What is caries?

Dental caries - everyone has heard of it or has unfortunately experienced it at one point. Derived from the Latin "caries" (decay), it refers to the destruction of enamel caused by the metabolic products of bacteria.

But how exactly does caries occur?

We have many microorganisms in our oral cavity. These tend to build up on and adhere to the surface of the tooth if they are not removed. A film of bacteria (plaque) develops. Plaque also contains caries bacteria (such as Streptococcus mutans and several Lactobacilli) that love sugary foodstuffs and need them for energy.

Figure 1: Images of the caries bacterium Streptococcus mutans under a scanning electron microscope.  

Caries bacteria transform sugar into lactic acid, an aggressive acid that attacks the surface of the tooth and demineralises or decalcifies it. This is similar to using citric acid to decalcify pots or coffee machines; the lactic acid removes minerals, mainly calcium and phosphates, from the hard tooth substance. The initial stages of this demineralisation can be reversed by the minerals in saliva.

If more minerals are removed from the tooth substance over a longer period of time, the destruction continues and the enamel becomes softer. Since this process is usually painless up to this stage, damage to the tooth often goes unnoticed. If caries spreads further into the dentine, a hole develops in the tooth. This carious defect manifests itself as pain when eating or drinking. Thus, caries does not appear overnight; it is fuelled by bacteria, a diet high in sugar and carbohydrates, poor oral care, a lack of saliva and time.

Ultimately, four main factors are required for caries formation.

Figure 2: Four main factors are required for caries formation.

Caries prevention

Good daily oral hygiene, a healthy and balanced diet as well as regular check-ups at the dentist can prevent caries. The risk of caries is also reduced by regularly removing the bacterial film from all surfaces of the teeth, cleaning the interdental spaces and giving caries bacteria as little sugar as possible to metabolise.