Wettability characteristics of an Al₂O₃/SiO₂-based ceramic modified with CO₂, Nd:YAG, excimer and high-power diode lasers

The interaction of CO 2 , Nd:YAG, excimer and high-power diode laser (HPDL) radiation with the surface of an Al 2 O 3 /SiO 2 based ceramic was found to effect significant changes in the wettability characteristics of the material. It was observed that interaction with CO 2 , Nd:YAG and HPDL radiation reduced the enamel contact angle from 118° to 31°, 34° and 33° respectively. In contrast, interaction with excimer laser radiation resulted an increase in the contact angle to 121°. Such changes were identified as being due to (i) the melting and partial vitrification of the Al 2 O 3 /SiO 2 -based ceramic surface as a result of interaction with CO 2 , Nd:YAG and HPDL radiation; (ii) the surface roughness of the Al 2 O 3 /SiO 2 -based ceramic increasing after interaction with excimer laser radiation; and (iii) the surface oxygen content of the Al 2 O 3 /SiO 2 -based ceramic increasing after interaction with CO 2 , Nd:YAG and HPDL radiation. The work has shown that the wettability characteristics of the Al 2 O 3 /SiO 2 -based ceramic could be controlled and/or modified by laser surface treatment, in particular, whether the laser radiation had the propensity to cause surface melting. However, a wavelength dependence of the change of the wetting properties could not be deduced from the findings of this work.