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Aim: To evaluate the shaping ability of the single‐file XP‐endo Shaper system (XP‐S; FKG Dentaire, La Chaux‐de‐Fonds, Switzerland) employing a different working time and of the multiple‐file ProTaper Next system (Dentsply Sirona, Ballaigues, Switzerland) using micro‐computed tomography (micro‐CT) technology. Methodology: Twenty long oval‐shaped canals in mandibular incisors were matched anatomically and scanned by micro‐CT (Skyscan 1172; Bruker micro‐CT, Kontich, Belgium). The canals were divided into two groups (n = 10) according to the canal preparation protocol: XP‐endo Shaper (XP‐S) with an extra 45 s of instrumentation and ProTaper Next (PTN X4). The images recorded before and after preparation were evaluated for morphometric measures of volume, surface area, structure model index and untouched walls. The data were compared statistically (Student's t‐test for homogenous variances and Mann–Whitney test) between the two groups (XP‐S and PTN X4) at α = 5%. Results: Root canal preparation significantly increased all parameters (volume, surface area, structure model index and untouched walls) tested in each group (P < 0.05). There was no significant difference (P > 0.05) in the percentage increase of volume (107.50%–93.13%), surface area (27.74%–29.68%) or untouched canal wall (13.08%–11.74%) between XP‐S and PTN X4, respectively. Conclusions: The XP‐endo Shaper system (single‐file) with an extra 45 s of instrumentation and the ProTaper Next system (multiple files) had a similar root canal shaping ability. Neither technique was able to fully prepare the long oval‐shaped canals of mandibular incisors. [ABSTRACT FROM AUTHOR]

Abstract: Aim: To determine the effect of photon‐initiated photoacoustic streaming (PIPS) on the extrusion of debris using multiple‐file (ProTaper Next‐PTN) and single‐file (One Shape‐OS) continuous rotary systems in curved canals in human molar teeth. Methodology: Sixty extracted maxillary first molar teeth with curved mesial roots, mature apices and of similar lengths were selected. Teeth having canals with apical diameters larger than size 15 were discarded. The teeth were randomly divided into four experimental groups (n = 15 teeth per group) according to the file used and irrigation systems: (i) OS with PIPS with a 2940 nm Er:YAG laser (0.3 W, 15 Hz, and 20 mJ), (ii) OS with conventional needle irrigation (CNI) with a 27‐G needle, (iii) PTN with PIPS and (iv) PTN with CNI. The PIPS and CNI was applied during each file change for 20 s. Total irrigation and activation time was 1 min, and a total volume of 7.5 mL of bidistilled water was used as the irrigant. The apically extruded debris was collected into pre‐weighed Eppendorf tubes. The tubes were then stored in an incubator at 70 °C for 5 days. The weight of dry extruded debris was assessed by subtracting the initial weight of the tube from the final weight. The results were analysed statistically using one‐way analysis of variance and Tukey's post hoc tests. Bonferroni correction was used to compare the groups. Results: The PIPS irrigation technique was associated with significantly more debris extrusion than the CNI system (P < 0.05). The single‐file (One Shape‐OS) rotary system was associated with more debris than the multiple‐file (ProTaper Next‐PTN) rotary systems when the same irrigation system was used (P > 0.05). The total amount of debris extruded apically by PIPS activation was significantly greater than that by CNI (P < 0.05). Conclusions: All file and irrigation systems extruded debris apically. PIPS activation was associated with significantly more extrusion debris in curved canals compared with no activation. [ABSTRACT FROM AUTHOR]

Aim To assess and compare the mechanical properties of TRUShape ( TRS) with several nickel-titanium rotary instruments. Methodology Cyclic fatigue, torsional resistance, flexibility and surface microhardness of TRS (size 25, 0.06v taper), ProTaper Next X2 ( PTN X2, size 25, 0.06 taper), ProTaper Gold ( PTG F2; size 25, 0.08 taper) and ProTaper Universal ( PTU F2; size 25, 0.08 taper) instruments were evaluated. The topographical structures of the fracture surfaces of instruments were assessed using a scanning electron microscope. The cyclic fatigue resistance, torsional resistance and microhardness data were analysed using one-way analysis of variance ( anova) and Tukey's post hoc tests. The fragment length and bending resistance data were analysed statistically with the Kruskal-Wallis H-test and Mann-Whitney U-tests. The statistical significance level was set at P < 0.05. Results PTN and PTG instruments revealed significantly higher resistance to cyclic fatigue than TRS and PTU instruments ( P < 0.001). PTN instruments revealed significantly higher torsional resistance compared with the other instruments ( P < 0.001). PTG instrument had significantly higher flexibility than the other tested brands ( P < 0.05). However, for microhardness, the PTU had significantly higher surface microhardness values compared with other tested brands ( P < 0.05). Conclusions TRS instruments had lower resistance to cyclic fatigue and lower flexibility compared with PTG and PTN instruments. TRS, PTG and PTU instruments had lower resistance to torsional stress than PTN instruments. TRS and PTG instruments had comparable surface microhardness. [ABSTRACT FROM AUTHOR]

Aim To compare the centring ability and transportation of ProTaper Next (PTN), ProTaper Universal (PTU), Race 123 and RevoS using micro-computed tomography (μCT). Methodology Sixty mesial root canals of thirty mandibular molars were divided virtually into coronal, middle and apical thirds, and two reproducible reference points were marked on the external surface of the roots creating 360 measurement points. Samples were randomly allocated to four NiTi instrumentation techniques. Group 1: PTU up to F2 ( n = 16), group 2: PTN up to X2 ( n = 18), group 3: Race 123 up to T2 ( n = 12) and group 4: RevoS up to SU ( n = 14). To reproduce a clinical situation, samples were prepared on a phantom head using a surgical operating microscope. Samples were scanned pre- and postoperatively using μCT to compare and calculate the transportation and centring ratio. The data were analysed using parametric statistics. Results In the coronal and middle third of the root canals, there were significant differences in centring between PTN and PTU (coronal P < 0.001), PTN and RevoS (coronal P < 0.001), Race and PTU (coronal P < 0.01), Race and RevoS (coronal P < 0.01), PTN and RevoS (middle P < 0.01) and Race and RevoS ( P < 0.05). Furthermore, there were significant differences in centring between PTN root canal preparations and other instruments in the apical third (PTN and PTU P < 0.01, PTN and Race P < 0.001, PTN and RevoS P < 0.001). In terms of transportation, in the coronal third, there was a significant difference between PTN and PTU ( P < 0.05). However, there were no significant differences between the other instruments. In the middle third, significant differences were observed between PTN and PTU ( P < 0.05), PTN and RevoS ( P < 0.05), Race and PTU ( P < 0.05) and Race and RevoS ( P < 0.05). However, there were no significant differences between other systems. There was no significant difference in terms of transportation between the four systems in the apical third. Conclusions ProTaper Next prepared more centred root canal shapes when compared with Race, PTU and RevoS. In the coronal and middle third of the root canals, the differences in centring between PTN and PTU/RevoS were significant. PTN root canal preparations were more centred than those achieved with all other instruments in the apical third. [ABSTRACT FROM AUTHOR]

Aim To investigate the influence of interrupted rotation on cyclic fatigue of two nickel-titanium rotary instruments. Methodology Cyclic fatigue of 300 new ProTaper Next size X1; X2 and Mtwo size 10, .04 taper; size 15, .05 taper; size 20, .06 taper and size 25, .06 taper instruments was tested in continuous or interrupted rotation. Fifty files of the same brand and size were randomly assigned to five groups ( n = 10). Group 1 instruments were tested in continuous rotation; groups 2 and 3 in paused rotation for 1 s every 10 or 20 s, respectively; groups 4 and 5 in interrupted rotation for 5 s every 10 or 20 s, respectively. Cyclic fatigue was expressed in time to fracture (TtF) in an artificial canal with 60° angle and 5 mm radius of curvature. The fracture surface was examined with a scanning electron microscope ( SEM). Data were evaluated by two-way analysis of variance. Results Cyclic fatigue of groups 2 and 4 of ProTaper Next X2 and Mtwo size 25, .06 taper was significantly lower than that of group 1 of the same instruments ( P < 0.01). ProTaper Next X2 had significantly reduced cyclic fatigue in groups 3 and 5 ( P < 0.05). No differences were found by interrupting the rotation for 1 or 5 s in all instruments ( P > 0.05). Fatigue of other instruments was not affected by interrupted rotation ( P > 0.05). Conclusions Interrupted rotation reduced cyclic fatigue resistance of ProTaper Next X2 and Mtwo size 25, .06 taper, especially when a higher number of interruptions was performed. [ABSTRACT FROM AUTHOR]

Aim To evaluate the amount of apically extruded debris after root canal instrumentation with ProTaper Next and HyFlex instruments in curved root canals. Methodology Forty extracted mandibular first molar teeth with curved mesial roots and of similar lengths were instrumented using ProTaper Next or HyFlex instruments. The extruded debris was collected into pre-weighed Eppendorf tubes. The tubes were stored in an incubator at 68 °C for 5 days. The tubes were weighed to obtain the final dry weight of the extruded debris. The weight of the extruded debris was determined by subtracting the initial weight from the final weight. Distribution of data was determined by Shapiro-Wilk test. Continuous variables were compared with the Independent Sample t-test or Mann-Whitney U-test. The significance level was set at P = 0.05. Results Both instruments were associated with apical debris extrusion. The HyFlex group had significantly less debris extrusion than the ProTaper Next group ( P = 0.014). Conclusion HyFlex CM was associated with significantly less apical extrusion than ProTaper Next. [ABSTRACT FROM AUTHOR]

Aim To compare the cyclic fatigue resistance of ProTaper Gold ( PTG, Dentsply Tulsa Dental Specialities, Tulsa, OK, USA), ProTaper Next ( PTN, Dentsply Tulsa Dental Specialities) and ProTaper Universal ( PTU, Dentsply Tulsa Dental Specialities) instruments at different levels. Methodology A total of 72 files were used to evaluate the cyclic fatigue of PTU (F2), PTN (X2) and PTG (F2) at 5 mm ( n = 12) and 8 mm ( n = 12) from the tip in 3-mm-radius steel canals with a 60° angle of curvature. The time to fracture was recorded. The Kolmogorov-Smirnov test was used to assess the normality of the samples distribution, and the statistical analysis was performed using the independent sample t-test ( P < 0.01). Results Significant differences were found amongst the instruments 5 mm from the tip ( P < 0.01). The PTG files had the highest CF resistance, and the PTN files displayed greater CF resistance than the PTU files. No significant differences were found between the PTG and PTN files 8 mm from the tip ( P > 0.01). The PTG and PTN files demonstrated greater CF resistance than the PTU files ( P < 0.01). Conclusions The PTG instruments were the most resistant 5 and 8 mm from the tip; however, at 8 mm, there was no difference between the PTG and PTN instruments. The PTU files had the lowest CF resistance at all levels. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Aim To assess and compare the amount of extruded debris after canal preparation using ProTaper Universal and ProTaper Next files. Methodology Forty extracted mandibular premolars with single canals and of similar lengths were instrumented using the ProTaper Universal F3 or the ProTaper Next X3. The extruded debris during instrumentation was collected into pre-weighed Eppendorf tubes. The tubes were stored in an incubator for 5 days. The tubes were weighed to obtain the final dry weight of the extruded debris. The amount of apically extruded debris was calculated by subtracting the initial weight of the tube from the final weight. The distribution of the data was examined using the Shapiro-Wilks test. Continuous variables were compared with an independent-samples t-test for two groups. Results All specimens were associated with apical debris extrusion. The ProTaper Universal group produced a significantly greater amount of debris extrusion ( P < 0.001). The lowest and highest amounts of debris for PTU and PTN groups were recorded as 0.00117-0.00165 g and 0.00017-0.00067 g, respectively. Conclusion ProTaper Next files was associated with significantly less extruded apical debris when compared to ProTaper Universal files. [ABSTRACT FROM AUTHOR]

Aim To compare the shaping ability of ProTaper Next, i Ra Ce and Hyflex CM rotary NiTi files during the preparation of severely curved root canals in extracted human molar teeth. Methodology Sixty mandibular molars with mesio-buccal canals having angles of curvature ranging from 25° to 35° were divided according to the instrument used into three groups of 20 teeth each: group PTN (ProTaper Next), group IR (i Ra Ce) and group HF (Hyflex CM). Using standardized pre- and post-instrumentation radiographs, straightening of canal curvature was determined using image analysis software. A double-digital standardized radiographic technique was used to determine apical transportation 0.5 mm from the working length (1.5-mm coronal of 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's test, and significance was set at P < 0.05. Results During root canal preparation, no instruments fractured. The use of PTN resulted in significantly greater canal straightening than IR and HF ( P < 0.05), with no significant differences between IR and HF ( P > 0.05). There were no significant differences between the three groups with respect to apical transportation ( P > 0.05). IR and HF were significantly faster than PTN ( P < 0.05), with no significant differences between IR and HF ( P > 0.05). Conclusions Under the conditions of this study, PTN, IR and HF respected original canal curvature well and were safe to use. [ABSTRACT FROM AUTHOR]

Aim To compare the cyclic fatigue resistance of Pro- Taper Next files (PTN; Dentsply Maillefer, Ballaigues, Switzerland) with Twisted Files (TF; SybronEndo, Orange, CA, USA), HyFlex CM (HF; ColténeEndo/ Whaledent, Inc, Cuyahoga Falls, OH, USA) and Pro- Taper Universal (PT; Dentsply Maillefer). Methodology Size 25, .06 taper for PTN X2, TF, HF and PT F1 size 20, .07 taper were rotated in simulated canals until failure, and the number of cycles to failure (NCF) was recorded to evaluate their cyclic fatigue resistance. A scanning electron microscope was used to characterize the topographic features of the fracture surfaces of broken files. The data of the NCF and fragment length values were analysed statistically using one-way analysis of variance and Tukey post hoc tests. Statistical significance level was set at P < 0.05. Results Twisted Files had a significantly higher resistance to cyclic fatigue than the other instruments (P < 0.05). No significant difference was found in NCF between PTN and HF (P > 0.05); however, there was a significant difference (P < 0.05) of both these systems with PT, which exhibited the lowest mean NCF. The ranking in the NCF values was: TF > PTN > HF > PT. The fracture cross-sections of all brands revealed similar fractographic features, including crack origins, fatigue zone and an overload fast fracture zone. Conclusions The new ProTaper Next had greater resistance to cyclic fatigue compared with ProTaper and HyFlex CM but not the Twisted Files. [ABSTRACT FROM AUTHOR]