The length of time that a teeth whitening can last would depend on various factors. If overconsumption of tea, coffee and other liquids is the cause, you would help by changing your behavior and attitude. Then a few touch ups may be enough to maintain white teeth. The same applies to smoking that could cause dark nicotine stains. Similarly if your teeth have been genetically stained or caused after a serious illness, you may require more frequent teeth whitening procedures. In most people whitened teeth rarely return back to their once deep stained form.