Dental cavities

Causes

Tooth decay is a common disorder, second only to the common cold. It usually occurs in children and young adults but can affect any person. Tooth decay is a common cause of tooth loss in younger people.

Bacteria are normally found in your mouth. These bacteria change foods -- especially sugar and starch -- into acids. Bacteria, acid, food pieces, and saliva combine in the mouth to form a sticky substance called plaque. Plaque sticks to the teeth. It is most common on the back molars, just above the gum line on all teeth, and at the edges of fillings.

Plaque that is not removed from the teeth turns into a substance called tartar. Plaque and tartar irritate the gums, resulting in gingivitis and periodontitis.

Plaque begins to build up on teeth within 20 minutes after eating. If it is not removed, tooth decay will begin.

The acids in plaque damage the enamel covering your teeth, and create holes in the tooth (cavities). Cavities usually do not hurt, unless they grow very large and affect nerves or cause a tooth fracture. An untreated cavity can lead to a tooth abscess. Untreated tooth decay also destroys the inside of the tooth (pulp), which leads to tooth loss.

Carbohydrates (sugars and starches) increase the risk of tooth decay. Sticky foods are more harmful than nonsticky foods because they remain on the teeth. Frequent snacking increases the time that acids are in contact with the surface of the tooth.

Symptoms

There may be no symptoms. If symptoms occur, they may include:

• Tooth pain or achy feeling, particularly after sweet, hot, or cold foods and drinks
• Visible pits or holes in the teeth

Exams and Tests

Most cavities are discovered in the early stages during routine dental checkups.

A dental exam may show that the surface of the tooth is soft. 

Dental x-rays may show some cavities before they are visible to the eye.

Treatment

Treatment can help prevent tooth damage from leading to cavities.

Treatment may involve:

• Fillings
• Crowns
• Root canals

Dentists fill teeth by removing the decayed tooth material with a drill and replacing it with a material such as silver alloy, gold, porcelain, or composite resin. Porcelain and composite resin more closely match the natural tooth appearance, and may be preferred for front teeth. Many dentists consider silver amalgam (alloy) and gold to be stronger, and these materials are often used on back teeth. There is a trend to use high strength composite resin in the back teeth as well.

Crowns or "caps" are used if tooth decay is extensive and there is limited tooth structure, which may cause weakened teeth. Large fillings and weak teeth increase the risk of the tooth breaking. The decayed or weakened area is removed and repaired. A crown is fitted over the remainder of the tooth. Crowns are often made of gold, porcelain, or porcelain attached to metal.

A root canal is recommended if the nerve in a tooth dies from decay or injury. The center of the tooth, including the nerve and blood vessel tissue (pulp), is removed along with decayed portions of the tooth. The roots are filled with a sealing material. The tooth is filled, and a crown is usually needed.

Outlook (Prognosis)

Treatment often saves the tooth. Early treatment is less painful and less expensive than treatment of extensive decay.

You may need numbing medicine (lidocaine) and prescription medications to relieve pain during or after dental work.

Nitrous oxide with novocaine or other medications may be preferred if you are afraid of dental treatments.

Possible Complications

• Discomfort or pain
• Fractured tooth
• Inability to bite down on tooth
• Tooth abscess
• Tooth sensitivity

When to Contact a Medical Professional

Call your dentist if you have a toothache.

Make an appointment with your dentist for a routine cleaning and examination if you have not had one in the last 6 months.

Prevention

Oral hygiene is necessary to prevent cavities. This consists of regular professional cleaning (every 6 months), brushing at least twice a day, and flossing at least daily. X-rays may be taken yearly to detect possible cavity development in high risk areas of the mouth.

Chewy, sticky foods (such as dried fruit or candy) are best if eaten as part of a meal rather than as a snack. If possible, brush the teeth or rinse the mouth with water after eating these foods. Minimize snacking, which creates a constant supply of acid in the mouth. Avoid constant sipping of sugary drinks or frequent sucking on candy and mints.

Dental sealants can prevent some cavities. Sealants are thin plastic-like coatings applied to the chewing surfaces of the molars. This coating prevents the accumulation of plaque in the deep grooves on these vulnerable surfaces. Sealants are usually applied on the teeth of children, shortly after the molars erupt. Older people may also benefit from the use of tooth sealants.

Fluoride is often recommended to protect against dental caries. It has been demonstrated that people who ingest fluoride in their drinking water or by fluoride supplements have fewer dental caries. Fluoride ingested when the teeth are developing is incorporated into the structure of the enamel and protects it against the action of acids.

Topical fluoride is also recommended to protect the surface of the teeth. This may include a fluoride toothpaste or mouthwash. Many dentists include application of topical fluoride solutions (applied to a localized area of the teeth) as part of routine visits.

Alternative Names

Caries; Tooth decay; Cavities - tooth

Update Date: 2/22/2012

Updated by: Paul Fotek, DMD, Florida Institute for Periodontics & Dental lmplants, West Palm Beach, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.