Dental caries, also known colloquially as tooth decay is a disease of the teeth resulting in damage to tooth structure. The cavities formed because of dental caries are called dental cavities.
Dental caries (tooth decay) is one of the most common of all disorders, second only to the common cold. It usually occurs in children and young adults, but can affect any person. It is the most significant cause of tooth loss in younger people. The mouth contains a wide variety of bacteria, but only a few specific strains of bacteria cause dental caries: S. Mutans and Lactobacilli. These bacteria convert foods?especially sugar and starch?into acids such as lactic acid created through fermentation processes. These acids seep into the tooth and can wear away tooth structure. If conditions in the mouth are favorable, S. Mutans and Lactobacilli will continue to thrive and continue to secrete these acids. Bacteria, acid, food debris, and saliva combine in the mouth to form a sticky substance called plaque that adheres to the teeth.
It is most prominent on the grooved chewing surfaces of back molars, just above the gum line on all teeth, and at the edges of fillings. Plaque that is not removed from the teeth mineralizes into calculus (tartar). Plaque and calculus irritate the gums, resulting in gingivitis and ultimately periodontitis.
The acids secreted by S.Mutans and Lactobacilli in the plaque dissolve the enamel surface of the tooth. As the bacteria become more prolific, the bacteria will follow the advancing front of acid damage and infect the dentin within the tooth. Left untreated, carious lesions will increase in severity from small discolored stains to actual holes in the tooth (cavities). Cavities are usually painless until they grow very large inside the internal structures of the tooth (the dentin and the pulp at the core) and can cause death of the nerve and blood vessels in the tooth. If left untreated, complications may occur such as acute pulpitis (infection of the pulp) or abcesses within the jaw.
Plaque and bacteria begin to accumulate within 20 minutes after eating, the time when most bacterial activity occurs. If plaque and bacteria are left on the teeth, cavities can develop, and untreated tooth decay can result in death of the internal structures of the tooth and ultimately the loss of the tooth.
Dietary sugars and starches (carbohydrates) increase the risk of tooth decay. The type of carbohydrate and the timing and frequency of ingestion are more important than the amount. Sticky foods are more harmful than nonsticky foods because they remain on the surface of the teeth. Frequent snacking increases the time that acids are in contact with the surface of the tooth.
Signs and symptoms
toothache (technically called odontalgia or odontalgy)-- particularly after sweet or hot or cold foods or drinks (sensitivity) visible pits or holes (cavities) in the teeth halitosis
The earliest sign of a carious lesion is the appearance of a white spot on the surface of the tooth (aka white spot lesion), indicating an area of demineralization caused by bacteria. As the lesion continues to demineralize, it begins to turn brown. If the lesion's progress continues unchecked, the demineralization can turn into a gross cavitation (a 'cavity'). Brown spot lesions that look shiny indicate that the demineralization process has stopped; this is now just a stain. Brown spot lesions that look dull indicate that active caries is present.
Most dental caries are discovered in the early stages during routine checkups. The surface of the tooth may be soft when probed with a sharp instrument, such as a dental explorer. Pain may not be present until the advanced stages of tooth decay, when the bacterial infection reaches the deeper layers of the tooth and begins to involve the nerve fibers at or near the pulp. Dental X-rays may show some cavities before they are visible to the eye.
Types of carious lesions (cavities)
Carious lesions may form on different surfaces on a tooth. A cavity on the Occlusal surface is on the chewing surface of the tooth. A cavity on the Buccal surface is on the surface of the tooth next to the cheek. A cavity on the Lingual surface is on the surface next to the tongue. Interproximal cavities occur in between two adjacent teeth.
Cavities that occur on the root usually occur when gross decay on the buccal surfaces extends downwards past the crown or when someone has exposed roots, either due to gingival recession or periodontitis. Since the root surfaces are nowhere as durable as enamel (they are made of cementum), root caries tend to progress much more aggressively than on other surfaces.
Diagnosis of caries
Large dental cavities are often visually apparent. Smaller cavities may require examination with a dental probe or imaging with dental X-rays. A laser can be used as an adjunct for the diagnosis of smaller cases of caries in the pits and fissures of the teeth.
Destroyed tooth structure does not generally regenerate, although remineralization of very small cavities may occur if dental hygiene is kept at optimal level. However, the progression of dental caries can be stopped by treatment. The goal of treatment is to preserve the tooth and prevent complications. In filling teeth, the decayed material is removed (by drilling) and replaced with dental fillings, made of a restorative material such as composite resin, porcelain, or gold. Composite resin and porcelain can be made to match the natural tooth appearance, and are therefore cosmetically superior. Some dentists still consider amalgam and gold as stronger, materials traditionally used on back teeth, although there is a trend to use high strength composite resin in the back teeth as well. Currently, there are many dissenting opinions on whether amalgam fillings pose a health risk due to the mercury contents in most amalgams. While most dentists are nowadays using composite fillings instead of amalgam fillings not all are doing so only for health reasons. Many dentists recommend composite fillings also for their cosmetic appearance and for the greater preservation of healthy tooth structure, as preparing a composite filling requires less drilling than an amalgam filling. Crowns are used if decay is extensive and there is limited tooth structure which may cause weakened teeth, which will increase the risk of the tooth breaking. The decayed or weakened area is removed and repaired and a covering jacket or "cap" (crown) is fitted over the remainder of the tooth. Crowns are often made of gold, porcelain or porcelain fused to metal. A root canal treatment is recommended if the nerve (pulp) in a tooth dies from decay or from a traumatic blow. The center of the tooth, including the nerve and vascular (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 may be placed over the tooth if needed. Removal of the decayed tooth extraction is performed if the tooth is too far destroyed from the decay process to effectively restore, or if the tooth considered non-functional (lack of opposing tooth, or tooth is in a non-useful position) or the patient does not wish to undergo the expense or procedure of restoring the tooth. Traditionally, a dental drill is used to remove decayed material from a tooth, however, newer painless methods have been developed in recent years. Various surgical lasers such as the Waterlaser (a device that uses water and laser to remove decayed material) have been developed. Also air abrasion is used to remove decayed material from a tooth.
Treatment often preserves the tooth. Early treatment is less painful and less expensive than treatment of extensive decay. Anesthetics -- local, nitrous oxide ("laughing gas"), or other prescription medications -- may be required in some cases to relieve pain during or following drilling or other treatment of decayed teeth. For those who fear dental treatment, nitrous oxide anesthesia may be preferred.
Oral hygiene is the primary prevention against dental caries. This consists of personal care (proper brushing at least twice a day and flossing at least daily) and professional care (regular dental examination and cleaning, every 6 months). Select 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.
The use of dental sealants is a good means of cavity prevention. Sealants are thin plastic-like coating 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 as part of routine visits.
Chewing gum containing xylitol, wood sugar, is widely used to protect teeth in some countries, being especially popular in Finnish candy industry. Its effect on reducing plaque is believed to be based on bacteria not being able to utilize it like other sugars.
It has also been found that certain kinds of cheese like cheddar can help counter tooth decay if eaten soon after having eaten foods potentially harmful for teeth.
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