Evaluation of cyclic fatigue behavior of RACE EVO rotary Files: In-vitro comparative study

Introduction

Comparative evaluation of the newly introduced; RACE EVO file system to the currently well-performing file systems like HyFlex EDM OneFile, Vortex Blue, ProTaper Gold (PTG) with regards to the cyclic fatigue resistance.

Materials

&Methods.The endodontic rotary files under evaluation were segregated into four groups as follows:; RACE EVO, PTG, Vortex Blue, and HyFlex EDM OneFile. A detailed physical analysis of the cyclic fatigue resistance was performed in 15 files of each type (n = 60). Under the test conditions of 37 °C the test samples were subjected to continuous motion at the manufacturer recommended speed within an artificial curved canal until it fractured. For all the test samples, with the recording of time of fracture, calculation was done for number of cycles to fracture (NCF). In addition, the length of the fractured segment was determined. The fractured surface was further evaluated with scanning electron microscopic (SEM) images.

Results

Highest significance for NCF was seen in HyFlex EDM OneFile followed by the Vortex Blue, PTG, and; RACE EVO (p < 0.05) by analyzing the data statistically. Significant differences among the lengths of the fractured segments were evident among tested files, ranging between 4.73 and 6.3 mm (p < 0.05) with HyFlex EDM OneFile uniquely differentiating from the others showing the fracture at 6.3 mm. The common features of cyclic fatigue failure was further substantiated by SEM images.

Conclusions

Compared to the HyFlex EDM OneFile, Vortex Blue, and PTG files; RACE EVO demonstrated significantly lower resistance to cyclic fatigue.

An Appraisal on Newer Endodontic File Systems: A Narrative Review

AIM

This narrative review aims to explore and elicit the newer endodontic file systems used for root canal treatments.

BACKGROUND

The primary goals of endodontic therapy continue to be the mechanical enlargement and shaping of the intricate endodontic root canal systems to aid in disinfection. Nowadays endodontists have access to a wide range of endodontic file systems for root canal preparations with various design characteristics and benefits.

REVIEW RESULTS

ProTaper Ultimate (PTU) files' tip have a triangular convex cross-section, an offset mass of rotating design, a maximum flute diameter of 1.0 mm, and are constructed of gold wire, hence, commonly applied in conditions with restricted accessibility or an extremely curved canal. TruNatomyhas advantages over other cutting-edge file systems like maximum flute diameter of the corona, reduced distance between active cutting flutes, and shorter handles in comparison to SX instruments. In comparison to PTU files, ProTaper Gold (PTG) files are noticeably more elastic and fatigue-resistant. Compared to files in the F1-F3 range, size S1 and S2 files have a significantly longer fatigue life. MicroMega One RECI is more resistant to cyclic fatigue because of its heat treatment and reciprocating action and the C-wire heat treatment of the former gives it flexibility and controlled memory, enabling the prebending of the file. The RECIPROC blue demonstrated enhanced flexibility, increased fatigue resistance, and lower microhardness while maintaining the same surface qualities.

CONCLUSION

As per the necessity and requirement on case to case basis, every endodontic file system has advantages and disadvantages as mentioned in this narrative review. According to the need, an endodontist can select the file system which is required specifically. Although several studies are comparing these various systems in the literature, this narrative review aims to give the clinician a summary of some recently launched endodontic rotary file systems available in the market and their clinical uses.

CLINICAL SIGNIFICANCE

As per the priority and need of the case, whether removal and extrusion of debris, reduction of micro-organisms, keeping canal anatomy, and cutting efficiency, a specific required file system can be utilized.

Effect of NaOCl and EDTA irrigating solutions on the cyclic fatigue resistance of EdgeTaper Platinum instruments

BACKGROUND

To compare the solution on the cyclic fatigue resistance of EdgeTaper Platinum (ETP) instruments with that of ProTaper Gold (PTG) in the presence of ethylenediaminetetraacetic acid (EDTA) or sodium hypochlorite (NaOCl) irrigating solutions.

METHODS

Sixty PTG and 60 ETP instruments with the same size (#25) and taper (8%) were tested under 17% EDTA, 5.25% NaOCl, or distilled water (n = 20 each). Cyclic fatigue was tested using artificial canals that were milled in stainless steel blocks using a laser micromachining technique. The canals had a curvature angle of 60 and a curvature radius of 5 mm. The center of maximum curvature was set at 5 mm from the instrument tip. The block of artificial canals was stabilized inside a container that was filled with one of the tested solutions. The temperature was fixed at 37 °C with a tolerance limit of 1 °C. The number of cycles to fracture (NCF) was calculated and the fractured surfaces were examined using a scanning electron microscope. All statistical analyses were performed using SPSS software Version 20 (IBM-SPSS Inc., Chicago, IL) at a confidence level of 95%.

RESULTS

ETP showed higher NCF than PTG in any of the tested solutions (P < 0.05). Within each group, NaOCl drastically decreased the NCF compared to water and EDTA (P < 0.05) and changing the solution from distilled water to EDTA did not affect the fatigue resistance (P > 0.05).

CONCLUSIONS

ETP showed improved cyclic fatigue performance compared to PTG in all tested irrigating solutions. EDTA can be used in combination with NiTi instruments during canal instrumentation without compromising the cyclic fatigue resistance of PTG and ETP instruments. However, NaOCl drastically decreased the NCF.

Shaping ability of modern Nickel-Titanium rotary systems on the preparation of printed mandibular molars

Introduction

This study aimed to evaluate the shaping ability of TruNatomy (Dentsply Maillefer, Ballaigues, Switzerland), VDW.ROTATE (VDW GmbH, Munich, Germany) and ProTaper Gold (Dentsply Maillefer, Ballaigues, Switzerland) during the preparation of resin-printed mandibular molar mesial root canals.

Materials and Methods

Thirty-three printed resin-based mandibular mesial roots with two canals were obtained from extract tooth cone-beam computed tomography (CBCT) image. The printed teeth were divided into three groups (n = 11) according to the system used for root canal preparation: TruNatomy, VDW.ROTATE, and ProTaper Gold. The specimens were scanned using CBCT imaging before and after root canal preparation. Then images were registered using a dedicated software and changes in the canal area, volume, untouched canal surface, and the maximum and minimum dentin wall wear were calculated.

Statistical Analysis Used

Data were statistically analyzed using Shapiro-Wilk for normality, one-way ANOVA, and Tukey or Kruskal-Wallis H tests with alpha set at 5%.

Results

No differences were observed for changes in the canal area, volume, untouched canal surface area, and minimum dentine wall wear parameters for the whole canal length (P > 0.05). The mean of untouched canal surface area for the TruNatomy, VDW.ROTATE, and ProTaper Gold was 40%, 44%, and 44%, respectively. The maximum dentine wall wear was significantly lower in the ProTaper Gold group than in the TruNatomy and VDW.ROTATE groups (P < 0.05).

Conclusions

TruNatomy, VDW.ROTATE, and ProTaper Gold systems showed similar shaping ability in printed resin-based mandibular mesial roots without clinically significant errors. A large amount of untouched canal surface area was observed for all systems.

Comparative Evaluation of Canal-shaping Abilities of RaceEvo, R-Motion, Reciproc Blue, and ProTaper Gold NiTi Rotary File Systems: A CBCT Study

AIM

To evaluate the canal transportation, canal-centering ability, and touched and untouched surfaces of the root canal dentin after instrumentation with various newer file systems in continuous rotation and reciprocating motion using cone-beam computed tomography (CBCT) imaging.

MATERIALS AND METHODS

This in vitro study was conducted on one hundred recently extracted human mandibular molars, which were selected and instrumented using the following rotary NiTi file systems: RaceEvo, R-Motion, Reciproc Blue, and ProTaper Gold. The canal preparations for all four (04) experimental groups were done according to the manufacturer's instructions; the CBCT imaging was done for all the teeth compared at different levels of 2 mm, 5 mm, 8 mm from the apex, before and after the canal preparations. The data thus collected were evaluated for variation where p <0.05 was calibrated as significant using "ANOVA and Mann-Whitney" statistical tests.

RESULT

When the file systems were compared at different levels of the canal i.e. 2 mm, 5 mm, 8 mm from the apex, we observed a statistically significant difference for all the experimental groups (p = 0.021, 0.023, 0.032) respectively for the canal transportation (CT), (p = 0.045, 0.040, 0.037) respectively for the canal centering ability (CCA), (p <0.001) respectively for the touched (TS) and untouched (US) surfaces. R-Motion showed the least CT, greater CCA, with maximum TS, and the least US dentinal surfaces in the root canal preparations followed by RaceEvo, Reciproc Blue, and ProTaper Gold.

CONCLUSION

R-Motion exhibited better canal centering ability, lower canal transportation due to its improved cutting efficiency down to the apex while preserving the dentin of the root canal walls and also exhibits lesser stress on dentin. The newer rotary file systems of R-Motion and RaceEvo described in this study could be recommended for clinical use during endodontic treatment.

CLINICAL SIGNIFICANCE

The newly introduced R-Motion and RaceEvo showed better preparations of the root canal compared to other file systems and could be used as a reliable alternative to the ProTaper file systems which is considered as the gold standard in rotary endodontics.

Evidence for reduced torsional resistance of rotary files under curved position

Objectives

The aim of this in vitro study was to investigate the torsional fatigue resistance of different rotary files in straight and curved positions at a simulated intracanal temperature.

Methods

Forty-eight size #25 files from ProTaper Universal (PTU), ProTaper Next (PTN) and ProTaper Gold (PTG) were tested for torsional resistance in both straight and curved (90 degrees) positions (n = 8 each). The experiment was conducted at a simulated intracanal temperature of 35 ± 1 °C. The torque gauge was reset before every use, and uniform torsional stress was applied by rotating the file clockwise at a speed of 40 rpm until fracture. Torque failure values were recorded, and fractured surfaces were tested using a scanning electron microscopy (SEM). Statistical analysis of the data was completed using one-way ANOVA and post-hoc test (LSD) in order to compare between the tested systems in each file position. Student’s t-test was also performed to compare between the two positions in each rotary system, and significance level was set at 5%.

Results

In the straight position, torsional resistance of PTN was significantly lower than that of PTU and PTG (p < 0.001), while the PTU and PTG had comparable results (p > 0.05). In the curved position, torsional resistance was found to be comparable among all systems (p > 0.05). Within each system, the curved position resulted in a significantly lower torsional resistance when compared to the straight position (p < 0.001). SEM examination revealed similar torsional failure behavior for all files tested under both positions.

Conclusions

Our study identified that placing files in a curved position was associated with a significant decrease in torsional resistance of all systems, and this necessitates reconsidering the torque settings proposed by the manufacturers. Whether these effects can be translated into in vivo studies remains to be investigated, and thus future studies are essential to provide confirming evidence.

[Comparison of three rotary file systems for removal of Enterococcus faecalis from infected root canals]

OBJECTIVE

To compare the efficacy of a novel rotary file system (EZ Pass) with two well-established rotary file systems(ProTaper Gold and ProTaper Next)for removal of Enterococcus faecalis from infected root canals in extracted maxillary central incisors.

METHODS

Models of root canal infection with Enterococcus faecalis were constructed in 51 extracted singlerooted maxillary central incisors.One of the incisor model with infected root canal was demineralized, sectioned, and stained with Brown & Brenn technique for microscopic observation; The remaining 50 models were randomly divided into 5 groups(n=10) for treatment with EZ Pass, ProTaper Gold, ProTaper Next, 0.9% NaCl or 2% NaOCl.Samples were collected from the infected root canals before and after the treatments to assess the percent reduction and logarithmic reduction value of CFU in the root canals.

RESULTS

The incisors with root canal infection by Enterococcus faecalis showed obvious biofilms on the surface of the root canals and massive bacterial invasion deep into the dentinal tubules, with a maximum invasion depth of about 475 μm.The percent reduction of the CFU did not differ significantly after treatments with EZ Pass, ProTaper Gold, ProTaper Next and 2% NaOCl (P > 0.05), but all these treatments resulted in significantly greater reduction than 0.9% NaCl (P < 0.01).The logarithmic reduction of CFU were comparable after treatments with EZ Pass (1.47±0.12), ProTaper Gold (1.74±0.14) and ProTaper Next (1.63±0.17;P > 0.05).

CONCLUSION

EZ Pass can significantly reduce the bacterial load in infected root canals with an equivalent bacterial elimination capacity to ProTaper Gold and ProTaper Next.

Shaping ability of ProTaper Gold, One Curve, and Self-Adjusting File systems in severely curved canals: A cone-beam computed tomography study

Aim:

The aim of the study was to evaluate and compare canal transportation (CT), centering ability (CA), and volumetric changes in severely curved canals prepared using ProTaper Gold (PTG), One Curve (OC), and Self-Adjusting File (SAF) systems via cone-beam computed tomography (CBCT).

Materials and Methods:

Sixty mesiobuccal canals of maxillary molars were selected. Pre- and postinstrumentation CBCT scans were taken in the same position. CT and CA were calculated at 1 mm, 4 mm, and 7 mm from the apex; change in volume for whole canal was measured and analyzed statistically.

Results:

SAF showed the least mean CT at all the levels with no statistically significant differences at 1 mm and 4 mm when compared to other groups while statistically significant differences were observed at 7 mm with PTG and OC. Regarding CA, SAF better maintained canal centricity than PTG and OC at all the levels assessed, though the differences were not statistically significant except at 7 mm where statistically significant difference was observed between SAF and OC. SAF removed less volume of dentin followed by PTG and the highest removal was shown by OC.

Conclusion:

SAF showed promising behavior with the least CT, most centered preparation, and minimal dentin removal.

Apically extruded debris associated with ProTaper Next, ProTaper Gold and TruNatomy systems: An in vitro study

Background. This research aimed to investigate and compare the amount of apically extruded debris after root canal preparation using ProTaper Next, ProTaper Gold, and TruNatomy systems. Methods. Forty-five extracted mandibular premolar teeth with single canals with similar lengths were used. The root canals were prepared using ProTaper Next (Dentsply Maillefer, Ballaigues, Switzerland), ProTaper Gold (Dentsply Maillefer, Ballaigues, Switzerland), or TruNatomy (Dentsply Maillefer, Ballaigues, Switzerland) files. Apically extruded debris during preparation was gathered into preweighed Eppendorf tubes. Then the Eppendorf tubes were incubated at 70°C for five days. The Eppendorf tubes were weighed again to determine their final weight plus the extruded debris. Results. The TRN system resulted in significantly less debris extrusion than the PTN system (P <0.05). There was no significant difference between the PTN and PTG groups and between the PTG and TRN groups (P >0.05). Conclusion. All the instrumentation systems caused apical extrusion of debris. However, the TRN system resulted in significantly less debris extrusion than the other systems.

Comparative evaluation of canal transportation, centering ability, and dentin removal between ProTaper Gold, One Curve, and Profit S3: An in vitro study

Aim:

The aim of the study was to compare the canal transportation, centering ability, and dentin removal of Profit S3 (PS3), One Curve (OC), and ProTaper Gold (PTG) systems using cone-beam computed tomography (CBCT).

Materials and Methods:

Thirty extracted human single-rooted premolars were used in the present study. Preinstrumentation scanning of all the teeth in arch form was taken using CBCT. To increase standardization, crowns were removed and only teeth measuring 16 mm were included in the study. The samples were randomly divided into three groups, with ten samples in each group; Group I was instrumented with PS3, Group II was instrumented with OC, and Group III – PTG. Postinstrumentation scans were performed, and the two scans were compared to determine canal transportation, centering ability, and dentin removal at 3, 6, and 9 mm, from the apex.

Statistical Analysis:

One-way-ANOVA and the independent t-test were done for the pairwise comparison. The significance level was set at P = 0.05; statistical analysis was performed with SPSS statistics version 20.0 (SPSS Inc., Chicago, IL, USA).

Results:

The mean canal centering ratio and canal apical transportation for PS3, OC and PTG show no statistical difference (P > 0.05). The mean value of dentin removal showed a statistically significant difference between the three groups (P < 0.05). PS3 and OC rotary file showed less removal of dentin compared to PTG (P < 0.00).

Conclusion:

It was evident that PS3, OC, and PTG had no statistically significant difference when analyzed based on canal transportation and canal centering ratio. However, there was a significant difference among the three groups comparing the removal of dentin. PS3 and OC rotary file showed less removal of dentin compared to PTG.

Comparison of Obturation Removal Efficiency from Straight Root Canals with ProTaper Gold or Reciproc Blue: A Micro-Computed Tomography Study

Background: The objective was to evaluate the efficiency of ProTaper Gold (PTG) and Reciproc Blue (RB) NiTi files in obturation material removal from straight root canals assessed by micro-computed tomography. Methods: Fifty-two anterior human teeth were shaped with a PTG rotary system until F2 (25/.08). Specimens were obturated with a continuous wave of condensation technique. For retreatment, specimens were randomly distributed in two experimental groups: PTG group (F4 file) and RB (R40 file). Micro-CT scans were performed before and after retreatment procedures. The percentage of the remaining obturation material compared to the original volume was calculated, as well as the retreatment time. The presence of separated files was recorded. A descriptive analysis was carried out, and nonparametric tests were employed. Results: The mean percentages of remaining obturation material in the PTG group and the RB group were 4.14 ± 4.30% and 4.18 ± 4.29%, respectively. The mean retreatment times for the PTG and RB groups were 144 ± 51 and 163 ± 88 s, respectively. There were no statistically significant differences, neither in removal efficiency (p > 0.05) nor in retreatment time (p > 0.05), between the two groups. The coronal and middle thirds presented significantly more remaining obturation material than the apical third (p < 0.05). No file separation occurred. Conclusions: ProTaper Gold and Reciproc Blue present with comparable efficiency in removing the obturation material, with a similar mean retreatment time.

An in vitro Comparative Evaluation of Volume of Removed Dentin, Canal Transportation, and Centering Ratio of 2Shape, WaveOne Gold, and ProTaper Gold Files Using Cone-Beam Computed Tomography

Objectives

The aim of this study was to compare the shaping ability of three file systems - 2Shape (2S), WaveOne Gold (WOG), and ProTaper Gold - using cone-beam computed tomography (CBCT).

Materials and  Methods

Forty-five freshly extracted mandibular teeth were chosen and instrumented using the following brands of NiTi files: 2S, WOG, and ProTaper Gold. Pre- and post-instrumentation CBCT imaging was performed to measure mesial and distal distance of the dentin walls and calculate the volume of removed dentin, apical transportation, and centering ratio. A statistical analysis of the data was performed using independent t-test. Statistical significance was set at 5%.

Results

There were no significant differences between the 2S and WOG in terms of the total volume of removed dentin, apical transportation, and centering ratio, whereas ProTaper showed a greater significant difference when compared to 2S and WOG.

Conclusion

Both 2S and WOG maintained the original canal anatomy better and did not remove excess dentin while chemomechanical preparation as compared to ProTaper Gold. Instruments that use rotary movement achieved an effect similar to that of the reciprocating instruments in relation to change in angle. 2S which is a two-file system and WOG which is a single-file system might perform better clinically and might show enhanced shaping ability with less canal transportation and more centered preparation when compared to ProTaper Gold that is a multiple file-system.

Fatigue resistance of ProTaper gold exposed to high-concentration sodium hypochlorite in double curvature artificial canal

This study aimed to evaluate and compare the fatigue resistance of ProTaper Gold (PTG) and ProTaper Universal (PTU) in artificial single and double curvature canals in 5% sodium hypochlorite (NaOCl) at body temperature (37 °C). PTG and PTU files (size F1) were subjected to fatigue tests in two different artificial ceramic canals. The single curvature model had a 60° curvature angle with a 5 mm radius. The double curvature model had a 60° curvature angle with a 5 mm radius and a second 30° curvature with a 2 mm radius. A file segment was introduced into the artificial canal and immersed in water or 5% NaOCl at 37 °C. The total number of cycles to fracture (NCF) was recorded. Data were analyzed using t-test and linear regression analysis. The NCF of all files was significantly influenced by the type of NiTi metal alloy (P < .01), canal curvatures (P < .01), and the environmental conditions (P < .05). PTG had higher fatigue resistance than PTU files in both single and double curvature canals (P < .05). The NCF of PTU files in 5% NaOCl was shorter than that in water (P < .05). The mean length of broken PTG was significantly shorter than those of PTU files in both single and double curvature canals (P < .01). The fatigue performance of PTG is better than that of PTU in both single and double curvature. Environmental conditions may affect the fatigue behavior of PTU files with single curvature.

Cyclic fatigue, bending resistance, and surface roughness of ProTaper Gold and EdgeEvolve files in canals with single- and double-curvature

Objectives

The purpose of this study was to evaluate the cyclic fatigue, bending resistance, and surface roughness of EdgeEvolve (EdgeEndo) and ProTaper Gold (Dentsply Tulsa Dental Specialties) nickel-titanium (NiTi) rotary files.

Materials and Methods

The instruments (n = 15/each) were tested for cyclic fatigue in single- (60° curvature, 5-mm radius) and double-curved (coronal curvature 60°, 5-mm radius, and apical curvature of 30° and 2-mm radius) artificial canals. The number of cycles to fracture was calculated. The bending resistance of both files were tested using a universal testing machine where the files were bent until reach 45°. Scanning electron microscopy and x-ray energy-dispersive spectrometric analysis were used for imaging the fractured segments, while the atomic force microscope was used to quantify the surface roughness average (Ra).

Results

EdgeEvolve files exhibited higher cyclic fatigue resistance than ProTaper Gold files in single- and double-curved canals (p < 0.05) and both files were more resistant to cyclic fatigue in single-curved canals than double-curved canals (p < 0.05). EdgeEvolve files exhibited significantly more flexibility than did ProTaper Gold files (p < 0.05). Both files had approximately similar Ni and Ti contents (p > 0.05). EdgeEvolve files showed significantly lower Ra values than ProTaper Gold files (p < 0.05).

Conclusions

Within the limitation of this study, EdgeEvolve files exhibited significantly higher cyclic fatigue resistance than ProTaper Gold files in both single- and double-curved canals.

Incidence of Dentinal Root Defects Caused by RECIPROC Blue, ProTaper Gold, ProTaper NEXT and RECIPROC Nickel Titanium Rotary Instruments

AIM

This in vitro study was conducted to measure and compare the incidence of dentinal defects caused by (RECIPROC blue, ProTaper Gold, ProTaper NEXT and RECIPROC) nickel titanium (NiTi) rotary instruments.

MATERIALS AND METHODS

Seventy-five palatal roots of freshly extracted human maxillary first molars were used in this study. The total samples were randomly divided into five groups. Each group contained 15 samples (N = 15): group I: single file RECIPROC system, group II: ProTaper Next system, group III: ProTaper GOLD system, group IV: single file RECIPROC blue system and Group V: control group (No preparation). Root canal instrumentation were carried out according to manufacturer's instructions for each instrumentation system to # 40 apical size. Each root sample was sectioned horizontally at 2 mm, 4.5 mm and 7 mm, respectively from the apex. All root sections were observed under a stereomicroscope at 25X magnification.

RESULTS

The roots prepared by Reciproc showed the highest incidence of dentinal defects followed by ProTaper NEXT, ProTaper Gold then RECIPROC blue group which showed the lowest incidence of dentinal defects. The data obtained were analyzed statistically using Fisher's exact test at or equal to 5% significance levels. Fisher's exact test revealed that RECIPROC groups had a significant difference when compared with RECIPROC blue (p ≤ 0.01) and with ProTaper Gold (p ≤0.05) groups. While, other comparisons between each pair of groups revealed a non-significant difference between groups (p > 0.05). Regarding dentinal defects at different levels (apical, middle, coronal), Fisher's exact test showed that there was a non-significant difference in the incidence of dentinal defects when comparing among different levels in the same group or when comparing among different groups at the same level (p > 0.05).

CONCLUSION

all experimental groups showed dentinal defects while no dentinal defects were observed in the negative control group.

CLINICAL SIGNIFICANCE

the potential of root fracture is reduced using more flexible Ni Ti rotary instruments.

Comparative Analysis of Apical Root Crack Propagation after Root Canal Preparation at Different Instrumentation Lengths Using ProTaper Universal, ProTaper Next and ProTaper Gold Rotary Files: An In vitro Study

Aim

To compare the incidence of apical root crack formation after root canal preparation at different instrumentation lengths using ProTaper Universal (PTU), ProTaper Next (PTN) and ProTaper Gold (PTG) file systems.

Subjects and Methods

Eighty-four mandibular first premolars with single and straight root canal were mounted in resin block after simulating periodontal ligaments. 1-2 mm of root apex was exposed followed by sectioning of 1 mm of root tip for better stereomicroscopic visualization. While the Control group was left unprepared, experimental groups were instrumented up to root canal length (RCL) and (RCL-1 mm) respectively using PTU, PTN and PTG. After staining the root apex with 1% methylene blue dye, stereomicroscopic images were obtained for evaluating apical root cracks. The data were analyzed using Chi-square, phi and Cramer test. The significance level was set at P < 0.05.

Results

Significantly less dentinal defects were seen between PTG and PTU while there was no significant difference between PTU-PTN and PTN-PTG. Furthermore, samples instrumented up to RCL-1 mm showed lesser cracks as compared with samples instrumented up to RCL.

Conclusion

PTG produced least number of cracks followed by PTN and PTU. Furthermore, instrumenting short of RCL reduced the crack formation risk.

Comparative study of ProTaper gold, reciproc, and ProTaper universal for root canal preparation in severely curved root canals

Aim

The aim of this study is to evaluate the root canal transportation, centering ability, and instrumentation times with the ProTaper Gold (Dentsply Tulsa Dental, Tulsa, OK, USA), Reciproc (VDW, Munich, Germany), and ProTaper Universal (Dentsply Maillefer, Ballaigues, Switzerland) using cone-beam computed tomography (CBCT).

Materials and Methods

Thirty mesial root canals of mandibular first molars with curvature angles of 35°-70° and radii of 2-6 mm were included in the study. Root canal instrumentation was performed up to F2 or R25. The instrumentation times were recorded. CBCT scanning was performed both pre- and post-instrumentation. Root canal transportation and the centering ratio were calculated for groups, and the data were analyzed using a one-way ANOVA and least significant difference post hoc tests for the instrumentation time, root canal transportation, and centering ratio at the 95% confidence level (P = 0.05).

Results

At 3, 5, and 7 mm levels, there was no significant difference in the root canal transportation and centering ratio among the groups (P > 0.05). There were significant differences between the Reciproc and ProTaper Universal groups in the instrumentation times (P < 0.05).

Conclusion

Root canal transportation and the centering ratio with the ProTaper Gold were similar to those obtained with the ProTaper Universal and Reciproc.

Comparison of canal transportation in simulated curved canals prepared with ProTaper Universal and ProTaper Gold systems

Objectives

The purpose of this study was to assess the ability of ProTaper Gold (PTG, Dentsply Maillefer) in maintaining the original profile of root canal anatomy. For that, ProTaper Universal (PTU, Dentsply Maillefer) was used as reference techniques for comparison.

Materials and Methods

Twenty simulated curved canals manufactured in clear resin blocks were randomly assigned to 2 groups (n = 10) according to the system used for canal instrumentation: PTU and PTG groups, upto F2 files (25/0.08). Color stereomicroscopic images from each block were taken exactly at the same position before and after instrumentation. All image processing and data analysis were performed with an open source program (FIJI). Evaluation of canal transportation was obtained for two independent canal regions: straight and curved levels. Student's t test was used with a cut-off for significance set at α = 5%.

Results

Instrumentation systems significantly influenced canal transportation (p < 0.0001). A significant interaction between instrumentation system and root canal level (p < 0.0001) was found. PTU and PTG systems produced similar canal transportation at the straight part, while PTG system resulted in lower canal transportation than PTU system at the curved part. Canal transportation was higher at the curved canal portion (p < 0.0001).

Conclusions

PTG system produced overall less canal transportation in the curved portion when compared to PTU system.