Which of the following is true about extrinsic stains?

Extrinsic stains are associated with the external surface of the teeth and are typically caused by factors such as food, beverages, smoking, or poor oral hygiene. These stains accumulate on the enamel and do not penetrate the tooth structure itself.

The ability to remove these stains through polishing is significant because it highlights a key aspect of dental hygiene practices. Polishing, often performed with a prophy paste during dental cleanings or by coronal polishing techniques, is effective in removing these surface stains, resulting in a cleaner and more aesthetically pleasing smile.

The other options describe characteristics that are not true for extrinsic stains. They do not originate from inside the tooth; instead, they reside on the tooth's exterior. Additionally, extrinsic stains are not permanent if proper oral hygiene practices are followed, and they are not caused solely by genetics, as external factors primarily contribute to their formation. Understanding this aspect is crucial for effective prevention and treatment strategies in dental care.