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Year : 2021  |  Volume : 9  |  Issue : 4  |  Page : 100-102

Analysis of the cutting efficiency of two different nickel–titanium rotary file systems: An in vitro study

Private Practitioner, Ahmedabad, Gujarat, India

Date of Submission25-Nov-2021
Date of Acceptance08-Dec-2021
Date of Web Publication27-Dec-2021

Correspondence Address:
Mr. Dharmik Patel
Aarsh Dental Clinic, 10, Aaryan Workspaces, Navrangpura, Ahmedabad, Gujarat.
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/INJO.INJO_36_21

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Aim: The aim of this study was to evaluate and compare the cutting efficiency using two rotary nickel–titanium file systems. Materials and Methods: Thirty-two resin endo training blocks (ETBs) were divided into two groups (16 for each group). Two groups of resin blocks were instrumented using two continuous rotary nickel–titanium instruments (NeoEndo Flexfile and Blueflex Acerfile). The cutting efficiencies of instruments were quotients of the loss weights of specimens, and the time needed for instrumentation. Results: Cutting efficiency of NeoEndo Flexfile was greater than that of Blueflex Acerfile on both resin root canals (P < 0.05). Conclusion: NeoEndo Flexfile instrument was more efficient than Blueflex Acerfile on root canals.

Keywords: Cutting efficiency, nickel–titanium, rotary, file system

How to cite this article:
Patel D, Patel F, Patel K, Desai N, Patel K, Shah P. Analysis of the cutting efficiency of two different nickel–titanium rotary file systems: An in vitro study. Int J Oral Care Res 2021;9:100-2

How to cite this URL:
Patel D, Patel F, Patel K, Desai N, Patel K, Shah P. Analysis of the cutting efficiency of two different nickel–titanium rotary file systems: An in vitro study. Int J Oral Care Res [serial online] 2021 [cited 2022 Jan 19];9:100-2. Available from: https://www.ijocr.org/text.asp?2021/9/4/100/333816

  Introduction Top

The biomechanical preparation is one of the most important stages of endodontic treatment. In whole endodontic therapy, mechanical instrumentation remains an important part of both purposes, although they cannot be separated.[1] The biomechanical preparation is performed in many ways nowadays, but rotary nickel–titanium instruments are the most common.[2]

Today, nickel–titanium instrument systems are widely available, and they continually improve in many aspects, including designs, materials, and modes of rotation. To make sure their instruments are successful in the clinical setting, the manufacturers continuously innovate to reduce time spent on use, complexity of use, and fatigue of clinicians.[3]

NeoEndo Flexfile is a third-generation rotary file with two files shaping system undergone Gold Thermal Treatment renders it extremely flexible. It is available in several sizes and tapers. NeoEndo Flexfile provides better cyclic fatigue resistance. The triangular cross-section and sharp cutting edges of these files will increase cutting efficiency. Noncutting tip prevents accidental apical transportation and also provides extreme flexibility in negotiating canals.[4]

Blue Flex is one of the U.S. Food and Drug Administration (FDA)-approved files with far greater resistance to cyclic fatigue, with an uncompromising cutting efficiency and unmatched flexibility. It is available in various sizes and tapers.[5]

In addition to the new features in design or in the treatment process, these new file systems required small torque values when used in root canals. This low-torque value enhanced the safety of rotary instruments in root canal preparation, but raised some questions about their efficiency and drawbacks. It was a concern whether these new instruments could maintain the cutting efficiencies needed to attain optimal results using such low torque values. Another concern was whether or not dentinal defects could be created using these new instruments.

This study aimed to evaluate and compare the cutting efficiency and dentinal defect rate of two nickel–titanium rotary file systems.

  Materials and Methods Top

A total of 32 L-type resin endo training blocks (ETBs) (Dentsply, Maillefer, Ballaigues, Switzerland) were used for this study. A total of 32 ETBs were divided into two equal groups: Groups 1 and 2 used for NeoEndo Flexfile and Blueflex Acerfile. Before starting the root canal preparation for the groups, specimens’ weights were measured using the AUW220D scale at 1/105 exact level (Shimadzu, Kyoto, Japan).

Group 1 was instrumented using NeoEndo Flexfile in the NSK Endomate DT Endomotor (NSK, Japan) with manufacturer’s parameters (1.5 N.cm and 300 rpm) up to size 25%–6%.

Group 2 was instrumented using Blueflex Acerfile in the NSK Endomate DT Endomotor (NSK, Japan) with the manufacturer’s parameters (2.0 N.cm and 300 rpm) up to size 25%–6%. Parcan––a 3% sodium hypochlorite solution (Septodont)––was used as irrigation for preparation.

Each instrument was used for a maximum of three ETBs. The actual time needed for root canal instrumentation was recorded for each specimen using an ADANAC 3000 watch at 1/102 exact level (Marathon Watch). This time did not include the instrument cleaning time and irrigation time.

The specimens were weighed using the AUW220D scale after instrumentation. The cutting efficiency was the result of the division of loss of specimen’s weight for the root canal preparation time. Data were analyzed using the Statistical Package for the Social Sciences (SPSS) software program, version 20.0 (IBM, Armonk, New York).

  Results Top

Time amounts needed for root canal preparations of experimental groups are illustrated in [Table 1]. There were significant differences between time amounts needed for instrumentations using NeoEndo Flexfile and Blueflex Acerfile, with time amounts for Blueflex Acerfile longer than that for NeoEndo Flexfile on ETBs. The cutting efficiencies of two instruments are displayed in [Table 2]. Blueflex Acerfile was less efficient than NeoEndo Flexfile on ETBs. The unit of cutting efficiency was mcg/s. However, the data were transformed using the function log10 (logarithm with the base of 10) to gain the normality of distribution.
Table 1: Time amounts (seconds) needed for root canal instrumentations

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Table 2: Cutting efficiencies (log10 [mcg/s]) of two experimental instruments

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  Discussion Top

In this study, resin ETBs were used because they had identical canal shapes, although their Knoop hardness was lower than that of human dentine (22 kg/mm2 vs. 40 kg/mm2).[6],[7] Preflared instruments are used before main instruments according to the manufacturer’s instructions. These instruments have large volumes and great tapers, so they could potentially cause dentinal problems before the main instruments are used.[8]

Manufacturers no longer recommend multiple uses of nickel–titanium rotary instruments, but a study reported that certain instruments could be used up to five canals without affecting metallurgical properties.[9]

One instrument prepared similar numbers of canals in this study as in previous studies[10] and less than in another study.[11] The time needed for preparation was calculated only for the actual working time of the instrument in canals, not including the cleaning time and irrigation time in this study. This way of time calculation for preparation was not similar to that of a previous study;[12] however, the results of both studies were similar with the time needed for preparation using Blueflex Acerfile is being greater than that of NeoEndo Flexfile.

A reliable method for measuring cutting efficiency was to calculate the weight of material lost over time.[13] This way was used in this study and was not similar to the method of a previous study,[12] in that, only extruded materials over the apical foramen were measured.

NeoEndo Flexfile’s cutting efficiency was maintained through ETBs, which could be attributable to the special design of the tool with appropriate changes along the root long axis and electropolishing.[4]

NeoEndo Flexfile has better cutting efficiency than Blueflex Acerfile, possibly due to its higher flexibility and low torque. This study showed that, even though ETBs had a lower Knoop hardness, they were harder to instrument than human root canals. A possible reason for this might be the fusible nature of resin when subjected to friction created by the instruments. Increased friction reduced the efficiency of cutting considerably. Researchers and educators should recognize this problem.

  Conclusion Top

NeoEndo Flexfile was more cutting efficient than Blueflex Acerfile on root canals.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Hulsmann M, Peters OA, Dummer PM. Mechanical preparation of root canals: Shaping goals, techniques and means. Endod Top 2005;10:30-76.  Back to cited text no. 1
Almanei KK. Quality of root canal treatment of molar teeth provided by Saudi dental students using hand and rotary preparation techniques: Pilot study. Saudi Endod J 2018;8:1-6.  Back to cited text no. 2
  [Full text]  
Saber SE, Nagy MM, Schäfer E. Comparative evaluation of the shaping ability of ProTaper next, iRaCe and Hyflex CM rotary NiTi files in severely curved root canals. Int Endod J 2015;48:131-6.  Back to cited text no. 3
Neoendo, India. Available from: http://neoendo.com/india/products/flex files. [Last accessed on 2021 Nov 24].  Back to cited text no. 4
Blueflex Files. Available from: https://blueflex-website.firebaseapp.com/. [Last accessed on 2021 Nov 24].  Back to cited text no. 5
Khalilak Z, Fallahdoost A, Dadresanfar B, Rezvani G. Comparison of extracted teeth and simulated resin blocks on apical canal transportation. Iran Endod J 2008;3:109-12.  Back to cited text no. 6
Al-Dhbaan AA, Al-Omari MA, Mathew ST, Baseer MA. Shaping ability of ProTaper gold and WaveOne gold nickel-titanium rotary file in different canal configurations. Saudi Endod J 2018;8:202-7.  Back to cited text no. 7
  [Full text]  
Kim HC, Lee MH, Yum J, Versluis A, Lee CJ, Kim BM. Potential relationship between design of nickel-titanium rotary instruments and vertical root fracture. J Endod 2010;36:1195-9.  Back to cited text no. 8
Park SK, Kim YJ, Shon WJ, You SY, Moon YM, Kim HC, et al. Clinical efficiency and reusability of the reciprocating nickel-titanium instruments according to the root canal anatomy. Scanning 2014;36:246-51.  Back to cited text no. 9
Arslan H, Gok T, Saygili G, Altintop H, Akçay M, Çapar ID. Evaluation of effectiveness of various irrigating solutions on removal of calcium hydroxide mixed with 2% chlorhexidine gel and detection of orange-brown precipitate after removal. J Endod 2014;40:1820-3.  Back to cited text no. 10
Bürklein S, Tsotsis P, Schäfer E. Incidence of dentinal defects after root canal preparation: Reciprocating versus rotary instrumentation. J Endod 2013;39:501-4.  Back to cited text no. 11
Ehsani M, Farhang R, Harandi A, Tavanafar S, Raoof M, Galledar S. Comparison of apical extrusion of debris by using single-file, full-sequence rotary and reciprocating systems. J Dent (Tehran) 2016;13:394-9.  Back to cited text no. 12
Vinothkumar TS, Miglani R, Lakshminarayananan L. Influence of deep dry cryogenic treatment on cutting efficiency and wear resistance of nickel-titanium rotary endodontic instruments. J Endod 2007;33:1355-8.  Back to cited text no. 13


  [Table 1], [Table 2]


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