Shaping ability of ProTaper Universal, WaveOne and ProTaper Next in simulated L-shaped and S-shaped root canals

Effect of preset torque setting on torque/force generation, shaping ability and surface changes of nickel titanium rotary instrument in different root canal curvature locations: An ex vivo study

The aim of this study was to evaluate how preset torque settings influence the torque, vertical force, and root canal-centering ability of ProGlider and ProTaper NEXT nickel-titanium rotary instruments in canals with different curvature locations. Based on micro-computed tomography, mesial roots of human mandibular molars (25°-40° curvature) were allocated to the apical curvature (apical 1-5 mm) or the middle curvature (apical 5-9 mm) groups, and mandibular incisors (curvature <5°) to the straight canal group. Each group was subjected to automated instrumentation and torque/force measurement with the preset torque of 1, 2.5, or 5 N•cm. Canal-centering ratios were determined with micro-computed tomography. Instrument fracture occurred only in the 2.5 and 5 N•cm groups in curved canals. The preset torque setting and curvature location did not influence canal shaping ability.

Impact of cooling on shaping ability of thermally treated files in canal models with double curvature

Background

This study compared the ability of thermally treated files in shaping simulated canals with double curvature. Fifty-six canals were enlarged to a final size of 25 with ProTaper Next (PTN) or ZenFlex (ZF).

Materials

Half of the samples were shaped with cooled files (n = 14 each). The amount of removed resin was measured and canal deviation was determined at eight levels. Shaping time and maximum shaping torque values were also recorded. Data were statistically analyzed using analysis of variance and LSD, Kruskal-Wallis, and chi-square tests at a 0.05 significance level.

Results

Compared to PTN and cooled PTN, ZF and cooled ZF required lesser time to shape the canals. The maximum torques were found comparable between the groups. All the groups generated negligible deviations at every canal level evaluated and maintained the canal geometry. Although not significant, the cooled PTN and ZF files exhibited lesser canal deviations than their counterparts.

Conclusion

All groups demonstrated similar shaping ability whilst maintaining the original curvature of the canal in simulated canals with double curvature. However, ZF groups were able to shape the canals faster than PTN groups. There was a trend that cooled files made lesser canal deviations compared to their counterparts.

An effective artificial testing model to reliability experiments for electronic apex locator devices used in endodontic practice

BACKGROUND AND AIM

This experimental study aimed to investigate the reliability of using electronic apex locator devices to determine the working length of artificial root canals.

MATERIALS AND METHODS

The experiments were performed using resin endoblocks and mandibular canine teeth (n = 20/group). After the same working length of root canal samples was provided, the teeth and artificial root canals were embedded in an alginate mold. The measurements with Root ZX® and Propex Pixi® apex locators were performed and recorded. The data were analyzed using SPSS software (SPSS V23; IBM Corp., Armonk, New York, USA) and the variance was set at P < 0.05.

RESULTS

There was no significant difference between the groups; mean distance from the actual working length using different apex locators (P = 0.633, P = 0.474), and endpoint positioning distributions (P = 0.591).

CONCLUSION

The results indicate that the artificial model could be a laboratory method of determining the accuracy of apex locators and efficient calibration of devices before their clinical use.

Comparative Assessment of the Shaping Ability of Reciproc Blue, WaveOne Gold, and ProTaper Gold in Simulated Root Canals

Maintaining the original trajectory of the root canal is a major challenge in endodontic therapy, especially in narrow and curved root canals. The present study aims to assess the shaping capacity of three endodontic systems made of different nickel−titanium alloys on simulated curved root canals. Thirty-six endodontic resin blocks (Ref. V040245, VDW) divided into three groups, each of twelve blocks (n = 12), were shaped, photographed, and analyzed: Group 1-Protaper Gold (PTG) (Dentsply Maillefer, Ballaigues, Switzerland) F2 25/08; Group 2-Reciproc Blue (RB), RB 25/08 (VDW, Munich, Germany); Group 3-WaveOne Gold (WOG) (Dentsply Maillefer), WOG 25/07. Each block was standardized and photographed before and after shaping in the same position, with the foramen oriented to the left. Post-shaping images were superimposed onto the initial ones. Thirteen measurement points were used for evaluation, spaced with 1 mm distance from one another, from level 0, apical foramen, to level 12, coronal orifice. The amount of removed resin from inner (X1) and outer (X2) walls, the direction of transportation (X1 − X2), and the centering ability (X1 − X2)/Y were measured, calculated, and comparatively analyzed. Statistical differences (p < 0.05) were observed between the shaping capacity of the considered systems in the middle and coronal thirds. PTG had a better centering ability than WOG and RB in the coronal third, while RB was more centered in the middle third in comparison to both WOG and PTG. In the apical third, the centering capacity of WOG was higher, without being statistically significant. WOG 25/07 and PTG 25/08 tend to cut more on the inner wall of the root canals, and RB 25/08 on the external one.

Root canal curvature as a prognostic factor influencing the diagnostic accuracy of radiographic working length determination and postoperative canal axis modification: an in vitro comparative study

Background

Radiographic analysis of tooth morphology is mandatory for accurate calibration of the degree of canal curvature angle and radiographic working length to its real dimensions in case difficulty assessment protocols. This study aimed to determine the impact of the degree of root canal curvature angle on maintaining the real working length and the original canal axis of prepared root canals using a reciprocating rotary instrumentation technique.

Methods

Radiographic image analysis was performed on 60 extracted single-rooted human premolar teeth with a moderate canal curvature (10°–25°) and severe canal curvature (26°–70°). Working length and longitudinal canal axis were determined using cone-beam computed tomography (CBCT) and digital periapical radiography. The real canal length was determined by subtracting 0.5 mm from the actual canal length. Root canals were prepared using the WaveOne Gold reciprocating file (Dentsply Maillefer, Ballaigues, Switzerland).

Results

There was no significant relation of the degree of canal curvature angle to the accuracy of radiographic working length estimated on CBCT and digital periapical radiographic techniques (P > 0.05). Postinstrumentation changes in the original canal axis between moderate and severe canal curvature angles, assessed on CBCT and periapical digital radiographic images were statistically non-significant (P > 0.05).

Conclusions

A standardized digital periapical radiographic method performed similarly to the CBCT technique near to its true working length. No significant interaction exists between the diagnostic working length estimation, postoperative root canal axis modification, and the degree of canal curvature angle, using reciprocating rotary instrumentation technique.

Comparative evaluation of dentin volume removal and centralization of the root canal after shaping with the ProTaper Universal, ProTaper Gold, and One-Curve instruments using micro-CT

Background. The main goal of our study was to assess the volume of dentin removed and transportation in root canals using ProTaper Universal (PTU), ProTaper Gold (PTG) and One-Curve (OC). Ni-Ti rotary instruments in extracted human teeth using by micro-CT.

Methods: Thirty human upper 1st premolar teeth with two separate root canals and sturdy, mature root tips were used in the present study. Specimens were decoronated and root length was standardized for micro CT scanning before root canal preparation done. The teeth were randomly separated into three categories (n = 10) according to the rotary NiTi system used for canal instrumentation, i.e., PTU (Dentsply, Maillefer), PTG (Dentsply, Maillefer), and OC (Micro-Mega SA). After root canal preparation, samples were scanned again on micro-CT by the same scanning parameters. Surface area, canal volume, structure model index (SMI), percentage of uninstrumented area and transportation parameters were obtained for each sample before and after micro-CT analyse.

Results: No significant differences between the PTG and PTU in terms of the total volume of removed dentin, surface area and percentage of uninstrumented areas were found. However, regarding to parameters above, OC showed a lower efficacy than PTG and PTU in coronal section. Regarding canal transportation, PTG and OC showed lower mean transportation values at all levels.

Conclusion: This paper demonstrated the root canal shaping abilities of the PTU, PTG, and OC NiTi file systems. The PTG and OC systems were associated less canal transportation and a better ability to preserve dentinal walls than PTU. There was no significance different between all rotary file systems for SMI values however, PTU and PTG showed greater canal volume and surface area change than OC file systems in coronal section.

Apical Transportation and Centering Ability After Root Canal Filling Removal Using Reciprocating and Continuous Rotary Systems: A CBCT Study

OBJECTIVE

To evaluate the apical transportation and centering ability promoted by reciprocating and continuous rotary systems after root canal filling removal.

MATERIALS AND METHODS

After obturation, 40 mesial root canals of mandibular molars were distributed into four groups (n = 20) for filling material removal: PTU group-F2 instrument (25.08) of ProTaper Universal system; R25 group-R25 instrument (25.08) of Reciproc system; X2 group-X2 instrument (25.06) of ProTaper Next system and X3 group-X2 instrument (25.06) of ProTaper Next system, followed by X3 instrument (30.07). Cone-beam computed tomographic analysis was performed before and after filling material removal for acquisition of apical images. Apical transportation (AT) and its direction, and centering ability (CA), were assessed using the equations AT = (X1-X2)-(Y1-Y2) and CA = (X1-X2/Y1-Y2 or Y1-Y2/X1-X2), respectively. Data were submitted to the nonparametric Kruskal-Wallis and Dunn multiple comparison tests (p < 0.05) for statistical analysis.

RESULTS

There was no statistically significant difference among groups for AT (p > 0.05), with a tendency toward transportation in the distal direction. Also, there was no statistically significant difference among groups regarding CA (p > 0.05).

CONCLUSIONS

The different systems, including ProTaper Next, caused AT within the acceptable clinical limit after filling removal. In addition, none of the tested systems presented adequate CA.

Fracture resistance of roots enlarged with various rotary systems and obturated with different sealers

Background. This in vitro study compared the fracture resistance of roots instrumented either with ProTaper or One Shape rotary systems and filled with one of the silicate, epoxy resin or silicone-based sealers. Methods. Sixty single-rooted extracted mandibular premolars were decoronated to a length of 13 mm and then randomly divided into two main groups (n=30) in terms of the rotary system used for preparation. Group 1 samples were instrumented with the ProTaper Universal system up to a master apical file of #F2, while samples in group 2 were enlarged with One Shape system. The two main groups were then divided into 3 subgroups in terms of the sealer used (n=10) and filled with guttapercha (either F2 or MM-GP points) of the rotary system used and one of the sealers as follows: group 1, BioRoot RCS + ProTaper F2 gutta-percha; group 2, AH Plus + ProTaper F2 gutta-percha; group 3, GuttaFlow + ProTaper F2 gutta-percha; group 4, BioRoot RCS+ MM-GP points; group 5, AH Plus + MM-GP points; and group 6, GuttaFlow + MM-GP points. Each specimen then underwent fracture testing by using a universal testing machine at a crosshead speed of 1.0 mm/min until the root fractured. Data were statistically analyzed. Results. Two-way ANOVA showed no significant differences between the groups. One Shape instruments showed significantly better fracture resistance compared to ProTaper instruments. Statistically, no significant difference was found between AHPlus, GuttaFlow and BioRoot RCS sealers. Conclusion. It can be concluded that the rotary system used for the instrumentation of teeth has some influence on the fracture resistance, while the root canal sealers do not have such an effect.

Residual smear layer after root canal instrumentation by using Niti, M-Wire and CM-Wire instruments: A scanning electron microscopy analysis

Objective:

The purpose of this study was to compare the amount of residual smear layer after root canal instrumentation by using Ni-Ti, M-Wire, and CM-Wire instruments.

Materials and Methods:

Seventy-two mandibular incisors were randomly divided into six groups according to the system used: WaveOne (WO), Reciproc (RP), Unicone (UC), ProTaper Next (PN), Mtwo (MT), and HyFlex (HF). Afterward, the specimens were cleaved in the mesiodistal and buccolingual direction for analysis by scanning electron microscopy.

Results:

Considering both directions and root canal thirds, there was no difference between HF, MT, and PN. RP, UC, and WO presented a significant difference between the directions, and the cervical third showed a significantly smaller quantity of residual smear layer compared with the apical third. When the systems were compared among them, there was a significant difference only between RP and WO.

Conclusions:

Residual smear layer observed after instrumentation with the different systems was similar, except for quantities between the reciprocating systems.

Impact of new cross-sectional designs on the shaping ability of rotary NiTi instruments in S-shaped canals

The aim was to compare the shaping ability of different rotary nickel-titanium instruments in simulated S-shaped canals. One hundred S-shaped canals in resin blocks were prepared to an apical size 25 using F6 SkyTaper (Komet), Silk Files .04, Silk Files .06, Prototypes .04, and Prototypes .06 (all Mani) (20 canals/group). Material removal was measured at 20 measuring points, beginning 1 mm from the endpoint of preparation. Incidence of canal aberrations, preparation time, and instrument failures were also recorded. Statistical analyses were performed using ANOVA, Student-Newman-Keuls and Chi-square test. Pooled data of all measuring points revealed that canals instrumented with Prototypes .04 were significantly better centered than those prepared with all other instruments, while Prototypes .06 and both Silk Files performed significantly better than F6 SkyTaper (p < 0.05). The preparation time differed significantly between all groups and Prototypes .04 allowed the fastest preparation (p < 0.05). There was no statistically significant association between type of instrument and incidence of aberrations (p > 0.05). The cross-sectional design had a marked impact on the shaping ability of the instruments, and less tapered instruments maintained the original canal curvature better than instruments having greater tapers.

A dental workforce strategy to make Australian public dental services more efficient

BACKGROUND

Dental services can be provided by the oral health therapy (OHT) workforce and dentists. This study aims to quantify the potential cost-savings of increased utilisation of the OHT workforce in providing dental services for children under the Child Dental Benefits Schedule (CDBS). The CDBS is an Australian federal government initiative to increase dental care access for children aged 2-17 years.

METHODS

Dental services billed under the CDBS for the 2013-2014 financial year were used. Two OHT-to-dentist workforce mix ratios were tested: Model A National Workforce (1:4) and Model B Victorian Workforce (2:3). The 30% average salary difference between the two professions in the public sector was used to adjust the CDBS fee schedule for each type of service. The current 29% utilisation rate of the CDBS and the government target of 80% were modelled.

RESULTS

The estimated cost-savings under the current CDBS utilisation rate was AUD 26.5M and AUD 61.7M, for Models A and B, respectively. For the government target CDBS utilisation rate, AUD 73.2M for Model A and AUD 170.2M for Model B could be saved.

CONCLUSION

An increased utilisation of the OHT workforce to provide dental services under the CDBS would save costs on public dental service funding. The potential cost-savings can be reinvested in other dental initiatives such as outreach school-based dental check programmes or resource allocation to eliminate adult dental waiting lists in the public sector.

A microcomputed tomography evaluation of the shaping ability of three thermally-treated nickel-titanium rotary file systems in curved canals

OBJECTIVE

To evaluate the shaping ability of three thermally-treated rotary nickel-titanium (NiTi) systems including ProTaper Next (PTN), HyFlex™ CM (HFCM) and HyFlex™ EDM (HFEDM) during root canal preparation in simulated root canals.

METHODS

A total of 45 simulated root canals were divided into three groups ( n = 15) and prepared with PTN, HFCM or HFEDM files up to size 25. Microcomputed tomography (microCT) was used to scan the specimens before and after instrumentation. Volume and diameter changes, transportations and centring ratios at 11 levels of the simulated root canals were measured and compared.

RESULTS

HFEDM caused significantly greater volume increases than HFCM and PTN in the entire root canal and in the apical and middle thirds. HFCM removed the least amount of resin in the coronal third compared with HFEDM and PTN. Overall, HFCM caused significantly less transportation in the apical 2 mm and was better centred than PTN in the apical 3 mm.

CONCLUSION

Under the conditions of this study, all systems prepared curved canals without significant shaping errors and instrument fracture. PTN and HFCM cut less resin than HFEDM. HFCM stayed centred apically and cut the least material coronally.

Comparative Evaluation of Apical Transportation and Canal Centric Ability in Apical Region of Newer nickel-titanium File Systems Using cone-beam computed tomography on Extracted Molars: An In Vitro Study

Background:

Objective in root canal preparation is to develop a shape that tapers from apical to coronal, maintaining the original canal shape. With advent of instruments manufactured from nickel-titanium (NiTi) alloys, there was a significant improvement of quality of root canal shaping, with predictable results and less iatrogenic damage.

Aim:

The aim of the study was to evaluate the canal centric ability and apical transportation in apical region of newer NiTi file system in root canal using cone-beam computed tomography (CBCT) on extracted molars.

Materials and Methods:

Root canal of thirty extracted human permanent teeth with mature root apices with 20°–40° of curvature were collected and divided into three groups after initial bio-mechanical preparation: Group 1: canal prepared using ProTaperNext (PTN) file system; Group 2: canal prepared using Mani silk system; and Group 3: canal prepared using V-taper file system. All samples were scanned before and after biomechanical preparation using CBCT. The data collected were evaluated using the Kruskal–Wallis analysis of variance test and Mann–Whitney U-test.

Results:

It was observed that in apical region Group I (PTN) showed significantly lower mean apical transportation and canal centric ability as compared to Group II (Mani Silk) and Group III (V-taper).

Conclusion:

It was concluded that PTN rotary system has no canal transportation and maintained centric ability in comparison to Mani and V-taper rotary file system in apical region of curved root canal.

Shaping Ability of Superelastic and Controlled Memory Nickel-Titanium File Systems: An In Vitro Study

Improvements in the thermomechanical processing procedures of NiTi wires have led to the development of new NiTi instruments that compose mainly of martensite crystals, making the wire stable at clinical condition. This study aimed at comparing the shaping ability of two rotary nickel-titanium systems manufactured from different NiTi wires. Twenty simulated root canals each with a curvature of 35° in resin blocks were divided into two groups of 10 canals each. Canals in the first group were prepared with superelastic F360 instruments (Gebr. Brasseler, Germany) while canals in the second group were prepared using controlled memory HyFlex®CM™ instruments (Coltène Whaledent, Switzerland). Images were taken before canal preparation and after the use of each instrument. The assessment of the canal shapes was accomplished with a computer image analysis program. Data were statistically analyzed using SPSS program. Within the limitation of this in vitro study, HyFlex®CM™ instruments remained better centered in the apical third of the canals. In most canal segments, no significant differences were observed between either system in the amount of material removed. Both systems were comparable to each other in regards to their ability to enlarge root canal in the same way without procedural errors.

Shaping ability of protaper next compared with waveone in late-model three-dimensional printed teeth

Background

Comparison of the shaping ability of advanced nickel-titanium (Ni-Ti) instruments is of great interest to the field of endodontics. However, the models used to study canal preparation still lack uniformity, relevance to reality and complexity. The aim of this study was thus to compare the shaping abilities of the ProTaper Next (PN) and WaveOne (WO) Ni-Ti instruments in three-dimensional (3D)-printed teeth, which may overcome the present defects of most real teeth and model teeth including 3D S-shaped canals.

Methods

Six teeth and their corresponding 3D-printed replicas were prepared using the same kind of Ni-Ti instrument. The pre- and post-preparation volumes, surface areas and transportation of the canals were measured to compare the teeth with their replicas. Twenty 3D-printed teeth with S-shaped canals were used to support the preparation study. The S-shaped canals were then scanned to measure their volumes and surface areas. Next, the two kinds of instruments were used to prepare the 3D-printed canals (n = 10 per group). The volume and surface area of the canals, the transportation along the two curvatures and the percentage of unprepared surface area were measured. Micro-CT and VGstudio2.2 (VG2.2) software were used to perform scans and collect data throughout the research. The paired-samples T test and Kruskal-Wallis H test were used for statistical analysis.

Results

There was no significant difference between the real canals and the printed ones post-preparation (P > .05). The printed S-shaped root canals had a unified shape, with a small standard deviation and range. The WO group had higher mean values for the volume and superficial area measurements compared with the PN group (P < .05). No differences in the untouched areas were found between the two systems (P > .05). PN caused less transportation at the apical curve than WO did (P < .05).

Conclusions

In conclusion, 3D-printed teeth are suitable for the study of Ni-Ti rotary instruments. Furthermore, the PN rotary system caused less transportation at the apical curve than the WO system did in complicated root canal procedures.

Comparative evaluation of the shaping ability of single-file system versus multi-file system in severely curved root canals

Background/purpose

Reciprocating single-file systems are the latest nickel-titanium instruments and little information is available concerning the shaping ability of these new systems. Comparison of these single-file systems with well-known rotary multi-file systems is necessary. The purpose of this study was to compare the shaping ability of single-file system (WaveOne, WO) versus multiple-file system (ProTaper Next, PTN) in severely curved canals.

Materials and methods

A total of 20 severely curved canals were prepared with WO or PTN. Micro-computed tomography was used to scan the specimens before and after instrumentation. Differences between two groups in canal surface area, volume, Structure Model Index (SMI), thickness, straightening, the ratio of uninstrumented surface area and canal transportation were evaluated.

Results

The outline of the canals after preparation showed smooth taper in both groups. Canal surface area, volume, SMI, Thickness and canal curvature were significantly increased after preparation in both groups, and no significant difference was found between groups. At apical third, canals prepared with WO showed larger values of transportation compared with those in PTN group in the direction of main curvature. Approximately 29–34% of the root canal surface remained uninstrumented after preparation and no significant difference was noticed between groups.

Conclusion

Both of the two instrument systems maintained the original outline of the canals well. The canals prepared with PTN had less transportation and were better centered in the apical region.

Canal Transportation and Centering Ability of Reciproc Blue, WaveOne Gold and ProTaper Next in Simulated Curved Canals

Introduction

The aim of this study was to evaluate the canal transportation and centering ability of ProTaper Next (PTN), WaveOne Gold (WOG) and Reciproc Blue (RCB) in simulated curved resin canals.

Methods and Materials

A total of 43 blocks of simulated resin canals with 40° of curvature were prepared to an apical size of 0.02. Flexofile #15 instruments were used along the root canal to reach patency. The blocks were randomly assessed and sequence instruments were used according to each system: PTN, RCB and WOG. The imposition of pre and post instrumentation images were composited and analyzed. The canal transportation and apical centralization were measured using the software GIMP (2.8.4, Creative Commons - Share Alike 4.0 International License, 2013). Data were statistically analyzed using the Shapiro-Wilk test, ANOVA test and Tukey's test. The level of significance was set at 0.05.

Results

There were no statistical differences in canal transportation between three systems. The general assessment of three systems presented the RCB group with higher values of centralization and more numbers of centralized points with significant differences between the PTN and RCB groups (P<0.05).

Conclusion

In this in vitro study, there were no statistical differences in canal transportation between the RCB, WOG and PTN systems. The lowest transportation was observed in the apical region at 3 mm performed with RCB system, followed by WOG and PTN systems. The RCB demonstrated higher values of centralization and more centralized points when assessed by regions.

A Comparative Study of ProTaper Universal and ProTaper Next Used by Undergraduate Students to Prepare Root Canals

INTRODUCTION

The purpose of this study was to determine whether final-year undergraduate dental students achieved better shaping outcomes using the new ProTaper Next (PTN; Dentsply Sirona, Ballaigues, Switzerland) system to prepare root canals for the first time compared with the existing ProTaper Universal (PTU, Dentsply Sirona) system on which they had trained. A secondary aim was to explore the attitudes and preferences of the students toward both systems.

METHODS

Forty students prepared 1 simulated S-shaped canal using PTN and another with PTU. Images of the canals were saved before and after preparation, and the outcomes assessed included the formation of aberrations and the amount of resin removed at specific points along the canal length. Student opinions relating to PTN and PTU were collected via a questionnaire completed immediately after using the systems. For statistical analysis, the McNemar test was used to compare the incidence of aberrations, and a paired t test was used to analyze the width measurements. Responses to the questionnaire were analyzed using frequencies. Thus, the McNemar test was used for paired binary data and the marginal homogeneity test for categoric data when more than 2 categories were used. Finally, the overall preferences (either PTN or PTU) were analyzed using the sign/binomial test, which is a standard statistical test that allows us to determine if the proportion preferring one or the other is equal or not.

RESULTS

Canal ledges were formed in 30% of the canals prepared with PTU, whereas no ledges were formed with PTN (P < .001). A middle constriction, a form of canal aberration, was created by both systems although it occurred significantly (P = .006) more often with PTN. The "number of files" was judged by students to be significantly higher (P < .001) for PTU compared with PTN. Even though using PTN for the first time, students were more likely to recommend the system to other students for preparing S-shaped canals than PTU (P = .018) and preferred to use PTN in the future (P < .001).

CONCLUSIONS

The students who had previous experience with the use of PTU were able to produce comparable shaping outcomes when they used PTN for the first time. For the preparation of S-shaped canals, the students preferred PTN over PTU in terms of the number of files and would prefer to use it in the future.

Comparison of the Shaping Ability of WaveOne Reciprocating Files with or without Glide Path in Simulated Curved S-shaped Root Canals

OBJECTIVES

The aim was to compare the shaping ability of WaveOne reciprocating files with or without glide path in simulated curved S-shaped root canals.

MATERIALS AND METHODS

Forty ISO #15, 0.02 taper, clear resin Endo Training Bloc-S blocks were studied. The simulated curved S-shaped canals were dyed using ink, preinstrumentation images were scanned, and resin blocks were prepared and divided into Group A: PathFile and WaveOne and Group B: WaveOne. All canals were postoperatively scanned. Pre- and postoperative images were superimposed and evaluated at 12 defined measuring points. The efficacy of the systems was compared based on the amount and direction of canal transportation, centering ability, amount of material removed, and presence of canal aberrations. Mann-Whitney U-test and independent t-test were used for statistical comparison.

RESULTS

Both systems produced transportation at all levels and straightened the curved S-shaped canals. No significant differences in the amount and direction of transportation and amount of material removed were observed between the groups at each level (P > 0.05). However, Group A had significantly greater centering ability at the coronal straight zone (P = 0.018) and apical curvature (P = 0.014) levels than did Group B. Moreover, Group B showed more canal aberrations than did Group A.

CONCLUSION

Within the limitations of the present study, the creation of a glide path with the PathFile system improved the centering ability of the WaveOne reciprocating file in the apical and straight coronal portions of the simulated curved S-shaped root canals and reduced the incidence of canal aberrations.

Influence of NiTi alloy on the root canal shaping capabilities of the ProTaper Universal and ProTaper Gold rotary instrument systems

Objective

This study aimed to evaluate the influence of the NiTi wire in Conventional NiTi (ProTaper Universal PTU) and Controlled Memory NiTi (ProTaper Gold PTG) instrument systems on the quality of root canal preparation.

Material and Methods

Twelve mandibular molars with separate mesial canals were scanned using a high-definition microcomputed tomography system. The PTU and PTG instruments were used to shape twelve mesial canals each. The canals were scanned after preparation with F2 and F3 instruments of the PTU and PTG systems. The analyzed parameters included the remaining dentin thickness at the apical and cervical levels, root canal volume and untouched canal walls. Data was analyzed for statistical significance by the Friedman and Dunn's tests. For the comparison of data between groups, the Mann-Whitney test was used.

Results

In the pre-operative analysis, there were no statistically significant differences between the groups in terms of the area and volume of root canals (P>.05). There was also no statistically significant difference between the systems with respect to root canal volume after use of the F2 and F3 instruments. There was no statistical difference in the dentin thickness at the first apical level between, before and after instrumentation for both systems. At the 3 cervical levels, the PTG maintained centralization of the preparation on the transition between the F2 and F3 instruments, which did not occur with the PTU. Conclusion The Conventional NiTi (PTU) and Controlled Memory NiTi (PTG) instruments displayed comparable capabilities for shaping the straight mesial root canals of mandibular molars, although the PTG was better than the PTU at maintaining the centralization of the shape in the cervical portion.

Root Canal Transportation and Centering Ability of Nickel-Titanium Rotary Instruments in Mandibular Premolars Assessed Using Cone-Beam Computed Tomography

Introduction:

The aim of this study was to evaluate, using cone-beam computed tomography (CBCT), transportation and centralization of different nickel-titanium (NiTi) rotary instruments.

Methods:

One hundred and twenty eight mandibular premolars were selected and instrumented using the following brands of NiTi files: WaveOne, WaveOne Gold, Reciproc, ProTaper Next, ProTaper Gold, Mtwo, BioRaCe and RaCe. CBCT imaging was performed before and after root canal preparation to obtain measurements of mesial and distal dentin walls and calculations of root canal transportation and centralization. A normal distribution of data was confirmed by the Kolmogorov-Smirnov and Levene tests, and results were assessed using the Kruskal-Wallis test. Statistical significance was set at 5%.

Results:

ProTaper Gold produced the lowest canal transportation values, and RaCe, the highest. ProTaper Gold files also showed the highest values for centering ability, whereas BioRaCe showed the lowest. No significant differences were found across the different instruments in terms of canal transportation and centering ability (P > 0.05).

Conclusion:

Based on the methodology employed, all instruments used for root canal preparation of mandibular premolars performed similarly with regard to canal transportation and centering ability.

Shaping Ability of ProTaper Next, WaveOne, and Reciproc in Simulated Root Canals

INTRODUCTION

The study aimed to compare the shaping and preservation of the original curvature of simulated curved root canals using the following instruments: Reciproc (Rcp), WaveOne (Wo), and the ProTaper Next system (Ptn).

MATERIALS AND METHODS

A total of 45 resin blocks with simulated curved root canals were divided into three groups (n = 15), prepared using the Rcp (R25), Wo (25/0.8), and Ptn (X2) instruments. Standardized photographs were taken before and after canal instrumentation. After the superimposition of the images, the amount of resin removed from the curvature's inner and outer walls was measured at six apical levels, at intervals of 1 mm. The canals' angles of curvature before and after instrumentation were subtracted.

RESULTS

There were no significant differences between the instruments in terms of the total amount of resin removed of the inner or outer walls of the apical curvature (p > 0.05). The Rcp instruments provided the best resin removed ratios between the walls. The means of the change in angle were as follows: Wo = 2.15°, Ptn = 0.92°, and Rcp = 0.21°. WaveOne caused significantly higher deviations than Rcp.

CONCLUSION

All of the instruments demonstrated a tendency to straighten the simulated root canal. Instruments that use rotary movement achieved an effect similar to that of the reciprocating instruments in relation to change in angle.

CLINICAL SIGNIFICANCE

Deviations from the original shape of the root canal could have a negative impact on the quality of a filling and consequently on the success of the endodontic treatment.

Influence of cervical preflaring on apical transportation in curved root canals instrumented by reciprocating file systems

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.