原著
Nex NiTiファイルの周期疲労破折耐性に対する熱処理の影響
2019 年 40 巻 2 号 p. 92-97
詳細
2019 年 40 巻 2 号 p. 92-97
Abstract : Purpose : The aim of this study was to compare the cyclic fatigue resistance of two different NiTi files on rotary movement within an artificial curved canal.
Methods : NEX-NiTi files (Co group) (ISO size : #25, taper : 0.06, length : 21mm, n=10) and NEX-NiTi Ms files (MS group) (ISO size : #25, taper : 0.06, length : 21mm, n=10) were tested. All files were tested by rotary movement and the testing device was a stainless-steel artificial canal with a 35° angle of curvature.
To simulate the clinical setting, the tests were done with up-and-down motion at 0.5sec/4mm. All samples were loaded with rotary movement until fracture.
Time to fracture and the lengths of broken fragments were recorded. After the cyclic fatigue resistance tests were completed, the fractured surface was inspected by a scanning electron microscope. The data were analyzed using Student's test.
Results : The time to fracture of the MS group was significantly longer than that of the Co group (p<0.01). The average length of broken fragments was 2.12-2.13mm, and there was no statistical significance between the two.
Scanning electron microscopic observations showed a crater-like formation along with numerous dimples and micro-bubbles in both groups.
Conclusion : NEX-NiTi Ms files showed higher cyclic fatigue resistance than NEX-NiTi files with continuous rotary movement.
