Dental Cavities: Why Do They Happen?

You may have received a diagnosis of dental cavity in the past. Perhaps your dentist has already treated the cavity. But did you wonder why dental cavities happen? What are some of the common ways to manage dental cavities?

Dental cavities are defined as permanently damaged areas that occur on the hard surfaces of teeth. In other words, cavities develop small holes or openings in the teeth. Cavities are commonly referred to as dental caries or tooth decay.

Risk factors and causes

Dental cavities are the most prevalent disease in the US and about 98% adults have dental caries by age 20 years. Some of the common risk factors of cavities are:

  • Bacterial infection
  • Sugar intake
  • Poor oral hygiene
  • Age

Bacterial infections usually trigger cavities. The presence of an open hole in the hard tissue of the tooth can trigger bacteria to accumulate and cause infection. Streptococcus mutans are responsible for the production of dextran which serves to stick the plaque on the teeth. These bacteria can produce lactic acid from the fermentation process which can reduce calcium levels in tooth enamel.

Furthermore, other factors such as the condition of the susceptible tooth surface, time of exposure to bacteria, and the amount of fermentable carbohydrate intake can trigger cavities. Therefore, poor oral and dental hygiene behavior, wrong brushing habits and ways, increasing age, and intake of foods and drinks rich in sugar can trigger cavities.

Apart from dental causes, cavities are also associated with several systemic diseases. For instance, patients with diabetes, obesity, asthma, cystic fibrosis, inflammatory GI diseases, and cerebral palsy have shown increased prevalence of dental caries. Although no specific preventative measures are recommended, it is a good idea to inform your dentist with health updates.

Stages of cavities

Cavities are related to the formation of biofilms caused by fluctuations in the pH of the oral cavity. This biofilm is formed by the accumulation of microbes in the oral cavity which causes the pH of the mouth to decrease. Sugar consumption also causes further decrease in the pH of the mouth making it acidogenic. This interaction between bacteria and sugar can cause the enamel (hard part of the teeth) to lose essential minerals which can lead to subsequent lesions.

The progression of cavities is through several stages. In the early stages of enamel damage, the damage is reversible and there are no painful symptoms. If a bacterial infection occurs, the decay may extend from the dentin to the pulp. It can trigger a sensitivity reaction and pain. In a more severe phase, decay can progress and cause excruciating pain, swelling, and loss of tooth structure.


Dental cavities can be prevented through several effective practices. The main cause of cavities is poor dental and oral hygiene behavior, which can be altered by daily oral care. Preventing the occurrence of plaque on the teeth can reduce the risk of cavities. Regular brushing, gargling, and flossing can be done to prevent cavities.

To further support efforts to prevent cavities, regular use of fluoride can reduce the incidence of tooth structure demineralization. Fluoride can make tooth enamel more resistant to acidic compounds and reactions. Fluoride is found in various oral health products such as toothpaste, mouthwash, chewing gum, and supplements.

In addition to fluoride, xylitol can also help in reducing the incidence of cavities. Xylitol can be used as a substitute for sugars such as sucrose and has anti-cariogenic properties. Xylitol can reduce the accumulation of Streptococcus mutans and its adhesion to teeth.

Furthermore, the application of sealants can be performed on children to improve dental and oral hygiene. These sealants form a mechanical barrier on the teeth which ensures that biofilms do not develop over teeth. These sealants could be made from fluoride varnishes or resin-based materials. Their use is typically recommended for permanent molars in children and adolescents.

Recent research mentions the potential for vaccines that can prevent dental cavities. Researchers have made some progress in the form of developing vaccines using proteins, conjugates, recombinant peptides, and DNA-based products. The underlying principle of the vaccine is that it can prevent the formation of Streptococcus mutans colonization by glucosyl transferase inhibition mechanism. However, until now there has been no vaccine released to the market for the prevention of cavities due to the lack of ability to induce adequate antibody production.


To treat dental cavities, dentists focus on early detection of lesions, assessing the risk and severity of caries, treating lesions, and maintaining dental health to prevent the recurrence of cavities. In the early stages, dental cavities can be managed through non-invasive procedures including plaque and biofilm removal, remineralization, and closure of gaps and cavities in teeth.

Silver diamine fluoride (SDF) can be effectively used to stop the progression of decay in cavities that form in teeth. SDF can be applied to teeth without the need for a dental drilling procedure. It is a cost-effective option. However, SDF does not fill the tooth cavity and produces a black color in the applied area. Most dentists recommend reapplying for SDF regularly twice a year.

If the carious lesions are of high severity and cannot be cleaned, surgical removal of the damaged tissue can be performed. Invasive treatment of high severity cavitary lesions can be performed through the removal of tooth tissue and structure. The cavitary lesion must first be investigated using a bitewing X-ray so that the treatment is carried out in the right area.

With oral hygiene practices and routines in place, dental cavities can be prevented, or their progression can be limited. A regular six-month dental check-up will help in diagnosing cavities early on. If you are experiencing any toothache or swelling, then consult your dentist soon for further treatment.

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