Transmission of Er:YAG laser through different ceramics

All-ceramic restorations provide excellent esthetic results and especially for anterior zone when compared metal supported restorations. Cementation of all-ceramic restoration process is done with adhesive resin cements. However after cementation of the restoration, debonding of the restoration is very difficult when any problem occured, because of the bond strength and material properties of resin cements. This study was aimed to evaluate the effect of different ceramic materials in different thicknesses during removal of the ceramic restorations using Er:YAG laser. Specimens were prepared from six different CAD/CAM ceramics, 2 different thicknesses (0.5 and 1 mm) and 1x1 cm sizes.Transmission rates of Er:YAG laser (2940 nm, 10 Hz, 100 ms and 133 mJ/pulse) through all ceramic materials measured by powermeter. Data were analysed by using two way variance analysis (ANOVA) and LSD tests. The highest transmission ratio was determined in lithium disilicate reinforced glass ceramic and zirconia reinforced lithium silicate ceramic with 0.5 mm thickness (70%) and the lowest one was determined in zirconium oxide core ceramic with 1 mm thickness (32%). The differences among the ceramics and the differences between the different thicknesses were found to be significant (p<0.05). Ceramic type and thickness should be taken into consideration to adjust the laser irradiation parameters during laser debonding of adhesively luted all ceramic restorations.