Aim: To evaluate the influence of resin cement on the color stability of lithium disilicate and zirconia restorations immersed in coffee after aging.
Materials and methods: Eighty maxillary premolars were classified into eight groups (n = 10) based on restorative material type (lithium disilicate or zirconia), resin cement type (G-CEM LinkForce; GC Corporation or Panavia SA Cement Plus Automix; Kuraray Noritake Dental), and preheating temperature (25°C or 54°C). Following tooth preparation, each restoration was bonded to its corresponding substrate. Using a reflectance spectrophotometer, Commission Internationale de l’Éclairage (CIE) tristimulus values were detected and calculated (D65 standard illumination, 10-degree observer angle). All specimens were aged (240,000 load cycles followed by 10,000 thermal cycles), then immersed in coffee (18 h). Following that, the second measurements of the color coordinates were determined. The total color differences were measured, and the data were statistically analyzed (α = 0.05).
Results: The temperature had a significant effect on ΔL΄ (P < 0.001), ΔC΄ (P < 0.001), and ΔH΄ (P < 0.001). The lithium disilicate restorations were more color stable than the zirconia restorations. Also, there was a significant difference (P = 0.047) between the LinkForce (2.28 ± 0.48) and Panavia SA (2.15 ± 0.46) cement. The restorations cemented at a temperature of 54°C (1.76 ± 0.11) showed significant color differences (P < 0.001) compared with those cemented at a temperature of 25°C (2.67 ± 0.15). A three-way analysis of variance (ANOVA) test revealed that the interaction between the ceramic material, cement type, and temperature had no statistically significant effect (P = 0.611) on the color stability of the ceramic restorations.
Conclusions: Cement type has a significant effect on the color stability of lithium disilicate and zirconia restorations. Cement at a temperature of up to 54°C enhances the color stability of lithium disilicate and zirconia restorations.