As the American Dental Association (ADA) explains, cavities are caused by certain bacteria in our mouths that feed on the sugar we eat and turn it into acid. This acid can destroy the outer tooth enamel. If allowed to progress, the acid can reach the layer underneath, known as dentin. Dental caries is the scientific term for cavities and “cavities" is another way of describing tooth decay.

Tooth decay is heavily influenced by our lifestyles, environment, behaviors, and heredity. What we eat, the presence of fluoride in our water or toothpaste, and dental hygiene habits all play a role in how susceptible your teeth may be to decay, according to an article in the Journal of the American Dental Association.

While cavities are generally more common among children, adults are also at risk.

Types of cavities include:

• Coronal cavities. The most common type occurring in both children and adults, coronal cavities usually are located on chewing surfaces or between the teeth.
• Root cavities. As we age, our gums recede, leaving parts of the tooth root exposed. Since there is no enamel covering tooth roots, these exposed areas easily decay.
• Arrested caries. Refers to a type of decay that is no longer progressing or active and is usually limited to areas of the teeth where plaque hasn't built up. This can change the appearance of the tooth causing discoloration or brown or white spot lesions. The affected area is typically shiny, as well. While active decay may appear to have a dark gray shadow, arrested decay does not because the decay hasn't reached the dentin underneath the enamel. Arrested cavities feel smooth and hard to touch, unlike progressing cavities, which have a sticky or soft feeling.
• Recurrent decay. Decay can form around existing fillings and crowns. This is because these areas tend to accumulate plaque, leading to decay.

When you eat foods that contain carbohydrates (sugars and starches), these carbohydrates feed the bacteria in plaque, producing acids that eat into the tooth. Over time, the tooth enamel begins to break down beneath the surface while the surface remains intact. When enough of the sub-surface enamel is eroded, the surface collapses, forming a cavity.

Adults are especially at risk for cavities if they suffer from dry mouth, a condition due to a lack of saliva. Dry mouth may be caused by illness, medications, radiation therapy and chemotherapy, and may be either temporary (days to months) or permanent, depending on its cause.

Cavities appear differently depending on their location and stage, and when you see your dentist, they will assess the severity of any decay in your teeth. Only your dentist can tell for sure whether you have a cavity. That's because cavities develop below the tooth's surface, where you can't see them.

Cavities are most likely to develop in pits on the chewing surfaces of the back teeth, in between teeth, and near the gumline. Regardless of where they occur, the best way to spot them and treat them before they become serious is by visiting your dentist regularly for checkups. If left untreated, a cavity can destroy your tooth and kill the delicate nerves at its center, which may result in an abscess, an area of infection at the root tip. Once an abscess forms, it can only be treated with a root canal, surgery or by extracting the tooth.

• Brush at least twice a day and floss daily to remove plaque from between teeth and below the gumline.

• Have regular dental checkups. Preventive care can help stop problems from occurring and keep minor problems from becoming major ones.

• Eat a well-balanced diet that limits starchy or sugary foods. When you do consume these foods, try to eat them with your meal instead of as a snack to minimize the number of times that your teeth are exposed to acid.

• Use dental products that contain fluoride, including toothpaste, and ask your dentist about fluoride applications or sealants to further protect your teeth.

• Make sure that your children's drinking water is fluoridated. If your water supply does not contain fluoride, your dentist or pediatrician may prescribe daily fluoride supplements.

Now that you know what a cavity is, what causes cavities and the factors that contribute to tooth decay, you can help prevent cavities before they start. Practice good oral hygiene and see your dentist for regular checkups to keep your mouth healthy and cavity-free.

This article is intended to promote understanding of and knowledge about general oral health topics. It is not intended to be a substitute for professional advice, diagnosis or treatment. Always seek the advice of your dentist or other qualified healthcare provider with any questions you may have regarding a medical condition or treatment.