Which type of stain occurs directly on the surface of the tooth?

Extrinsic stains are those that occur directly on the enamel surface of the tooth and are usually caused by external factors such as food, beverages, tobacco, and poor oral hygiene. These stains can often be removed through professional dental cleanings or at-home oral hygiene practices, as they do not penetrate the tooth structure itself.

In contrast, intrinsic stains are a result of internal factors, such as developmental disorders or dental trauma, and they are located within the tooth’s structure. Structural stains also refer to changes in the tooth's composition or development, and systemic stains arise from systemic factors affecting the body, such as medications or illnesses that influence tooth development. These types of stains cannot be removed by surface cleaning and require more involved dental treatments. Understanding the nature of these different stain types helps clinicians effectively address and treat dental discoloration issues.