Yttria-stabilised polycrystalline zirconia ceramics (Y-TZP¿s) possess a unique combination of properties that make them attractive for dental prosthetic applications: strength, toughness, bio-compatibility, manufacturability, and long term stability. They combine well with veneering porcelain layers to produce restorations of excellent aesthetic quality. However, clinical practice demonstrates that in as many as 5% of cases, the intricate interplay between the transformability of Y-TZP under loading and the thermal property mismatch between zirconia and porcelain leads to veneer chipping and costly restoration failure. In order to optimise the performance of the system, it is important to examine the fundamentals of transformation and deformation of Y-TZP ceramics under the combined influence of temperature and stress.