What is the primary objective of amalgam cavity preparation?

• A. Remove decay and preserve sound tooth structure and to create a preparation with proper resistance, retention, and marginal integrity for a durable restoration.
• B. Remove healthy tooth structure to allow for a stronger amalgam buildup.
• C. Use selective etching to bond with dentin for a stronger restoration.
• D. Emphasize aesthetics over function in the prep.

Answer: (A)

The aim of an amalgam cavity preparation is to remove decayed tissue while conserving as much healthy tooth structure as possible, and to shape the cavity so the restoration is mechanically stable. Amalgam relies on its cavity geometry for retention and resistance, not on bonding, so the prep should provide resistance to occlusal forces, retention to prevent dislodgement, and a good marginal seal to avoid leakage. That means preserving sound enamel and dentin, ensuring adequate depth and proper wall convergence, and placing margins on sound enamel for a durable, long-lasting restoration. Other ideas like bonding to dentin or prioritizing aesthetics over function don’t drive the preparation for amalgam, since it is a non-bonded restoration whose success hinges on the preparation’s mechanical form and preservation of tooth structure.