The oral cavity is subjected to many types of exogenous and endogenous substances which can stain teeth.Some of the stains are intrinsic which are incorporated into the teeth at the time of tooth development.
Tobacco stains :Seen on the teeth of smokers often resulting in yellowish brown to black deposit.
Brown stains :A thin ,brown ,delicate pellicle like structure occur on teeth and is also thought to be composed of salivary mucin.
Black stains :Black stain may be caused by chromogenic bacteria.
Green stains :Coloration of remenants of Nasmyths membrane possibly by blood pigment , maybe responsible for the stain .