How Does Dental Decay Start?

Dental decay is caused by the presence of undisturbed dental plaque biofilm in your mouth. This is an organised collection of specific dental bacteria (mainly lactobacillus), combined with other oral debris including proteins from saliva, that adhere to an area of tooth surface which is difficult to reach with your toothbrush or other oral hygiene implement.

There are particular areas of the tooth that are especially at risk – the deep grooves and fissures of molar teeth are especially vulnerable in young children because of the difficulty of cleaning these areas. In teenagers and adults, the most vulnerable location is just beneath the contact area between adjacent teeth. This is an area that is very often inadequately cleansed because of failure to use dental floss. In the population over 65, the most vulnerable area is the root surface, which becomes exposed due to gum disease. It does not have a protective hard enamel layer, only cement-like material that gets washed away. Oral hygiene for this age group becomes more important than ever to control the spread of dental decay.

Dental Decay Stage 1

The dental plaque biofilm acts like a small chemical factory producing enamel-dissolving acid at the site where it is located. If it is left undisturbed for a prolonged period of time it will cause demineralisation of the outside enamel of the tooth, causing dental decay level 1 with an intact outer surface and no cavity present. This may appear to the naked eye as a white spot with a shiny hard surface.

Dental Decay Stage 2

If the decay is more aggressive there may be a break in the enamel surface, and it will have a duller appearance and be softer to touch. However, on radiographic examination it is still contained within the enamel layer. This is dental decay level 2. This is important because dental decay at levels 1 and level 2 can be controlled by changes to the diet, better oral hygiene techniques which removes the plaque biofilm and fluoride toothpaste which helps to harden and remineralise the damaged enamel.

Dental Decay Stage 3

If there is no improvement in diet or oral hygiene, the plaque biofilm will dissolve so much enamel that bacteria are able to penetrate through the enamel surface to the dentine (dental decay level 3) and set up similar chemical mini-factories inside the tooth. These factories depend on a constant supply of carbohydrates and sugars to maintain the spread of dental decay into the tooth. A filling will usually be required at this stage.

Dental Decay Stage 4

Further progression of dental decay will lead to the pulp and nerve of the tooth (dental decay level 4). A filling may be successful at this stage but sometimes a root canal may be required to save the tooth.

How can I control Dental Decay?

Dental decay can be stopped in its tracks and prevented from spreading by modifying your diet and improving your oral hygiene technique, including maximising the benefits you receive from fluoride in toothpaste.


Reduce frequency of eating carbohydrate or sweet foods between meals. This type of food dramatically increases the bacterial count for lactobacillus, the main bacteria associated with dental decay.

Oral hygiene

Brush at least twice a day with fluoride toothpaste. Ask your dentist if you need to use higher dose fluoride toothpaste (available in the clinic or at your local pharmacy). Fluoride in toothpaste and in water slows down the activity of bacteria in the mouth and also assists with remineralisation of tooth surface affected by tooth decay, making it more resistant to future attacks from dental plaque biofilms.

Interdental cleaning

Interdental cleaning is essential for removing dental plaque biofilm from hard-to-reach areas of tooth surface which are vulnerable to developing tooth decay, such as the areas beneath the contact point of adjacent teeth. Dental floss and Interdental Brushes (both available at the clinic) are effective for interdental cleaning.


Fissure sealants are hard, plastic glass-like adhesive materials that are extremely successful at preventing dental decay from occurring in the deep fissures and grooves of the permanent molar teeth in young children. Ideally, they are placed as soon as the first permanent molar teeth appear in the mouth. Once placed they should be checked each year to ensure they are retained up to at least 16 years of age, covering the period of greatest risk for a child to develop dental decay in the permanent molar teeth. The retention rates are very high – up to 80% after 5 years.

Topical fluorides

High strength fluoride toothpaste and varnishes can be prescribed for adults and children who are at high risk because of dental decay.