Effects of Yb:KYW thin-disk femtosecond laser ablation on enamel surface roughness

• The surface roughness of fs-laser ablated enamel was investigated quantitatively.
• Laser ablation with scanning systems is a novel tool for laser applications.
• Surface roughness not line roughness was used.
• Effects of scanning speeds, scanning line spacings and laser fluences were studied.

This study aimed to quantitatively evaluate the surface roughness of enamel following ablation with a Yb:KYW thin-disk femtosecond pulsed laser at different fluences (F), scanning speeds and scanning line spacings. Thirty human extracted teeth were sectioned into crowns and roots along the cementum–enamel junction, and then the crowns were cut longitudinally into sheets about 1.5 mm thick. The samples were randomly divided into ten groups (n=3). Samples of groups 1–8 were irradiated with a femtosecond pulsed laser. These enamel samples were fixed on a stage at focus plane, and a laser beam irradiated onto the samples through a galvanometric scanning system, with which rectangular movement could be achieved. Samples of groups 9 and 10 were prepared with grinding instruments. Following ablation and preparation, the samples were examined for surface roughness with a three-dimensional laser profile measurement microscope. The results showed that scanning speed and scanning line spacing had little influence on the surface roughness of femtosecond pulsed laser-ablated enamel, except when F=4 J/cm2. When a lower fluence was used, the enamel surface roughness was higher, and vice versa. This study showed that various laser fluences, scanning speeds and scanning line spacings can affect and alter enamel surface roughness. Therefore, adequate parameters should be chosen to achieve the proper therapeutic benefits.