• The Journal of the Korean dental association
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• v.52 no.2
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• pp.60-68
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• 2014

Nickel-Titanium(NiTi) rotary instruments have brought a big step toward "efficient" practice of endodontic procedure. The rotary files help clinicians to reduce their working time and also increase the clinical success rate with minimal procedural errors by stainless steel instruments. In spite of these advantages, NiTi instruments still have a few drawbacks including unpredictable fatigue fracture. Clinicians may reduce the potential risk of instruments fracture by following some clinical guidelines for rotary instruments. In some clinical cases of instruments fracture, we may try to remove the instruments' fragments or bypass the fragment to reach the apical canal. In some limited cases, the fractured instruments' fragments would not jeopardize the clinical prognosis of root canal treatment. However, it is impossible to be overemphasized that the fragment removal is more difficult than the prevention of fracture. Clinicians need to understand the fracture mechanisms and, in clinic, need to discard the used instruments timely.

• The Journal of the Korean dental association
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• v.54 no.8
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• pp.640-650
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• 2016

Nickel-Titanium (NiTi) rotary instruments have brought a big step toward "efficient" practice of endodontic procedure. The rotary files help clinicians to reduce their working time and also increase the clinical success rate with minimal procedural errors. However, NiTi instruments still have a few drawbacks including unpredictable fatigue fracture. Clinicians may reduce the potential risk of instruments fracture by following some clinical guidelines for rotary instruments. In some clinical cases of instruments fracture, we may try to remove the instruments' fragments or bypass the fragment to reach the apical canal. In some limited cases, the fractured instruments' fragments would not jeopardize the clinical prognosis of root canal treatment. Nevertheless, it is impossible to be overemphasized that the prevention of file fracture is much easier than the removal of fracture fragment. Clinicians need to understand the fracture mechanisms and, in clinic, need to discard the used instruments timely.

• Restorative Dentistry and Endodontics
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• v.41 no.3
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• pp.176-181
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• 2016

Objectives: This study aimed to compare two nickel-titanium systems (rotary vs. reciprocating) for their acceptance by undergraduate students who experienced nickel-titanium (NiTi) instruments for the first time. Materials and Methods: Eighty-one sophomore dental students were first taught on manual root canal preparation with stainless-steel files. After that, they were instructed on the use of ProTaper Universal system (PTU, Dentsply Maillefer), then the WaveOne (WO, Dentsply Maillefer). They practiced with each system on 2 extracted molars, before using those files to shape the buccal or mesial canals of additional first molars. A questionnaire was completed after using each file system, seeking students' perception about 'Ease of use', 'Flexibility', 'Cutting-efficiency', 'Screwing-effect', 'Feeling-safety', and 'Instrumentation-time' of the NiTi files, relative to stainless-steel instrumentation, on a 5-point Likert-type scale. They were also requested to indicate their preference between the two systems. Data was compared between groups using t-test, and with Chi-square test for correlation of each perception value with the preferred choice (p = 0.05). Results: Among the 81 students, 55 indicated their preferred file system as WO and 22 as PTU. All scores were greater than 4 (better) for both systems, compared with stainless-steel files, except for 'Screwing-effect' for PTU. The scores for WO in the categories of 'Flexibility', 'Screwing-effect', and 'Feeling-safety' were significantly higher scores than those of PTU. A significant association between the 'Screwing-effect' and students' preference for WO was observed. Conclusions: Novice operators preferred nickel-titanium instruments to stainless-steel, and majority of them opted for reciprocating file instead of continuous rotating system.

• The Journal of the Korean dental association
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• v.51 no.10
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• pp.551-555
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• 2013

The purpose of this study was to give a guideline for selecting the nickel-titanium (NiTi) file by review from many studies. Since the early 1990s, several instrument systems manufactured from NiTi have been introduced into endodontic practice. The specific design characteristics vary, such as tip shape and size, cross sectional view, helix angle, and pitch space. Some of the early systems have been removed from the market or play only minor roles; others are still widely used. New designs continually are produced, but the extent to which clinical outcomes will depend on design characteristics is difficult to forecast. In this study, I have reviewed the different design characteristics in respect of the safety and efficiency. With the review from many studies, I concluded that the clinicians must be understand the specific design characteristics for selecting the ideal NiTi rotary instruments.

• Restorative Dentistry and Endodontics
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• v.29 no.3
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• pp.212-218
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• 2004

The purpose of this study was to quantify the amount of remaining gutta-percha/sealer on the walls of root canals when three types of nickel-titanium rotary instruments (Profile. ProTaper and $K^3$) and a hand instrument(Hedstrom file) used to remove these materials. The results of this study were as follows: 1. In the total time for gutta-percha removal. Profile group was the fastest and followed by $K^3$, Protaper, Hedstrom file group. 2. In case of the evaluation of the volume of remained gutta-percha from radiograph. $K^3$ group got the highest score and followed by Protaper. Hedstrom file. Profile group in the apical 1/3. 3. In case of the evaluation of the volume of gutta-percha remained from stereomicroscope, $K^3$ group got the highest score and followed by Protaper. Hedstrom file. Profile group in the apical 1/3. These results showed that instrumentation using nickel-titanium rotary instrument groups was faster than that using hand instrument group. The effect of gutta-percha removal using Profile group was better than that using Protaper and $K^3$ group in the nickel-titanium rotary instrument groups.

• Proceedings of the KACD Conference
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• 2003.11a
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• pp.552-552
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• 2003

The purpose of this study was to quantify the amount of remaining gutta-percha/sealer on the walls of root canals when three types of nickel-titanium rotary instruments and a hand instrument were used to remove these materials. Forty extracted mandibular premolars were prepared by step-back method and obturated with gutta-percha and sealer. Gutta-percha removal for group 1 was done using hand file with chloroform, group 2 using Profile and group 4 using K3. The following factors were evaluated : Time taken to reach working length, total time for gutta-percha removal and number of fractured instruments.(중략)

• Journal of Korean Dental Science
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• v.15 no.2
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• pp.112-120
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• 2022

In this article, the contemporary root canal treatment procedure using nickel-titanium (NiTi) instruments was reviewed to understand the correlations between the properties of files and safety of the clinical usage. Literatures were reviewed according to the process of clinical procedure of the root canal preparation, mainly for shaping during orifice flaring, glide-path preparation, and main canal instrumentation. Considering the reasons for NiTi file fracture, clinically implacable issues and ideas were discussed to reduce the fracture risk and increase clinical efficiency of the NiTi file systems. Various kinds of NiTi file systems have their own characteristics and properties given from their geometries and heat treatments and so on. Proper selection and careful usage of the NiTi file systems may reduce the risk of file fracture and increase the efficiency of NiTi file systems. Understanding of the clinical implications from the mechanical properties and characteristics of the engine driven NiTi instruments may decrease the risk of NiTi file fractures and increase the success rate in root canal treatment.

• Restorative Dentistry and Endodontics
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• v.42 no.4
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• pp.301-308
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• 2017

Objectives: It was aimed to compare the cyclic fatigue resistances of ProTaper Universal (PTU), ProTaper Next (PTN), and ProTaper Gold (PTG) and the effects of sterilization by autoclave on the cyclic fatigue life of nickel-titanium (NiTi) instruments. Materials and Methods: Eighty PTU, 80 PTN, and 80 PTG were included to the present study. Files were tested in a simulated canal. Each brand of the NiTi files were divided into 4 subgroups: group 1, as received condition; group 2, pre-sterilized instruments exposed to 10 times sterilization by autoclave; group 3, instruments tested were sterilized after being exposed to 25%, 50%, and 75% of the mean cycles to failure, then cycled fatigue test was performed; group 4, instruments exposed to the same experiment with group 3 without sterilization. The number of cycles to failure (NCF) was calculated. The data was statistically analyzed by using one-way analysis of variance and post hoc Tukey tests. Results: PTG showed significantly higher NCF than PTU and PTN in group 1 (p < 0.05). Sterilization significantly increased the NCF of PTN and PTG (p < 0.05) in group 2. PTN in group 3 had significantly higher cyclic fatigue resistance than PTN group 4 (p < 0.05). Also, significantly higher NCF was observed for PTG in group 2 than in groups 3 and 4 (p < 0.05). Conclusions: PTG instrument made of new gold alloy was more resistant to fatigue failure than PTN and PTU. Autoclaving increased the cyclic fatigue resistances of PTN and PTG.

• Journal of Dental Rehabilitation and Applied Science
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• v.23 no.4
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• pp.293-302
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• 2007

I. Objectives The purpose of this study was to compare the shaping ability between the single length technique performed with Mtwo instruments (VDW, Munich, Germany) and the crown-down technique using K3 (SybronEndo, West Collins, CA, USA) and RaCe (FKG, La Chaux-de-Fonds, Switzerland) instruments. II. Materials & Methods Forty five curved canals in resin blocks were equally divided in to three groups. Group 1 (Mtwo) was instrumented used the full length of canal according to the manufacturer's instructions. The simulated canals was prepared to an instrument size of 35, 0.04 taper canal terminus. In group 2 (Race) and group 3 (K3) was instrumented in a crown-down manner and prepared to an instrument size of 30, 0.06 taper canal terminus. Pre- and post-instrumentation images were scanned and assessment of canal shape was completed with a computer image analysis program. Material removal was measured at 7 measuring points, beginning 1mm from the end point of preparation. Differenced of centering ratio were statistically analyzed using One-way ANOVA followed by Duncan's test. II. Results & Conclusion There was no significant difference on 1, 2, 3 and 7mm measuring point. At 4 and 5 measuring point, significant difference showed between the Mtow instruments and other two instruments. (p<0.05)

• Restorative Dentistry and Endodontics
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• v.40 no.3
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• pp.253-254
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• 2015