Effect of different lithium silicate ceramics with variable shades, thickness and curing modes on the degree of conversion of resin cement

Abstract

Purpose:The bond strength between ceramics and tooth structure is affected by the degree of polymerization of resin cement. This study evaluated the effect of two light curing modes on polymerization of light cured resin cement through three lithium silicate-based ceramics (Lithium disilicate-reinforced glass ceramic (E.max CAD), Zirconia reinforced Lithium Silicate (Celtra Duo). And Zirconia reinforced Lithium Silicate (Vita Suprinity) with two shades (A2 and B1) and two ceramic thickness (0.5 and 1mm). Materials and methods:Two hundred forty ceramic samples (n=240) were divided into three main groups (n=80) according to the material. Each group was subdivided into 2 subgroups (n=40) according to ceramic shade (A2 and B1). Each subgroup was subdivided into 2 divisions (n=20) according to thickness (0.5mm and 1mm). Then each division was subdivided into two subdivisions (n=10) according to light curing method (Continuous and pulsating light curing). Samples cemented and scanned using OMNIC 5.1c software connected to the FTIR unit. Results:The results illustrated that there was no statistical significance difference in degree of conversion between the three ceramic materials. A higher degree of conversion was recorded with B1 ceramic shade than A2 shade. Also, there was a significant effect on the degree of conversion (DC%) with different thicknesses of the ceramic materials and there was a higher degree of conversion in the continuous light curing mode than the pulsating mode. Conclusions:Within the limitations of this study, the results indicated that with respect to the ceramic thickness used, the ceramic type did not affect the degree of conversion of light cured resin cement. On the other hand, thicknesses up to 1.0 mm have a significant effect on the polymerization of resin cements. Higher degrees of conversion were shown with lighter ceramic shades. Also, mode of light curing had a pronounced effect on the degree of conversion of resin cements (3638)