Modeled restorations with different constructive designs: (a) sharp transition between framework and veneer; (b) interlayer of constant composition (porcelain volume fractions of 10%, 30%, 50%, 70% or 90%) between framework and veneer; and (c) compositionally stepwise graded interlayer between framework and veneer. The graded interlayer comprised 10 thin layers, each with a different volume fraction of porcelain (5%, 15%, 25%, 35%, 45%, 55%, 65%, 75%, 85% and 95%), from the bottom to top layer, respectively.