The effects of autoclave sterilization on the cyclic fatigue resistance of ProTaper Universal, ProTaper Next, and ProTaper Gold nickel-titanium instruments

Abstract

ObjectivesIt 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 MethodsEighty 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.ResultsPTG 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).ConclusionsPTG 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.

Influence of autoclave sterilization procedures on the cyclic fatigue resistance of heat-treated nickel-titanium instruments: a systematic review

“…Since NiTi properties are highly influenced by thermomechanical processing, the effects of additional heat retreatment promoted during autoclaving procedures can affect the mechanical properties of these instruments. This issue has been demonstrated in previously published studies that showed the influence of autoclave sterilization on the cyclic fatigue strength of NiTi instruments [7,9,11,12]. However, these findings remained controversial.…”

“…An overall of 203 studies was retrieved. The title and abstract reading resulted in 10 studies [4,7,[9][10][11][12][15][16][17][18] that matched the eligibility criteria. No additional study was included after the manual search of the references of these 10 studies.…”

“…After reading the full text of these studies, 2 were excluded because heat-treated instruments were not used [8,18], and 3 studies due to the lack of a control group without autoclave sterilization [10,11,15]. Therefore, after the removal of duplicates, the systematic databases search resulted in 5 studies [4,7,9,12,16], as demonstrated in the flow diagram (Figure 1).…”

“…From the 5 included studies, 1 presented low risk of bias [4], 3 presented moderate [7,9,12], and 1 high risk [16]. All studies standardized the included samples, the autoclave sterilization cycle, and the test design.…”

“…All studies standardized the included samples, the autoclave sterilization cycle, and the test design. The power analysis of the included studies resulted in satisfactory effect size for 3 studies [9, 12,16].…”