Dental caries
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}} 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.
Contents |
Causes
Dental caries is one of the most common disorders affecting humans [1] [2]. 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 species of bacteria cause dental caries: Streptococcus 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 molars, just above the gum line on all teeth, and at the margins of fillings. Plaque that is not removed from the teeth may mineralize into calculus (formerly known as tartar). Plaque and calculus irritate the gums, resulting in gingivitis. Periodontitis occurs when there is loss of gingival attachment.
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 kill the nerve and disrupt the blood vessels in the tooth. If left untreated, complications may occur such as acute irreversible pulpitis (infection of the pulp) or acute apical pulpitis (abcesses within the mandible.)
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 (bad breath)
The earliest sign of a carious lesion is the appearance of a chalky white spot on the surface of the tooth (aka white spot lesion), indicating an area of demineralization caused by acid. 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 radiographs, produced when X-rays are shot through the jaw and picked up on film, may show some cavities before they are visible to the eye.
An image showing various stages of dental caries is shown here.
Types of dental caries (cavities)
Carious lesions may form on different surfaces on a tooth. Occlusal caries are on the chewing surface, facial caries are on the surface of the tooth opposite the tongue, and lingual caries are on the surface facing the tongue. Interproximal cavities occur in between two adjacent teeth. Facial caries can be further subdivided by nomenclature: facial surfaces of posterior teeth are termed buccal while those of anterior teeth are termed labial.
Cavities that occur on the root usually occur when gross decay on the facial or lingual surfaces extends apically (towards the root, or the apex) past the CEJ (cementoenamel junction) or when the root surfaces have been exposed due to gingival recession. Because the cementum enveloping the root surface is not nearly as durable as the enamel encasing the crown, root caries tends to progress much more aggressively than decay on other surfaces.
Diagnosis of caries
Large dental cavities are often visually apparent. Smaller cavities may require examination with magnification and visible light, dental explorer, or imaging with dental radiographs. A laser can be used as an adjunct for the diagnosis of smaller cases of caries in the pits and fissures of the teeth.
Treatment
Destroyed tooth structure does not fully 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/or scraping, and replaced with dental fillings, made of a restorative material such as composite resin, porcelain, dental amalgam or gold. Composite resin and porcelain can be made to match the color of a patient's natural teeth, and are thus indicated in aesthetic areas (the front of the mouth). However, composite restorations may be too weak to withstand the cyclic forces that are naturally placed on the occlusal (chewing) surface of posterior teeth. Some dentists therefore consider dental amalgam and gold the only advisable intracoronal restoration ("filling") for the biting surface of posterior teeth (premolars and molars). Composites also undergo polymerization shrinkage, (that is, they shrink when they polymerize, or harden), and they pull away from the walls and margins of the cavity preparation, leaving an opening for bacteria to enter and cause recurrent decay.
Currently, there are many dissenting opinions on whether amalgam fillings pose a health risk due to the mercury contents in amalgams. This is part of the dental amalgam controversy. Many dentists today use composite instead of amalgam for all fillings, not all are doing so for health reasons only. Many dentists recommend composite fillings for their cosmetic appearance and for the greater preservation of healthy tooth structure, as preparing for a composite filling requires less drilling than an amalgam filling. However, composites may need to be replaced more often than amalgams, and more tooth structure can be lost each time a preparation is made. It is important to note, however, that both materials have advantages and disadvantages, and that dentists must determine which material is appropriate on a case by case basis and obtain informed consent prior to treatment.
Crowns are used if decay is extensive enough to preclude an intracoronal restoration (filling). Simply put, if there is not enough tooth structure remaining after the decay is removed, a restorative material cannot be placed within the remaining tooth structure. The restorative material must be fashioned into a sort of cap that encloses the remaining tooth structure. This "cap," or crown, is fitted over the remainder of the natural crown of the tooth. Crowns are often made of gold, porcelain or porcelain fused to metal (PFM). In certain cases, it may be necessary for root canal therapy to be peformed on a tooth in order to place a crown.
Root canal therapy (also called "endodontic therapy") is recommended if the nerve (pulp) in a tooth dies (i.e. pulpal necrosis). Pulpal necrosis can occur as a result of infection of the pulp with decay-causing bacteria as well as from the unavoidable trauma associated with excavation of caries near the pulp. There are also pathologic processes that occur within the supporting bone that may result in death of the pulp. Traumatic injuries to teeth (such as those that might occur while playing contact sports) are also known causes of pulpal necrosis. The pulp of the tooth, including the nerve and vascular (blood vessel) tissue, is removed along with decayed portions of the tooth. The canals in which the pulpal tissue resided are subsequently instrumented with endodontic files (rasps which clean and shape the canals), and are then filled with a rubber-like material called "gutta percha". The tooth is filled and a crown may be placed over the tooth if needed. Upon completion of a root canal, the tooth is now "non-vital", as it is devoid of any living tissue.
Removal of the decayed tooth, an extraction is performed if the tooth is too far destroyed from the decay process to effectively restore, or if the tooth is considered non-functional (e.g. wisdom teeth frequently, teeth that lack an opposing tooth, or a tooth 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 Erbium:YAG (2940nm) or Erbium,Cr3+:YSGG (2780nm) lasers have been developed for carious tissue removal, amongst other applications. Also air abrasion devices can be used to remove decayed material from a tooth. These devices offer advantages over the mechanical drill but have certain limitations in removing some pre-existing filling materials.
Expectations
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.
Prevention
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 the 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.
Furthermore, recent research shows that low intensity laser radiation of argon-ion lasers may prevent the susceptibility for enamel caries and white spot lesions, as indicated in the publications below.
Lastly, a vaccine for dental caries has been researched through previous years, but no effective vaccine has been created yet. Research is currently ongoing.
External links
- 5 basic rules for healthy teeth
- What causes cavities; an indepth look
- Links to tooth decay pictures (Hardin MD/Univ of Iowa)
See also
- Literature in peer-reviewed journals for prevention using argon-ion lasers:
Westerman GH, Hicks MJ, Flaitz CM, Ellis RW, Powell GL: Argon laser irradiation and fluoride treatment effects on caries-like enamel lesion formation in primary teeth: an in vitro study. Am J Dent. 2004 Aug;17(4):241-4.
Blankenau RJ, Powell G, Ellis RW, Westerman GH: In vivo caries-like lesion prevention with argon laser: pilot study. J Clin Laser Med Surg. 1999 Dec;17(6):241-3.
Anderson JR, Ellis RW, Blankenau RJ, Beiraghi SM, Westerman GH: Caries resistance in enamel by laser irradiation and topical fluoride treatment. J Clin Laser Med Surg. 2000 Feb;18(1):33-6.ar:نخر الأسنان zh-min-nan:Chiù-khí da:Caries de:Zahnkaries es:Caries eo:Kario fr:Carie dentaire it:Carie dentaria he:עששת lt:Dantų kariesas nl:Cariës ja:う蝕 km:Nathan pl:Próchnica zębów pt:Cárie ru:Кариес sk:Zubný kaz fi:Karies sv:Karies zh:齲齒