Abstract
Two testing methods were designed to quantitatively evaluate the chipping beh\avior of dental stones. One method measured the average and maximum widths of the chipped area along the edges of a groove that was cut with the rotating saw of a microcutter in a flat surface of a board-shaped specimen of dental stone. A CCD camera connected to a personal computer was used to record the chipped area, and the resulting graphic data were analyzed using a personally developed software. The other method measured the minimum thickness of a thin unbroken piece sliced with the rotating saw from a cylinder-shaped specimen of dental stone. The minimum thickness was determined statistically using the staircase method.
The two testing methods were employed to study the effects of the rotation speed and the cutting load of the saw on the values of the widths and the thickness using a dental stone and a high-strength dental stone. The average and maximum widths increased generally as the rotation speed increased and as the cutting load decreased. The minimum thickness increased with increasing rotational speed, but was almost independent of the cutting load. The two testing methods appeared to be useful in quantitatively evaluating the chipping behavior of dental stone.