Final answer:
In dentistry, the occlusal cavosurface margin for a Class I amalgam restoration should maintain a 90-degree angle to ensure strength and prevent bacterial entry.
Step-by-step explanation:
The occlusal cavosurface margin for a Class I amalgam restoration should be 90°. This specific design helps to ensure the strength of the amalgam at the margin and resists fracture. A 90° angle is also referred to as a butt joint and is known to provide the best marginal seal for amalgam restorations, preventing the entry of bacteria and subsequent decay.