Abstract:  

The purpose of this study was to determine the possible effects of the veneering porcelain thickness, and of repeated firing on the final shade of IPS e.max Press. Sixty disc-shaped IPS e.max Press specimens were fabricated and divided into 6groups according to shade (A2, C2) and porcelain thickness (0.5, 1.0 and 1.5 mm). Repeated firing (3, 5 and 7firings) was performed and the colour differences (AE) were determined. With increased thickness, A2 specimens showed a significant reduction in L* values and increase in a* and b* values while C2 specimens showed reductions in L*a*b values (P < 0.01). We would conclude that clinically, the preparation should provide at least 1 mm of thickness for the aesthetic potential of this dentine porcelain to be realized.