Surface Engineering and Veneer Optimisation of Y-TZP Zirconia: A Critical Review of Phase Stability, Mechanical Reliability, and Clinical Performance

Abstract

Background: Yttria-stabilised tetragonal zirconia polycrystal (Y-TZP) has improved fixed prosthodontics because of its strong mechanical properties and biocompatibility. Still, it is challenging to achieve good esthetics without losing strength, particularly during glazing and veneering. This review looks at new glazing and layering techniques for Y-TZP zirconia. It considers how these methods affect surface features, phase stability, bond strength, appearance, and long-term clinical results.

Materials and Methods. The authors searched PubMed, Scopus, and Web of Science for in vitro studies, clinical trials, and systematic reviews on glazing materials, veneering ceramics, CAD/CAM layering, heat-pressed veneering, monolithic zirconia staining, surface pretreatment, bioactive glazes, multilayer zirconia, and laser polishing. The review included studies that reported on surface roughness, flexural strength, phase transformation, veneer chipping, and clinical survival.

Results. New low-fusing nanofilled glaze systems make surfaces smoother and glossier. Heat-pressed and CAD/CAM veneering techniques offer better consistency and bond strength than traditional layering. Monolithic and multilayer zirconia systems help prevent veneer chipping and keep good esthetic qualities. Careful surface treatment and controlled firing are important for phase stability. Bioactive and antibacterial glazes are new options that may benefit implant use.

Conclusions. Modern prosthodontics is using more monolithic and multilayer zirconia to solve mechanical problems. Careful surface engineering, especially in glazing and firing, is still key for long-term clinical success. In the future, digital customization and biologically active surfaces are likely to be combined.