Whilst there are horror stories of tooth damage via cheap whitening alternatives, if used correctly teeth whitening is a perfectly safe treatment. Your teeth have tiny pores just as your skin does and it is through these small holes that dark coloured food and drinks penetrate. Smoking, red wine, curries, tomato based sauces and coffee are renown for staining teeth. It is a compound called chromogens which give certain food and drinks their bold colour and stain your teeth, also tannins and acids make your teeth much more susceptible to staining. The active ingredients used in the whitening process work by opening the pores and gently lifting the stains out. The teeth then naturally rehydrate and remineralise after treatment.