Monolithic zirconia crowns are produced by completely milling a single block of zirconia disc using CAD/CAM technology, and they do not contain any top porcelain layer; this results in extremely high flexural strength ($1000-1200 MPa) and virtually zero risk of fracture due to chewing forces. In porcelain laminated zirconia, a traditional feldspathic porcelain layer is fired onto a zirconia substructure to enhance aesthetics. While this combination offers excellent light transmission, micro-fractures and chipping, known as “delamination” or “chipping,” can occur in the fragile top porcelain layer due to incompatibilities in the thermal expansion coefficients between porcelain and zirconia or shear forces during chewing; therefore, monolithic structures are preferred in posterior molars, while highly translucent monolithic or lithium disilicate systems are preferred over laminates in anterior aesthetic areas.
