Assertion: whitening's teeth | /r/HasProperty | stained
Facets:
value: internally
type: DEGREE
Source sentences:
text: Some teeth are internally stained, [so using teeth whitening products will] amount to a waste of time and money.
text: Teeth can be stained from colored foods, such as berries, red sauces, coffee, tea, red wine and dark-colored sodas – as well as smoking cigarettes.