Spectrophotometer Analysis of Cad-Cam Zirconia Reinforced Lithium Silicate and Lithium Disilicate Glass Ceramics

Abstract

INTRODUCTION: Matching dental ceramic translucency is the optimal esthetic goal in restorative dentistry. Several types of ceramics evolved over the years in an attempt to optimize physical mechanical and optical properties of the previous types. OBJECTIVES: The aim of this study is to compare and analyze light transmission, light reflection and light absorption of high translucency zirconia reinforced lithium silicate ceramic, low translucency zirconia reinforced lithium silicate ceramic, high translucency lithium disilicate glass-ceramic and low translucency lithium disilicate glass-ceramic. MATERIALS AND METHODS: Serial cutting of the E.max cad and Vita suprinity blocks was done using isomet 4000 micro-saw microtome. Ten ceramic specimens were obtained for each material, 5 of which were 1.5 mm thick and the other 5 were 1 mm thick to be veneered by 0.5 mm of the corresponding veneering material according to manufacturer's instruction. Spectrophotometric analysis was carried out for the forty ceramic specimens. RESULTS: Light transmission for the four groups of zirconia reinforced lithium silicate was significantly higher than their corresponding groups of lithium disilicate (p<0.005). Light reflection and light absorption for the four groups of zirconia reinforced lithium silicate was significantly lower than their corresponding groups of lithium disilicate (p<0.005). Veneering increased light transmission and light reflection however it decreased light absorption for both materials significantly. CONCLUSIONS: Translucency of zirconia reinforced lithium silicate is better than lithium disilicate. Veneering improved optical properties for both zirconia reinforced lithium silicate and lithium disilicate.

Color Masking Ability of Three Dental Ceramics with Different Translucencies

“…Results of the current study were against some previous studies. Some of them reported that zirconia-reinforced lithium silicate (ZLS)has better translucency than IPS E.max, due to ZRO 2 which act as nucleating center and produces fine grain size that gave ZLS higher translucency than IPS E.max, and others reported that both materials have the same translucency as they have similar composition (25)(26)(27) . This was not in accordance with the results of some studies, which assess translucency of (ZLS) zirconia reinforced lithium silicate in both translucencies (high and low) and (LDS) lithium disilicate glass ceramics in also both translucencies (high and low).…”

“…it was concluded that ZLS demonstrated better translucency than LDS. This might be due to the presence of ZRO 2 particles that acted as centers of nucleation, leading to more homogenous structure with fine grain size (0.5µm) for vita suprinity, so producing more translucent appearance for vita suprinity and less translucency for LDS (25) .…”

“…Translucency is the relative amount of light transmission or diffuse reflectance from a surface. For translucent materials most of the incident light is transmitted and some of them is absorbed, whereas less translucent materials reflect and absorb light dropping on it (7) .…”

“…Lithium disilicate is available in two forms: pressable and CAD-CAM. It appears to be the ideal material because rather than cutting back the core and applying ceramic powder and liquid ceramic on top, the preparation is milled to anatomical shape and stained, resulting in a highly strong restoration (9) . The success of CAD-CAM technology and materials science has led to the development of new materials such as Zirconia reinforced-lithium Silicate (ZLS).…”

Efficiency of Er: YAG Laser in Veneers Debonding with Two Materials & Thicknesses-An in Vitro Study

“…17 Two types of dental ceramic materials were selected for this study, lithium disilicate glass ceramics and cubic zirconia (Ultra translucent zirconia) were selected in this study due to their good esthetics & good mechanical strength, owing to incorporation of crystalline materials in the glassy matrix in case of lithium disilicate materials & in case of cubic zirconia FULL crystalline material giving high mechanical strength & improved edge strength. 18 Previous studies showed high successful rates of laminate veneers fabricated from lithium disilicate and zirconia reinforced lithium silicate. 19 which derived us to choose cubic zirconia as newly introduced material to test its bonding strength.…”