Around 97% people in the world develop tooth cavities in their lifetime.

This clearly indicates how common this dental condition is, and why so many people are seen visiting dentists for treatment of this problem. Dental caries are a result of demineralization of teeth due to acid. When the pH in the oral cavity decreases below 5.5, demineralization of tooth enamel starts occurring. However, if the pH increases above 5.5, the process of remineralization begins, preventing the development of caries. The process of remineralization is governed by factors like fluoride ion concentration, saliva, and rate and extent of saliva production. High extent of demineralization affects the tooth enamel and root, resulting in the development of cavities.

The formation of cavities varies in individuals. This can be cited by a simple example that members of a family having similar lifestyle have varied susceptibility towards developing dental caries. One child of the family may be found suffering from caries more often than the other child. The reasons behind some people being more prone to cavities than others are -

Tooth Structure
The general morphology of teeth is same in every individual. However, each one has some morphological differences that are peculiarly found in that person. For example, some people may have deep groves on their molars which automatically render them more prone to cavities. Deep groves make the removal of plaque difficult from the tooth surface thus, increasing the possibility of dental caries.

Food Habits
Cavity formation is a result of acid attack. Bacteria in the oral cavity depend on sugars as a source of energy. Breakdown of sugar in the oral cavity leads to the formation of lactic acid which is responsible for demineralization of tooth enamel. People who indulge in eating sweet items quite often are more susceptible to develop cavities. This is because frequent intake of sweets causes frequent production of lactic acid and increased time of contact of the teeth with the acid. People who restrict eating sweets only during meals have less chances of dental caries than others.

Oral Hygiene
Dentists advise people to maintain oral hygiene by brushing teeth twice daily and flossing regularly. However, the extent to which oral hygiene is maintained depends on a person. An individual following proper oral cleaning habits has less chance of developing cavities than a person with poor oral hygiene. Regular brushing and flossing prevents the accumulation of bacterial biofilm in the oral cavity thus, reducing cavity formation.

Salivary Secretion
The amount of saliva secreted in the mouth is also a controlling factor in cavity formation. A person who salivates more is less prone to dental caries than someone who has less salivation, as saliva acts as a natural source of cleaning germs and acid in the mouth. Susceptibility to cavities also depends on viscosity of saliva. A highly viscous salivary secretion may not have the required flow characteristics to be able to cleanse the bacterial biofilm in the oral cavity.

Bacterial Strains
Not every strain of bacteria is responsible for dental caries. Some bacterial biofilms may not cause any harm, while others may be capable of producing enough lactic acid for cavity formation. Thus, it can be inferred that quantity of plaque is not the only factor responsible, but the strain of cavity-forming bacteria also holds relevance.

Some studies suggest that pregnant women are more prone to cavities because of reduced salivation during pregnancy. The amount of saliva produced during pregnancy is not sufficient to protect against bacteria and reduce acid attack on teeth.

Above factors clearly explain why some people are more prone to cavities. These people suffer from cavity pain which can be unbearable. It is important to maintain good oral hygiene and look for symptoms of cavity so that you are quick enough to identify the problem and treat it before the pain becomes unbearable.