Impact of repressing and thermomechanical fatigue on color stability and translucency of IPS Emax and Celtra press: an in vitro study.

To evaluate the stain resistance of repressed IPS Emax and Celtra Press after thermo-mechanical fatigue. Two pressable glass ceramics, IPS e.max press (Ivoclar, Vivadent) and Celtra press (Dentsply, Sirona), were used in this study. Thirty discs (2 × 10 mm) were fabricated: (n = 15) e.max press (Group E) and Celtra press (Group C). The discs were fabricated using a repressing technique where remnant buttons from the initial press were reshaped as new ingots by removing all sprues. Each group was subdivided into three equal subgroups after thermo-mechanical fatigue according to the immersion solution: subgroup (AS): Artificial saliva (control immersion medium), subgroup(T): Tea solution and subgroup (C): Cola solution, (n = 5). Color and translucency measurements were recorded for all specimens. Data was collected and statistically analyzed using a two-way ANOVA test to study the interaction of study variables. Statistical analysis revealed that IPS e.max Press displayed significantly greater color deviation (ΔE) compared to Celtra Press in artificial saliva and tea groups, whereas no significant difference was observed between groups immersed in cola (p = 0.064).TP increased after staining, particularly in cola subgroups, with Celtra Press/cola showing the highest values. Two-way ANOVA revealed significant effects of material, staining medium, and their interaction on both ΔE and TP (p < 0.001). Both repressed IPS e.max Press and Celtra Press ceramics are susceptible to changes in color stability and translucency following exposure to common staining agents and thermomechanical aging.