(PO14) Effect of Multiple Dry Heat Sterilization Cycles on Time to Separation for VTaper Rotary NiTi Files

Abstract: In an austere environment where unconventional sterilization methods are occasionally required, rotary files that are not used in a procedure may be subjected to multiple sterilization cycles prior to use. Although heat-treated nickel titanium (NiTi) rotary files often come pre-sterilized from the manufacturer, the effect of additional exposures to dry-heat sterilization on the cyclic fatigue of VTaper2H NiTi rotary files is presently unknown. The objective of this study was to determine the effect of multiple dry-heat sterilization cycles on the time to separation (TTS) for VTaper2H files used in a simulated curve. One hundred eighty size 25/v06 VTaper2H files were randomly divided into four groups (n=45). Test groups included files exposed to 1, 3, or 5 dry-heat sterilization cycles (S1, S3, S5, respectively). Pre-sterilized files from the manufacturer served as a control. Files were rotated at 500 RPMs in a jig, simulating a 60-degree curvature and a 6 mm radius. TTS decreased significantly with exposure to 5 sterilization cycles. No significant difference was noted between S1 and S3 or between S3 and S5 groups. Considering the limitations of this study, it appears that subjecting unused VTaper2H files to 1, 3, or 5 sterilization cycles can diminish the TTS.