Teeth may be stained internally or externally. External stains due to food, mouth-rinse, chromogenic bacteria, or smoking, can be removed by vigorous polishing of the teeth. Foods like red wine, coffee, tea, betel nut, mangosteen, etc, will discolour the teeth. Internal stains may be caused by medicines (e.g. tetracycline), tooth decay, pulp death, amalgam fillings, fluorosis, abnormal enamel formation, and ageing. Intrinsic stains in the enamel or dentine may be removed by tooth whitening gel, or they may have to be drilled out and replaced with a filling.
See also: Root canal treatment