Abstract
The influence of number of autoclave treatment
cycles (N) on rotational speed and total indicated
run-out of commercially available air-turbine
handpieces from five manufacturers was investigated
at N=0, 50, 100, 150, 200, 250 and 300
cycles, and the significance in the test results was
assessed by Dunnett’s multiple comparison test.
Some air-turbine handpieces showed the significant
differences in rotational speed at N=300
cycles, however, the decreases of the rotational
speeds were only 1 to 3.5 percent. Some air-turbine
handpieces showed the significant differences in
total indicated run-out, however, the respective
values were smaller than that at N=0 cycle.
Accordingly, it can be considered that the ball
bearing in the air-turbine handpieces is not affected
significantly by autoclave. To further evaluate
rotational performance, this study focused on the
rotational vibration of the ball bearing components
of the air-turbine, as measured by Fast
Fourier Transform (FFT) analysis; the power spectra
of frequency of the ball’s revolution, frequency
of the cage’s rotation and frequency of the ball’s
rotation were comparatively investigated at N=0,
150 and 300 cycles, and the influence of autoclave
was evaluated qualitatively. No abnormalities in the
ball bearings were recognized.
