Which of the following is one of the five fundamental principles of amalgam cavity preparation?

• A. Precision in carving occlusal anatomy
• B. Preservation of tooth structure
• C. Use of gold foil as liner
• D. Immediate cusp coverage for all posterior preparations

Answer: (B)

Preserving tooth structure is central to amalgam cavity preparation. The idea is to remove only diseased or compromised tooth tissue while leaving as much healthy tooth as possible, because the remaining tooth provides the strength and support the restoration relies on. When you conserve structure, the tooth is less prone to fracture, the margins stay more durable, and the restoration can function with better long-term prognosis.

Carving occlusal anatomy precisely is important for proper occlusion and aesthetics, but it’s a finishing/detailing step rather than a fundamental aim guiding how the cavity is prepared. Using gold foil as a liner belongs to a different technique and material system, not a principle governing amalgam prep. Immediate cusp coverage for all posterior preparations isn’t a universal rule; cusp coverage is case-dependent and not a blanket principle of the preparation itself.