EFFECT OF THICKNESS OF LITHIUM DISILICATE MATERIAL ON THE DEGREE OF CONVERSION OF THE LIGHT-CURE RESIN CEMENT: AN IN-VITRO STUDY

Dr. Prerika Agarwal*, Dr. Samarth Kumar Agarwal, Dr. Romil Singhal

ABSTRACT

The durability of glass-ceramic restorations relies on sufficient polymerization of the underlying resin cement influencing light transmission and polymerization efficiency. The degree of conversion (DC) of resin cement is a key factor in restoration success. This article aims to assess and compare the degree of conversion of light-cured resin cement beneath lithium disilicate ceramics of differing thicknesses (0.5, 1.0, and 1.5 mm) under in vitro conditions. Heat-pressed lithium disilicate discs (0.5-, 1.0-, and 1.5-mm thickness) were fabricated. A stainless-steel guide plate ensured uniform resin cement application. Cement was light-cured through test specimens (n=40) or a Mylar strip (control group), stored for 24 hours in dark at room temperature for DC measurement by Fourier transform infrared spectroscopy (FTIR). ANOVA and Tukey’s post hoc tests analyzed data (p < 0.05). DC values inversely correlated with ceramic thickness with control group showing the highest DC (69.40 ± 0.33). 0.5 mm group showed DC (68.07 ± 1.74) statistically comparable to control, while 1.5 mm group had the lowest DC (61.05 ± 2.19). ANOVA confirmed significant intergroup differences (p < 0.01). The study concluded that increased lithium disilicate thickness significantly reduces resin cement polymerization efficiency.

Keywords: Ceramics, Lithium Disilicate, Degree of conversion, Fourier transform infrared spectroscopy, Heat-pressed ceramics, Light-cure resin cement.