What is dental caries?
Dental caries is the scientific term for tooth decay or cavities. It is caused by specific types of bacteria. They produce acid that destroys the tooth’s enamel and the layer under it, the dentin.
Many different types of bacteria normally live in the human mouth. They build up on the teeth in a sticky film called plaque. This plaque also contains saliva, bits of food and other natural substances. It forms most easily in certain places. These include:
- Cracks, pits or grooves in the back teeth
- Between teeth
- Around dental fillings or bridgework
- Near the gum line
The bacteria turn sugar and carbohydrates (starches) in the foods we eat into acids. The acids dissolve minerals in the hard enamel that covers the tooth’s crown (the part you can see). The enamel erodes or develops pits. They are too small to see at first. But they get larger over time.
Acid also can seep through pores in the enamel. This is how decay begins in the softer dentin layer, the main body of the tooth. As the dentin and enamel break down, a cavity is created.
If the decay is not removed, bacteria will continue to grow and produce acid that eventually will get into the tooth’s inner layer. This contains the soft pulp and sensitive nerve fibres.
Tooth roots exposed by receding gums also can develop decay. The root’s outer layer, cementum, is not as thick as enamel. Acids from plaque bacteria can dissolve it rapidly.
One way you can prevent cavities is by reducing the amount of plaque and bacteria in your mouth. The best way to do this is by brushing and flossing daily. You also can use antibacterial mouth rinses to reduce the levels of bacteria that cause cavities. Other rinses neutralize the acid in your mouth to make the environment less friendly to the growth of these bacteria.
You can reduce the amount of tooth-damaging acid in your mouth by eating sugary or starchy foods less often during the day. Your mouth will remain acidic for several hours after you eat. Therefore, you are more likely to prevent caries if you avoid between-meal snacks.
Another way to reduce your risk of cavities is through the use of fluoride, which strengthens teeth. A dentist can evaluate your risk of caries and then suggest appropriate fluoride treatments. Fluoride in water strengthens teeth from within, as they develop, and also on the outside. Dentists also can paint fluoride varnish on children’s primary teeth to protect them from decay.
In adults, molars can be protected with sealants. In children, both baby molars and permanent molars can be sealed. Dentists also can use sealants on molars that have early signs of tooth decay, as long as the decay has not broken through the enamel.
If caries is not treated, it likely will cause the tooth to decay significantly. Eventually, uncontrolled decay may destroy the tooth.
Having caries increases your risk of more caries for several reasons:
- Caries is caused by bacteria. The more decay you have, the more bacteria exist in your mouth.
- The same oral care and dietary habits that led to the decay of your teeth will cause more decay.
- Bacteria tend to stick to fillings and other restorations more than to smooth teeth, so those areas will be more likely to have new caries.
- Cracks or gaps in the fillings may allow bacteria and food to enter the tooth, leading to decay from beneath the filling.
See our Preventing damage page for more advice and information.