Causes of Tooth Decay: Why Cavities Form on Teeth

The question "why do cavities form" is usually asked in the chair, when a filling is just around the corner. In fact, there isn't just one cause but several, and they form a chain. Below is how exactly enamel breaks down and what raises the risk.

How tooth decay develops: the mechanism of enamel destruction

Tooth decay is a chronic dental disease in which hard tissues are destroyed by acids released by bacteria. The process is slow. First, focal demineralization of the inorganic part of enamel occurs, then its organic matrix is destroyed.

Enamel is the hardest tissue in the body; it is 96% minerals, mainly hydroxyapatites. These are the very minerals sensitive to acid: destruction begins at a pH of 4.5. The process then reaches the dentin, and a cavity forms. Without treatment, inflammatory complications arise from the pulp and periodontium.

Dental plaque and bacteria as the main cause

Tooth decay starts with plaque. Bacteria create a sticky layer on the teeth that over time damages the surface. This plaque harbors acid-producing streptococci — Streptococcus mutans, Str. sanguis, Str. mitis, Str. salivarius — and some lactobacilli. They are characterized by anaerobic fermentation.

The mechanism is simple: microbes ferment carbohydrates (glycolysis) and release organic acids. Under the plaque, the pH on the tooth surface drops — and enamel begins to lose minerals.

The role of sugar and snacking frequency

Of all carbohydrates, the main "supplier" of the problem is sucrose, the main component of table sugar. Salivary enzymes easily convert it into glucose, which becomes a substrate for anaerobic glycolysis.

Eating patterns matter too, not just the amount of carbohydrates. Soft, carbohydrate-rich food additionally promotes plaque formation.

• a lot of sugar and sweet drinks in the diet
• frequent snacks between main meals
• soft food rich in carbohydrates
• insufficient plaque removal
• little viscous saliva

Saliva, enamel and other risk factors

Saliva protects the teeth: it has remineralizing potential, buffering properties, and nonspecific and specific defense factors. If there is little saliva and it is viscous, bacteria attach more easily to the pellicle and form plaque.

The second factor is enamel fluoride saturation. Fluorapatites, which form when hydroxyapatites are replaced, are more resistant to acids. According to WHO recommendations, fluoridation of drinking water reduces the incidence of tooth decay by 30–50%.

There are also general causes: the state and diseases of the body, shifts in its functional state, and environmental influences. The doctor assesses the cariogenic situation — examination, enamel staining, determination of plaque and the resistance of hard tissues to acids — and classifies resistance as high, medium or low.

The scale of the problem: tooth decay is the most common human disease, affecting over 93% of people. In 80–90% of children with primary dentition and about 80% of adolescents by the end of school there are carious cavities, and 95–98% of adults have filled teeth.

Why tooth decay occurs in children and adults

Tooth decay is common in children, so teeth and gums need to be monitored from an early age. In adults the causes are the same: plaque, dietary carbohydrates, saliva properties and enamel fluoride saturation.

The dentist advises regular check-ups even if nothing hurts: 2 years without an examination is a reason to book an appointment; for children under 18 — once a year.

When to see a dentist

At first, tooth decay may cause no symptoms at all. Later a hole appears in the tooth, and with it — toothache, sharp pain with hot, cold or sweet foods, and white, brown or black spots on the tooth.

Sometimes the tooth or gum becomes infected and a painful accumulation of pus forms — an abscess. That is already a reason not to delay.

You should book a dentist appointment if there is pain or sharp pain when eating and drinking, and also if the gums hurt, swell or bleed when brushing. Diagnosis is simple: history-taking, examination, probing with instruments, and in some cases an X-ray.

Tooth decay itself is not a reason to call an ambulance; 103/112 — only in a life-threatening condition.

This material is for reference and does not replace a dentist's consultation.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer