Color Stability of Lithium Disilicate and Monolithic Zirconia in Various Staining Liquids: An Invitro Study

Abstract

Introduction The demand for aesthetic dental services is on a constant upsurge due to an aesthetic conscious society. Aesthetic dental practice has brought numerous innovative clinical procedures and a revolution in dental materials.Zirconia has been used to develop crowns, bridges, posts, and implants due to its high biocompatibility, increased toughness, and improved fracture resistance. Lithium disilicate is the commonly used glass-ceramic because of its exceptional optical properties, superior strength and ease of fabrication.The color stability of the restoration is critical for the long-term success of the aesthetic restorations.

Objectives: To compare the color stability of monolithic zirconia and lithium disilicate after immersion in various staining liquids. The null hypothesis was that immersion in coffee, green tea and chlorhexidine, would have no effect on the color stability of the ceramics.

Methods: Total thirty specimens ( n=30 ) were made of monolithic zirconia and lithium disilicate. Each group was divided into 3 subgroups depending on the staining solutions (coffee, green tea and chlorexidine). After the immersion period of 28 days, the specimens were removed from the testing solution. The color measurements were performed via a spectrophotometer. The results were analyzed using statistical software (SPSS, version 22; SPSS Inc., Chicago, IL, USA). The means and standard deviations were compared using analysis of variance (ANOVA) and a multiple comparisons test.

Results: The greatest ∆E value (5.6) was observed for zirconia and the lowest ∆E was observed for the  lithium disilicate samples immersed in chlorhexidine (1.42).

Conclusions: Within the limitations of this in vitro study, the following conclusions were drawn: (1) Discoloration from coffee was more significant in monolithic zirconia compared to lithium disilicate ceramic. (2) Lithium disilicate ceramic was found to have better color stability compared to monolithic zirconia. (3) Monolithic zirconia displayed the least color stability among all the tested discoloring agents.