Taha Özyürek

Cyclic Fatigue Resistance of OneShape, HyFlex EDM, WaveOne Gold, and Reciproc Blue Nickel-titanium Instruments

Introduction: The purpose of this study was to compare the cyclic fatigue resistances of Reciproc Blue (VDW, Munich, Germany), HyFlex EDM (Coltene/Whaledent, Altstätten, Switzerland), WaveOne Gold (Dentsply Maillefer, Ballaigues, Switzerland), and OneShape (Micro Mega, Besancon, France) single‐file NiTi systems. Methods: Thirty Reciproc Blue R25 (25/.08), 30 HyFlex EDM (25/.˜), 30 WaveOne Gold Primary (25/.07), and 30 OneShape (25/.06) instruments were included in this study. All the instruments were rotated in artificial canals, which were made of stainless steel with an inner diameter of 1.5 mm, a 60° angle of curvature, and radii of curvatures of 5 mm until fracture occurred, and the time to fracture was recorded in seconds using a digital chronometer. The data were analyzed statistically using Kruskal‐Wallis and post hoc Dunn tests via SPSS 21.0 software (SPSS Inc, Chicago, IL). The statistical significance level was set at 5%. Results: The HyFlex EDM file (3456.33 ± 633.37) file had the statistically highest fatigue resistance, and the OneShape file (1221.63 ± 812.4) had the least fatigue resistance (P < .05). The mean number of cycles to fracture of the Reciproc Blue file (2875.89 ± 105.35) file was statistically higher than the WaveOne Gold file (1737.00 ± 376.32) (P < .05). There was no statistically significant difference (P > .05) in the mean length of the fractured fragments of the files (P > .05). Conclusion: Within the limitations of the present in vitro study, it was found that cyclic fatigue resistance of HyFlex EDM files was higher than the cyclic fatigue resistances of OneShape, Reciproc Blue, and WaveOne Gold files. HighlightsWe compared the fatigue resistance of the novel Reciproc Blue nickel‐titanium instrument with HyFlex EDM, WaveOne Gold, and OneShape single‐file NiTi instruments.HyFlex EDM files were found to have statistically significantly higher cyclic fatigue resistance than Reciproc Blue, WaveOne Gold, and OneShape files (P < .05).Reciproc Blue showed statistically higher resistance to static cyclic fatigue compared with WaveOne Gold files (P < .05).In vivo studies are needed in order to determine the clinical performance of Reciproc Blue files.

Apically Extruded Debris after Retreatment Procedure with Reciproc, ProTaper Next, and Twisted File Adaptive Instruments

Introduction The aim of this study was to compare the amount of debris extruded from the apex during retreatment procedures with ProTaper Next (PTN; Dentsply Maillefer, Ballaigues, Switzerland), Reciproc (RCP; VDW, Munich, Germany), and Twisted File Adaptive (TFA; SybronEndo, Orange, CA) files and the duration of these retreatment procedures. Methods Ninety upper central incisor teeth were prepared and filled with gutta‐percha and AH Plus sealer (Dentsply DeTrey, Konstanz, Germany) using the vertical compaction technique. The teeth were randomly divided into 3 groups of 30 for removal of the root filling material with PTN, RCP, and TFA files. The apically extruded debris was collected in preweighed Eppendorf tubes. The time for gutta‐percha removal was recorded. Data were statistically analyzed using Kruskal‐Wallis and 1‐way analysis of variance tests. Results The amount of debris extruded was RPC > TFA > PTN, respectively. Compared with the PTN group, the amount of debris extruded in the RPC group was statistically significantly higher (P < .001). There was no statistically significant difference among the RCP, TFA, and PTN groups regarding the time for retreatment (P > .05). Conclusions Within the limitations of this in vitro study, all groups were associated with debris extrusion from the apex. The RCP file system led to higher levels of apical extrusion in proportion to the PTN file system. In addition, there was no significant difference among groups in the duration of the retreatment procedures. HighlightsWe compare the amount of debris extruded from the apex during retreatment procedures with ProTaper Next, Reciproc, and Twisted File Adaptive files.Compared with the ProTaper Next group, the amount of debris extruded in the Reciproc group was statistically higher.There was no statistically significant difference among the groups regarding the time for retreatment.In vivo studies are needed in order to determine the clinical importance of apically extruded debris of tested systems.

The Effects of Endodontic Access Cavity Preparation Design on the Fracture Strength of Endodontically Treated Teeth: Traditional Versus Conservative Preparation

Introduction: The aim of this study was to compare the fracture strengths of mandibular molar teeth prepared using traditional endodontic cavity (TEC) and conservative endodontic cavity (CEC) methods and restored using SDR (Dentsply Caulk, Milford, DE) and EverX Posterior (GC Dental, Tokyo, Japan) base composite materials. Methods: A hundred mandibular first molar teeth were randomly divided into 5 groups. In group 1 (the control group), samples were kept intact. In group 2, TECs were prepared, and the samples were restored with EverX Posterior and composite resin. In group 3, CECs were prepared, and the samples were restored with EverX Posterior and composite resin. In group 4, TECs were prepared, and the samples were restored with SDR and composite resin. In group 5, CECs were prepared, and the samples were restored with SDR and composite resin. This load was applied on the samples at 1‐mm/min speed using a 6‐mm round‐head tip until fracture. The forces resulting in fracture were recorded in newton units. The data were analyzed using Kruskal‐Wallis and Pearson correlation tests at a 5% significance level. Results: The fracture strengths of the samples in the control group were significantly higher than the experimental groups (P < .05). There was no statistically significant difference in the endodontic access cavities prepared used the TEC and CEC methods and restored using the same composite base material (P > .05). Conclusions: CEC preparation did not increase the fracture strength of teeth with class II cavities compared with TEC preparation. The fracture strength of teeth restored with the SDR bulk‐fill composite was higher than that of teeth restored with EverX Posterior. HIGHLIGHTSThe effect of traditional and conservative access cavity preparation and base material selection on fracture strength of endodontically treated teeth was evaluated.The fracture strengths of the samples in the control group were significantly higher than those in the experimental groups did (P < .05).There was no statistically significant difference in the endodontic access cavities prepared used the TEC and CEC methods and restored using the same composite base material (P > .05).

Cyclic Fatigue of Reciproc and Reciproc Blue Nickel-titanium Reciprocating Files at Different Environmental Temperatures

Introduction The aim of the present study was to investigate the impact of ambient temperature on the life span of nickel‐titanium (NiTi) files. Methods Cyclic fatigue testing of NiTi instruments was performed in a stainless steel artificial canal. During the experiment, 4 different temperatures (0°C, 20°C, 35°C, and 39°C) were used in a thermostatic bath controlled using electronic and infrared controls. Eighty R25 Reciproc Blue (VDW, Munich, Germany) and 80 R25 Reciproc (VDW) instruments were reciprocated in the artificial canal until fracture occurred, and the time to fracture and the length of the fractured fragment were recorded. The phase transformation temperature for 3 instruments of each type was analyzed by differential scanning calorimetry. One‐way analysis of variance and Bonferroni tests were used to statistically analyze the data at a 5% significance level (P < .05). Results Reciproc Blue instruments were significantly more resistant to cyclic fatigue than Reciproc at all the temperatures tested (P < .05). Fatigue resistance was proportionally higher as the environmental temperature decreased (0°C > 20°C > 35°C > 39°C). No signiÜcant difference was registered for the length of the fractured fragment of both instruments tested at all temperatures tested (P > .05). Conclusions Blue alloy significantly increases the cyclic fatigue resistance of Reciproc files compared with M‐Wire alloy. Temperature significantly affects the life span of NiTi files. When the ambient temperature increases between 0°C and 35°C, the fatigue resistance of the files statistically decreases. HighlightsEnvironmental temperature may drastically affect the cyclic fatigue resistance of nickel‐titanium files.Reciproc Blue instruments were statistically more resistant to cyclic fatigue than Reciproc M‐Wire at all the temperature conditions tested.The fatigue resistance of both file types tested was proportionally higher as the environmental temperature decreased (0°C > 20°C > 35°C > 39°C), with differences ranging from 35%–421%.The 2 different instruments analyzed displayed different transformation temperatures.

Effect of adaptive motion on cyclic fatigue resistance of a nickel titanium instrument designed for retreatment

Objectives The aim of this study was to evaluate the cyclic fatigue resistance of the ProTaper Universal D1 file (Dentsply Maillefer) under continuous and adaptive motion. Materials and Methods Forty ProTaper Universal D1 files were included in this study. The cyclic fatigue tests were performed using a dynamic cyclic fatigue testing device, which had an artificial stainless steel canal with a 60° angle of curvature and a 5 mm radius of curvature. The files were randomly divided into two groups (Group 1, Rotary motion; Group 2, Adaptive motion). The time to failure of the files were recorded in seconds. The number of cycles to failure (NCF) was calculated for each group. The data were statistically analyzed using Students t-test. The statistical significant level was set at p < 0.05. Results The cyclic fatigue resistance of the adaptive motion group was significantly higher than the rotary motion group (p < 0.05). Conclusion Within the limitations of the present study, the ‘Adaptive motion’ significantly increased the resistance of the ProTaper Universal D1 file to cyclic facture.

The effects of autoclave sterilization on the cyclic fatigue resistance of ProTaper Universal, ProTaper Next, and ProTaper Gold nickel-titanium instruments

Objectives It was aimed to compare the cyclic fatigue resistances of ProTaper Universal (PTU), ProTaper Next (PTN), and ProTaper Gold (PTG) and the effects of sterilization by autoclave on the cyclic fatigue life of nickel-titanium (NiTi) instruments. Materials and Methods Eighty PTU, 80 PTN, and 80 PTG were included to the present study. Files were tested in a simulated canal. Each brand of the NiTi files were divided into 4 subgroups: group 1, as received condition; group 2, pre-sterilized instruments exposed to 10 times sterilization by autoclave; group 3, instruments tested were sterilized after being exposed to 25%, 50%, and 75% of the mean cycles to failure, then cycled fatigue test was performed; group 4, instruments exposed to the same experiment with group 3 without sterilization. The number of cycles to failure (NCF) was calculated. The data was statistically analyzed by using one-way analysis of variance and post hoc Tukey tests. Results PTG showed significantly higher NCF than PTU and PTN in group 1 (p < 0.05). Sterilization significantly increased the NCF of PTN and PTG (p < 0.05) in group 2. PTN in group 3 had significantly higher cyclic fatigue resistance than PTN group 4 (p < 0.05). Also, significantly higher NCF was observed for PTG in group 2 than in groups 3 and 4 (p < 0.05). Conclusions PTG instrument made of new gold alloy was more resistant to fatigue failure than PTN and PTU. Autoclaving increased the cyclic fatigue resistances of PTN and PTG.

Comparison of the antimicrobial activity of direct pulp-capping materials: Mineral trioxide aggregate-Angelus and Biodentine.

Purpose: To compare the antimicrobial activity of the tricalcium silicate-based Biodentine (BD) and mineral trioxide aggregate (MTA)-Angelus cement with the aid of agar diffusion test. Materials and Methods: Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Enterococcus faecium were inoculated in the Brucella liquid medium and were incubated at 37°C for 24 h. Thereafter, 100 >μl of the liquid culture of bacteria inoculated in the Mueller-Hinton agar with spread plate technique. Petri plates were dried in room temperature. For every microorganism, 3 petri plates were prepared (12 in total). In the medium, in every petri plate, 2 holes with 5 mm diameter and 2 mm depth were made. Afterward, BD and MTA-Angelus were filled into these holes under aseptic conditions according to the instructions of the manufacturing company. Then, the plates were kept in the incubator at 37°C for 24 h, and the diameters of the inhibition zones were measured with a digital caliper. Results: Inhibition zones formed by BD against E. coli and S. aureus were significantly larger than the zones formed by MTA-Angelus (P < 0.05). However, the inhibition zones formed by MTA-Angelus against P. aureus and E. faecium were larger than the zones formed by BD (P < 0.05). Conclusion: Within the limits of the present study, tricalcium silicate-based MTA-Angelus and BD have antimicrobial activity against E. coli, S. aureus, P. aureus, and E. faecium.

The effect of root canal preparation on the surface roughness of WaveOne and WaveOne Gold files: atomic force microscopy study

Objectives To examine the surface topography of intact WaveOne (WO; Dentsply Sirona Endodontics) and WaveOne Gold (WOG; Dentsply Sirona Endodontics) nickel-titanium rotary files and to evaluate the presence of alterations to the surface topography after root canal preparations of severely curved root canals in molar teeth. Materials and Methods Forty-eight severely curved canals of extracted molar teeth were divided into 2 groups (n = 24/each group). In group 1, the canals were prepared using WO and in group 2, the canals were prepared using WOG files. After the preparation of 3 root canals, instruments were subjected to atomic force microscopy analysis. Average roughness and root mean square values were chosen to investigate the surface features of endodontic files. The data was analyzed using one-way analysis of variance and post hoc Tamhanes tests at 5% significant level. Results The surface roughness values of WO and WOG files significantly changed after use in root canals (p < 0.05). The used WOG files exhibited higher surface roughness change when compared with the used WO files (p < 0.05). Conclusions Using WO and WOG Primary files in 3 root canals affected the surface topography of the files. After being used in root canals, the WOG files showed a higher level of surface porosity value than the WO files.

Effect of Sodium Hypochlorite and EDTA on Surface Roughness of HyFlex CM and HyFlex EDM Files

The aim of the present study was to compare the effect of exposure to sodium hypochlorite (NaOCl) and ethylenediaminetetraacetic acid (EDTA) on the surface topography and roughness of HyFlex controlled memory (CM) and HyFlex electrical discharge machining (EDM) using atomic force microscopy (AFM). Twenty HyFlex EDM (25/.08) and 20 HyFlex CM (25/.06) files were divided into five groups (n = 4). One group served as a negative control group. The files in the other groups were exposed to 5.25% NaOCl and 17% EDTA solutions at 37°C for 5 and 10 min, respectively, and examined using AFM after each exposure. The data were analyzed using one‐way ANOVA test. The lowest values were observed in the control group of HyFlex EDM files (p < .05). The highest values were observed in the HyFlex EDM and HyFlex CM files immersed in EDTA for 10 min (p < .05). In conclusion, the tested irrigants had a significant negative effect on the surface porosity of NiTi files.

Push-out bond strength of intra-orifice barriermaterials: Bulk-fill composite versus calcium silicate cement

Background. The aim of this study was to compare the push-out bond strengths of calcium silicate-based ProRoot MTA and Biodentine cements and SureFil SDR and EverX Posterior bulk-fill composite resins. Methods. Twenty-four single-rooted maxillary central incisors were sectioned below the cementoenamel junction, and the root canals were instrumented using rotary files. Thereafter, a parallel post drill was used to obtain a standardized root canal dimension. The roots were randomly assigned to one of the following groups with respect to the intra-orifice barrier used: ProRoot MTA; Biodentine; SureFil SDR; EverX Posterior. Five 1-mm-thick sections were obtained from the coronal aspect of each root. Push-out bond strength testing was performed and data were analyzed with Kruskal-Wallis and post hoc Dunn tests (P<0.05). Results. SureFil SDR and EverX Posterior bulk-fill composite resins’ bond strengths were significantly higher than ProRoot MTA and Biodentine calcium silicate cements. However, no statistically significant differences were observed between bulk-fill composite resins values and calcium silicate cement values. Conclusion. Within the limitations of present study, calcium silicate-based ProRoot MTA cement’s push-out bond strength was lower than those of Biodentine, SureFil SDR and EverX Posterior materials.