Effect of different acidic solutions on the optical behavior of lithium disilicate ceramics

Statement of problem: The stability of the optical characteristics of dental ceramics is essential. Degradation of these materials resulting from pH or temperature alterations in the oral cavity can lead to treatment failure.

Purpose: The purpose of this in vitro study was to evaluate the color change (ΔE), the L* coordinate, the translucency parameter, and the contrast ratio of lithium disilicate ceramic exposed to commonly used and potentially colorant solutions.

Material and methods: Fifty lithium disilicate specimens were prepared and divided into 5 groups according to the immersion solution (artificial saliva, orange juice, cola, coffee, and red wine). Immersions in acidic beverages were alternated in a thermocycler with artificial saliva. The control group was immersed in artificial saliva at 37°C throughout the immersion period. After 168 hours of immersion, the color parameters were assessed with a spectrophotometer and calculated using the because system on 2 backgrounds (black and white) and in 2 time periods, before thermocycling and after thermocycling. Data were submitted to analysis of variance followed by the Tukey honest significant difference test (α=.05).

Results: Greater color change (ΔE) and lower L* coordinate values were observed after immersion in orange juice and cola. Regarding the translucency parameter and contrast ratio, the immersion in coffee resulted in greater opacity and lower translucency of the material.

Conclusions: Alterations in the color stainability, the L* coordinate values, the translucency parameter, and the contrast ratio of the lithium disilicate ceramic were observed, according to the acidic solutions tested.