Which statement best defines extrinsic stains?

Extrinsic stains refer to discolorations that appear on the surface of the teeth, primarily on the enamel. These stains are typically caused by external factors such as food, beverages, tobacco use, and certain oral hygiene products. One of the distinguishing characteristics of extrinsic stains is that they can usually be removed through professional dental cleaning or effective at-home oral hygiene practices, such as brushing and using whitening agents.

In contrast to extrinsic stains, intrinsic stains are found within the tooth structure and can't be removed by these means, making the option about stains that occur on internal surfaces inaccurate. The incorrect choices also include references to stains that cannot be removed or are caused by fluoride treatments, both of which do not accurately reflect the nature and removability of extrinsic stains. This reinforces the understanding that the most accurate definition of extrinsic stains focuses on their location on the enamel surface and their potential for removal.