Early toothpastes - The Greeks used crushed bones and oyster shells. Later on 'tooth powders' were made with chalk, salt and brick dust!
Modern toothpastes have several more sophisticated components
Abrasives- like Aluminium Hydroxide and Silicas. If too abrasive it can dull the enamel, cause sensitivity and make enamel more translucent (showing up the
yellow dentine below)
Fluoride- Sodium Fluoride (NaF) is the commonest. It strengthens enamel, repairs early decay and controls gingivitis. 'Full-strength' toothpaste (<1500ppm) is advised for all ages (just a 'smear' of toothpaste for under 3s).
Surfactants Sodium Lauryl Sulphate is a foaming agent which helps distribute the toothpaste evenly.
Other Additives - Strontium Chloride and Potassium Nitrate can reduce sensitivity. Sodium polyphosphate can reduce the formation of tartar.
Whitening toothpastes - The abrasive in these toothpaste remove the stains but cannot alter the natural color of teeth. Abrasives polish the teeth and agents like Sodium Tripolyphosphate help break down stains. Two of the most effective seem to be Beverley Hills and Colgate Max White One.
Weird Facts - After using toothpaste, orange juice and other juices have an unpleasant taste. This may be due to a chemical reaction between Stannous Fluoride and the acetic acid in the juice. Sodium lauryl sulfate (surfactant) alters taste perception. It can inhibit taste receptors for sweetness, making food taste bitter. However Apples can taste more pleasant after using toothpaste!