ALTHOUGH all mammals have teeth, most do not suffer from bad teeth or what is known as tooth decay. Why is this so? Well, tooth decay occurs when several factors coincide. First, there must be a tooth that is susceptible to decay. Second, there must be dental plaque, i.e. bacteria that ferment carbohydrates to produce acids, which in turn erode the tooth enamel. Finally, carbohydrates must be present to be fermented by the bacteria. In addition, there must be sufficient time for demineralisation (dissolution of the tooth enamel) to occur and insufficient time for the body’s natural defence mechanism, which remineralises the tooth, to repair the damage.

Each of these three factors is, in turn, affected by other factors. For example, the presence of fluoride aids remineralisation and alters the tooth structure. The net effect is that the tooth surface is less vulnerable to decay. The frequency of eating is also important because the more often food is eaten, the more opportunities bacteria have to ferment carbohydrates. Saliva also plays a role by neutralising acid, providing minerals for remineralisation, and helping to clear food from the mouth more quickly. So, the more saliva produced in the mouth, the less chance there is of tooth decay.

A Dutch study found that the time food is retained in and around the mouth is more important for tooth decay than the sugar content of the foods. The researchers compared sugar solutions to meals plus snacks and found that carbohydrate-rich foods that tend to cling to the teeth were more likely to cause tooth decay than sugar solutions. These foods are not necessarily those we think of as “sticky”—for example, toffee melts and clears from the mouth more quickly than some starch-containing foods.

The major emphasis on sugar and sugar-containing foods as being implicated in tooth decay has shifted. It is now known that many carbohydrate-containing foods traditionally believed to be tooth-friendly, such as bread, have the potential to contribute to tooth decay. For example, starchy foods like bread lead to the production of acid by plaque bacteria, and all fruit has the potential to cause tooth decay, yet we should continue to eat these foods for pleasure and because of their health benefits.

Good oral hygiene and the use of fluoride, particularly when applied topically via fluoride toothpaste, have lessened the importance of diet in tooth decay. However, in countries where fluoridated toothpastes are not widely available, frequent intake of carbohydrate-containing foods remains an essential factor in tooth decay.

The primary source of dietary fluoride is drinking water with fluoride content. Fluoride is ubiquitous in foodstuffs, with the richest sources being tea and marine fish. Good oral hygiene and the use of fluoride are now considered the main factors in preventing tooth decay. The following tips provide advice for helping to keep teeth caries-free.

Begin dental care early; start brushing teeth as soon as the first baby teeth erupt. Do not make it a habit for infants to go to sleep while drinking from a bottle of milk, juice, or sweetened beverages. The sugars remain on the teeth for long periods and can lead to baby bottle tooth decay. Clean with fluoride toothpaste twice daily, and clean around the teeth with dental floss or toothpicks once a day. Avoid eating after cleaning teeth at bedtime, as salivary flow decreases while we sleep. Sugar-free chewing gum has been shown to be tooth-friendly as it helps increase saliva flow and clears food debris from the mouth. How often you eat and drink counts. Allow time between eating occasions for saliva to neutralise the acids. Do not nibble food or sip drinks continuously. Advice on diet should be based on good dietary practices consistent with general healthy eating guidelines.