Teeth discolorations can be extrinsic or intrinsic.
Extrinsic stains
Extrinsic stains can be due to Tooth deposits called tartar/calculus. Excess Intake of beverages like coffee, tea, cola or consuming food with artificial colorants can stain teeth.
Smoking Tobacco/betel nut chewing are some of the other reasons for extrinsic stains.
Intrinsic Stains
There can be several reasons for intrinsic discoloration of teeth:
Aging
Intake of certain medicines like tetracycline during the formative stages of teeth
