Smoking
We know that smoking causes staining and discolouration of teeth, due to the nicotine and tar in cigarettes. But things can get much more serious than stained teeth. Smoking has also been linked to a decrease of blood flow to the teeth and gums, bone shrinkage, teeth loss, and an inhibiting of the production of the right kind of saliva (a serious problem given how crucial a role it plays in protecting your teeth from decay).
By far the most serious effect of prolonged tobacco use is oral cancer, which is nine times more likely to occur in smokers than non-smokers.
To avoid any of these issues, the solution is to ideally cut down on smoking and aim to seek support to help you quit.