. Moreover, the centering ability of the EdgeFile system was higher than that of the WaveOne and Reciproc systems., Conclusions: The EdgeFile rotary system showed the lowest transportation in both the mesiodistal and buccolingual directions and the highest centering ability. The Reciproc system showed the highest transportation and the lowest centering ability., (Copyright © 2018 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

A comparison of the abilities of rotary versus reciprocating files to eliminate viable Enterococcus faecalis populations from the long oval root canals of extracted human teeth. Fifty teeth were contaminated and randomly distributed into two groups (n = 25 each): BT-RaCe group and WaveOne group. Two microbial samples were obtained from each tooth before (S1) and after (S2) instrumentation. The CFUs from the S1 and S2 measurements were calculated and compared between the groups. Both groups showed significantly fewer CFUs in the S2 samples (P < 0.001). In the S2 intragroup comparison, BT-RaCe resulted in significantly fewer CFUs than WaveOne (P = 0.010). In the direct comparison between the rotary multiple file shaping system and the reciprocating single-file system, the multiple file system was more efficient at reducing the microbiological load of viable E. faecalis from long oval root canals., (© 2017 Australian Society of Endodontology Inc.)

Introduction: The aim of this study was to evaluate the amount of vertical force induced with WaveOne (WO; Dentsply Sirona, York, PA) and WaveOne Gold (WOG, Dentsply Sirona) systems during the canal shaping of extracted teeth., Methods: Thirty canals in 15 maxillary premolars were divided into 2 groups: WO and WOG. The canals were gently shaped with WO/WOG Primary instruments according to the manufacturer's instructions. The vertical forces induced during canal shaping in the apical and coronal directions were recorded. The apically and coronally directed peak forces were used for analysis using the Mann-Whitney U test. The instrumentation time was analyzed using the Student t test. All statistical analyses were performed using SPSS software (Version 22.0; IBM, Armonk, NY) at a 5% significance level., Results: The force increased with the successive instrument insertions within each group. The apically and coronally directed peak forces of the WO and WOG groups ranged from 2.89-11.58 N and from 1.53-2.92 N, respectively. In the 3 insertions, WO showed higher peak forces in both directions. For apically directed peak forces, WO had significantly higher peak forces in the first and third insertions than WOG (P < .01). For coronally directed peak forces, WO had significantly higher values in the first and second insertions (P < .05)., Conclusions: The WOG system had significantly lower apically and coronally directed peak force values compared with the WO system., (Copyright © 2018 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Background: The root canal glide path has been recommended as the foundation for a safer root canal preparation. The aim of this study was to compare glide paths created with K-files, PathFiles, and the ProGlider file, and their effects on subsequent WaveOne preparation regarding canal transportation, canal volume increase, apical extruded debris, and working time in curved canals., Methods: Sixty mesial canals of extracted human mandibular first molars were randomly assigned to the K-file (KF), PathFile (PF) and ProGlider file (PG) groups for glide path preparation. Then, canals were prepared using WaveOne files. Specimens were scanned (voxel size: 18 μm) three times using micro-computed tomography: pre-glide path, post-glide path, and post-root canal preparation. Canal transportations were measured at 1, 3, and 5 mm levels from the apical foramen, and canal volume increases were also accounted. Apical extruded debris during preparation was collected for measurement. Meanwhile,working time was recorded. Data were analyzed statistically using one-way analysis of variance and Tukey's post hoc tests (p < 0.05)., Results: After glide path preparation, the PG and PF groups showed significantly less canal transportation than the KF group at all levels (P < 0.05), while the PG group exhibited a significantly larger canal volume increase than the PF and KF groups (P < 0.05). After the subsequent canal preparation with WaveOne, the PG and PF groups showed significantly less canal transportation than the KF group at 3 and 5 mm levels, and the PG group showed significantly less canal transportation than the PF group at 5 mm level (P < 0.05). However, statistically similar canal volume increases occurred among the three groups. Additionally, the PG and PF groups produced less apical extruded debris compared to the KF group (P < 0.05). The working time of the PG group was the shortest, while that of the KF group was the longest., Conclusion: Compared with the PathFiles and K-files, the ProGlider file combined with the WaveOne file showed reduced canal transportation and working time.

Introduction: The purpose of this study was to evaluate the effect of sodium hypochlorite (NaOCl) and EDTA solutions on the cyclic fatigue resistance of WaveOne (WO) and WaveOne Gold (WOG) nickel-titanium reciprocating files., Methods: A hundred WO (25/.08), and 100 WOG (25/.07) were randomly divided into 5 groups: group 1, no immersion; group 2, immersion in 5.25% NaOCl at 37°C ± 1°C for 5 minutes; group 3, immersion in 5.25% NaOCl at 37°C ± 1°C for 10 minutes; group 4, immersion in 17% EDTA at 37°C ± 1°C for 5 minutes; and group 5, immersion in 17 % EDTA at 37°C ± 1°C for 10 minutes. Then, the instruments were reciprocated in an artificial canal until fracture occurred, and the time to fracture was recorded. The data were statistically analyzed using 1-way analysis of variance and the Student t test via SPSS 21.0 software (IBM Corp, Armonk, NY) with the significance level set at P < .05., Results: The cyclic fatigue resistance of the WOG was statistically higher than the WO in all the conditions tested (P < .05). There was no statistically significant difference among the different conditions tested in terms of cyclic fatigue resistance for both WO and WOG files (P > .05). Among the groups, there was no significant difference in the fracture lengths (P > .05)., Conclusions: Within the limitations of the present study, it was determined that NaOCl and EDTA solutions did not have any effect on the cyclic fatigue resistance of WO and WOG files., (Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: Reciprocating instruments were developed to improve and simplify the preparation of the root canal system by allowing greater centralization of the canal and requiring a shorter learning curve. Despite the risk of instrument separation, using a reciprocating instrument in more than 1 case is a relatively common clinical practice. The aim of this study was to evaluate the fracture resistance of Reciproc (R25; VDW, Munich, Germany) and WaveOne (Primary; Dentsply Maillefer, Ballaigues, Switzerland) instruments according to the number of uses during the preparation of root canals in up to 3 posterior teeth., Methods: A prospective clinical study was conducted by 3 experienced specialists who performed treatment of 358 posterior teeth (1130 canals) over a period of 12 months using 120 reciprocating instruments, 60 of which were Reciproc R25 and 60 were WaveOne Primary. The motion used during instrumentation followed the recommendations of the respective manufacturers. After each use, the instruments were observed under a dental operating microscope at 8× magnification. In the case of fracture or deformation, the instrument was discarded., Results: None of the instruments showed any signs of deformation, but 3 instruments fractured (0.26% of the number of canals and 0.84% of the number of teeth). All fractures occurred in mandibular molars (1 WaveOne Primary file during the third use and 2 Reciproc R25 files, 1 during the first use and the other during the third use)., Conclusions: There was a low incidence of fracture when reciprocating files were used in up to 3 cases of endodontic treatment in posterior teeth., (Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Objectives: The objective of this study is to determine the potential for microcracks in the radicular dentin of first maxillary premolars using three different mechanized endodontic instrumentation systems., Methods: Eighty extracted maxillary first premolars with two root canals and no externally visible microcracks were selected. Root canal instrumentation was performed with either the ProTaper file system, the WaveOne primary file, or the self-adjusting file (SAF). Teeth with intact roots served as controls. The roots were cut into segments and examined with an intensive, small-diameter light source that was applied diagonally to the entire periphery of the root slice under ×20 magnification; the presence of microcracks and fractures was recorded. Pearson's chi-square method was used for statistical analysis, and significance was set at p < 0.05., Results: Microcracks were present in 30 and 20 % of roots treated with the ProTaper and WaveOne systems, respectively, while no microcracks were present in the roots treated with the SAF (p = 0.008 and p = 0.035, respectively). Intact teeth presented with cracks in 5 % of the roots. The intensive, small-diameter light source revealed microcracks that could not be detected when using the microscope's light alone., Conclusions: Within the limitations of this study, it could be concluded that mechanized root canal instrumentation with the ProTaper and WaveOne systems in maxillary first premolars causes microcracks in the radicular dentin, while the use of the SAF file causes no such microcracks., Clinical Relevance: Rotary and reciprocating files with large tapers may cause microcracks in the radicular dentin of maxillary first premolars. Less aggressive methods should be considered for these teeth.

Introduction: The objective of this study was to use light-emitting diode (LED) transillumination to assess the presence of dentinal defects in roots instrumented with 3 different root canal preparation systems: ProFile (Dentsply Tulsa Dental Specialties, Tulsa, OK), TRUShape (Dentsply Tulsa Dental Specialties), and WaveOne Gold (Dentsply Tulsa Dental Specialties)., Methods: Eighty mesial roots of mandibular molars presenting 2 canals were randomly divided into 4 different groups (n = 20) as follows: the control group, no root canal preparation was performed; the ProFile group, root canals were prepared with nickel-titanium ProFile sizes 20.06 and 25.06; the TRUShape group, root canals were prepared with nickel-titanium rotary TRUShape instrument sizes 20.06 and 25.06; and the WaveOne Gold group, root canals were prepared with the reciprocating WaveOne Gold instrument #25.07. The specimens were sliced at 3, 6, and 9 mm from the apex with a low-speed saw under water cooling. Microscopic pictures of the specimens were taken with the aid of LED; the root canal space was masked, and 2 independent evaluators assessed the images for the assessment of dentinal defects. The number of dentinal defects was recorded, and the chi-square test was used for statistical analysis (P < .05)., Results: The number of specimens presenting dentinal defects was as follows: the control group = 10, the ProFile group = 10, the TRUShape group = 13, and the WaveOne Gold group = 10., Conclusions: Using the novel LED method, no difference in the visualization of dentinal defects was found among the ProFile, TRUShape, and WaveOne systems and the control group. Previous studies using the traditional sectioning method lack proper control and should be evaluated with caution., (Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: Micro-computed tomographic scanning was used to evaluate the influence of operator's experience on the time and quality of instrumentation of the mesial root canals of mandibular molars using WaveOne Primary files (Dentsply Maillefer, Ballaigues, Switzerland)., Methods: Thirty mandibular molars with 2 separate mesial canals were submitted to preoperative micro-CT scans. Teeth were randomly allocated to 3 groups: and experienced operator group and inexperienced groups before and after training with WaveOne files. Second scans were obtained after instrumentation. The volume of the untreated canal, the volume of dentin removed after preparation; the amount of the uninstrumented area; and transportation to the coronal, middle, and apical thirds of canals were measured. The preparation time was also recorded., Results: Instrumentation of canals increased their volume and surface area in all groups. No significant differences between experienced and inexperienced (with and without training) groups in the apical, middle, and coronal sections were detected although coronal transportation was slightly larger in both inexperienced groups than in the experienced group. The inexperienced operator without training used significantly more time for instrumentation than the experienced operator (P < .05); after training for 1 month, the instrumentation time by the same inexperienced operator was reduced (P < .05) to close to the time of the experienced operator (P > .05)., Conclusions: The WaveOne instrumentation technique required a short learning curve for the inexperienced user in order to master this technology., (Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: The aim of this study was to evaluate through computed microtomography the transportation and centralization of root canals instrumented using the WaveOne system (Dentsply Maillefer, Ballaigues, Switzerland) associated or unassociated with previous apical and cervical enlargements., Methods: Thirty-six mandibular molars were selected with independent mesial roots and curvatures and randomized into the following groups: PathFile (Dentsply Maillefer) before WaveOne Primary (the PFWO group), ProTaper Universal SX (Dentsply Maillefer) before WaveOne Primary (the SXWO group), and WaveOne Primary (the WO group). Computed microtomographic imaging was performed pre- and postpreparation to obtain measurements of mesial and distal dentin walls and calculations of root canal transportation (%) and centralization. One-way analysis of variance was performed to compare the different groups, repeated measures analysis of variance for comparison of the root thirds in each group, and the Student t test for comparisons between the mesiobuccal and mesiolingual canals., Results: Transportation of the cervical and middle thirds to the danger zone was observed in both roots, whereas the apical thirds were transported to the outer face of the curvature. In the PFWO and SXWO groups, less transportation was observed in the middle thirds of the mesiobuccal canals compared with the WO group (P < .05). Centralization remained almost unchanged in the SXWO group (P < .05)., Conclusions: In each group, transportation toward the danger zone was mostly observed in the cervical thirds of the mesiobuccal canals. Cervical or apical enlargement resulted in reduced transportation and improved centralization of the middle thirds compared with the exclusive use of the WaveOne system., (Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: The purpose of this study was to evaluate the incidence and mode of WaveOne (Dentsply Tulsa Dental Specialties, Tulsa, OK) instrument defects after single use at different endodontic clinics., Methods: A total of 438 WaveOne instruments were collected after clinical use from the 4 specialist clinics over a 12-month period and from 1 graduate program over a 20-month period. The incidence and type of instrument defects were analyzed. The lateral surfaces of part of the defective instruments and fracture surfaces of fractured files were examined using scanning electron microscopy. Unused and clinically used files were examined by a nanoindentation test., Results: Of the 438 WaveOne instruments collected, 42 (9.6%) had defects: 40 (9.1%) were distorted and 2 (0.5%) files had fractured, 1 Small and 1 Primary file. Clear differences in the frequency of defects were found among the 3 file sizes; the occurrence of distortion and fracture were highest with the Small file (21.2% and 0.7%, respectively) followed by the Primary file (4.4% and 0.4%, respectively) (P < .05). No defects were detected on the Large file. The cause of the 2 fractures was shear stress. Instruments from various clinics showed no significantly different occurrence of instrument deformation. Unwinding occurred at 1.2-3.1 mm from the tip. No significant difference in nanohardness was detected among unused and used instruments., Conclusions: The risk of WaveOne fracture is very low when files are singly used by endodontists and residents. Unwinding of the files occurred most frequently in the Small file. The frequency of defects of WaveOne instruments were not influenced by the operator., (Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: The objective of the present study was to clinically compare the incidence of postoperative pain and the intake of analgesic medication (frequency and quantity) after endodontic treatment of posterior teeth using 2 reciprocating systems and a continuous rotary system., Methods: In a prospective randomized clinical study, 210 patients with vital teeth indicated for conventional endodontic treatment were treated by 5 specialists according to a pre-established protocol. The teeth were randomly assigned to 1 of 3 groups (n = 70) according to the instrumentation system used: ProTaper Next (Dentsply Tulsa Dental Specialties, Johnson City, TN), WaveOne (Dentsply Tulsa Dental Specialties), or Reciproc (VDW, Munich, Germany). Treatments were performed in a single visit. After the visit, the patients were given a prescription for ibuprofen 400 mg to be taken every 6 hours if they experienced pain. Participants were asked to rate the intensity of the postoperative pain on a visual analog scale according to 4 classes (no pain, mild pain, moderate pain, and severe pain) after 24 hours, 48 hours, 72 hours, and 7 days. Patients were also asked to record the number of prescribed analgesic medication tablets taken at these time points., Results: No statistically significant difference was found among the 3 groups in relation to postoperative pain or analgesic medication intake at the 4 time points assessed (P > .05, Kruskal-Wallis test)., Conclusions: The reciprocating systems and the continuous rotary system were found to be equivalent in regard to the incidence of postoperative pain and intake of analgesic medication at the time points assessed., (Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: Root canal anatomy and canal preparation instruments affect the outcome of endodontic treatment. The purpose of this study was to determine the root surface strain (SS) generated and the extent of canal center transportation during canal shaping using 3 different nickel-titanium instruments., Methods: Simulated root canals in resin blocks (n = 10 per group) were prepared using adaptive rotary motion with twisted files (Twisted File Adaptive [TFA]; SybronEndo, Orange, CA), reciprocating rotary motion with WaveOne (WO; Dentsply Maillefer, Ballaigues, Switzerland) files, and continuous rotary motion with ProTaper Next files (PTN, Dentsply Maillefer). Electrical strain gauges at 3 sites recorded SS real time during canal shaping, and the blocks were scanned by micro-computed tomographic imaging to assess the canal center deviation at 3 sections after root canal instrumentation. The mean maximum SS and the canal center transportation for all groups and sites were derived and analyzed for a possible correlation between them., Results: An overall increase in root SS was observed after root canal instrumentation. A significant difference in the induced mean maximum SS between TFA, WO, and PTN at specific sites of curved root canals was observed. A statistically significant difference in the mean distance of canal center transportation was observed among the 3 shaping techniques at the apical section. Finally, the mean maximum SS values induced during canal shaping strongly correlated with canal center transportation in the apical section and the coronal section., Conclusions: The curved canals prepared using TFA exhibited lower SS and less canal center transportation at the apical section than the WO and PTN systems. SS generated during canal shaping correlated with canal center transportation in a site-specific manner., (Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Aim: To evaluate the apical extrusion of debris associated with several root canal preparation systems in vitro., Methodology: Forty-five extracted human mandibular premolars with single canals and similar lengths were used. The root canals were instrumented using ProTaper Next (Dentsply Maillefer, Ballaigues, Switzerland), Twisted File (SybronEndo, Orange, CA, USA) or WaveOne (Dentsply Maillefer, Ballaigues, Switzerland). Debris extruded apically during instrumentation was collected into pre-weighed Eppendorf tubes. The Eppendorf tubes were then stored in an incubator at 70 °C for 5 days. The Eppendorf tubes were weighed to obtain the final weight of the Eppendorf tubes plus extruded debris. Three consecutive weights were obtained for each tube. The groups were compared using the Kruskal-Wallis one-way analysis of variance on Ranks and Tukey's test., Results: The ProTaper Next group produced the highest mean extrusion value whilst WaveOne produced less debris compared with all the other instruments (P > 0.05). There was a significant difference between the ProTaper Next and WaveOne group (P < 0.05)., Conclusions: Apically extruded debris was associated with all instrumentation techniques. The WaveOne system extruded less debris compared with the Twisted File and ProTaper Next., (© 2014 International Endodontic Journal. Published by John Wiley & Sons Ltd.)

Aim: To compare apical extrusion of debris in canals prepared with two reciprocating file systems and two different irrigation systems., Methodology: Forty single straight root canals in human mandibular pre-molars were prepared using Reciproc R40 (REC) and WaveOne Large (WO) instruments. Before preparation, the dimensions of a size 40 instrument from each system were measured under scanning electron microscopy (SEM) at 80X. The teeth were randomly divided into four different groups of 10: REC and VPro EndoSafe (REC/VPro); WO/VPro; REC and conventional irrigation (REC/CI); and WO/CI Eppendorf tubes containing a single tooth were weighed on an analytical balance to the nearest 0.1 mg before instrumentation. Irrigation was performed with a total volume of 8 mL of 2.5% sodium hypochlorite. After instrumentation, the teeth were removed from the Eppendorf tube and incubated at 37 °C for 15 days to evaporate the liquid. The tubes were weighed again, and the difference between the initial and final debris weights was calculated and statistically evaluated using analysis of variance (two-way anova) with a significance level of 0.05., Results: No significant difference was observed between the VPro and CI irrigation systems (P > 0.05). Apical extrusion of debris was confirmed in all samples, and extrusion was greater in the REC groups than in the WO groups (P < 0.05). The WO file had a 20% smaller diameter at the tip (D0 ) than the measurement provided by the manufacturer., Conclusions: All systems were associated with apical extrusion of debris. The WO system was associated with less extrusion than the REC system. The amount of extruded debris was independent of the irrigation system used and was related to the instrumentation technique. Morphological analysis of instruments using SEM revealed no correlation between the diameter provided by the manufacturer and the measured diameter for the WO Large file., (© 2014 International Endodontic Journal. Published by John Wiley & Sons Ltd.)

Introduction: WaveOne is a single-file reciprocating instrumentation system with the benefits of M-Wire alloy that has increased flexibility and improved resistance to cyclic fatigue over the conventional alloy. Root canal preparation techniques may cause postoperative pain. The goal of the present study was to compare the intensity and duration of postoperative pain when using WaveOne or ProTaper Universal systems for instrumentation of root canals., Methods: Forty-two patients who fulfilled specific inclusion criteria were assigned to 2 groups according to the root canal instrumentation technique used, WaveOne or ProTaper Universal. Root canal treatment was carried out in 2 appointments, and the severity of postoperative pain was assessed by numerical rating scale (NRS) score after each session until complete pain relief was achieved. Analgesic consumption, duration of pain, and root canal preparation time were also recorded., Results: The mean NRS score and duration of pain after both appointments were significantly higher in the WaveOne group (P < .05); however, the mean analgesic consumption was only significantly higher in the WaveOne group after the first appointment (P < .05). In all groups the highest mean NRS score was seen 6 hours after each therapeutic appointment. Canal preparation time was significantly shorter in the WaveOne group (P < .001)., Conclusions: Postoperative pain was significantly lower in patients undergoing canal instrumentation with ProTaper Universal rotary instruments compared with the WaveOne reciprocating single-file technique., (Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: Reciprocating angle and torsional load at the superelastic limit were investigated for nickel-titanium (NiTi) instruments used with reciprocating movements., Methods: Two reciprocating NiTi instruments (Reciproc R25 [VDW, Munich, Germany] and WaveOne Primary [Dentsply Maillefer, Ballaigues, Switzerland]) and ProTaper F2 (Dentsply Maillefer) were tested for 2 torsional conditions using a custom-designed testing device. Rotational angles were applied, and generated torque values were recorded. The first test condition fixed the files at 5 mm and repetitively rotated them with gradually increasing angles up to 250° (n = 10). The second test subjected the files to a single continuous rotation until fracture (n = 10). The superelastic limits of the instruments were determined from their torque-rotation curves. Statistical analysis was performed (Kruskal-Wallis) at a 95% significance level. The tested specimens were examined under a scanning electron microscope., Results: It was found that the angle at the superelastic limit was higher for R25 and Primary files than the ProTaper file (P < .05). Repetitive torsional loading with a gradually increasing rotational angle reduced the torsional resistance compared with the single rotation motion. At the 5-mm fixation level all files had superelastic limit angles higher than the 170° set in the dedicated reciprocating motor. The scanning electron microscopic analysis showed features of torsional failure., Conclusions: Under the conditions of this study, the 170° set angle of dedicated motors for reciprocating file systems is safe at the 5-mm level. Reuse of reciprocating systems, even with the movements within the elastic limit, may cause deterioration of the instruments., (Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Aim: To compare the shaping ability of WaveOne, Reciproc and OneShape single-file systems in severely curved root canals in extracted human molar teeth., Methodology: Sixty mandibular molars with mesio-buccal canals with curvatures ranging between 25° and 35° and radii of curvature ranging between 4 and 9 mm were divided into three groups of 20 teeth each: group W (WaveOne), group R (Reciproc) and group O (OneShape). Using standardized pre- and post-instrumentation radiographs, straightening of canal curvatures was determined using the NIH Image J software. A double-digital standardized radiographic technique was used to determine apical transportation at 0.5 mm from the working length (1.5 mm coronal to the major foramen). Preparation time and instrument failures were also recorded. Data were analysed using one-way analysis of variance (anova) and post-hoc Tukey-test., Results: During root canal preparation, no instruments fractured but all OneShape instruments were deformed after preparation of four canals. The use of OneShape resulted in significantly greater canal straightening and apical transportation than WaveOne and Reciproc (P < 0.05), with no significant differences between WaveOne and Reciproc (P > 0.05). Instrumentation with OneShape was significantly faster than with WaveOne and Reciproc (P < 0.05), whilst Reciproc was significantly faster than WaveOne (P < 0.05)., Conclusions: All instruments were safe to use. Reciproc and WaveOne instruments respected the original canal curvature better than OneShape files. The use of OneShape instruments required less time to prepare the curved canals compared with Reciproc and WaveOne., (© 2014 International Endodontic Journal. Published by John Wiley & Sons Ltd.)

The aim of this study was to evaluate the effect of glide path preparation on the surface topography changes of WaveOne and OneShape single files using atomic force microscopy analysis. Two commercially available brands of single file systems were analyzed, including 15 specimens/brand as following: Group I; WaveOne 0.08/25 (Dentsply Maillefer, Ballaigues, Switzerland) and Group II; OneShape 0.06/25 (Micro Mega, Besançon, France). In each group, 3 new files were subjected to AFM analysis as received from manufacturer, and 12 files were analyzed after preparation of root canals. A total of 20 human maxillary molar teeth were selected. In each group, 12 files were divided into 4 subgroups according to instruments that were used in one or three root canals with or without a previous glide path (n = 3). After preparation the surface analysis of single files was performed on 11 different points located along a 3-mm section starting at the tip of each file using AFM. Root mean square (RMS) values were recorded to investigate the surface features of endodontic files. The differences between RMS values were tested by one-way ANOVA. There was no statistically significant difference between the groups (p > 0.05). Creation of a glide path did not affect the surface topography of single file systems., (© 2014 Wiley Periodicals, Inc.)

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., (Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: This study aimed to investigate the torsional resistance of 2 reciprocating nickel-titanium instruments (Reciproc [VDW, Munich, Germany] and WaveOne [Dentsply Maillefer, Ballaigues, Switzerland]) operated at the maximum rotating angle in a proprietary motor., Methods: With the file tip secured at various levels (3, 4, or 5 mm) of Reciproc R25 and WaveOne Primary, the distortion angles and torsional loads were monitored during counterclockwise movement at 2 rpm until fracture (n = 10 at each level) for a load-distortion graph. The rotation angles and loads at the beginning point of the plateau, the ultimate torsional strength, final fracture angle, and toughness were determined. The data were analyzed using 1-way analysis of variance and the Tukey post hoc test at α = .05. The lateral longitudinal aspect and the fracture cross-section of each specimen were examined by scanning electron microscopy after the test., Results: The rotation angle at the beginning point of the plateau was significantly greater for a binding site farther away from the tip of the instrument for both systems (P < .05), and all were greater than 170° (preset in the dedicated motor from manufacturer). The ultimate strength and toughness also increased significantly at levels farther away from the instrument tip (P < .05). All specimens showed typical topographic features of torsional fracture, including the circular abrasion marks and fibrous dimples near the rotation center after the test., Conclusions: It was determined that the 2 brands of reciprocating files are safe when operated at the rotational angle in the proprietary motor., (Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

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., (Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: The purpose of this pilot study in a cadaver model was to compare 2 different shaping techniques regarding the induction of dentinal microcracks., Methods: Three lower incisors from each of 6 adult human cadaver skulls were randomly distributed into 3 groups: the control group (CG, no instrumentation), the GT group (GT Profile hand files; Dentsply Tulsa Dental, Tulsa, OK), and the WO group (WaveOne; Dentsply Tulsa Dental). In the GT group, manual shaping in a crown-down sequence with GT Profile hand files was performed. In the WO group, Primary WaveOne files were used to the working length. Teeth were separated from the mandibles by careful removal of soft tissue and bone under magnification. Roots were sectioned horizontally at 3, 6, and 9 mm from the apex using a low-speed saw. Color photographs at 2 magnifications (25× and 40×) were obtained. Three blinded examiners registered the presence of microcracks (yes/no), extension (incomplete/complete), direction (buccolingual/mesiodistal), and location. Data were analyzed with chi-square tests at P < .05., Results: Microcracks were found in 50% (CG and GT) and 66% (WO) of teeth at 3 mm, 16.6% (CG) and 33.3% (GT and WO) at 6 mm, and 16.6% in all 3 groups at 9 mm from the apex. There were no significant differences in the incidence of microcracks between all groups at 3 (P = .8), 6 (P = .8), or 9 mm (P = 1). All microcracks were incomplete, started at the pulpal wall, and had a buccolingual direction., Conclusions: Within the limitations of this pilot study, a relationship between the shaping techniques (GT hand and WaveOne) and the incidence of microcracks could not be shown compared with uninstrumented controls., (Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: Despite metallurgical advancements in the nickel-titanium file manufacturing process, file separation remains a concern. The purpose of this prospective clinical study was to assess the separation incidence of the reciprocating WaveOne file (Dentsply Tulsa Dental Specialties, Tulsa, OK) when used to prepare root canals of posterior teeth., Methods: File separation incidence was assessed over an 18-month period in which 4 experienced and calibrated endodontists performed conventional endodontic treatment on posterior teeth using the WaveOne file system. The separation incidence was determined based on both the number of teeth and the number of canals instrumented during this time period., Results: A total of 2,215 canals (711 teeth) were treated. Three instruments (two 21.06 and one 25.08) separated during use and were deemed to be irretrievable. The overall instrument separation incidence in relation to the number of canals shaped was found to be 0.13% (0.42% teeth)., Conclusions: Based on the results of this study, the incidence of endodontic instrument separation when using the WaveOne reciprocating file was considerably low., (Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

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., (Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

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., (Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: The aim of the present study was to evaluate the bending resistance and the dynamic and static cyclic fatigue life of Reciproc R40 and WaveOne large instruments., Methods: A sample of 68 nickel-titanium instruments (25 mm in length) for use under reciprocation movement (Reciproc and WaveOne) from 3 different lots was tested. Reciproc R40 and WaveOne Large files, both of which had a nominal size of 0.40 mm at D0, were selected. The bending resistance was performed in 10 instruments of each system by using a universal testing machine. Dynamic and static models for cyclic fatigue testing were performed by using a custom-made device. For these tests, an artificial canal measuring 1.4 mm in diameter and 19 mm total length was fabricated from a stainless steel tube. Scanning electron microscopy analysis was performed to determine the mode of fracture. Statistical analysis was performed by using parametric methods, 1-way analysis of variance. Post hoc pair-wise comparisons were performed by using Tukey test for multiple comparisons., Results: WaveOne instruments presented significantly higher bending resistance than Reciproc (P < .05). Moreover, Reciproc revealed a significantly longer cyclic fatigue life (P < .05) in both static and dynamic tests (P < .05)., Conclusions: Reciproc R40 instruments resisted dynamic and static cyclic fatigue significantly more than WaveOne Large instruments. Furthermore, WaveOne instruments presented significantly less flexibility than Reciproc., (Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Aim: To compare the chemomechanical reduction and regrowth of Enterococcus faecalis between rotary and reciprocating systems in root canal preparation., Methodology: Seventy-six single-rooted human mandibular premolars were selected and standardized to 15 mm in length. Root canals were enlarged up to a size 25 K-file and irrigated with distilled water and then were infected with E. faecalis for 4 weeks. The specimens were divided into 3 groups (n = 24) for instrumentation with Mtwo, Twisted File and WaveOne. Each group was further divided into two subgroups (n = 12) according to the irrigant used: distilled water or 5.25% sodium hypochlorite (NaOCl). Before and after rotary preparation, microbiological samples were collected using three sterilized paper points, and efficacy was expressed as reduction in percentage. The proportion of grown samples for 60 days was evaluated using nonparametric Kaplan-Meier survival analysis. Differences amongst groups were tested using the log-rank test at a significance level of 0.05., Results: In the main root canal, the percentage reduction in the distilled water and 5.25% NaOCl groups ranged from 95.9% to 100%, with no significant differences amongst the three systems (P > 0.05). The bacterial regrowth in NaOCl groups revealed that Mtwo had the lowest number of samples regrown at 60 days, giving statistically significant differences with respect to Twisted File (P = 0.029) and WaveOne (P = 0.005)., Conclusions: Reciprocating and rotary systems resulted in similar percentage reduction in E. faecalis when using either distilled water or 5.25% NaOCl solution. Over time, the Mtwo system was more effective regarding disinfection., (© 2013 International Endodontic Journal. Published by John Wiley & Sons Ltd.)

Introduction: The aim of this study was to compare by scanning electron microscopy the presence of smear layer and debris on root canal walls after preparation with the single-file system WaveOne (Dentsply Maillefer, Ballaigues, Switzerland) versus the rotary ProTaper system (Dentsply Maillefer, Ballaigues, Switzerland) under 2 final irrigant regimens., Methods: Forty freshly extracted single-rooted human teeth were randomly divided into 4 groups (n = 10). The ProTaper and ProTaper and rotary CanalBrush (Coltène Whaledent GmbH+ Co KG, Langenau, Germany) groups were instrumented with the ProTaper system. Groups WaveOne and WaveOne and rotary CanalBrush were instrumented with the WaveOne system. The irrigant in all groups was 2 mL 5.25% sodium hypochlorite (NaOCl) solution, whereas the final irrigation after preparation in the ProTaper and WaveOne groups was 1 mL Smear Clear solution (Sybron Endo, Orange, CA) and then 5.25% NaOCl applied with a plastic syringe, and in the ProTaper and rotary CanalBrush and WaveOne and rotary CanalBrush groups, it was 1 mL Smear Clear solution and then 5.25% NaOCl (rotary CanalBrush agitation). Roots were processed for scanning electron microscopic examination for debris and smear layer scoring. Data were statistically analyzed., Results: All groups showed more efficient smear layer and debris removal coronally than in the middle and apical regions, whereas the mean total debris score and the mean smear layer score in all groups were less in the WaveOne and rotary CanalBrush groups than the ProTaper and rotary CanalBrush and the WaveOne and ProTaper groups., Conclusions: Using the rotary CanalBrush in canals prepared with WaveOne produced the cleanest canal walls, and the WaveOne system gave superior results compared with the ProTaper system., (Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: The purpose of this study was to evaluate the apical preparation sizes resulting from repetitive pecking motions at the working length (WL) by using reciprocating files., Methods: Sixty simulated endodontic training blocks with a J-shaped root canal were instrumented using Reciproc R25 (VDW, Munich, Germany) or WaveOne Primary (Dentsply Maillefer, Ballaigues, Switzerland) (n = 30 each). Each group was divided into 3 subgroups based on the repetitive pecking times at the WL: 1, 2, and 4 times. All specimens were prepared by 1 operator who was competent in instrumenting canals with both file systems. All of the procedures, including the WL measurement, were performed under an operating microscope. The replica of the prepared canal was taken with silicone impression material. After 24 hours of allowing the impression to set, each sample was evaluated under a scanning electron microscope at the apical tip, and the apical preparation size (diameter) was measured at the D0 level of the impression. The data were analyzed statistically using 2-way analysis of variance and the Tukey post hoc test at P = .05., Results: The mean diameter (μm) varied between 253 and 274 and between 258 and 277 for Reciproc and WaveOne, respectively, without significant differences. However, more repetitive pecking motions at the WL resulted in a significantly larger apical preparation size than the subgroups with less pecking times (P < .05)., Conclusions: Under the conditions of this study, the results indicate that a greater number of repetitive pecking times at the WL may result in an apical preparation size that is larger than the actual file size., (Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Objective This study aimed to evaluate the efficacy of three methods in root canal retreatment to remove the filling material in the root canals. Methods Ninety tooth roots filled by gutta percha or plasticized material (n=45, each) were randomly divided into three groups (n=15). WaveOne (WaveOne group), 1#P drill+WaveOne (1#P+WaveOne group), and ultrasound P5 working end ET25+ProTaper Universal (P5+ProTaper Universal group) were used to remove the root canal filling material and prepare for root canal. The operating time of each canal was recorded and the percentage of residual filling material area was measured on the root canal wall of the mesial and distal dissected root section. The degree of deviation of the root canal after operation was measured for the root samples filled by gutta percha. Results The type of root filling material and the method of root canal retreatment had no significant effect on the percentage of residual area of the filling material (P>0.05). However, the remaining filling material area of apical 1/3 of the root canal was significantly higher than that of cervical 1/3 of the root canal (P<0.05). The average operating times for removing gutta-percha or plasticized material in the W and 1#P+WaveOne groups were significantly less than that in the P5+ ProTaper Universal group (P=0.000). The root canal retreatment methods had no significant effect on the curvature of the root canal (P=0.650). Conclusion WaveOne single file's cleaning ability and center positioning ability were similar to those of ProTaper Universal. Moreover, WaveOne can be independently used for most root canals without a pathway when removing the root canal fillings, thereby simplifying the process of root canal retreatment. [ABSTRACT FROM AUTHOR]

Introduction: The aim of this in vitro study was to evaluate the effects of establishing glide path on the centering ability and preparation time of two single-file reciprocating systems in mesial root canals of mandibular molars. Methods and Materials: Sixty extracted mandibular molars with curvatures of 25-39 degrees and separate foramina for the mesiobuccal and mesiolingual canals, were divided into four groups (n=15); WaveOne+glide path; WaveOne; Reciproc+glide path and Reciproc. Non-patent canals were excluded and only one canal in each tooth was instrumented. A manual glide path was established in first and third groups with #10, 15 and 20 hand K-files. Preparation was performed with reciprocating in-and-out motion, with a 3-4 mm amplitude and slight apical pressure. Initial and final radiographs were taken to analyze the amount of dentin removed in the instrumented canals. The radiographs were superimposed with an image editing software and examined to assess discrepancies at 3- , 6- and 9-mm distances from the apex. The Kruskal-Wallis test was used for statistical analysis. The level of significance was set at 0.05. Results: Preparation in groups without glide paths was swifter than the other groups (P=0.001). However, no difference was observed regarding centering ability. Conclusion: Establishing a glide path increased the total instrumentation time for preparing curved canals with WaveOne and Reciproc instruments. Glide path had no influence on the centering ability of these systems. [ABSTRACT FROM AUTHOR]

Background: The aim of this study was to evaluate the influence of cervical preflaring on apical transportation in curved root canals prepared using the Reciproc and WaveOne reciprocating file systems. Methods: Sixty curved canals were instrumented using Reciproc R25 and WaveOne Primary files, with and without preflaring (n = 15). A double-digital technique was used to digitally superimpose the file before instrumentation (#15 K-file) on the final apical reciprocating file (#25/08). The angle between the tip of the initial and final file was measured and recorded. Groups were compared using the Kruskal--Wallis test, and significance was set at p < 0.05. Results: The mean and standard deviation for apical transportation was 0.93 ± 2.48 for the Reciproc Group, 0.84 ± 1.94 for the Preflaring + Reciproc Group, 0.40 ± 1.14 for the WaveOne Group, and 0.83 ± 2.20 for the Preflaring + WaveOne Group. No statistically significant differences were found among the groups (p = 0.9509). Conclusions: Under the conditions of this study, cervical preflaring did not influence apical transportation in curved root canals instrumented using Reciproc R25 and the WaveOne Primary files. Based on the in vitro measurements of apical transportation, the reciprocating files may be used without preflaring in curved root canals. [ABSTRACT FROM AUTHOR]

Introduction: The aim of this study was to compare the shaping ability of two single-file systems and conventional rotary instruments in severely curved root canals of extracted human molars. Methods and Materials: Mesiobuccal canals of 120 mandibular molars with angles of curvature ranging between 25° and 35° and radii of curvature from 5 to 9 mm, were divided into three groups (n=40). In each group the canals were instrumented with either WaveOne (W), Reciproc (R) or ProTaper (P). The time required for canal shaping and the frequency of broken instruments were recorded. The standardized pre and post-instrumentation radiographs were taken to determine changes in working length (WL) and straightening of canal curvature. The presence of blockage or perforation was also evaluated. Data were analyzed using the one-way analysis of variance (ANOVA) and post-hoc Tukey's test. The level of significance was set at 0.05. Results: Both singleinstrument systems reduced the canal preparation time by approximately 50% (P<0.05). No incidence of broken instruments from single-file systems was reported; however, two F2 instruments in the P group were broken (P<0.05). Reduction in WL and straightening of canal curvature was observed in all three systems with the highest scores belonging to P system (P<0.05). No case of blockage or perforation was found during shaping in any group. Conclusion: Single-file systems shaped curved canals with substantial saving in time and a significant decrease in incidence of instrument separation, change in WL, and straightening of canal curvature. [ABSTRACT FROM AUTHOR]