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Dental caries, also described as '''tooth decay''', is an infectious disease which damages the structures of can lead to Pain , Tooth Loss , Infection , and, in severe cases, Death . There is a long history of dental caries, with evidence showing the disease was present in the Bronze , Iron , and Medieval Ages but also prior to the Neolithic period. Epidemiology of Dental Disease , hosted on the University of Illinois at Chicago website. Page accessed January 9, 2007. The largest increases in the prevalence of caries have been associated with diet changes. Epidemiology of Dental Disease , hosted on the University of Illinois at Chicago website. Page accessed January 9, 2007.Suddick, Richard P. and Norman O. Harris. "Historical Perspectives of Oral Biology: A Series" . Critical Reviews in Oral Biology and Medicine, 1(2), pages 135-151, 1990. Today, it remains one of the most common diseases throughout the world. There are numerous ways to classify dental caries.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. 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, Radiograph s 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 Acid -producing Bacteria which cause damage in the presence of Fermentable Carbohydrate s such as Sucrose , Fructose , and Glucose .Hardie, J.M. (1982). The microbiology of dental caries. ''Dental Update'', 9, 199-208.Holloway, P.J. (1983). The role of sugar in the etiology of dental caries. ''Journal of Dentistry'', 11, 189-213. The resulting acidic levels in the mouth affect teeth because a tooth's special Mineral content causes it to be sensitive to low PH . Specifically, a tooth (which is primarily mineral in content) is in a constant state of back-and-forth demineralization and remineralization between the tooth and surrounding saliva. When the pH at the surface of the tooth drops below 5.5, demineralization proceeds faster than remineralization (i.e. there is a net loss of mineral structure on the tooth's surface). This results in the ensuing decay. Depending on the extent of tooth destruction, various treatments can be used to Restore teeth to proper Form , function, and Aesthetics , but there is no known method to 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. Oral Health Topics: Cleaning your teeth and gums . Hosted on the American Dental Association website. Page accessed August 15, 2006. HISTORY Archaeological evidence shows that dental caries is an ancient disease. is also believed to have caused an increase in caries. A , Egypt , Japan , and China .Suddick, Richard P. and Norman O. Harris. "Historical Perspectives of Oral Biology: A Series" . Critical Reviews in Oral Biology and Medicine, 1(2), pages 135-151, 1990. Unearthed ancient skulls show evidence of primitive dental work. In of Assyria during 668 to 626 BC , writings from the king's physician specify the need to extract a tooth due to spreading Inflammation .Suddick, Richard P. and Norman O. Harris. "Historical Perspectives of Oral Biology: A Series" . Critical Reviews in Oral Biology and Medicine, 1(2), pages 135-151, 1990. During the Roman occupation of Europe, wider consumption of cooked foods led to a small increase in caries prevalence.Touger-Decker, Riva and Cor van Loveren. Sugars and dental caries , The American Journal of Clinical Nutrition, 78, 2003, pages 881S–892S. The Greco-Roman civilization, in addition to the Egyptian, had treatments for pain resulting from caries.Suddick, Richard P. and Norman O. Harris. "Historical Perspectives of Oral Biology: A Series" . Critical Reviews in Oral Biology and Medicine, 1(2), pages 135-151, 1990. The rate of caries remained low through the , the patroness of dentistry, were meant to heal pain derived from tooth infection. Elliott, Jane. Medieval teeth 'better than Baldrick's' , hosted on the BBC news website. October 8, 2004. Page accessed January 11, 2007. 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. Epidemiology of Dental Disease , hosted on the University of Illinois at Chicago website. Page accessed January 9, 2007. By the , known as the father of modern dentistry, was one of the first to reject the idea worms caused tooth decay and noted that sugar was detrimental to the teeth and Gingiva .McCauley, H. Berton. 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. In 1850, another sharp increase in the prevalence of caries occurred and is believed to be a result of widespread diet changes.Suddick, Richard P. and Norman O. Harris. "Historical Perspectives of Oral Biology: A Series" . Critical Reviews in Oral Biology and Medicine, 1(2), pages 135-151, 1990. 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.Kleinberg, I. "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), pages 108-125, 2002. This explanation is known as the chemoparasitic caries theory.Baehni, P.C. and B. Guggenheim. "Potential of Diagnostic Microbiology for Treatment and Prognosis of Dental Caries and Periodontal Disease" . Critical Reviews in Oral Biology and Medicine, 7(3), page 262, 1996. 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.Suddick, Richard P. and Norman O. Harris. "Historical Perspectives of Oral Biology: A Series" . Critical Reviews in Oral Biology and Medicine, 1(2), pages 135-151, 1990. 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. 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 World Health Organization . (File in pdf format.) Page accessed on August 15, 2006. In the United States, dental caries is the most common Chronic childhood disease, being at least five times more common than Asthma . Healthy People: 2010 . Html version hosted on Healthy People.gov website. Page accessed August 13, 2006. It is the primary pathological cause of tooth loss in children. Frequently Asked Questions , hosted on the American Dental Hygiene Association website. Page accessed August 15, 2006. Between 29% and 59% of adults over the age of fifty experience caries." Dental caries ", from the Disease Control Priorities Project. Page accessed August 15, 2006. The number of cases has decreased in some developed countries, and this decline is usually attributed to increasingly better , Nepal , and Sweden , have a low incidence of cases of dental caries among children, whereas cases are more numerous in Costa Rica and Slovakia ."[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. CLASSIFICATION Caries can be classified by location, etiology, rate of progression, and affected hard tissues.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. 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.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. The location, development, and progression of smooth-surface caries differ from those of pit and fissure caries. Pit and fissure caries Pits and fissures are anatomic landmarks on a tooth where Tooth Enamel infolds creating such an appearance. Fissures are formed during the development of grooves, and have not fully fused (unlike grooves), thus possessing a unique linear-like small depression in enamel's surface structure, which would be a great place for dental caries to develop and flourish. Fissures are mostly located on the occlusal (chewing) surfaces of Posterior teeth and Lingual surfaces of Maxillary Anterior teeth. Pits are small, pinpoint depressions that are found at the ends or cross-sections of grooves.Ash & Nelson, "Wheeler's Dental Anatomy, Physiology, and Occlusion." 8th edition. Saunders, 2003, p. 13. ISBN 0-7216-9382-2. In particular, buccal pits are found on the facial surface of 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.Doniger, Sheri, B. " Sealed ." Dental Economics, 2003. Page accessed August 13, 2006. Among children, pit and fissure caries represent 90% of all dental caries. Oral Health Resources - Dental Caries Fact Sheet . Hosted on the Centers for Disease Control and Prevention website. Page accessed August 13, 2006. 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 Dentin at 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. Proximal caries are the most difficult type to detect.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. 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, Radiograph s are needed for early discovery of proximal caries. Heatlh Strategy Oral Health Toolkit , hosted by the New Zealand's Ministry of Health. Page accessed on August 15, 2006. 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 . Page 19. Page accessed on August 15, 2006. 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.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. 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 In some instances, caries are described in other ways that might indicate the cause. " 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 Until caries progresses, a person may not be aware of it. Health Promotion Board: Dental Caries , affiliated with the Singapore government. Page accessed on August 14, 2006. The earliest sign of a new carious lesion, referred as incipient decay, is the appearance of a chalky White spot on the surface of the tooth, indicating an area of demineralization of enamel. As the lesion continues to demineralize, it can turn brown but will eventually turn into a cavitation, a "cavity". The process before this point is reversible, but once a cavitation forms, the lost tooth structure cannot be 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 can spread from the tooth to the surrounding Soft Tissue s which may become life-threatening, as in the case with Ludwig's Angina . Ludwig's Anigna , hosted on Medline Plus. Page accessed on August 14, 2006. DIAGNOSIS Primary Diagnosis involves inspection of all visible tooth surfaces using a good light source, Dental Mirror and Explorer . Dental Radiographs , produced when X-ray s are passed through the Jaw and picked up on film or digital sensor, may show dental caries before it is otherwise visible, particularly in the case of caries on interproximal (between the teeth) surfaces. Large dental caries are often apparent to the naked eye, but smaller lesions can be difficult to identify. Unextensive dental caries was formerly found by searching for soft areas of tooth structure with a Dental Explorer . Visual and Tactile inspection along with radiographs are still employed frequently among dentists, particularly for pit and fissure caries.Rosenstiel, Stephen F. 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. Some dental researchers have cautioned against the use of dental explorers to find caries.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. In cases where a small area of tooth has begun demineralizing but has not yet cavitated, the Pressure from the dental explorer could cause a cavitation. Since the carious process is reversible before a cavitation is present, it may be possible to arrest the caries with 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 , Laser s 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 Carbohydrate s (such as Sucrose ); and time.Soames, J.V. and Southam, J.C. (1993). ''Oral Pathology'', second edition, chapter 2 - Dental Caries. 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.Kidd, E.A.M. and Smith, B.G.N. (1990). ''Pickard's Manual of Operative Dentistry'', Sixth Edition. Chapter 1 - Why restore teeth?. 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.Neville, B.W., Douglas Damm, Carl Allen, Jerry Bouquot. "''Oral & Maxillofacial Pathology.''" 2nd edition, 2002, page 89. ISBN 0-7216-9003-3. Dentinogenesis Imperfecta is a similar disease. 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.Neville, B.W., Douglas Damm, Carl Allen, Jerry Bouquot. "''Oral & Maxillofacial Pathology.''" 2nd edition, 2002, page 94. ISBN 0-7216-9003-3. 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.Cate, A.R. Ten. "''Oral Histology: development, structure, and function.''" 5th edition, 1998, p. 1. ISBN 0-8151-2952-1. These minerals, especially and Cementum are more susceptible to caries than Enamel because they have lower mineral content.Mellberg, J.R. (1986). Demineralization and remineralization of root surface caries. ''Gerodontology'', 5, 25-31. 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. Bacteria The mouth contains a wide variety of bacteria, but only a few specific species of bacteria are believed to cause dental caries: '' Streptococcus Mutans '' and '' Lactobacilli '' among them.Hardie, J.M. (1982). The microbiology of dental caries. ''Dental Update'', 9, 199-208. Particularly for root caries, the most closely associated bacteria frequently identified are '' Lactobacillus Acidophilus '', '' Actinomyces Viscosus '', '' Nocardia Spp. '', and '' Streptococcus Mutans ''. Bacteria collect around the teeth and gums in a sticky, creamy-coloured mass called Plaque , which serves as a Biofilm . Some sites collect plaque more commonly than others. The grooves on the biting surfaces of Molar and Premolar teeth provide microscopic retention, as does the point of contact between teeth. Plaque may also collect along the Gingiva . In addition, the edges of Fillings or Crowns can provide protection for bacteria, as can intraoral appliances such as orthodontic braces or removable partial Denture s. Fermentable carbohydrates Bacteria in a person's mouth convert material left behind would disintegrate, forming a cavity or hole. Time The frequency of which teeth are exposed to cariogenic (acidic) environments affects the likelihood of caries development. "Dental Health" , hosted on the British Nutrition Foundation website, 2004. Page accessed August 13, 2006. After meals or snacks containing sugars, the bacteria in the mouth never returns to normal levels, thus the tooth surfaces cannot remineralize, or regain lost mineral content. The carious process can begin within days of a tooth erupting into the mouth if the diet is sufficiently rich in suitable carbohydrates, but may begin at any other time thereafter. The speed of the process is dependent on the interplay of the various factors described above but is believed to be slower since the introduction of fluoride.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. 75. ISBN 0-86715-382-2. Compared to coronal smooth surface caries, proximal caries progress quicker and take an average of 4 years to pass through enamel in permanent teeth. 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 rapidly than decay on other surfaces. The progression and loss of mineralization on the root surface is 2.5 times faster than caries in enamel. In very severe cases where oral hygiene is very poor and where the diet is very rich in fermentable carbohydrates, caries may cause cavitation within months of tooth eruption. This can occur, for example, when children continuously drink sugary drinks from baby bottles. On the other hand, it may take years before the process results in a cavity being formed, if at all. Other risk factors In addition to the four main requirements for caries formation, reduced saliva is also associated with increased caries rate since the buffering capability of saliva is not present to counterbalance the acidic environment created by certain foods. As a result, medical conditions that reduce the amount of saliva produced by as a known side effect.Neville, B.W., Douglas Damm, Carl Allen, Jerry Bouquot. "''Oral & Maxillofacial Pathology.''" 2nd edition, 2002, page 398. ISBN 0-7216-9003-3. Radiation therapy to the head and neck may also damage the Cell s in salivary glands, increasing the likelihood for caries formation. Oral Complications of Chemotherapy and Head/Neck Radiation , hosted on the National Cancer Institute website. Page accessed January 8, 2007. The use of Tobacco may also increase the risk for caries formation. Smokeless Tobacco frequently contains high sugar content in some brands, possibly increasing the susceptibility to caries.Neville, B.W., Douglas Damm, Carl Allen, Jerry Bouquot. "''Oral & Maxillofacial Pathology.''" 2nd edition, 2002, page 347. ISBN 0-7216-9003-3. Tobacco use is a significant risk factor for periodontal disease, which can allow the Gingiva to Recede . Tobacco Use Increases the Risk of Gum Disease , hosted on the American Academy of Periodontology . Page accessed on January 9, 2007. As the gingiva loses attachment to the teeth, the root surface becomes more visible in the mouth. If this occurs, root caries is a concern since the cementum covering the roots of teeth is more easily demineralized by acids in comparison to enamel.Banting, D.W. " 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. Page 19. Page accessed on August 15, 2006. Currently, there is not enough evidence to support a causal relationship between smoking and coronal caries, but there is suggestive evidence of a causal relationship between smoking and root-surface caries. Executive Summary of U.S. Surgeon General's report titled, "The Health Consequences of Smoking: A Report of the Surgeon General," hosted on the CDC website, page 12. Page accessed January 9, 2007. PATHOPHYSIOLOGY Enamel Enamel is a highly mineralized acellular Tissue , and caries act upon it through a chemical process brought on by the acidic environment produced by bacteria. The effects of this process include the demineralization of crystals in the enamel, caused by acids, over time until the bacteria physically penetrate the dentin. Enamel Rod s, which are the basic unit of the enamel structure, run perpendicularly from the surface of the tooth to the dentin. Since demineralization of enamel by caries generally follows the direction of the enamel rods, the different triangular patterns between pit and fissure and smooth-surface caries develop in the enamel because the orientation of enamel rods are different in the two areas of the tooth .Kidd, E.A.M. and O. Fejerskov. " What Constitutes Dental Caries? Histopathology of Carious Enamel and Dentin Related to the Action of Cariogenic Biofilms ," Journal of Dental Research, 83(Spec Iss C):C35-C38, 2004. As the enamel loses minerals , and dental caries progress, they develop several distinct zones, visible under a light microscope. From the deepest layer of the enamel to the enamel surface, the identified areas are the: translucent zone, dark zones, body of the lesion, and surface zone.Darling, A.I. " Resistance of the Enamel to Dental Caries ," Journal of Dental Research, 42(1): 488-496, 1963. The translucent zone is the first visible sign of caries and coincides with a 1-2% loss of minerals.Robinson, C., R.C. Shore, S.J. Brookes, S. Strafford, S.R. Wood, and J. Kirkham. " The Chemistry of Enamel Caries ," Critical Reviews in Oral Biology & Medicine, 11(4):481-495, 2000. A slight remineralization of enamel occurs in the dark zone, which serves as an example of how the development of dental caries is an active process with alternating changes.Cate, A.R. Ten. "''Oral Histology: development, structure, and function.''" 5th edition, 1998, p. 417. ISBN 0-8151-2952-1. The area of greatest demineralization and destruction is in the body of the lesion itself. The surface zone remains relatively mineralized and is present until the loss of tooth structure results in a cavitation. Dentin
In dentin from the deepest layer to the enamel, the distinct areas affected by caries are the translucent zone, the zone of bacterial penetration, and the zone of destruction.Kidd, E.A.M. and O. Fejerskov. " What Constitutes Dental Caries? Histopathology of Carious Enamel and Dentin Related to the Action of Cariogenic Biofilms ," Journal of Dental Research, 83(Spec Iss C):C35-C38, 2004. The translucent zone represents the advancing front of the carious process and is where the initial demineralization begins. The zones of bacterial penetration and destruction are the locations of invading bacteria and ultimately the Decomposition of dentin. Sclerotic dentin The structure of dentin is an arrangement of microscopic channels, called dentinal tubules, which radiate outward from the pulp chamber to the exterior cementum or enamel border.Ross, Michael H., Gordon I. Kaye, and Wojciech Pawlina, 2003. ''Histology: a text and atlas.'' 4th edition. Page 450. ISBN 0-683-30242-6. The diameter of the dentinal tubules is largest near the pulp (about 2.5 μm) and smallest (about 900 nm) at the junction of dentin and enamel.Cate, A.R. Ten. "''Oral Histology: development, structure, and function.''" 5th edition, 1998, p. 152. ISBN 0-8151-2952-1. The carious process continues through the dentinal tubules, which are responsible for the triangular patterns resulting from the progression of caries deep into the tooth. The tubules also allow caries to progress faster. In response, the fluid inside the tubules bring and Phosphorus are released, allowing for the precipitation of more crystals which fall deeper into the dentinal tubule. These crystals form a barrier and slow the advancement of caries. After these protective responses, the dentin is considered sclerotic. Fluids within dentinal tubules are believed to be the mechanism by which pain receptors are triggered within the pulp of the tooth.Dababneh, R.H., A.T. Khouri and M. Addy. " Dentine hypersensitivity - an enigma? a review of terminology, mechanisms, aetiology and management ." British Dental Journal, vol. 187, no. 11, December 11, 1999. Page accessed June 22, 2007. The referred to theory is the widely-accepted hydrodynamic theory of sensitivity. Since sclerotic dentin prevents the passage of such fluids, pain that would otherwise serve as a warning of the invading bacteria may not develop at first. Consequently, dental caries may progress for a long period of time without any sensitivity of the tooth, allowing for greater loss of tooth structure. Tertiary dentin In response to dental caries, there may the production of more dentin toward the direction of the pulp. This new dentin is referred to as tertiary dentin.Cate, A.R. Ten. "''Oral Histology: development, structure, and function.''" 5th edition, 1998, p. 152. ISBN 0-8151-2952-1. Tertiary dentin is produced to protect the pulp for as long as possible from the advancing bacteria. As more tertiary dentin is produced, the size of the pulp decreases. This type of dentin has been subdivided according to the presence or absence of the original odontoblasts.Smith, A.J., P.E. Murray, A.J. Sloan, J.B. Matthews, S. Zhao. " Trans-dentinal Stimulation of Tertiary Dentinogenesis ," Advances in Dental Research, 15, pp. 51 -54, August, 2001. Page accessed June 23, 2007. If the odontoblasts survive long enough to react to the dental caries, then the dentin produced is called "reactionary" dentin. If the odontoblasts are killed, the dentin produced is called "reparative" dentin. In the case of reparative dentin, other cells are needed to assume the role of the destroyed odontoblasts. s and Mesenchymal cells of the pulp.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. 14. ISBN 0-86715-382-2. Reparative dentin is produced at an average of 1.5 μm/day, but can be increased to 3.5 μm/day. The resulting dentin contains irregularly-shaped dentinal tubules which may not line up with existing dentinal tubules. This dimishes the ability for dental caries to progress within the dentinal tubules. TREATMENT Destroyed tooth structure does not fully regenerate, although remineralization of very small carious lesions may occur if dental hygiene is kept at optimal level. Dental Cavities , ''MedlinePlus Medical Encyclopedia'', page accessed August 14, 2006. For the small lesions, topical fluoride is sometimes used to encourage remineralization. For larger lesions, the progression of dental caries can be stopped by treatment. The goal of treatment is to preserve tooth structures and prevent further destruction of the tooth. Generally, early treatment is less painful and less expensive than treatment of extensive decay. of some sort to return the tooth to functionality and aesthetic condition. Restorative materials include dental may be needed. This restoration appears similar to a cap and is fitted over the remainder of the natural crown of the tooth. Crowns are often made of gold, porcelain, or porcelain fused to metal. In certain cases, root canal therapy may be necessary for the restoration of a tooth. What is a Root Canal? , hosted by the Academy of General Dentistry. Page accessed on August 16, 2006. Root Canal therapy, also called "endodontic therapy", is recommended if the pulp in a tooth dies from infection by decay-causing bacteria or from trauma. During a root canal, the pulp of the tooth, including the nerve and vascular tissues, is removed along with decayed portions of the tooth. The canals are instrumented with endodontic files to clean and shape them, and they are then usually filled with a rubber-like material called Gutta Percha . FAQs About Root Canal Treatment , hosted on the American Association of Endodontists website. Page accessed August 16, 2006. The tooth is filled and a crown can be placed. Upon completion of a root canal, the tooth is now non-vital, as it is devoid of any living tissue. An Extraction can also serve as treatment for dental caries. The removal of the decayed tooth is performed if the tooth is too far destroyed from the decay process to effectively restore the tooth. Extractions are sometimes considered if the tooth lacks an opposing tooth or will probably cause further problems in the future, as may be the case for Wisdom Teeth . Wisdom Teeth , packet in pdf format hosted by the American Association of Oral and Maxillofacial Surgeons. Page accessed on August 16, 2006. Extractions may also be preferred by patients unable or unwilling to undergo the expense or difficulties in restoring the tooth. PREVENTION es are commonly used to clean teeth.]] Oral hygiene Personal hygiene care consists of proper brushing and es, Water Pick s, and Mouthwash es. Professional hygiene care consists of regular dental examinations and cleanings. Sometimes, complete plaque removal is difficult, and a dentist or Dental Hygienist may be needed. Along with oral hygiene, radiographs may be taken at dental visits to detect possible dental caries development in high risk areas of the mouth. Dietary modification For dental health, the frequency of sugar intake is more important than the amount of sugar consumed. "Dental Health" , hosted on the British Nutrition Foundation website, 2004. Page accessed August 13, 2006. In the presence of sugar and other carbohydrates, bacteria in the mouth produce acids which can demineralize enamel, dentin, and cementum. The more frequently teeth are exposed to this environment, the more likely dental caries are to occur. Therefore, minimizing snacking is recommended, since snacking creates a continual supply of nutrition for acid-creating bacteria in the mouth. Also, chewy and sticky foods (such as dried fruit or candy) tend to adhere to teeth longer, and consequently are best eaten as part of a meal. Brushing the teeth after meals is recommended. For children, the American Dental Association and the European Academy of Paediatric Dentistry recommend limiting the frequency of consumption of drinks with sugar, and not giving baby bottles to infants during sleep. A Guide to Oral Health to Prospective Mothers and their Infants , hosted on the European Academy of Paediatric Dentistry website. Page accessed August 14, 2006. Oral Health Topics: Baby Bottle Tooth Decay , hosted on the American Dental Association website. Page accessed August 14, 2006. Mothers are also recommended to avoid sharing utensils and cups with their infants to prevent transferring bacteria from the mother's mouth. Guideline on Infant Oral Health Care , hosted on the American Academy of Pediatric Dentistry website. Page accessed January 13, 2007. It has been found that (wood sugar) is widely used to protect teeth in some countries, being especially popular in the Finnish candy industry. "History" , hosted on the Xylitol.net website. Page accessed October 22, 2006. Xylitol's effect on reducing plaque is probably due to bacteria's inability to utilize it like other sugars.Ly KA, Milgrom P, Roberts MC, Yamaguchi DK, Rothen M, Mueller G. '' Linear response of mutans streptococci to increasing frequency of xylitol chewing gum use: a randomized controlled trial .'' BMC Oral Health. 2006 Mar 24;6:6. Chewing and stimulation of flavour receptors on the tongue are also known to increase the production and release of saliva, which contains natural buffers to prevent the lowering of pH in the mouth to the point where enamel may become demineralised.Bots CP, Brand HS, Veerman EC, van Amerongen BM, Nieuw Amerongen AV. Preferences and saliva stimulation of eight different chewing gums . Int Dent J. 2004 Jun;54(3):143-8. Other preventive measures The use of Dental Sealant s is a good means of 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 and thus prevents the formation of pit and fissure caries, the most common form of dental caries. 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, but usually their dental history and likelihood of caries formation are taken into consideration. or mouthwash. Many dentists include application of topical fluoride solutions as part of routine visits. Furthermore, recent research shows that low intensity . SEE ALSO FOOTNOTES AND SOURCES REFERENCES Printed sources
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