Chemistry of Toothpaste

Toothpaste is used to clean teeth. It is slightly basic to neutralise the acids in food. A commonly used base is aluminium hydroxide. Fluoride is also added to help prevent tooth decay. This works by increasing the growth rate and size of enamel crystals causing a process called remineralization, where minerals are deposited on cavities caused by plaque. It also makes teeth less prone to decay in future. A polishing agent is another ingredient, added to scrub teeth. Common polishing agents used include dicalcium phosphate, CaHPO4.2H2O, calcium pyrophosphate and insoluble sodium metaphosphate.

There are many more ingredients in toothpaste, added for various reasons. The toothpaste must, of course, be marketable. To sweeten it, saccharin or cyclamate is often added. Titanium dioxide is used to give the white colour.

A liquid such as glycerine, C3H803, is included for plasticity i.e. it keeps the paste together and prevents it from drying out. Sodium salicylate is often used to make an antiseptic for toothpaste and also for mouthwashes.

The last of toothpaste's main ingredients is a binder, which helps the paste keep its shape when on the brush. Many different binders are used including gum tragacanth and seaweed or cellulose derivatives.