What type of stain can be removed from the external surfaces of teeth?

Extrinsic stains are those that occur on the external surfaces of teeth and are primarily caused by food, beverages, tobacco, and poor oral hygiene. These stains can usually be removed through professional cleaning techniques, such as scaling and polishing performed by a dental hygienist. Additionally, certain whitening treatments can effectively address extrinsic stains by targeting the surface discoloration.

Intrinsic stains, on the other hand, develop within the tooth structure and are often the result of factors such as trauma, high levels of fluoride during childhood, or certain medications. These stains cannot be removed through surface cleaning methods, as they are embedded in the enamel and dentin.

Acid-induced stains are typically related to dental erosion and demineralization rather than a specific staining process. They do not fit neatly into the categorization of intrinsic or extrinsic, and they result from chemical interactions that erode the enamel, leading to a change in tooth color rather than a removable stain.

Thus, understanding the nature of extrinsic stains and their ability to be cleaned off from the tooth surface clarifies why this is the correct choice.