Preliminary Study on the Optimization of Femtosecond Laser Treatment on the Surface Morphology of Lithium Disilicate Glass-Ceramics and Highly Translucent Zirconia Ceramics

Abstract

All-ceramic restorations have become increasingly popular in dentistry. Toward ensuring that these restorations adhere to the tooth structure, this study determines the optimal femtosecond laser (FL) treatment parameters for lithium disilicate glass-ceramics and highly translucent zirconia ceramics with respect to surface morphology. For both the ceramics, the following surface conditions were investigated: (1) as-sintered; (2) Al2O3 sandblasted; (3) FL treatment (dot pattern with line distances of 14, 20, and 40 µm); (4) FL treatment (crossed-line pattern with a line distance of 20 and 40 µm). Surface roughness parameters were estimated using a 3D confocal laser microscope; microstructures were analyzed using a scanning electron microscope. Peak fluence (Fpeak) values of 4 and 8 J/cm2 and irradiation numbers (N) of 20 and 10 shots were selected to create dot patterns in highly translucent zirconia and lithium disilicate glass-ceramics, respectively. Furthermore, Fpeak = 8 J/cm2 and N = 20 shots were chosen to obtain crossed-line patterns in both ceramics. Our results show that lithium disilicate glass-ceramics and highly translucent zirconia exhibit a similar surface morphology under each of the surface treatment conditions. Therefore, FL irradiation of dot or crossed-line patterns (at a distance of 20 and 40 µm) are potential candidates for future investigations.

Surface modification of zirconia or lithium disilicate-reinforced glass ceramic by laser texturing to increase the adhesion of prosthetic surfaces to resin cements: an integrative review

“…The findings revealed similar morphological aspects for both glass ceramic and zirconia considering the surface modification parameters. The laser-textured surfaces with crossed-line patterns at a distance of 20 or 40 µm revealed a great potential for further studies [ 17 ].…”

“…The surface modification of implants and prosthetic structures by high intensity laser irradiation has gathered attention to improve roughness and wettability for adhesion to resin-matrix cements [7,10,[12][13][14][15]. Currently, different morphological surface features (i.e., micro-grooves, cross-lines, pits, valleys, and peaks) can be produced on ceramics and glass ceramics by using different laser intensity, type, time, and frequency [7,10,[12][13][14][15][16][17]. Previous studies have reported the surface modification of zirconia leading to an increased roughness after short (mili-to nano-seconds) or ultra-short (pico-to femtoseconds) periods of time (pulses) using different types of lasers such as Nd:YAG, Er:YAG, CO 2 , Er,Cr:YSGG, and Nd:YVO 4 [7,10,[12][13][14][15][16][17][18][19].…”

“…Currently, different morphological surface features (i.e., micro-grooves, cross-lines, pits, valleys, and peaks) can be produced on ceramics and glass ceramics by using different laser intensity, type, time, and frequency [7,10,[12][13][14][15][16][17]. Previous studies have reported the surface modification of zirconia leading to an increased roughness after short (mili-to nano-seconds) or ultra-short (pico-to femtoseconds) periods of time (pulses) using different types of lasers such as Nd:YAG, Er:YAG, CO 2 , Er,Cr:YSGG, and Nd:YVO 4 [7,10,[12][13][14][15][16][17][18][19]. However, zirconia is susceptible to defects such as cracks depending on the mode and intensity of the laser irradiation.…”