Effect of food-simulating solvents on the stainability and mechanical properties of partially and fully crystallized lithium disilicate glass-ceramics.

STATEMENT OF PROBLEM: The effect of food-simulating solvents (FSSs) on the staining susceptibility and mechanical properties of partially and fully crystallized lithium disilicate glass-ceramics (LDGCs) remains unclear.

PURPOSE: The purpose of this in vitro study was to evaluate the color change, hardness, flexural strength, and reliability of LDGCs exposed to FSSs.

MATERIAL AND

METHODS

Two machinable LDGCs, partially crystallized (IPS e.max CAD, EC) and fully crystallized (Initial LiSi Blocks, LS) (n=120), were assigned to different FSS groups: artificial saliva, citric acid, or ethanol. Color coordinates were obtained using a spectrophotometer, and the color stability (ΔE00) was computed using the CIEDE2000 color difference formula. Martens hardness (HM) data were acquired from a hardness testing machine, and biaxial flexural strength (σ) was measured with a universal testing machine. Characteristic strength (σ0) and reliability (m̂U) were computed by Weibull analysis. Data for ΔE00, HM, and σ were analyzed by 2-way ANOVA, Tukey HSD, Student t tests, and Pearson correlations (α=.05).

RESULTS

LDGC material type, FSS treatment, and their interaction had a significant effect on ΔE00, HM, and σ (P≤.024). Considering published ΔE00 thresholds, EC and LS had perceptible color changes after ethanol immersion, and LS had unacceptable color changes after citric acid immersion. Citric acid had a stronger harmful effect on LS than EC for all outcomes (P<.010). Higher σ0 and m̂U were verified in EC across all FSS groups (P<.001).

CONCLUSIONS

Fully crystallized LDGC displayed color stability similar to that of partially crystallized LDGC after accelerated artificial saliva aging; however, acidic FSSs negatively impacted fully crystallized LDGC's colorimetric and mechanical properties to a greater degree.