Compare feldspathic porcelain and lithium disilicate regarding bonding and strength.

• A. Feldspathic porcelain has excellent esthetics but lower strength; lithium disilicate offers higher strength and good esthetics with reliable bonding
• B. Feldspathic porcelain has higher strength; lithium disilicate has poor bonding
• C. Both have identical bonding
• D. Lithium disilicate bonds worse than feldspathic

Answer: (A)

The key idea is how the material’s internal structure affects both strength and bonding. Feldspathic porcelain is a very esthetic, glassy ceramic—the high glass content gives superb translucency that closely mimics natural enamel. But that same glassy matrix provides limited crystalline reinforcement, so its flexural strength is comparatively low (roughly in the tens of MPa range), meaning it’s more prone to cracking under function. That makes it ideal for veneers or other thin restorations in areas with lighter occlusal loads, where esthetics are prioritized over high strength.

Lithium disilicate, on the other hand, has a crystalline phase that forms needle-like rods within the glass, which strengthens the material substantially. This improved strength translates to higher fracture resistance, allowing use in a wider range of restorations, including crowns and onlays, while still offering solid esthetics. Bonding to both materials is reliable when proper adhesive protocols are used: feldspathic porcelain responds well to hydrofluoric acid etching followed by silane and resin cement, but its limited strength confines its indications; lithium disilicate also benefits from etching and silane treatment and tends to show robust resin bonding, contributing to durable restorations.

So the statement that feldspathic porcelain provides excellent esthetics with lower strength, while lithium disilicate offers higher strength with good esthetics and reliable bonding, best reflects these differences.