Synonyms: tooth decay, cavities, caries
A dental caries is the most common disease of the teeth, it is browning, softening and forming of a hole in the surface of the tooth, which over time becomes more profound. In Bulgaria, nearly 98% of people have at least one tooth decay, which is a sign of neglect of oral health.
Why does a caries develop?
There are three major and numerous minor factors which are important in the development of caries.
The three main factors are: oral microorganisms (S.mutans), type of the food intake (carbohydrates) and strength of the enamel.
The secondary factors include the habit and skills of teeth cleaning, the protective effect of the saliva, some genetic factors, etc. The development of caries occurs with a different combination of primary and secondary factors.
Caries can be defined as an infectious disease, because it is caused by a bacterium (S.mutans) which is a normal inhabitant in the mouth, but under favorable conditions (intake of sugary foods and carbohydrates and ineffective teeth cleaning lead to the accumulation of plaque, which is an ideal environment for the bacteria) the number of microorganisms starts to increase, and this leads to the formation of caries. S.mutans uses the carbohydrates from the tooth plaque which are found abundantly in sweet foods and pastry products, and digests them to acids, which are released into the environment around the bacteria. Thus, when there is high intake of carbohydrates the bacteria proliferate successfully and the amount of acid increases. On the other hand the enamel consists of minerals that are susceptible to degradation by the acids secreted by the bacteria. Thus, an increased intake of sugary foods, and lack of or insufficient cleaning of the teeth, the bacteria S.mutans have been provided with favorable environment in the plaque and begin to release a greater amount of acids that break down the enamel and lead to the development of caries.
The third important factor in the development of caries is the strength of the enamel. It depends both on genetic factors, lifestyle and nutrition of the individual. If during childhood the child has followed a healthy diet and received food rich in vitamins and minerals, the enamel is made of high quality crystals (fluorapatite crystals) that are more resistant to degradation by acid and a caries develops more difficult.
Hence the development of caries is determined by the presence of plaque on the teeth and the condition of the enamel. With teeth which are normally arranged, there are two main places in which plaque accumulates. These are the fissures on the chewing surface of the teeth – where an occlusal caries can develop (most common in children), the other location is in the contact points between two adjacent teeth – an approximal caries can develop (most common in adults).
As it can be seen the caries is a disease that is extremely dangerous for the tooth. This is because it initially takes place asymptomatically. The diagram to the right illustrates a cross section of an extracted tooth, which has an amalgam filling in the enamel and adjacent to it a large secondary caries has developed in the dentine, which has almost reached the nerve of the tooth. In this situation the patient has no symptoms and the old amalgam is the only thing that is visible in the mouth. Dental cavities as this one can be established only during regular dental check-ups and X-ray pictures. Caries should be treated as soon as possible in early stages – this is because the enamel and dentine have different resistance to the development of caries. Dentine is much more susceptible to tooth decay and much faster destroyed. The picture below shows a cross section of an extracted tooth with an approximal caries in the enamel, which has reached the dentine. It can be clearly seen how the caries has spread in the dentine both in width and depth towards the nerve. At the same time the entrance of caries in the enamel is relatively smaller and hides the true size of destruction. If such a caries is left untreated, the destruction in dentine becomes bigger and bigger over time and when it is already very close to the nerve of the tooth, pain appears from cold and sweet. The occurrence of pain is an indicator that the caries is very deep and if you do not visit the dentist after time the caries destruction will reach the nerve of the tooth. When a caries overcomes the dentine, bacteria from the oral cavity, may enter in the nerve and will lead to acute pulpitis, which will require killing of the tooth.
Therefore it is important to regularly visit the dentist, maintain a perfect oral hygiene, proper nutrition and timely treatment of all cavities.