Prosthodontic Materials Science
Prosthodontic Materials Science tests ceramics, zirconia, metal-ceramic, resins, cements, and bonding. The exam focuses on property-to-application matching rather than brand names.
Core rules
- Lithium disilicate is etchable with hydrofluoric acid and suits adhesive anterior and single-unit posterior restorations when supported.
- Zirconia has high flexural strength and fracture toughness but is not etched like glass ceramic; use airborne-particle abrasion and appropriate primers.
- Metal-ceramic remains predictable when framework design and porcelain thickness are controlled.
- Resin cements vary by initiation mode and filler; try-in pastes are not final cements.
- Polymerization shrinkage, opacity, and wear behavior affect material choice.
Worked example
A posterior molar needs a single crown in a bruxing patient with 1.5 mm occlusal clearance. Reasoning: lithium disilicate may be adequate if bonded and supported, but monolithic zirconia offers higher strength with less need for veneering porcelain. However, zirconia requires adequate occlusal space and careful surface treatment. If esthetics demand a glass ceramic, confirm adhesion and clearance; if clearance is minimal, adjust the preparation rather than choose a weaker material.
Traps that cost marks
- Etching zirconia as if it were lithium disilicate.
- Using try-in paste as final cement.
- Ignoring occlusal clearance for monolithic ceramics.
- Selecting a material by brand rather than properties.
- Forgetting that resin cement shade affects final esthetics.