Which statement best describes how amalgam interacts with tooth structure?

• A. Amalgam bonds chemically to dentin with resin tags.
• B. Amalgam bonds to dentin via adhesives.
• C. Amalgam requires enamel bevels to hold.
• D. Amalgam relies on mechanical retention because it does not bond.

Answer: (D)

Amalgam relies on mechanical retention rather than chemical bonding. It doesn’t form a true bond with dentin or enamel, so the way it stays in place is by the shape of the cavity prep itself. By creating undercuts, dovetails, and other retentive features in the cavity walls, the condensed amalgam locks into place and resists dislodgement under chewing forces. The material sits in and fills those physical spaces, and its retention comes from how well the cavity walls grip it.

That’s why statements about chemical bonding to dentin, resin tags, or adhesives aren’t appropriate for amalgam—the traditional way to secure it is purely mechanical. Enamel bevels aren’t a requirement for amalgam and are more relevant to bonding techniques used with other restorative materials.