Due to lack of dental hygiene (Brushing,flossing etc) and our diets,we can't keep our teeth completely white and stain free. As human beings, we eat lots of starches, processed foods, coffee and tea, all of which tend to leave stains on the teeth. Over time, these stains become worked into the bone, so even the hardest brushing won't do the trick. 

This is where teeth whitening products come in to help and particulaly Laser teeth whitening.