A Novel Method for Adjusting the Taper and Adaption of Automatic Tooth Preparations with a High-Power Femtosecond Laser

This study explored the effect of the light-off delay setting in a robotically controlled femtosecond laser on the taper and adaption of resin tooth preparations. Thirty resin teeth (divided into six equal groups) were studied under different light-off delay conditions. Tapers from six vertical sections of the teeth were measured and compared among the light-off delay groups. The mean taper decreased from 39.268 degrees +/- 4.530 degrees to 25.393 degrees +/- 5.496 degrees as the light-off delay increased (p < 0.05). The average distance between the occlusal surfaces of the scanned data and the predesigned preparation data decreased from 0.089 +/- 0.005 to 0.013 +/- 0.030 mu m as the light-off delay increased (p < 0.05). The light-off delay of the femtosecond laser is correlated with the taper and adaption of automatic tooth preparations; this setting needs to be considered during automatic tooth preparation.