Why is Class IV gold not suitable for use as a filling material in cavities?

Class IV gold is a dental material primarily used for cast restorations, especially in areas where aesthetics are not the primary concern, such as posterior teeth. However, it is not suitable for filling cavities, primarily because it cannot be polished effectively. Polishing is a crucial step in dental procedures as it helps to create a smooth surface that reduces plaque accumulation and improves the longevity of the restoration.

While gold can be shaped and polished to a certain degree, Class IV gold is designed for applications that require strength and durability rather than the fine characteristics needed for smooth filling surfaces. This makes it less ideal for fillings, where a high level of polish is necessary to prevent bacteria buildup and ensure a good aesthetic appearance.

In addition to the polishing issue, Class IV gold may also be softer compared to other dental filling materials, but this is not the primary reason for its unsuitability as a filling material. Therefore, when considering filling materials for cavities, it's crucial to select those that can be polished effectively and meet the functional demands of the dental restoration.