What is the term for the shape and perimeter of the cavity preparation in width, length, and depth?

• A. Outline form
• B. Resistance form
• C. Retention form
• D. Convenience form

Answer: (A)

Outline form defines the external boundary of a cavity preparation—the overall shape and margins as seen on the tooth, including its width, length, and depth. This term focuses on the size and perimeter of the cavity to be prepared, which determines how much tooth structure is removed and where the cavosurface margins will lie. Resistance form, by contrast, concerns maintaining enough remaining tooth structure and wall thickness to resist occlusal forces; retention form deals with features that prevent the restoration from being dislodged; convenience form relates to access and visibility during preparation.