|Year : 2017 | Volume
| Issue : 1 | Page : 8-15
The root canal shaping ability of WaveOne and Reciproc versus ProTaper Universal and Mtwo rotary NiTi systems
Ahmed S Abu Haimed1, Tariq S Abuhaimed2, Paul E Dummer3, Susan T Bryant3
1 Department of Dental and Maxillofacial, King Fahad Specialty Hospital, Dammam, Saudi Arabia
2 Department of Operative Dentistry, Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia
3 Department of Restorative Dentistry, School of Dentistry, Cardiff University, Cardiff, UK
|Date of Web Publication||10-Jan-2017|
Ahmed S Abu Haimed
King Fahad Specialty Hospital, Dammam
Source of Support: None, Conflict of Interest: None
Aim: The aim of this study is to compare the root canal shaping ability of two reciprocating instruments: WaveOne and Reciproc versus two rotary instruments – ProTaper Universal (PTU) and Mtwo.
Materials and Methods: A total of 160 simulated root canals in resin blocks were constructed with two curvatures located at two positions creating four different combinations: 20°/8 mm, 20°/12 mm, 40°/8 mm, and 40°/12 mm. Canals were prepared using continuous rotation (PTU and Mtwo) or reciprocating (WaveOne and Reciproc) instruments according to the manufacturer's recommendations. Each system was used to prepare 10 canals of each shape. Each file or a set of files was used to prepare one canal. Using Image Analysis Software, pre- and post-instrumentation matching images were superimposed and analyzed for canal width and transportation. Instrument fractures, time of preparation, and change in working length were also recorded. The effect of instrument and canal type on shaping ability were analyzed using two-way ANOVA test followed by post hoc Pearson Chi-square test and sum of squares test at level of significance 5%.
Results: The largest mean canal width and transportation values were associated with the Mtwo system (P < 0.001) and 40°/8 mm canals (P < 0.001). Canal aberrations were limited to rotary instruments mainly in canals with 40° curves. The reciprocating instruments prepared canals significantly faster than continuous rotation systems (P < 0.001).
Conclusions: Continuous rotation and reciprocating files were safe and maintained the original canal anatomy. However, continuous rotation instruments have a higher tendency for canals transportation and aberrations, especially with larger curvatures. Reciprocating files were faster than continuous rotation files in shaping simulated root canals in resin blocks.
Keywords: Continuous rotation files, reciprocating files, shaping ability, time of instrumentation
|How to cite this article:|
Abu Haimed AS, Abuhaimed TS, Dummer PE, Bryant ST. The root canal shaping ability of WaveOne and Reciproc versus ProTaper Universal and Mtwo rotary NiTi systems. Saudi Endod J 2017;7:8-15
|How to cite this URL:|
Abu Haimed AS, Abuhaimed TS, Dummer PE, Bryant ST. The root canal shaping ability of WaveOne and Reciproc versus ProTaper Universal and Mtwo rotary NiTi systems. Saudi Endod J [serial online] 2017 [cited 2020 Aug 10];7:8-15. Available from: http://www.saudiendodj.com/text.asp?2017/7/1/8/197981
| Introduction|| |
The main objective of root canal treatment is to cure pulpal and periapical disease by removal of root canal contents and disinfection of the colonizing microorganisms through shaping and cleaning processes. Ideally, shaped canal should have a continuously tapering funnel that preserves the original anatomy with the smallest diameter at the end point and the largest at the orifice.
Many endodontic instruments have been developed in the hope that they can effectively achieve the ideal funnel form without creating aberrations, which may affect the clinical outcome of root canal treatment. Maintaining the anatomy of the root canals requires flexible instruments. Compared with stainless steel, NiTi instruments are more flexible and more resistant to fracture. Consequently, canals preparation with NiTi files resulted in less procedural errors., However, the need for multiple files to complete the preparation and the risk of fractures are still disadvantages of rotary NiTi files.
A recent development in canal shaping techniques was described by Yared in 2008 using a single NiTi file in reciprocating motion to prepare curved canals in molar teeth. The new technique has the advantage of reducing the number of files as well as increasing the life span of NiTi files when compared to continuous rotation technique.,
Two Reciprocating NiTi files systems, Reciproc (VDW, Munich, Germany) and WaveOne (Dentsply Maillefer, Ballaigues, Switzerland), are currently available. These files are made of thermally treated NiTi wire called M-wire and used in reciprocating movement, which consists of a greater counter clockwise motion (cutting motion) and a smaller clockwise motion (release of the instrument). Altogether, these mechanical modifications have reduced the cyclic fatigue of the NiTi files.,,
The performance of the new reciprocating systems including shaping ability, resistance to fracture, and time of preparation has been compared to different continuous rotation systems and showed promising results.,, However, for a better evaluation, systems with similar cross-sections should be compared to each other. Reciproc and Mtwo have the same S-shaped cross-section but opposite directions. WaveOne has a convex triangle with radial lands cross-section converting to convex triangle toward the tip, which is similar to ProTaper Universal (PTU). Hence, Mtwo and ProTaper were chosen as control in the present study since they were previously investigated.
The aim of the present study was to evaluate the shaping ability of two reciprocating systems, Reciproc and WaveOne and two continuous rotation systems, Mtwo and PTU. The variables being investigated include shaping ability, instrument deformations, and change in working length and preparation time.
The null hypothesis is that there is no difference in canal shaping ability between the two reciprocating systems and two continuous rotation systems.
| Materials and Methods|| |
Construction of simulated root canal blocks
A total of 160 simulated root canals in plastic blocks were constructed based on the technique described by Dummer et al. Annealed size 15 silver points were used to create the canal shape and were embedded in clear resin blocks (Stycast Resin 1266, HITEK Electronic Materials Ltd., Scunthorpe, UK). The canals were made in four different shapes according to the angle and position of curvature from orifice (n = 40/shape): 20°/8 mm, 20°/12 mm, 40°/8 mm, and 40°/12 mm. All canals had 16 mm radius as measured by the technique of Pruett et al.
Each group of blocks (representing one canal type) was divided randomly into four subgroups (n = 10) according to the system used for preparation: ProTaper, Mtwo, WaveOne, and Reciproc. Therefore, each system was used to prepare 10 canals of each canal shape.
Preparation of simulated canals
The resin blocks were mounted in a mandibular jaw in a phantom head and covered with putty impression material exposing only the top of the block to insure that the process was carried out under clinical-like conditions. The order of preparation of the groups of the resin blocks was randomized and performed by one experienced operator. All canals were prepared according to the manufacturer's recommendations to a working length of 16 mm using one motor (SILVER ® motor, VDW, Munich, Germany). Glide path with size 10 K-file was created before instrumentation. Copious irrigation using tap water was maintained during instrumentation using disposable syringes (Monoject, Ballymoney, UK). The preparation sequence varied according to the shape of the canal and the system used as follows:
PTU (Dentsply Maillefer, Ballaigues, Switzerland): A set of files in the sequence S1, S2, F1, and F2 were used at the speed of 300 rpm until each file reached the working length.
Mtwo (VDW, Munich, Germany): A set of files in the sequence 10/0.04, 15/0.05, 20/0.06, 25/0.06, and 25/0.07 were used at the speed of 300 rpm until each file reached the working length.
WaveOne (Dentsply Maillefer, Ballaigues, Switzerland): A primary WaveOne file (25.08) was used in a pecking motion until the working length is reached.
Reciproc (VDW, Munich, Germany): A Reciproc R25 (25/0.08) was used in a pecking motion until the working length is reached.
A new file or set of files were used to prepare one canal and were observed for any signs of deformation or fracture during shaping process.
Assessment of canal preparation
All prepared canals were assessed using composite images of pre- and post-instrumentation [Figure 1]. A camera (Panasonic F10 CCD, Osaka, Japan) secured at a fixed distance (32 cm) from a microscope stage was used to capture the images, which were then saved on a desktop computer. To help align pre- and post-instrumentation photographs, each block was marked with four reference points (indentations with sharp metal instrument). The composite images were analyzed using image analysis software (Image-Pro Plus Media Cybernetics, Silver Springs, MD, USA) [Figure 1].
|Figure 1: Captured pre- and post-instrumentation images in Image-Pro Plus software (a and b, respectively). (c) Composite image. (Note the four reference points used to superimpose the pre- and post-instrumentation images). Arrows indicate the levels of evaluation, at orifice, beginning of curve, and halfway between them|
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Canal width and transportation
Using the composite images, measurements of canal width and transportation (to the nearest 0.001 mm) were carried out perpendicular to the axis of the original canal using Image-Pro Plus software (Media Cybernetics, Silver Springs, MD, USA) at three positions: Canal orifice, beginning of the curve, and halfway between the orifice and the beginning of the curve.
Loss of working length
Inserting a new instrument (similar to the final instrument used) into the canal and measuring it to the nearest 0.5 mm determined the final length of the prepared canals. The measured length was then subtracted from the original working length (16 mm) to determine the change either decrease or increase in working length (file was extended beyond the original working length).
Following analysis of the composite images of pre- and post-instrumentation, the presence and position of several canal aberrations including zipping, ledges, and outer widening were recorded as described by Bryant et al.
Total preparation time (in seconds) was recorded, including changing files and irrigation using a digital stopwatch.
Data storage and analysis
Data analysis was carried out using two-way ANOVA test in SPSS analysis program (SPSS Inc., Chicago, IL, USA). The effect of canal and instrument type on shaping ability was carried out using Pearson Chi-square and sum of squares tests with significance level of 5%.
| Results|| |
Total canal width
[Table 1] shows the mean total widths of canals at the orifice, halfway, and the beginning of the curve by instrument and canal type.
|Table 1: Mean total canal width (mm) at different positions by instrument and canal type|
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At the canal orifice and halfway, the total canal width was significantly influenced by the canal type (P< 0.001) and instrument type (P< 0.001). The largest widths were associated with Mtwo rotary instruments and canal type 40°/8.
At the beginning of the curve, Mtwo was associated with greater mean canal width in 40°/8 mm and 20°/8 mm canals while Reciproc was associated with greater canal width in 40°/12 mm and 20°/12 mm canals. The effect of canal and instrument type on the total canal width was significant (P< 0.001 and P < 0.001, respectively).
Canal transportation and direction of transportation
[Table 2], [Table 3], [Table 4] show the direction of transportation by canal type, instrument type, and absolute transportation, respectively.
|Table 2: Number of canals following direction of transportation by canal type|
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|Table 3: Number of canals following direction of transportation according to instrument type|
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|Table 4: Absolute transportation values (mm) according to canal and instrument type|
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At orifice: Absolute transportation values were significantly associated with rotary files (P< 0.001), which showed significantly outer transportation (P< 0.001). Reciprocating files showed balanced outer and inner transportation. Canals type 40°/8 mm exhibited significantly outer transportation (P< 0.001) and absolute transportation values (P< 0.001).
At halfway: The effect of canal type on direction of transportation was not significant (P = 0.119) while instrument type was significant (P< 0.003). PTU and Reciproc showed higher outer transportation and Mtwo showed more inner transportation (P< 0.001). Absolute transportation values regardless of the direction of transportation were significantly associated with rotary instruments (P< 0.001) and canal type 40°/8 mm (P< 0.001).
At the beginning of the curve: Outer transportation was more visible than inner with all canal and instrument types. The effect of canal and instrument type was not significant (P = 0.676). However, the highest absolute transportation values were also associated with Mtwo rotary instruments and canal type 40°/8 mm (P< 0.001).
Zips and ledges
No ledges or zipping were created.
Seven canals were affected but limited to rotary instruments, ProTaper (2 canals, 5%), and Mtwo (5 canals, 12.5%). Outer widening was mainly associated with canals having 40° curves.
Seven danger zones were created, all in 40°/8 mm canals, 2 (5%) were associated with ProTaper, and 5 (12.5%) with Mtwo.
Instrument deformation and fracture
No deformations or fractures were recorded.
[Table 5] gives the mean time of canal preparation by canal and instrument type. The reciprocating instruments (WaveOne and Reciproc) prepared the canals significantly faster than ProTaper and Mtwo (P< 0.001).
|Table 5: Mean preparation times (s) and standard deviation according to canal and instrument type|
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The effect of instrument type on preparation time was significant (P< 0.001) while the canal type was not (P = 0.219).
Change in length
[Table 6] and [Table 7] show the mean working length and the change in working length by instrument and canal type, respectively. The least mean change in length (16–16.5 mm) was associated with the Reciproc and the greatest change (15–17 mm) was associated with WaveOne. The effect of instrument type on the change of length was not significant (P = 0.618).
For canal type, the least change in length (16–16.5 mm) was associated with the 20°/8 and 40°/8 canal types. Moreover, the greatest change (15–16.5 mm) was associated with 40°/12 canals. The effect of canal type on the mean change of canal length was significant (P = 0.005).
| Discussion|| |
Mechanical preparation of root canals without mishaps is an important step that contributes to the success of treatment. The aim of the present study was to compare the shaping ability under controlled laboratory conditions of two Reciprocating instruments, WaveOne and Reciproc versus continuous rotation, PTU, and Mtwo using four simulated canal shapes.
Simulated canals in the resin blocks were used to eliminate the anatomical variables encountered when using natural teeth., In this way, appropriate assessments and comparisons of the preparations and instrument performance are possible. In addition, the simulated canals were standardized in terms of length, shape, and curvature, which may provide a valid substitute for natural teeth.
A drawback of using machine-assisted instruments in simulated canals in clear resin blocks is heat generation and softening of the resin material, which may lead to binding of cutting blades and deformation or fracture. At the same time, the normal variations in natural teeth in terms of canal curvature, length, and diameter are not addressed using simulated canals. Another issue is the physical properties of the resin are different than dentine. Obviously, care should be exercised before extrapolation of the results to the use of the instruments in natural teeth.
The resin blocks were mounted in a mandibular jaw in a phantom head and covered with putty impression material exposing only the top of the block to insure that the process was carried out by tactile sensation and under more realistic clinical-like conditions. Other reports used covered but blocks without mounting, which may result in inconsistent orientation of the file during preparation.,
When comparing the shaping ability of reciprocating versus continuous rotation systems, it is recommended to eliminate the factors of tip size, taper, and cross-section design. In the current report, all instruments have the same tip size #25 and apical taper 0.08 except Mtwo, which has a taper of 0.07. While Reciproc and Mtwo have similar S-shaped cross-section, ProTaper and WaveOne have relatively the same convex triangle cross-section.
The results of this report showed differences among different systems in shaping ability; therefore, the null hypothesis was rejected.
The total width of resin removed during instrumentation was associated significantly with canal and instrument type. Instrumentation with Mtwo rotary files resulted in the widest preparations at the orifice and halfway in all canal types as well as at the beginning of the curve in canal having 8 mm straight part. However, Reciproc showed wider canals at the curve level in canals where the curve is located closer to the apex. These findings can be attributed to multiple factors. First, Mtwo and Reciproc share the same S-shaped cross-section, which has a high cutting ability resulting in wider canals than PTU and WaveOne. Second, the reciprocating and higher flexibility wire of Reciproc and WaveOne resulted in less resin removal in the coronal portions of the canal. Third, the bigger apical taper of R25 Reciproc file compared to Mtwo file revealed wider canals where the curve is closer to the apex. Therefore, it may be concluded that motion of rotation, cutting ability, and flexibility of the file are major factors affecting the shaping ability of any file system. In agreement with these findings, Giuliani et al. showed that ProTaper files used in continuous rotation motion removed more resin when compared to both ProTaper and WaveOne files used in reciprocating motion. Similarly, Yoo and Cho showed that reciprocating systems, Reciproc and WaveOne, showed better shaping ability than continuous rotation systems (ProTaper and Profile).
In terms of canal type, canals with 40° curves were associated with more resin removal than those with 20° curves as a result of straightening of the canals in accordance with previous reports.,
Overall, transportation values were also more visible with rotary files at all levels of evaluations regardless of the type of the canal. Therefore, the motion of rotation has the main impact on the transportation value. It has been shown that reciprocating files tend to be more centered in the canals when compared to rotary files resulting in less transportation,, Another possible factor is that several files were needed to complete the preparation with rotatory systems, which may have increased the likelihood of transportation. Berutti et al. reported that WaveOne Primary instrument better maintained the original canal anatomy with less modification of the canal curvature compared with the ProTaper up to F2 in simulated canals in resin blocks in agreement with the present results.
The direction of transportation was prominent toward the outer direction at the orifice and the beginning of the curve but evenly distributed at halfway as a result of canal straightening. This was true with all instruments and canal types with minimal variations. Similar findings reported that Profile NiTi files had a tendency to cut from the outer side of the curve at the orifice and the beginning of the curve., However, in other studies, it was shown that inner transportation was more prominent at the curve. In resin block models, it was shown that Reciproc, WaveOne, Profile, and ProTaper removed more resin from the outer side of the curvature at the canal orifice and more inner resin at the beginning of the curve., Similarly, in extracted teeth model, more inner material was removed coronal to the curve using ProTaper files. Therefore, at the canal orifice, the result of the current study agreed with the previous studies but they differ at the level of beginning of the curve. One possible explanation is that the resin blocks used in this study were mounted in a phantom jaw while previous reports used different settings, where the blocks were not mounted, which could lead to inconsistent instrumentation procedure.
Only a small number of canal aberrations were recorded which were mainly related to rotatory instruments. Previous reports agree with these findings regarding the ProTaper , and Mtwo. The small number of canal aberrations could be a result of the small size of the apical preparation. Bryant et al. found no canal aberrations when the apical preparation stopped at size 25/0.04 taper, but when apical preparation increased to size 35, the incidence of canal aberrations increased.
There was no instrument deformation or fracture during preparation of any canals. This is justifiable due to the fact that each instrument or set of instruments was used to prepare one canal only. Similar results were reported previously.
Preparation time was in favor of reciprocating files. WaveOne and Reciproc systems were significantly faster than Mtwo and ProTaper with no significant difference between WaveOne and Reciproc or Mtwo and ProTaper. This could be a direct result of using one file versus multiple files with rotary systems. Bürklein et al. compared the shaping ability of WaveOne, Reciproc, ProTaper, and Mtwo in extracted teeth and found that Reciproc was significantly faster than all other systems in preparing root canals while in the present study, WaveOne was faster than Reciproc. In the current report, Reciproc instruments occasionally locked inside the resin blocks and time was taken to free the instrument, thus adding to the overall preparation time. Kuzekanani et al. found no significant difference in preparation time between ProTaper and Mtwo.
The ability to control working length is important, especially when using automated systems (continuous rotation or Reciprocating) due to the loss of tactile sensation. In the present study, all instruments controlled working length with minimum changes in agreement with other reports on continuous rotation NiTi instruments., The minor reduction in working length that did occur is attributed to the straightening of the curved canals during preparation. This finding was confirmed previously for continuous rotation NiTi instruments  and reciprocating instruments. However, there were canals with extended working length, which was a result of over preparation of the canal.
| Conclusions|| |
Under the limitations of this study, it can be concluded that:
- Both NiTi continuous rotation instruments and M-Wire Reciprocating instruments prepared severely curved simulated canals efficiently without instrument failure
- The reciprocating instruments prepared all types of canals significantly faster than continuous rotation instruments
- Canals prepared with reciprocating instruments were free of aberrations while several aberrations were associated with canals prepared with continuous rotation instruments. These aberrations were associated with the 40° curve canals
- Working length changes were minimal and within ±0.5 mm for all instruments
- Continuous rotation instruments were associated with more canal transportation in contrast with the reciprocating instruments. Operators should be cautious when preparing severely curved canals not to cause danger zones or strip perforations.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Kakehashi S, Stanley HR, Fitzgerald RJ. The effects of surgical exposures of dental pulps in germ-free and conventional laboratory rats. Oral Surg Oral Med Oral Pathol 1965;20:340-9.
Schilder H. Cleaning and shaping the root canal. Dent Clin North Am 1974;18:269-96.
Gorni FG, Gagliani MM. The outcome of endodontic retreatment: A 2-yr follow-up. J Endod 2004;30:1-4.
Walia HM, Brantley WA, Gerstein H. An initial investigation of the bending and torsional properties of Nitinol root canal files. J Endod 1988;14:346-51.
Schäfer E, Schulz-Bongert U, Tulus G. Comparison of hand stainless steel and nickel titanium rotary instrumentation: A clinical study. J Endod 2004;30:432-5.
Esposito PT, Cunningham CJ. A comparison of canal preparation with nickel-titanium and stainless steel instruments. J Endod 1995;21:173-6.
Parashos P, Messer HH. Rotary NiTi instrument fracture and its consequences. J Endod 2006;32:1031-43.
Yared G. Canal preparation using only one Ni-Ti rotary instrument: Preliminary observations. Int Endod J 2008;41:339-44.
Hwang YH, Bae KS, Baek SH, Kum KY, Lee W, Shon WJ, et al.
Shaping ability of the conventional nickel-titanium and reciprocating nickel-titanium file systems: A comparative study using micro-computed tomography. J Endod 2014;40:1186-9.
De-Deus G, Moreira EJ, Lopes HP, Elias CN. Extended cyclic fatigue life of F2 ProTaper instruments used in reciprocating movement. Int Endod J 2010;43:1063-8.
Gambarini G, Gerosa R, De Luca M, Garala M, Testarelli L. Mechanical properties of a new and improved nickel-titanium alloy for endodontic use: An evaluation of file flexibility. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2008;105:798-800.
Kim HC, Kwak SW, Cheung GS, Ko DH, Chung SM, Lee W. Cyclic fatigue and torsional resistance of two new nickel-titanium instruments used in reciprocation motion: Reciproc versus WaveOne. J Endod 2012;38:541-4.
Giuliani V, Di Nasso L, Pace R, Pagavino G. Shaping ability of waveone primary reciprocating files and ProTaper system used in continuous and reciprocating motion. J Endod 2014;40:1468-71.
Bürklein S, Hinschitza K, Dammaschke T, Schäfer E. Shaping ability and cleaning effectiveness of two single-file systems in severely curved root canals of extracted teeth: Reciproc and WaveOne versus Mtwo and ProTaper. Int Endod J 2012;45:449-61.
Dummer PM, Alodeh MH, al-Omari MA. A method for the construction of simulated root canals in clear resin blocks. Int Endod J 1991;24:63-6.
Pruett JP, Clement DJ, Carnes DL Jr. Cyclic fatigue testing of nickel-titanium endodontic instruments. J Endod 1997;23:77-85.
Bryant ST, Dummer PM, Pitoni C, Bourba M, Moghal S. Shaping ability of 04 and 06 taper ProFile rotary nickel-titanium instruments in simulated root canals. Int Endod J 1999;32:155-64.
Pettiette MT, Metzger Z, Phillips C, Trope M. Endodontic complications of root canal therapy performed by dental students with stainless-steel K-files and nickel-titanium hand files. J Endod 1999;25:230-4.
Schäfer E, Tepel J, Hoppe W. Properties of endodontic hand instruments used in rotary motion. Part 2. Instrumentation of curved canals. J Endod 1995;21:493-7.
Thompson SA, Dummer PM. Shaping ability of ProFile. 04 Taper series 29 rotary nickel-titanium instruments in simulated root canals. Part 1. Int Endod J 1997;30:1-7.
Smith RB, Edmunds DH. Comparison of two endodontic handpieces during the preparation of simulated root canals. Int Endod J 1997;30:369-80.
Calberson FL, Deroose CA, Hommez GM, De Moor RJ. Shaping ability of ProTaper nickel-titanium files in simulated resin root canals. Int Endod J 2004;37:613-23.
Schäfer E, Vlassis M. Comparative investigation of two rotary nickel-titanium instruments: ProTaper versus RaCe. Part 1. Shaping ability in simulated curved canals. Int Endod J 2004;37:229-38.
Yoo YS, Cho YB. A comparison of the shaping ability of reciprocating NiTi instruments in simulated curved canals. Restor Dent Endod 2012;37:220-7.
Aminsobhani M, Ghorbanzadeh A, Dehghan S, Niasar AN, Kharazifard MJ. A comparison of canal preparations by Mtwo and RaCe rotary files using full sequence versus one rotary file techniques; a cone-beam computed tomography analysis. Saudi Endod J 2014;4:70-6.
Berutti E, Paolino DS, Chiandussi G, Alovisi M, Cantatore G, Castellucci A, et al.
Root canal anatomy preservation of WaveOne reciprocating files with or without glide path. J Endod 2012;38:101-4.
Thompson SA, Dummer PM. Shaping ability of ProFile. 04 Taper series 29 rotary nickel-titanium instruments in simulated root canals. Part 2. Int Endod J 1997;30:8-15.
Bergmans L, Van Cleynenbreugel J, Beullens M, Wevers M, Van Meerbeek B, Lambrechts P. Progressive versus constant tapered shaft design using NiTi rotary instruments. Int Endod J 2003;36:288-95.
Schirrmeister JF, Strohl C, Altenburger MJ, Wrbas KT, Hellwig E. Shaping ability and safety of five different rotary nickel-titanium instruments compared with stainless steel hand instrumentation in simulated curved root canals. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2006;101:807-13.
Veltri M, Mollo A, Mantovani L, Pini P, Balleri P, Grandini S. A comparative study of Endoflare-Hero Shaper and Mtwo NiTi instruments in the preparation of curved root canals. Int Endod J 2005;38:610-6.
Kuzekanani M, Walsh LJ, Yousefi MA. Cleaning and shaping curved root canals: Mtwo vs ProTaper instruments, a lab comparison. Indian J Dent Res 2009;20:268-70.
Paqué F, Musch U, Hülsmann M. Comparison of root canal preparation using RaCe and ProTaper rotary Ni-Ti instruments. Int Endod J 2005;38:8-16.
Thompson SA, Dummer PM. Shaping ability of Hero 642 rotary nickel-titanium instruments in simulated root canals: Part 1. Int Endod J 2000;33:248-54.
Berutti E, Chiandussi G, Paolino DS, Scotti N, Cantatore G, Castellucci A, et al.
Effect of canal length and curvature on working length alteration with WaveOne reciprocating files. J Endod 2011;37:1687-90.
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7]