Effect of Er,Cr:YSGG laser debonding & two surface treatments on color & translucency of Lithium Disilicate restorations

Abstract

Debonding of lithium disilicate restorations represent challenges. To overcome these difficulties, the use of lasers was recently introduced as a more comfortable and more conservative restoration removal technique. This study evaluated the effect of Er;Cr;YSGG laser debonding & two different surface treatments on color stability & translucency of lithium disilicate restorations 28 ceramic E.max CAD samples were prepared, samples were divided into 2 groups according to thickness whether 0.5 mm or 1mm (each group =14 samples). Each group divided into 2 subgroups according to different surface treatments, whether hydrofluoric acid (n=7) or laser surface modification (n=7). 28 freshly extracted, non-carious bovine permanent incisors were prepared to receive lithium disilicate discs, after bonding of samples to the prepared teeth they were subjected to laser irradiation using specific wavelength Er;Cr:YSGG (2780 nm), debonding time was calculated for each sample. 2 different surface treatments were applied to the samples (acid etching & laser etching) color & translucency was measured before & after debonding & surface treatments. Surface of the samples was analyzed by SEM to evaluate the difference between before & after debonding & surface treatments. Color measurements for all specimens were performed with CIELab color system using a clinical spectrophotometer. To analyze the effects of surface treatment procedures, color difference was calculated before and after surface treatments on the gray background with the following equation.