Teeth whiteners

Achieving a gleaming smile is a common aspiration and comes down to a bit of chemistry. 

Teeth have a transparent outer layer of enamel 2 mm thick, and an inner layer of white dentine. Both are forms of the mineral calcium phosphate. The enamel layer is hydroxyapatite, which is one of the hardest and most insoluble of minerals. Unfortunately it is also slightly porous, which is why teeth become stained by things like tea, red wine, red berries, and cigarette smoke.