{{DiseaseDisorder infobox |
  Name           = 龋齿 |
  ICD10          =  |
  ICD9           =  |
  ICDO           = |
  Image          = |
  Caption        = |
  Width          = 150 |
  OMIM           = |
  MedlinePlus    = 001055 |
  eMedicineSubj  = |
  eMedicineTopic = |
  DiseasesDB     = 29357 |
}}
'''龋齿'''（俗稱'''蛀牙'''）是牙体组织被龋蚀，逐渐毁坏崩解，形成龋洞的一种疾病，是口腔的常见病和多发病。齲齒是繼感冒後最常見的疾病，它經常發出在小孩和年輕成年人身上，但亦會影響所有人，是導致脫牙的主要原因之一。

導致蛀牙的原因是由細菌引致的．口腔中的細菌，食物殘渣，唾液形成牙菌膜（黏性的透明薄膜）並黏附在牙齒表面．細菌把殘留在口腔的食物中的糖分解，產生酸，這些酸能溶解琺瑯質，口腔的臨界pH值低於5.5時就會有機會發生蛀牙．初期的蛀牙是琺瑯質開始被侵蝕，如果沒有受治療．侵蝕會漫延到牙本質再漫延至髓腔刺激神經線，引致牙痛，再沒治療就要拔掉牙齒，因為會引致牙肉膿腫．

==防止蛀牙的基本原則==

* 儘量減少攝取過多糖份
* 餐後刷牙以清除牙菌膜
* 使用品質良好的牙刷和含有氟的牙膏，每三個月轉換新的牙刷
* 定期使用牙線，最好是每天
* 每六個月到牙醫處檢查
* 減少進食的次數

==補牙==
如果蛀牙的情況不太嚴重，牙醫會把蛀牙的部分鑽去，再用汞合金把蛀牙的地方修補．如果蛀牙的部分較大，可能就要使用牙套修補，情況最嚴重時，要把蛀牙拔掉，繼而換上假牙．

Category:口腔科疾病

{{DiseaseDisorder infobox |
  Name           = Dental caries |
  ICD10          =  |
  ICD9           =  |
  ICDO           = |
  Image          = Toothdecay.png |
  Caption        = Destruction of a tooth by cervical decay from dental caries |
  Width          = 150 |
  OMIM           = |
  MedlinePlus    = 001055 |
  eMedicineSubj  = |
  eMedicineTopic = |
  DiseasesDB     = 29357 |
}}
'''Dental caries''' is a disease which damages the structures of teeth.<ref name="medline">[http://www.nlm.nih.gov/medlineplus/ency/article/001055.htm Dental Cavities], ''MedlinePlus Medical Encyclopedia''. Page accessed August 14, 2006.</ref>  '''Tooth decay''' or '''cavities''' are consequences of caries.  If left untreated, the Bronze, Iron, and Medieval ages but also prior to the neolithic period.<ref name="uicanthropology">[http://www.uic.edu/classes/osci/osci590/11_1Epidemiology.htm Epidemiology of Dental Disease], hosted on the University of Illinois at Chicago website. Page accessed January 9, 2007.</ref>  The largest increases in the prevalence of caries have been associated with diet changes.<ref name="uicanthropology">[http://www.uic.edu/classes/osci/osci590/11_1Epidemiology.htm Epidemiology of Dental Disease], hosted on the University of Illinois at Chicago website. Page accessed January 9, 2007.</ref><ref name="suddickhistorical">Suddick, Richard P. and Norman O. Harris. [http://crobm.iadrjournals.org/cgi/reprint/1/2/135.pdf "Historical Perspectives of Oral Biology: A Series"]. Critical Reviews in Oral Biology and Medicine, 1(2), pp. 135-151, 1990.</ref>  Today, it remains one of the most common diseases throughout the world.

There are numerous ways to classify dental caries.<ref name="sonis139">Sonis, Stephen T. "Dental Secrets: Questions and Answers Reveal the Secrets to the Principles and Practice of Dentistry." 3rd edition. Hanley & Belfus, Inc., 2003, p. 130. ISBN 1-56053-573-3.</ref>  Although the presentation may differ, the risk factors and development among distinct types of caries remain largely similar.  Initially, it may appear as a small chalky area but eventually develop into a large, brown cavitation.  Though sometimes caries may be seen directly, radiographs are frequently needed to inspect less visible areas of teeth and to judge the extent of destruction.

Tooth decay is caused by certain types of fermentable remineralization between the tooth and surrounding restore teeth to proper regenerate large amounts of tooth structure.  Instead, dental health organizations advocate preventive and prophylactic measures, such as regular oral hygiene and dietary modifications, to avoid dental caries.<ref name="adaoralhealth">[http://www.ada.org/public/topics/cleaning.asp Oral Health Topics: Cleaning your teeth and gums]. Hosted on the American Dental Association website. Page accessed August 15, 2006.</ref>

== History ==
thumb|right|An image from 1300s (A.D.) England depicting a dentist extracting a tooth with forceps.

Archaeological evidence shows that dental caries is an ancient disease dating far into prehistory.  Skulls dating from a million years ago through the neolithic period show signs of caries, excepting those from the Paleolithic and Mesolithic ages.<ref name="uicanthropology">[http://www.uic.edu/classes/osci/osci590/11_1Epidemiology.htm Epidemiology of Dental Disease], hosted on the University of Illinois at Chicago website. Page accessed January 9, 2007.</ref>  The increase of caries during the neolithic period may be attributed to the increase of plant foods containing carbohydrates.<ref>Richards, MP. [http://www.nature.com/ejcn/journal/v56/n12/full/1601646a.html "A brief review of the archaeological evidence for Palaeolithic and Neolithic subsistence."] European Journal of Clinical Nutrition, 56. 2002.</ref>  A wooden bow drill available in the neolithic period would have been able to make a hole in a tooth to relieve an abscess in 5½ minutes.<ref>Freeth, Chrissie. [http://www.britarch.ac.uk/ba/ba43/ba43feat.html "Ancient history of trips to the dentist"] British Archaeology, 43, April 1999. Page accessed January 11, 2007.</ref>  The beginning of rice cultivation in South Asia is also believed to have caused an increase in caries. 

A Sumerian text from 5000 BC describes a "tooth worm" as the cause of caries.<ref name="adahistory">[http://www.ada.org/public/resources/history/timeline_ancient.asp History of Dentistry: Ancient Origins], hosted on the [http://www.ada.org American Dental Association] website. Page accessed January 9, 2007.</ref>  Evidence of this belief has also been found in India, Egypt, Japan, and China.<ref name="suddickhistorical">Suddick, Richard P. and Norman O. Harris. [http://crobm.iadrjournals.org/cgi/reprint/1/2/135.pdf "Historical Perspectives of Oral Biology: A Series"]. Critical Reviews in Oral Biology and Medicine, 1(2), pp. 135-151, 1990.</ref>  

Unearthed ancient skulls show evidence of primitive dental work.  In Sargonid dynasty of Assyria during 668 to 626 BC, writings from the king's physician specify the need to extract a tooth due to spreading inflammation.<ref name="suddickhistorical">Suddick, Richard P. and Norman O. Harris. [http://crobm.iadrjournals.org/cgi/reprint/1/2/135.pdf "Historical Perspectives of Oral Biology: A Series"]. Critical Reviews in Oral Biology and Medicine, 1(2), pp. 135-151, 1990.</ref>  During the Roman occupation of Europe, wider consumption of cooked foods led to a small increase in caries prevalence.<ref name="Tougersugars">Touger-Decker, Riva  and Cor van Loveren. [http://www.ajcn.org/cgi/reprint/78/4/881S.pdf Sugars and dental caries], The American Journal of Clinical Nutrition, 78, 2003, pp. 881S–892S.</ref>  The Greco-Roman civilization, in addition to the Egyptian, had treatments for pain resulting from caries.<ref name="suddickhistorical">Suddick, Richard P. and Norman O. Harris. [http://crobm.iadrjournals.org/cgi/reprint/1/2/135.pdf "Historical Perspectives of Oral Biology: A Series"]. Critical Reviews in Oral Biology and Medicine, 1(2), pp. 135-151, 1990.</ref>

The rate of caries remained low through the Bronze and Iron ages, but sharply increased during the Medieval age.<ref name="uicanthropology">[http://www.uic.edu/classes/osci/osci590/11_1Epidemiology.htm Epidemiology of Dental Disease], hosted on the University of Illinois at Chicago website. Page accessed January 9, 2007.</ref>  Periodic increases in caries prevalence had been small in comparison to the 1000 AD increase, when sugar cane became more accessible to the Western world.  Treatment consisted mainly of herbal remedies and charms, but sometimes also included bloodletting.<ref>Anderson, T. [http://www.nature.com/bdj/journal/v197/n7/full/4811723a.html "Dental treatment in Medieval England"], British Dental Journal, 2004, 197, pp. 419-425.</ref>  The tooth extractions.<ref name="suddickhistorical">Suddick, Richard P. and Norman O. Harris. [http://crobm.iadrjournals.org/cgi/reprint/1/2/135.pdf "Historical Perspectives of Oral Biology: A Series"]. Critical Reviews in Oral Biology and Medicine, 1(2), pp. 135-151, 1990.</ref>  Learning their training from apprenticeships, these health providers were quite successful in ending tooth pain and likely prevented systemic spread of infections in many cases.  Among Roman Catholics, prayers to Saint Apollonia, the patroness of dentistry, were meant to heal pain derived from tooth infection.<ref> Elliott, Jane. [http://news.bbc.co.uk/1/hi/health/3722598.stm Medieval teeth 'better than Baldrick's'], hosted on the BBC news website.  October 8, 2004. Page accessed January 11, 2007.</ref>  

There is also evidence of caries increase in North American Indians after contact with colonizing Europeans.  Before colonization, North American Indians subsisted on hunter-gatherer diets, but afterwards there was a greater reliance on maize agriculture, which made these groups more susceptible to caries.<ref name="uicanthropology">[http://www.uic.edu/classes/osci/osci590/11_1Epidemiology.htm Epidemiology of Dental Disease], hosted on the University of Illinois at Chicago website. Page accessed January 9, 2007.</ref>  

In the medieval Islamic world, Muslim physicians such as al-Gazzar and Avicenna (in ''The Canon of Medicine'') provided the earliest known treatments for caries, though they also believed that it was caused by tooth worms like what the ancients believed. This was eventually proven false in 1200 by another Muslim dentist named Gaubari, who in his ''Book of the Elite concerning the unmasking of mysteries and tearing of veils'', was the first to reject the idea of caries being caused by tooth worms, and he stated that tooth worms in fact do not even exist. The theory of the tooth worm was thus no longer accepted in the Islamic medical community from the 13th century onwards.<ref>Salma Almahdi (2003), "Muslim Scholar Contribution in Restorative Dentistry", ''Journal of the International Society for the History of Islamic Medicine'' '''2''', pp. 56-57.</ref>

During the European Age of Enlightenment, the belief that a "tooth worm" caused caries was also no longer accepted in the European medical community.<ref>Gerabek, W.E. "The tooth-worm: historical aspects of a popular medical belief." Clinical Oral Investigations. March 1999, 3(1), pp. 1-6. Abstract hosted on the PubMed [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?CMD=Display&DB=pubmed here].</ref>   Pierre Fauchard, known as the father of modern dentistry, was one of the first to reject the idea that worms caused tooth decay and noted that sugar was detrimental to the teeth and gingiva.<ref>McCauley, H. Berton. [http://www.fauchard.org/dentalworld/2001/DW.08/DWpfaAug01-page1.htm Pierre Fauchard (1678-1761)], hosted on the Pierre Fauchard Academy website. The excerpt comes from a speech given at a Maryland PFA Meeting on March 13, 2001. Page accessed January 17, 2007.</ref>  In 1850, another sharp increase in the prevalence of caries occurred and is believed to be a result of widespread diet changes.<ref name="suddickhistorical">Suddick, Richard P. and Norman O. Harris. [http://crobm.iadrjournals.org/cgi/reprint/1/2/135.pdf "Historical Perspectives of Oral Biology: A Series"]. Critical Reviews in Oral Biology and Medicine, 1(2), pp. 135-151, 1990.</ref>  Prior to this time, cervical caries was the most frequent type of caries, but increased availability of sugar cane, refined flour, bread, and sweetened tea corresponded with a greater number of pit and fissure caries.

In the 1890s, W.D. Miller conducted a series of studies that led him to propose an explanation for dental caries that was influential for current theories. He found that bacteria inhabited the mouth and that they produced acids which dissolved tooth structures when in the presence of fermentable carbohydrates.<ref>Kleinberg, I. [http://crobm.iadrjournals.org/cgi/content/full/13/2/108 "A mixed-bacteria ecological approach to understanding the role of the oral bacteria in dental caries causation: an alternative to ''Streptococcus mutans'' and the specific-plaque hypothesis."] Critical Reviews in Oral Biology and Medicine, 13(2), pp. 108-125, 2002.</ref>  This explanation is known as the chemoparasitic caries theory.<ref>Baehni, P.C. and B. Guggenheim. [http://crobm.iadrjournals.org/cgi/reprint/7/3/259.pdf "Potential of Diagnostic Microbiology for Treatment and Prognosis of Dental Caries and Periodontal Disease"]. Critical Reviews in Oral Biology and Medicine, 7(3), pp. 262, 1996.</ref>  Miller's contribution, along with the research on plaque by G.V. Black and J.L. Williams, served as the foundation for the current explanation of the etiology of caries.<ref name="suddickhistorical">Suddick, Richard P. and Norman O. Harris. [http://crobm.iadrjournals.org/cgi/reprint/1/2/135.pdf "Historical Perspectives of Oral Biology: A Series"]. Critical Reviews in Oral Biology and Medicine, 1(2), pp. 135-151, 1990.</ref>

In 1921, Major Army Dental Corps discovered the bacteriology of dental caries.  His findings were published in the December issue of the ''Military Dental Journal'' titled "The Specific Study of the Bacteriology of Dental Cavities".  Rodríguez Vargas also developed the techniques and methods of analysis.<ref name="GH"></ref> On September 28, 2008, Rodriguez Vargas published in the "Journal of the American Medical Association" his findings in the effectiveness of Iodine and other chemical agents as disinfectants of the mucous membranes of the mouth.<ref name="AH">"Asuntos Historicos: Tributo Al Extinto Comandante Fernando E. Rodriguez"; by Dr. Jose Munoz Barait, Page 29</ref> Since then, other scientists have used the findings of his investigations as the basis in the study of the bacteriology of dental caries.

== Epidemiology ==
An estimated 90% of schoolchildren worldwide and most adults have experienced caries, with the disease being most prevalent in Asian and Latin American countries and least prevalent in African countries.<ref>[http://www.who.int/oral_health/media/en/orh_report03_en.pdf The World Oral Health Report 2003: Continuous improvement of oral health in the 21st century – the approach of the WHO Global Oral Health Programme], released by the chronic childhood disease, being at least five times more common than asthma.<ref>[http://www.healthypeople.gov/Document/HTML/Volume2/21Oral.htm Healthy People: 2010].  Html version hosted on [http://www.healthypeople.gov Healthy People.gov] website.  Page accessed August 13, 2006.</ref>  It is the primary pathological cause of tooth loss in children.<ref>[http://www.adha.org/faqs/index.html Frequently Asked Questions], hosted on the American Dental Hygiene Association website. Page accessed August 15, 2006.</ref> Between 29% and 59% of adults over the age of fifty experience caries.<ref name="DCPP">"[http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=dcp2.section.5380 Dental caries]", from the Disease Control Priorities Project.  Page accessed August 15, 2006.</ref> 

The number of cases has decreased in some developed countries, and this decline is usually attributed to increasingly better fluoride treatment.<ref name="whostatement2">[http://www.who.int/water_sanitation_health/oralhealth/en/index1.html World Health Organization] website, "World Water Day 2001: Oral health", p. 2. Page accessed August 14, 2006.</ref>  Nonetheless, countries that have experienced an overall decrease in cases of tooth decay continue to have a disparity in the distribution of the disease.<ref name="DCPP">"[http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=dcp2.section.5380 Dental caries]", from the Disease Control Priorities Project.  Page accessed August 15, 2006.</ref>  Among children in the United States and Europe, 60-80% of cases of dental caries occur in 20% of the population.<ref name="Tougersugars">Touger-Decker, Riva  and Cor van Loveren. [http://www.ajcn.org/cgi/reprint/78/4/881S.pdf Sugars and dental caries], The American Journal of Clinical Nutrition, 78, 2003, pp. 881S–892S.</ref>  A similarly skewed distribution of the disease is found throughout the world with some children having none or very few caries and others having a high number.<ref name="DCPP">"[http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=dcp2.section.5380 Dental caries]", from the Disease Control Priorities Project.  Page accessed August 15, 2006.</ref>  Some countries, such as Australia, Nepal, and Sweden, have a low incidence of cases of dental caries among children, whereas cases are more numerous in Costa Rica and Slovakia.<ref name="DCPPchart">"[http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=dcp2.table.5381  Table 38.1.  Mean DMFT and SiC Index of 12-Year-Olds for Some Countries, by Ascending Order of DMFT]", from the Disease Control Priorities Project.  Page accessed January 8, 2007.</ref>

== Classification ==

Caries can be classified by location, etiology, rate of progression, and affected hard tissues.<ref name="sonis139">Sonis, Stephen T. "Dental Secrets: Questions and Answers Reveal the Secrets to the Principles and Practice of Dentistry." 3rd edition. Hanley & Belfus, Inc., 2003, p. 130. ISBN 1-56053-573-3.</ref> When used to characterize a particular case of tooth decay, these descriptions more accurately represent the condition to others and may also indicate the severity of tooth destruction.

=== Location ===

Generally, there are two types of caries when separated by location: caries found on smooth surfaces and caries found in pits and fissures.<ref name="summit30">Summit, James B., J. William Robbins, and Richard S. Schwartz. "Fundamentals of Operative Dentistry: A Contemporary Approach." 2nd edition. Carol Stream, Illinois, Quintessence Publishing Co, Inc, 2001, p. 30. ISBN 0-86715-382-2.</ref> The location, development, and progression of smooth-surface caries differ from those of pit and fissure caries.  G.V. Black created a classification system that is widely used and based on the location of the caries on the tooth.  The original classification distinguished caries into five groups, indicated by the word, "Class", and a Roman numeral.  Pit and fissure caries is indicated as Class I; smooth surface caries is further divided into Class II, Class III, Class IV, and Class V.<ref name="scheid434">Scheid, Rickne C. "Woelfel's Dental Anatomy: Its Relevance to Dentistry." 7th edition. Lippincott Williams & Wilkins, 2007, p. 434. ISBN 0-78176-860-8. Preview located [http://books.google.com/books?id=dXaHkgo336oC&printsec=frontcover&dq=class+i+caries#PPT443,M1 here].</ref>  A Class VI was added onto Black's classification and also represents a smooth-surface carious lesion.

right|thumb|The pits and fissures of teeth provide a location for caries formation.

==== Pit and fissure caries ====

Pits and fissures are anatomic landmarks on a tooth where molars.  For all types of pits and fissures, the deep infolding of enamel makes oral hygiene along these surfaces difficult, allowing dental caries to be common in these areas.  

The occlusal surfaces of teeth represent 12.5% of all tooth surfaces but are the location of over 50% of all dental caries.<ref>Doniger, Sheri, B. "[http://de.pennnet.com/Articles/Article_Display.cfm?Section=Archi&Subsection=Display&P=56&ARTICLE_ID=187325&KEYWORD=isolite Sealed]." Dental Economics, 2003. Page accessed August 13, 2006.</ref>  Among children, pit and fissure caries represent 90% of all dental caries.<ref>[http://www.cdc.gov/OralHealth/factsheets/dental_caries.htm Oral Health Resources - Dental Caries Fact Sheet]. Hosted on the Centers for Disease Control and Prevention website. Page accessed August 13, 2006.</ref>  Pit and fissure caries can sometimes be difficult to detect.  As the decay progresses, caries in enamel nearest the surface of the tooth spreads gradually deeper.  Once the caries reaches the dentino-enamel junction, the decay quickly spreads laterally.  Within the dentin, the decay follows a triangle pattern that points to the tooth's pulp.  This pattern of decay is typically described as two triangles (one triangle in enamel, and another in dentin) with their bases conjoined to each other at the dentino-enamel junction (DEJ). This base-to-base pattern is typical of pit and fissure caries, unlike smooth-surface caries (where base and apex of the two triangles join).

==== Smooth-surface caries ====

There are three types of smooth-surface caries.  Proximal caries, also called interproximal caries,  form on the smooth surfaces between adjacent teeth.  Root caries form on the root surfaces of teeth.  The third type of smooth-surface caries occur on any other smooth tooth surface.

left|thumb|In this radiograph, the dark spots in the adjacent teeth show proximal caries.

Proximal caries are the most difficult type to detect.<ref name="summit31">Summit, James B., J. William Robbins, and Richard S. Schwartz. "Fundamentals of Operative Dentistry: A Contemporary Approach." 2nd edition. Carol Stream, Illinois, Quintessence Publishing Co, Inc, 2001, p. 31. ISBN 0-86715-382-2.</ref>  Frequently, this type of caries cannot be detected visually or manually with a dental explorer.  Proximal caries form cervically (toward the roots of a tooth) just under the contact between two teeth.  As a result, radiographs are needed for early discovery of proximal caries.<ref>[http://www.newhealth.govt.nz/toolkits/oralhealth/radiography.htm Health Strategy Oral Health Toolkit], hosted by the New Zealand's Ministry of Health. Page accessed August 15, 2006.</ref> Under Black's classification system, proximal caries on posterior teeth (premolars and molars) are designated as Class II caries.<ref name="Qualtrough28">Qualtrough, A. J. E. , J D Satterthwaite, L A Morrow, Paul A. Brunton. "Principles of Operative Dentistry." Blackwell Publishing, 2005, p. 28. ISBN 1-40511-821-0.</ref> Proximal caries on anterior teeth (incisors and canines) are indicated as Class III if the incisal edge (chewing surface) is not included and Class IV if the incisal edge is included.

Root caries, which are sometimes described as a category of smooth-surfaces caries, are the third most common type of caries and usually occur when the root surfaces have been exposed due to plaque.  The root surface is more vulnerable to the demineralization process than enamel because cementum begins to demineralize at 6.7 pH, which is higher than enamel's critical pH.<ref name="banting19">Banting, D.W.  "[http://www.nidcr.nih.gov/NR/rdonlyres/5A4386A8-E750-43E9-8450-651F4789D09A/0/David_Banting.pdf The Diagnosis of Root Caries]."  Presentation to the National Institute of Health Consensus Development Conference on Diagnosis and Management of Dental Caries Throughout Life, in pdf format, hosted on the National Institute of Dental and Craniofacial Research,  p. 19.  Page accessed  August 15, 2006.</ref>  Regardless, it is easier to arrest the progression of root caries than enamel caries because roots have a greater reuptake of fluoride than enamel.  Root caries are most likely to be found on facial surfaces, then interproximal surfaces, then lingual surfaces.  Mandibular molars are the most common location to find root caries, followed by mandibular premolars, maxillary anteriors, maxillary posteriors, and mandibular anteriors.

Lesions on other smooth surfaces of teeth are also possible.  Since these occur in all smooth surface areas of enamel except for interproximal areas, these types of caries are easily detected and are associated with high levels of plaque and diets promoting caries formation.<ref name="summit31">Summit, James B., J. William Robbins, and Richard S. Schwartz. ''Fundamentals of Operative Dentistry: A Contemporary Approach.'' 2nd edition. Carol Stream, Illinois, Quintessence Publishing Co, Inc, 2001, p. 31. ISBN 0-86715-382-2.</ref>  Under Black's classification system, caries near the gingiva on the facial or lingual surfaces is designated Class V.<ref name="Qualtrough28">Qualtrough, A. J. E. , J D Satterthwaite, L A Morrow, Paul A. Brunton. "Principles of Operative Dentistry." Blackwell Publishing, 2005, p. 28. ISBN 1-40511-821-0.</ref>  Class VI is reserved for caries confined to cusp tips on posterior teeth or incisal edges of anterior teeth.

==== Other general descriptions ====

Besides the two previously mentioned categories, carious lesions can be described further by their location on a particular surface of a tooth.  Caries on a tooth's surface that are nearest the cheeks or lips are called "facial caries", and caries on surfaces facing the tongue are known as "lingual caries".  Facial caries can be subdivided into buccal (when found on the surfaces of posterior teeth nearest the cheeks) and labial (when found on the surfaces of anterior teeth nearest the lips).  Lingual caries can also be described as palatal when found on the lingual surfaces of maxillary teeth because they are located beside the hard palate.

Caries near a tooth's cervix—the location where the crown of a tooth and its roots meet—are referred to as cervical caries.  Occlusal caries are found on the chewing surfaces of posterior teeth.  Incisal caries are caries found on the chewing surfaces of anterior teeth.  Caries can also be described as "mesial" or "distal."  Mesial signifies a location on a tooth closer to the median line of the face, which is located on a vertical axis between the eyes, down the nose, and between the contact of the central incisors.  Locations on a tooth further away from the median line are described as distal.

=== Etiology ===
right|thumb|Rampant caries as seen here may be due to [[methamphetamine use.]]
In some instances, caries are described in other ways that might indicate the cause.  "Baby bottle caries", "early childhood caries", or "deciduous (baby) teeth.  The teeth most likely affected are the maxillary anterior teeth, but all teeth can be affected.<ref>[http://www.ada.org/public/topics/decay_childhood_faq.asp ADA Early Childhood Tooth Decay (Baby Bottle Tooth Decay)]. Hosted on the American Dental Association website.  Page accessed August 14, 2006.</ref>  The name for this type of caries comes from the fact that the decay usually is a result of allowing children to fall asleep with sweetened liquids in their bottles or feeding children sweetened liquids multiple times during the day.  Another pattern of decay is "rampant caries", which signifies advanced or severe decay on multiple surfaces of many teeth.<ref>[http://www.dent.ohio-state.edu/radiologycarie/classification.htm Radiographic Classification of Caries].  Hosted on the Ohio State University website.  Page accessed August 14, 2006.</ref>  Rampant caries may be seen in individuals with tooth resorption when new teeth erupt or later from unknown causes.

=== Rate of progression ===

Temporal descriptions can be applied to caries to indicate the progression rate and previous history.  "Acute" signifies a quickly developing condition, whereas "chronic" describes a condition which has taken an extended time to develop. Recurrent caries, also described as secondary, is caries that appears at a location with a previous history of caries.  This is frequently found on the margins of fillings and other dental restorations.   On the other hand, incipient caries describes decay at a location that has not experienced previous decay.  Arrested caries describes a lesion on a tooth which was previously demineralized but was remineralized before causing a cavitation.

=== Affected hard tissue ===

Depending on which hard tissues are affected, it is possible to describe caries as involving enamel, dentin, or cementum.  Early in its development, caries may affect only enamel.  Once the extent of decay reaches the deeper layer of dentin, "dentinal caries" is used.  Since cementum is the hard tissue that covers the roots of teeth, it is not often affected by decay unless the roots of teeth are exposed to the mouth.  Although the term "cementum caries" may be used to describe the decay on roots of teeth, very rarely does caries affect the cementum alone.  Roots have a very thin layer of cementum over a large layer of dentin, and thus most caries affecting cementum also affects dentin.

==Signs and symptoms== 
right|thumb|75px|Dental explorer used for caries diagnosis.

Until caries progresses, a person may not be aware of it.<ref>[http://www.hpb.gov.sg/hpb/default.asp?pg_id=865&aid=198 Health Promotion Board: Dental Caries], affiliated with the Singapore government. Page accessed August 14, 2006.</ref>  The earliest sign of a new carious lesion, referred as incipient decay, is the appearance of a chalky regenerated.  A lesion which appears brown and shiny suggests dental caries was once present but the demineralization process has stopped, leaving a stain.  A brown spot which is dull in appearance is probably a sign of active caries. 

As the enamel and dentin are destroyed further, the cavitation becomes more noticeable.  The affected areas of the tooth change color and become soft to the touch.  Once the decay passes through enamel, the dentinal tubules, which have passages to the nerve of the tooth, become exposed and cause the tooth to hurt.  The pain can be worsened by heat, cold, or sweet foods and drinks.<ref name="medline">[http://www.nlm.nih.gov/medlineplus/ency/article/001055.htm Dental Cavities], ''MedlinePlus Medical Encyclopedia''. Page accessed August 14, 2006.</ref>  Dental caries can also cause bad breath and foul tastes.<ref>[http://www.med.nyu.edu/patientcare/patients/library/article.html?ChunkIID=11496 Tooth Decay], hosted on the New York University Medical Center website. Page accessed August 14, 2006.</ref> In highly progressed cases, infection can spread from the tooth to the surrounding soft tissues which may become life-threatening, as in the case with cavernous sinus thrombosis and Ludwig's angina.<ref>[http://www.webmd.com/a-to-z-guides/cavernous-sinus-thrombosis Cavernous Sinus Thrombosis], hosted on WebMD. Page accessed May 25, 2008.</ref> <ref>[http://www.nlm.nih.gov/medlineplus/ency/article/001047.htm Ludwig's Anigna], hosted on Medline Plus. Page accessed August 14, 2006.</ref> <ref>Hartmann, Richard W. [http://www.aafp.org/afp/990700ap/109.html Ludwig's Angina in Children], hosted on the American Academy of Family Physicians website. Page accessed May 25, 2008.</ref>

==Diagnosis==

Primary dental mirror and explorer.  Dental dental explorer.  Visual and tactile inspection along with radiographs are still employed frequently among dentists, particularly for pit and fissure caries.<ref>Rosenstiel, Stephen F. [http://www.lib.umich.edu/dentlib/nihcdc/abstracts/rosenstiel.html Clinical Diagnosis of Dental Caries: A North American Perspective]. Maintained by the University of Michigan Dentistry Library, along with the National Institutes of Health, National Institute of Dental and Craniofacial Research. 2000. Page accessed August 13, 2006.</ref>

thumb|right|250px|'''(A)''' A small spot of decay visible on the surface of a tooth.  '''(B)''' The radiograph reveals an extensive region of demineralization within the dentin (arrows).  '''(C)''' A hole is discovered on the side of the tooth at the beginning of decay removal. '''(D)''' All decay removed.

Some dental researchers have cautioned against the use of dental explorers to find caries.<ref name="summit31">Summit, James B., J. William Robbins, and Richard S. Schwartz. "Fundamentals of Operative Dentistry: A Contemporary Approach." 2nd edition. Carol Stream, Illinois, Quintessence Publishing Co, Inc, 2001, p. 31. ISBN 0-86715-382-2.</ref>  In cases where a small area of tooth has begun demineralizing but has not yet cavitated, the fluoride to remineralize the tooth surface.  When a cavitation is present, a restoration will be needed to replace the lost tooth structure.  A common technique used for the diagnosis of early (uncavitated) caries is the use of air blown across the suspect surface, which removes moisture, changing the optical properties of the unmineralized enamel.  This produces a white 'halo' effect detectable to the naked eye.  Fiberoptic transillumination, lasers and disclosing dyes have been recommended for use as an adjunct when diagnosing smaller carious lesions in pits and fissures of teeth.

==Causes==

There are four main criteria required for caries formation: a tooth surface (enamel or dentin); cariogenic (or potentially caries-causing) bacteria; fermentable carbohydrates (such as sucrose); and time.<ref>Soames, J.V. and Southam, J.C. (1993). ''Oral Pathology'', second edition, chapter 2 - Dental Caries.</ref>  The caries process does not have an inevitable outcome, and different individuals will be susceptible to different degrees depending on the shape of their teeth, oral hygiene habits, and the buffering capacity of their saliva.  Dental caries can occur on any surface of a tooth that is exposed to the oral cavity, but not the structures which are retained within the bone.<ref>Kidd, E.A.M. and Smith, B.G.N. (1990). ''Pickard's Manual of Operative Dentistry'', Sixth Edition. Chapter 1 - Why restore teeth?.</ref> 

=== Teeth ===

There are certain diseases and disorders affecting teeth which may leave an individual at a greater risk for caries.  Amelogenesis imperfecta, which occurs between 1 in 718 and 1 in 14,000 individuals, is a disease in which the enamel does not form fully or in insufficient amounts and can fall off a tooth.<ref name="neville89">Neville, B.W., Douglas Damm, Carl Allen, Jerry Bouquot. "''Oral & Maxillofacial Pathology.''" 2nd edition, 2002, p. 89. ISBN 0-7216-9003-3.</ref> In both cases, teeth may be left more vulnerable to decay because the enamel is not as able to protect the tooth as it would in health.<ref name="neville94">Neville, B.W., Douglas Damm, Carl Allen, Jerry Bouquot. "''Oral & Maxillofacial Pathology.''" 2nd edition, 2002, p. 94. ISBN 0-7216-9003-3.</ref>  

In most people, disorders or diseases affecting teeth are not the primary cause of dental caries.  Ninety-six percent of tooth enamel is composed of minerals.<ref>Cate, A.R. Ten. "''Oral Histology: development, structure, and function.''"  5th edition, 1998, p. 1.  ISBN 0-8151-2952-1.</ref>  These minerals, especially enamel because they have lower mineral content.<ref>Mellberg, J.R. (1986). Demineralization and remineralization of root surface caries. ''Gerodontology'', 5, 25-31.</ref>  Thus, when root surfaces of teeth are exposed from gingival recession or periodontal disease, caries can develop more readily.  Even in a healthy oral environment, the tooth is susceptible to dental caries.  

The anatomy of teeth may affect the likelihood of caries formation.  In cases where the deep grooves of teeth are more numerous and exaggerated, pit and fissure caries are more likely to develop.  Also, caries are more likely to develop when food is trapped between teeth.

right|thumb|A gram stain image of ''Streptococcus mutans''.

=== Bacteria ===

The mouth contains a wide variety of bacteria, but only a few specific species of bacteria are believed to cause dental caries: ''Lactobacilli'' among them.<ref name="Hardie1982">Hardie, J.M. (1982). The microbiology of dental caries. ''Dental Update'', 9, 199-208.</ref><ref name=AnthonyHRogers></ref>  Particularly for root caries, the most closely associated bacteria frequently identified are ''plaque, which serves as a molar and fillings or crowns can provide protection for bacteria, as can intraoral appliances such as orthodontic braces or removable partial dentures.

=== Fermentable carbohydrates ===

Bacteria in a person's mouth convert fermentation.<ref name="holloway1983">Holloway, P.J. (1983). The role of sugar in the etiology of dental caries. ''Journal of Dentistry'', 11, 189-213.</ref> If left in contact with the tooth, these acids may cause demineralization, which is the dissolution of its neutralized; suitable minerals are available in the mouth from saliva and also from preventative aids such as fluoride toothpaste, dental varnish or mouthwash.<ref>Silverstone, L.M. (1983). Remineralization and dental caries: new concepts. ''Dental Update'', 10, 261-273.</ref>  The advance of caries may be arrested at this stage. If sufficient acid is produced over a period of time to the favor of demineralization, caries will progress and may then result in so much mineral content being lost that the soft organic material left behind would disintegrate, forming a cavity or hole.

=== Time ===