Translucency and Wear of Pressable Lithium Disilicate and Zirconia-reinforced Lithium Silicate Glass-ceramics: An In-vitro Study

Introduction: New ceramic materials have been introduced with less research on their aesthetic outcome and durability for clinical implications. Lithium disilicate is one of the widely used materials for restoration. Recently, Zirconia-reinforced Lithium Silicate (ZLS) glass-ceramic enriched with 10% zirconia in highly dispersed glass phase of ceramic has been introduced.

Aim: To investigate the translucency of pressable Lithium Disilicate (LS2) and ZLS and their effects on wear of opposing enamel.

Materials and Methods: This in-vitro study was carried out at MGM Dental College and Hospital, Mumbai, Maharashtra, India, between January 2017 and January 2020. Twenty disks of 15×3 mm; 10 each of LS2 and ZLS were fabricated by hot pressing method. For translucency Commission Internationale de l’Eclairage (CIE) L*a*b values for each sample were measured against black and white background using a laboratory reflectance spectrophotometer. Translucency was calculated using Translucency Parameter (TP)={(L*B-L*W)2+(a*B-a*W)2+(b*B-b*W)2}1/2. For wear testing same 20 disks were used as an antagonist. Enamel specimen of 20 maxillary premolar were abraded against each antagonist with two body wear testing machine in rotational motion under a constant load of 20 N at 350 rpm for 5000 cycles. The initial readings and final readings of enamel specimen in μm were measured using contact stylus profilometer. Non parametric Mann-Whitney U test was used to compare the significance of difference between two groups.

Results: The TP values obtained were 23.07 and 24.04 for LS2 and ZLS, respectively (p-value=0.004). The mean wear values obtained were 0.71860 μm and 1.09500 μm for LS2 and ZLS, respectively (p-value=0.049). The difference for both the parameters was statistically significant.

Conclusion: Within the limitation of this study, ZLS showed higher translucency values than LS2. Wear rate of opposing enamel was more with ZLS than LS2. Thus ZLS may provide excellent aesthetics which can be used as an option for rehabilitation in aesthetic zone.