HomeThe science of cosmeticsHow do oral care products work?How does toothpaste work?

In the section 'How do our teeth work?' we saw that teeth are composed of layers and that damage to these layers and to the gums can lead to oral problems such as tooth decay. In particular the enamel outer layer is constantly under attack. It can be chipped or damaged and can be dissolved by acid. Dental plaque is a mixture of bacteria firmly adhering to the tooth surface. Bacteria from the plaque in our mouths feed off the carbohydrates/sugars we eat and produce two things:

  • acid - which eats into tooth enamel to produce cavities
  • volatile sulphur molecules - which can give breath an unpleasant odour

Toothpastes contain mild abrasives which physically scrub away the plaque and food debris without damaging the tooth enamel. Most toothpastes contain fluoride which protects the tooth enamel. Some also contain antimicrobial ingredients to reduce the formation of plaque which could lead to tartar build-up and further problems.

How does fluoride work?

It is found naturally in some foods such as tea, fish, vegetables and fruit juices, but its inclusion into toothpaste has been a major public health advance. Fluoride has been the major factor in reducing the incidence of dental decay and has been used in toothpastes for almost 50 years.

It works by promoting a chemical reaction in tooth enamel that draws in replacement minerals including calcium. Fluoride incorporates itself into enamel weakened by acid attack, making the tooth more resistant to future acid attacks.

What other ingredients are necessary in toothpaste?

Each make of toothpaste has a slightly different formulation, to appeal to different consumer needs. However, most will contain the following ingredients:

  • abrasives: these remove stains and plaque, and polish the teeth. They must be abrasive enough to do this without damaging the enamel or any exposed dentine. Examples include calcium carbonate, silica and alumina.

  • detergents: these create the foaming action which helps dislodge food debris and bacterial plaque as well as providing a pleasant mouth feel. A common detergent is sodium lauryl sulphate.

  • Humectants (eg. glycerin): these give toothpaste its texture and retain moisture so the toothpaste doesn't dry out.

  • thickeners (such as cellulose gum) are also used for texture. They help the toothpaste to stay on the brush when squeezed from the tube/pump.

  • preservatives: prevent the growth of bacteria or other micro-organisms in toothpaste.

  • flavouring and colouring agents: without these, toothpaste would look and taste less palatable.

Is toothpaste safe?

The majority of toothpastes on the market are cosmetic products, although some may be licensed medicines. In both cases, UK and European laws ensure toothpastes are safe for consumers. Whether medicines or cosmetics, a large selection of toothpastes may be found alongside each other on supermarket and pharmacy shelves.

Is it safe to use fluoride toothpastes on children?

Fluoride is a very safe and effective way to help prevent tooth decay, so is an important ingredient in toothpaste and mouthwashes. It works by making the enamel (that's the tooth's hard outer surface) more resistant to acids produced by the bacteria living on the teeth and gums. Read more on fluoride and tooth decay in young children from NHS Choices.

The levels of fluoride in toothpaste are safe but the advice is not to allow children to swallow large amounts (the small amount naturally swallowed is safe) and not to use too much paste (only a pea-sized amount) at one time. The use of fluoride in toothpastes is controlled by European laws for cosmetic products which set the maximum level that can be used. However, recognising that people may feel strongly about this issue and should have personal choice, there are toothpastes widely available that are without fluoride.

How does toothpaste get its stripes?

The stripes are created by first making the colours in separate vats at the factory. From their separate vats, the coloured stripes are pumped through pipes at the filling machine at carefully controlled speeds and pressures. At the filling machine, the coloured stripes are brought together with the white toothpaste in correct proportions. Then all three are pumped into the toothpaste tube to form perfect stripes all the way through.

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