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Effect of internal stress on cyclic fatigue failure in .06 taper ProFile


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Effect of internal stress on cyclic fatigue failure in .06 taper ProFile

Article information

Restor Dent Endod. 2012;37(2):79-83
Publication date (electronic) : 2012 May 18
doi : https://doi.org/10.5395/rde.2012.37.2.79
Hye-Rim Jung, DDS, MSD, Jin-Woo Kim, DDS, PhD, Kyung-Mo Cho, DDS, PhD, Se-Hee Park, DDS, PhD
Department of Conservative Dentistry, Gangneung-Wonju National University School of Dentistry, Gangneung, Korea.
Correspondence to Se-Hee Park, DDS, PhD. Assistant Professor, Department of Conservative Dentistry, Gangneung-Wonju National University School of Dentistry, Gangneung Daehangno 120, Gangneung, Korea 210-702. TEL, +82-33-640-2760; FAX, +82-33-640-3103; drendo@gwnu.ac.kr
Received 2011 December 20; Revised 2012 February 15; Accepted 2012 February 24.

Abstract

Objectives

The purpose of this study was to evaluate the relation between intentionally induced internal stress and cyclic fatigue failure of .06 taper ProFile.

Materials and Methods

Length 25 mm, .06 taper ProFile (Dentsply Maillefer), and size 20, 25, 30, 35 and 40 were used in this study. To give the internal stress, the rotary NiTi files were put into the .02 taper, Endo-Training-Bloc (Dentsply Maillefer) until auto-stop by torque controlled motor. Rotary NiTi files were grouped by the number of induced internal stress and randomly distributed among one control group and three experimental groups (n = 10, Stress 0 [control], Stress 1, Stress 2 and Stress 3). For cyclic fatigue measurement, time for separation of the rotary NiTi files was recorded. The fractured surfaces were observed by field emission scanning electron microscope (FE-SEM, SU-70, Hitachi). The time for separation was statistically analyzed using two-way ANOVA and post-hoc Scheffe test at 95% level.

Results

In .06 taper ProFile size 20, 25, 30, 35 and 40, there were statistically significant difference on time for separation between control group and the other groups (p < 0.05).

Conclusion

In the limitation of this study, cyclic fatigue failure of .06 taper ProFile is influenced by internal stress accumulated in the files.

Keywords: Auto-reverse; Auto-stop; Cyclic fatigue failure; Internal stress; Separation; .06 tper ProFile

Notes

No potential conflict of interest relevant to this article was reported.

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Article information Continued

©Copyights 2012. The Korean Academy of Conservative Dentistry.
(open-access) :

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Figure 1

Figure 1

Representative image of cyclic fatigue testing using inclined glass plane.

Figure 2

Figure 2

FE-SEM micrographs of separated surface of .06 taper ProFile. The surfaces in all experimental groups showed same patterns of cyclic fatigue fracture. There is no circular abrasion mark which is feature of surface of torsional fracture. (a) #30 Stress 3 group (×200); (b) #35 Stress 3 group (×200). Black arrow, initiation zone; white arrow, overload zone. FE-SEM, Field emission scanning electron microscope.

Table 1

Time for separation of .06 taper ProFile

Table 1

Same superscripts shows no statistically significant difference in same size.

Stress0, Stress1, Stress2 and Stress3 are grouped by the number of induced internal stress.