What is causing my teeth to stain?

Your teeth are porous in nature so anything you put in your mouth that has colour will absorb into them. Wine, coffee, tea, smoking and dark foods are all very effective at staining teeth. Over time, the natural colour of your teeth become darker due to these stains. These stains will never go away unless you actively remove them. Properly prescribed teeth whitening gels work by absorbing into your teeth and gently breaking down the stain molecules.