Extrinsic stain can be removed by prophylaxis procedure. After removal of extrinsic stain, then evaluate if you really need vital bleaching of natural tooth.
Whitening at the dentist is expensive and isn't always covered by insurance (cosmetic), but they do a better job than the OTC products. If you do get your teeth whitened, be prepared for them to be quite sensitive for a while. Usually the dentist will apply a fluoride treatment to help with the sensitivity and recommend that you use some kind of fluoride rinse.
The procedure involves a strong hydrogen peroxide solution and bright light. Teeth cleaning before whitening is recommended I think.
A person who smokes can go for teeth whitening services. A dentist will examine your teeth strength & then give the appropriate consultation for teeth whitening. Actually teeth whitening procedure uses products that are sensitive to your teeth. A dentist checks the teeth strength & prescribe the suitable whitening treatment for you.