Int J Stomatol ›› 2021, Vol. 48 ›› Issue (3): 297-304.doi: 10.7518/gjkq.2021053

• Original Articles • Previous Articles     Next Articles

Comparative study on the shaping ability of thermally treated continuous rotating nickel-titanium systems for severely curved simulated canals

Wang Hongyuan1(),He Lu1,Zhang Ru1,Zheng Deqiang2,Li Hong1()   

  1. 1. Dept. of Endodontics, Beijing Stomatological Hospital, Capital Medical University, Beijing 100050, China
    2. School of Public Health, Capital Medical University, Beijing 100069, China
  • Received:2020-09-15 Revised:2020-12-29 Online:2021-05-01 Published:2021-05-14
  • Contact: Hong Li;
  • Supported by:
    Research and Cultivation Fund of Capital Medical University(PYZ19076)


Objective This study aimed to compare the centring ability of three different thermally treated continuous rotating systems in severely curved simulated canals. Methods Sixty single-curved canals in resin blocks were prepared by using the Twisted File (group TF, R-phase),ProTaper Next (group PTN, M-wire), Hyflex CM (group HCM, CM-wire), and Mtwo (group Mtwo, traditional nickel-titanium alloy) systems (n=15), and the preparation time was recorded. The reduction in the working length after the preparation was measured. The weight change in the resin block was measured using an electronic balance. Images of pre- and post-instrumentation were recorded by digital camera and then superimposed by Photoshop. The amount of resin removed was measured by ImageJ. The differences between the groups were determined using one-way ANOVA, the Kruskal-Wallis and post hoc Bonferroni tests. Results No significant difference was observed in the changes in working length in the four groups (P>0.05). The weight change in the resin block was highest in the group Mtwo (P<0.05), and those of the three other groups were not significantly different (P>0.05). No significant difference was observed in the transportation of the canal at the apical foramen and in the coronal plane portion among four nickel-titanium instruments (P>0.05). In the apical part of the curvature, the group TF had the least root canal transportation (P<0.05), and the group Mtwo had higher root canal transportation than the three other groups in each measurement point (P<0.05). The Twisted File and the ProTaper Next could complete the preparation in a shorter time than the Mtwo and the Hyflex CM (P<0.05). Conclusion All tested files could prepare and maintain the original shape of severely curved canals effectively. This study showed that the Twisted file, ProTaper Next, and Hyflex CM systems had better centring ability than the Mtwo system and that the Twisted file system was demonstrated to have superior shaping ability compared with the others in the apical part.

Key words: shaping ability, curved canal, transportation, thermal treatment, continuous rotating nickel-titanium system

CLC Number: 

  • R781.05


Fig 1

Schematic diagram of the custom platform for resin simulated root canal"

Fig 2

The image of resin simulated root canal on the custom platform and schematic diagram of curvature"

Tab 1

The procedures of the four nickel-titanium systems"

组别 镍钛锉 马达(生产商) 预备程序 转速/(r·min-1 扭矩/(N·cm)
TF Twisted File Sybron Endo(Sybron Endo公司,美国) (25#/0.04)→(25#/0.06) 500 1.5
HCM Hyflex CM VDW Silver (VDW公司,德国) (20#/0.04)→(20#/0.06)→
500 2.5
PTN ProTaper Next X-Smart(Dentsply Maillefer公司,瑞士) (17#/0.04)→(25#/0.06) 300 2.0
Mtwo Mtwo VDW Silver (VDW公司,德国) (10#/0.04)→(15#/0.05)→
280 1.2(10#/0.04);1.3(15#/0.05);

Tab 2

Working length and weight changes after pre-paration of four nickel-titanium systems n=15, x-±s"

组别 工作长度变化值/mm 树脂切削量/mg
TF 0.249±0.181 0.039 3±0.081 9
HCM 0.249±0.112 0.078 6±0.052 2
PTN 0.227±0.137 0.065 0±0.053 7
Mtwo 0.218±0.158 0.275 0±0.069 3

Fig 3

Representative images of resin simulated root canal before and after preparation using by four nickel-titanium systems"

Fig 4

A line chart demonstrating the direction and amount of canal deviation at the various measurement points of four nickel-titanium systems"

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