The mechanisms that control at the quantum level the adhesion of metals to ZrO2 are studied on the basis of density functional theory calculations of the Ni/c-ZrO2 interface. Our results indicate that the interface fragility is inherently connected to the ability of the ceramic matrix to locally reconstruct from the stabilized cubic structure toward the more stable low temperature phases. We consider with special detail the impact on the metal-ceramic bonding of the O vacancies and dopants that actually exist in the oxide lattice. Whereas vacancies greatly reduce the adhesion, the presence of dopants of large atomic volume such as Y inhibit the reconstruction of the ceramic, reinforcing the metal-ceramic bonds.