Fatigue of Dental Highspeed, Air-Driven Handpiece by Steam Sterilization

Objectives: Autoclaving dental high-speed, air driven handpieces (HPs) is a recommended standard for infection prevention and control. Subjection to repeated sterilization may cause fatigue, possible corrosion, for most handpiece mechanics. The purpose of this study was to evaluate the effect of steam sterilization on the mechanical properties of HP and to determine whether sterility inside the handpiece lumen can be maintained after thermal cyclic fatigue induced by repeated sterilization.
Methods: Six commercially available brands of HPs (n=6/brand) were selected: TiMax-Z (NSK), Mastertorque-mini-Lux (Kavo), Experttorque-Lux (Kavo), Midwest Tradition Pro-TBF (Dentsply), Midwest Phoenix ZRK (Dentsply), and Midwest Stylus Plus-SPK (Dentsply). The HPs were subjected to 180 cycles of steam sterilization without lubrication to accelerate the effect of fatigue aging. Prior to baseline and after 60, 90, 120, and 180 sterilization cycles, the HPs were inoculated with bacteria and sterilized (Tuttnauer 2540EKP), after which bacterial loads were quantified. Using a custom-made universal-testing machine (ACUMEN, MTS), HP fatigue parameters such as stall torque, power, and revolution per minute (RPM) were measured. Data were analyzed with repeated-measures ANOVA/Tukey (α=0.05).
Results: Experttorque-Lux, Mastertorque-mini- Lux, Midwest Phoenix ZRK, Midwest Stylus Plus-SPK, and TiMax-Z maintained similar power as baseline over 180 cycles of sterilization. Midwest Tradition Pro-TBF demonstrated the greatest loss in power (20%) and RPM (18%) over 180 cycles than all other brands, but still maintained the greatest power. After 120 cycles of repeated sterilization without lubrication, one Midwest Tradition Pro-TBF HP experienced mechanical failure and was excluded from further testing. No signs of corrosions or fractures were noted. No bacterial colony formation was observed inside the lumen for any HP after 180 cycles of sterilization.
Conclusions: All handpieces, except one handpiece from the Midwest Tradition Pro-TBF group, maintained functionality after the sterilization processes. Routine care with appropriate maintenance is strongly advised to maximize longevity and optimal performance of dental HP.



The views expressed in this abstract are those of the author and do not reflect the official policy of the U.S. Government.