Effects of ceramic thickness, ceramic translucency, and light transmission on light-cured bulk-fill resin composites as luting cement of lithium disilicate based-ceramics

Abstract

Lithium disilicate, a reinforced pressable glass ceramic, is a popular option for large-defect restoration owing to its esthetic feature and promising strength [1,2]. Ceramic cementation is a critical issue for achieving restoration longevity [3]. Features such as the degree of conversion, mechanical properties, bond strength, working time, shade stability, restorative thickness, and retention form design are criteria for cement selection consideration [4][5][6][7]. A higher degree of conversion (DC) ensures lower solubility of cement and results in restoration with less marginal discrepancy [8]. Dual-cured resin ce-ment is thought to be the first choice for ceramic restoration to avoid insufficient polymerization of the resin cement because of its chemical polymerization constituent [9], which allows more time to remove excess cement before hardening. Recently, more practitioners and studies have used purely light-cured resin composites as luting cement to achieve stronger mechanical properties, higher micro-tensile bond strength, longer working time, easier handling for excess control, higher shade stability, and greater marginal integrity [9][10][11][12]. Some scholars have even used preheated light-cured packable composite restorative materials, mainly to reduce the film thickness and increase the flowability to act as a luting cement [13][14][15]. However, most of these studies have used light-cured conventional resin composites. Light transmittance through the restoration may cause insufficient polymerization, leading to unpredictable outcomes. The light transmission rate is affected by the thickness, translucency, and color of the restoration. When the light transmittance decreases, less light intensity reaches the cement layer, possibly causing an uncured J Prosthodont Res. 2023; **(**):

Impact of CAD/CAM Material Thickness and Translucency on the Polymerization of Dual-Cure Resin Cement in Endocrowns

“…These CAD/CAM materials for endocrowns are available in HT and LT grades and offer different levels of optical translucency to achieve aesthetically pleasing tooth restorations. Previous studies have investigated the impact of ceramic translucency on the polymerization of resin-based cements by the light irradiation of ceramic [ 21 , 42 , 43 ]. Kuijper et al [ 21 ] examined the influence of lithium disilicate translucency at thicknesses of 4.0 mm and 7.5 mm on the degree of conversion of dual-cure resin cement.…”

“…Their findings suggested that the translucency grade of the lithium disilicate glass did not affect the degree of conversion. Similarly, Chen et al [ 42 ] explored the effect of lithium disilicate glass translucency on the polymerization of dual-cure resin cement through 1 mm- and 2 mm-thick samples, finding no significant effect on the microhardness or degree of conversion. In line with these findings, the present study revealed that differences in the translucency of all the examined CAD/CAM materials affected the polymerization of the dual-cure resin cement immediately after light irradiation, with little or no influence on polymerization after aging.…”