Ceramics-Silikáty 68, (2) 278 - 285 (2024)

This study evaluated and compared the effects of simulated tooth brushing and Arabic coffee thermocycling on the colour stability of lithium disilicate and translucent zirconia dental restorative materials. Sixty disc-shaped specimens (10×1.2 mm²) were fabricated from zirconia and lithium disilicate (N=30). The specimens from each material were allocated to three groups (n=10) based on the surface interventions - simulated tooth brushing (TB), Arabic coffee thermocycling (TC), and TC followed by TB (TC+TB) - to be received. The colour of the specimens was recorded at baseline and after the interventions using a spectrophotometer in 3D CIEL*a*b* colour space. The colour difference (ΔE) between the groups was statistically analysed using an analysis of variance (ANOVA) and the least significant difference post-hoc test (p˂0.05). The mean ΔE for both lithium disilicate and translucent zirconia was high after all the interventions (p˂0.05). The mean ΔE was high after TC+TB, followed by TB, and TC for both the tested materials. The overall mean ΔE was highest (1.98±0.92) in lithium disilicate after TC+TB and the least in translucent zirconia after TC (0.96±0.87). In comparison with translucent zirconia, the ΔE was highest in lithium disilicate after TC+TB followed by TB and the least in TC. For the lithium disilicate group, the mean ΔE was highest after TC+TB and the least after TC (p˂0.05). Similarly, the mean ΔE for the zirconia group was highest after TC+TB and the least after TC (p˃0.05). In comparison with the translucent zirconia, the ΔE was higher in lithium disilicate demonstrating lower colour stability. In conclusion, the combined effect of simulated tooth brushing and Arabic coffee thermocycling demonstrated the highest ΔE among the interventions, irrespective of the materials tested. Although the colour differences presented in the study were clinically perceptible following the interventions, the overall differences were clinically insignificant.