[Effects of electropolishing on rupture resistance in cyclic fatigue and on the surface condition of endodontic instruments].

UNLABELLED

The Nickel-titanium (Ni-Ti) instruments superelasticity does not does not allow to anticipate rupture.

AIM

This study evaluates the effect of electropolishing time on the rupture resistance in flexion fatigue of the endodontics Ni-Ti instruments.

METHODS

48 HeroShapers 6% 25/100 are divided into 4 groups of surface treatment (without electropolishing, with electropolishing of 70, 80 or 90 seconds). The surface of the instruments is observed under a scanning electron microscope. Each instrument is driving by an inGet control motor at 275 rpm and put on a fatigue bench (stainless steel pipe angled at 60 degrees with r = 10 mm). The number of turn before rupture is recorded by a specific meter. Data were analysed by analysis of variance and a Fischer probable least-square difference test (PLSD) at a significance level of 0.05.

RESULTS

The mean number of rotation to failure in each group of instrument decreases (407 to 355 tours) with the increase of the electropolishing time. There were no statistically significant difference (p = 0, 3508) between the different groups.

CONCLUSION

Electropolishing from 70 till 90 seconds improves the surface state without modifying the rupture resistance in flexion fatigue of triple helix endodontic instruments with 6% taper.