Which type of stains result from external sources according to dental classifications?

Extrinsic stains are those that occur on the outer surface of the teeth due to external factors, such as food, beverages, tobacco use, and poor oral hygiene. These stains are often removable through dental cleanings and coronal polishing because they have not penetrated the enamel structure itself.

In contrast, intrinsic stains originate from within the tooth, often related to developmental issues, trauma, or exposure to certain substances during tooth formation, making them much more challenging to treat. The term 'internal stains' typically refers to conditions similar to intrinsic stains. While 'surface stains' could describe conditions related to extrinsic stains, the terminology aligns more closely with the classification of extrinsic stains for professional use. Thus, recognizing extrinsic stains is essential for effective dental care and patient education about maintaining oral hygiene to prevent these types of discoloration.