Tea and Cola Stainability of Full Veneer Crowns Constructed from Repressed Conventional and Novel Lithium Disilicate Ceramic Ingots: An In Vitro Study.

Background: A large number of dental restorations are constructed from heat-pressed lithium disilicate (LDS) glass-ceramic ingots. These ingots' mechanical properties have not been adversely affected by repressing or repeating their processing. Despite this, little is known about the stainability of these LDS ceramic ingots that have been repeatedly processed.

Objective: To evaluate change in colour of ceramic crowns constructed from 3 different repressed ceramic ingots: lithium disilicate (LS), lithium silicate material reinforced with zirconia (ZLS) and repressed lithium silicate crowns with high-density micronization technology (LS- HDM) following immersion in tea, and cola solutions and followed by brushing.

Materials & methods: Three distinct heat-processed LDS ceramic ingots representing three groups (N= 24) E-max (EM), Lisi (Li), and Celtra (CA) were used to manufacture seventy-two identical ceramic crowns. Three subgroups (n = 8) representing the experimental (tea, and cola) and control (artificial saliva) groups were created from each group. Colour changes were measured at the beginning, following tea and cola staining, and after brushing, using the CIE L * a * b * system. The colour change (ΔE, ΔL, Δa, and Δb) were evaluated using one-way ANOVA, and post-hoc analysis was done to determine any significant differences between the groups.

Results: The analysis revealed significant differences in color attributes (L, a, and b values) among crown materials, with variations observed following immersion in saliva and staining solutions. While all materials exhibited a decrease in L values post-immersion, only CA showed significant changes in a and b values, indicating shifts in red and yellow components. Additionally, the overall color change (ΔE) remained below acceptability thresholds post-brushing, suggesting minimal perceptible differences. These findings underscore the material-specific responses to staining agents.

Conclusion: Immersion of ceramic crowns made from LS, LS-HDM, and ZLS in tea and cola solutions resulted in noticeable color changes. However, regular tooth brushing effectively restored the satisfactory color appearance of stained ceramic crowns fabricated from repeatedly processed LS-based ingots.