Which restoration is made of metal, acrylic or porcelain and replaces one or more of the cusps of the tooth?

• A. Inlay
• B. Onlay
• C. Crown
• D. Bridge

Answer: (B)

Onlay is a partial crown restoration that replaces one or more cusps of a tooth. It can be made from metal, acrylic, or porcelain, offering strength and aesthetics while conserving as much natural tooth structure as possible.

An inlay, by contrast, fits within the groove boundaries of the biting surface and does not cover any cusps, so it doesn’t replace cusp height. A crown completely encases the visible portion of the tooth, replacing all surfaces above the gum line, not just cusps. A bridge is not a single-tooth restoration at all—it spans a gap to replace a missing tooth, anchored to adjacent teeth.

So when cusp damage exists and a restoration needs to cover those cusps without full-crown encasement, an onlay is the best fit.