What is the purpose of glazing and firing porcelain?

• A. To reduce the need for occlusal adjustments after seating
• B. To increase the fracture toughness of metal alloys
• C. To apply finishing stains only
• D. To seal porosities and create a lustrous surface with improved stain resistance

Answer: (D)

Glazing and firing porcelain creates a glassy surface layer that fills and seals micro-porosities, smoothing the ceramic and giving it a shiny, lustrous finish. When the glaze melts and reflows during firing, it densifies the surface, reduces roughness, and makes the restoration easier to clean. This smoother, less porous surface resists staining much better and mirrors the natural enamel’s appearance, contributing to both esthetics and longevity. While stains can be added as part of esthetic work, the primary purpose is sealing porosities and producing a glossy, stain-resistant surface. It isn’t aimed at improving metal toughness or simply applying stains, so those options don’t fit as well.