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100-484: Mán Bạc is located on a loess plateau in an area dotted with limestone karst . The site currently lies adjacent to a Catholic cemetery. The site is currently about 25 km (16 mi) away from the modern coastline; however, at the time of occupation at the site, the coastline was much closer and less than 1 km (1 mi) away. Although the term Neolithic has been used to describe Mán Bạc, Oxenham suggests that "Pre-Neolithic Pottery using Cultures" (PNPC) would be

200-423: A causal relationship between smoking and coronal caries, but evidence does suggest a relationship between smoking and root-surface caries. Exposure of children to secondhand tobacco smoke is associated with tooth decay. Intrauterine and neonatal lead exposure promote tooth decay. Besides lead, all atoms with electrical charge and ionic radius similar to bivalent calcium , such as cadmium , mimic

300-439: A cavity. Since the carious process is reversible before a cavity is present, it may be possible to arrest caries with fluoride and remineralize the tooth surface. When a cavity is present, a restoration will be needed to replace the lost tooth structure. At times, pit and fissure caries may be difficult to detect. Bacteria can penetrate the enamel to reach dentin, but then the outer surface may remineralize, especially if fluoride

400-457: A child from a caretaker's kiss or through feeding pre-masticated food. Bacteria in a person's mouth convert glucose, fructose, and most commonly sucrose (table sugar) into acids, mainly lactic acid, through a glycolytic process called fermentation. If left in contact with the tooth, these acids may cause demineralization, which is the dissolution of its mineral content. The process is dynamic, however, as remineralization can also occur if

500-402: A constriction of the tubules, which is an attempt to slow the bacterial progression. In addition, as the acid from the bacteria demineralizes the hydroxyapatite crystals, calcium 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,

600-437: A few specific species of bacteria are believed to cause dental caries: Streptococcus mutans and Lactobacillus species among them. Streptococcus mutans are gram-positive bacteria which constitute biofilms on the surface of teeth. These organisms can produce high levels of lactic acid following fermentation of dietary sugars and are resistant to the adverse effects of low pH, properties essential for cariogenic bacteria. As

700-452: A greater risk for cavities. Molar incisor hypo-mineralization seems to be increasingly common. While the cause is unknown it is thought to be a combination of genetic and environmental factors. Possible contributing factors that have been investigated include systemic factors such as high levels of dioxins or polychlorinated biphenyl (PCB) in the mother's milk, premature birth and oxygen deprivation at birth, and certain disorders during

800-426: A high cation exchange capacity (the ability of the soil to retain nutrients) and porosity (the air-filled space in the soil). The fertility of loess is not due to organic matter content, which tends to be rather low, unlike tropical soils which derive their fertility almost wholly from organic matter. Even well managed loess farmland can experience dramatic erosion of well over 2.5 kg/m per year. In China,

900-563: A hundred meters in areas of Northwestern China and tens of meters in parts of the Midwestern United States. Loesses generally occur as blanket deposits that cover hundreds of square kilometers. The deposits are often tens of meters thick. Loesses often have steep or vertical faces. Because the grains are angular, loesses will often stand in banks for many years without slumping . This type of soil has "vertical cleavage", and thus, it can be easily excavated to form cave dwellings, which

1000-399: A low rate of salivary flow (molar fissures). Grooves on the occlusal surfaces of molar and premolar teeth provide microscopic retention sites for plaque bacteria, as do the interproximal sites. Plaque may also collect above or below the gingiva , where it is referred to as supra- or sub-gingival plaque, respectively. These bacterial strains, most notably S. mutans , can be inherited by

1100-483: A more appropriate term to describe the culture at the site. Although Man Bac is linked to the Bronze Age Phùng Nguyên culture, no bronze artifacts were recovered from the site. Mán Bạc also lacks direct evidence for rice cultivation. However, the people at Man Bac are thought to have farmed rice and raised pigs and dogs, as well as supplementing their diet with protein derived from hunting and fishing. Mán Bạc

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1200-419: A mother's dental caries may decrease the risk in her children by decreasing the number of certain bacteria she may spread to them. Screening can result in earlier detection. Depending on the extent of destruction, various treatments can be used to restore the tooth to proper function, or the tooth may be removed . There is no known method to grow back large amounts of tooth. The availability of treatment

1300-410: A pH of 5.5. Dentin and cementum are more susceptible to caries than enamel because they have lower mineral content. 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, however, the tooth is susceptible to dental caries. The evidence for linking malocclusion and/or crowding to dental caries

1400-488: A persistent grassland biome . When the valuable A-horizon topsoil is eroded or degraded, the underlying loess soil is infertile, and requires the addition of fertilizer in order to support agriculture . The loess along the Mississippi River near Vicksburg, Mississippi , consists of three layers. The Peoria Loess , Sicily Island Loess , and Crowley's Ridge Loess accumulated at different periods of time during

1500-434: A tooth that is exposed to the oral cavity, but not the structures that are retained within the bone. Tooth decay is caused by biofilm (dental plaque) lying on the teeth and maturing to become cariogenic (causing decay). Certain bacteria in the biofilm produce acids, primarily lactic acid , in the presence of fermentable carbohydrates such as sucrose , fructose , and glucose . Caries occur more often in people from

1600-413: A zone of demineralized dentin due to acid and has no bacteria present. The zones of bacterial penetration and destruction are the locations of invading bacteria and ultimately the decomposition of dentin. The zone of destruction has a more mixed bacterial population where proteolytic enzymes have destroyed the organic matrix. The innermost dentin caries has been reversibly attacked because the collagen matrix

1700-560: Is a clastic , predominantly silt -sized sediment that is formed by the accumulation of wind-blown dust . Ten percent of Earth's land area is covered by loesses or similar deposits . A loess is a periglacial or aeolian (windborne) sediment, defined as an accumulation of 20% or less of clay with a balance of roughly equal parts sand and silt (with a typical grain size from 20 to 50 micrometers), often loosely cemented by calcium carbonate . Usually, they are homogeneous and highly porous and have vertical capillaries that permit

1800-427: Is a chronic condition that forms a large, shallow lesion and slowly invades first the root's cementum and then dentin to cause a chronic infection of the pulp (see further discussion under classification by affected hard tissue). Because dental pain is a late finding, many lesions are not detected early, resulting in restorative challenges and increased tooth loss. The presentation of caries is highly variable. However,

1900-519: Is a disease in which the enamel does not fully form or forms in insufficient amounts and can fall off a tooth. In both cases, teeth may be left more vulnerable to decay because the enamel is not able to protect the tooth. In most people, disorders or diseases affecting teeth are not the primary cause of dental caries. Approximately 96% of tooth enamel is composed of minerals. These minerals, especially hydroxyapatite , will become soluble when exposed to acidic environments. Enamel begins to demineralize at

2000-613: Is a popular method of making human habitations in some parts of China. However, loesses can readily erode. In several areas of the world, loess ridges have formed that had been aligned with the prevailing winds during the last glacial maximum . These are called " paha ridges" in America and "greda ridges" in Europe. The formation of these loess dunes has been explained as a combination of wind and tundra conditions. The word loess , with connotations of origin by wind-deposited accumulation,

2100-412: Is a significant risk factor for periodontal disease, which can cause the gingiva to recede . As the gingiva loses attachment to the teeth due to gingival recession, 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 than enamel. Currently, there is not enough evidence to support

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2200-461: Is also found in Australia and Africa. Loess tends to develop into very rich soils. Under appropriate climatic conditions, it is some of the most agriculturally productive terrain in the world. Soils underlain by loess tend to be excessively drained. The fine grains weather rapidly due to their large surface area, making soils derived from loess rich. The fertility of loess soils is due largely to

2300-484: Is also known as brickearth . Non-glacial loess can originate from deserts , dune fields , playa lakes , and volcanic ash . Some types of nonglacial loess are: The thick Chinese loess deposits are non-glacial loess having been blown in from deserts in northern China. The loess covering the Great Plains of Nebraska , Kansas , and Colorado is considered to be non-glacial desert loess. Non-glacial desert loess

2400-463: Is an ecologic shift within the dental biofilm from a balanced population of microorganisms to a population that produces acids and can survive in an acid environment. Tooth 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. As the bacteria consume the sugar and use it for their own energy, they produce lactic acid. The effects of this process include

2500-520: Is characterized by a high mortality rate for infants and subadults, very high levels of fertility, and high levels of population growth. Most of the burials were interred with grave goods, with pottery being predominant. The artifact assemblage at Mán Bạc consists of a diverse range of tools and finished goods, including items such as nephrite beads, bracelets, bangles, rings, adzes , axes, chisels , blades, bone hooks, grinding stones, net sinkers, shell ornaments, lithic ornaments and ceramics . Mán Bạc

2600-437: Is characterized by demineralization of the tooth surface, altering the tooth's optical properties. Technology using laser speckle image (LSI) techniques may provide a diagnostic aid to detect early carious lesions. Caries can be classified by location, etiology, rate of progression, and affected hard tissues. These forms of classification can be used to characterize a particular case of tooth decay to more accurately represent

2700-453: Is in fact more cariogenic than a mixture of equal parts of glucose and fructose. This is due to the bacteria using the energy in the saccharide bond between the glucose and fructose subunits. S.mutans adheres to the biofilm on the tooth by converting sucrose into an extremely adhesive substance called dextran polysaccharide by the enzyme dextran sucranase. The frequency with which teeth are exposed to cariogenic (acidic) environments affects

2800-564: Is mainly deposited in plateau-like situations in the Danube basins , likely derived from the Danube River system. In south-western Europe, relocated loess derivatives are mostly restricted to the Ebro Valley and central Spain. The Loess Hills of Iowa owe their fertility to the prairie topsoils built by 10,000 years of post-glacial accumulation of organic-rich humus as a consequence of

2900-559: 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 salivary glands , in particular the submandibular gland and parotid gland , are likely to lead to dry mouth and thus to widespread tooth decay. Examples include Sjögren syndrome , diabetes mellitus , diabetes insipidus , and sarcoidosis . Medications, such as antihistamines and antidepressants, can also impair salivary flow. Stimulants, most notoriously methylamphetamine , also occlude

3000-432: Is not severely damaged, giving it potential for repair. 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. 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. The carious process continues through

3100-418: Is often diagnosed by blowing air across the suspect surface, which removes moisture and changes the optical properties of the unmineralized enamel. Some dental researchers have cautioned against the use of dental explorers to find caries, in particular sharp ended explorers. In cases where a small area of tooth has begun demineralizing but has not yet cavitated, the pressure from the dental explorer could cause

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3200-416: Is often poor in the developing world. Paracetamol (acetaminophen) or ibuprofen may be taken for pain. Worldwide, approximately 3.6 billion people (48% of the population) have dental caries in their permanent teeth as of 2016. The World Health Organization estimates that nearly all adults have dental caries at some point in time. In baby teeth it affects about 620 million people or 9% of

3300-425: Is present until the loss of tooth structure results in a cavitation. Unlike enamel, the dentin reacts to the progression of dental caries. After tooth formation , the ameloblasts , which produce enamel, are destroyed once enamel formation is complete and thus cannot later regenerate enamel after its destruction. On the other hand, dentin is produced continuously throughout life by odontoblasts , which reside at

3400-419: Is present. These caries, sometimes referred to as "hidden caries", will still be visible on X-ray radiographs, but visual examination of the tooth would show the enamel intact or minimally perforated. The differential diagnosis for dental caries includes dental fluorosis and developmental defects of the tooth including hypomineralization of the tooth and hypoplasia of the tooth. The early carious lesion

3500-438: Is still unknown if the identification of high-risk individuals can lead to more effective long-term patient management that prevents caries initiation and arrests or reverses the progression of lesions. Saliva also contains iodine and EGF . EGF results effective in cellular proliferation, differentiation and survival. Salivary EGF, which seems also regulated by dietary inorganic iodine, plays an important physiological role in

3600-413: Is the first visible sign of caries and coincides with a one to two percent loss of minerals. 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. The area of greatest demineralization and destruction is in the body of the lesion itself. The surface zone remains relatively mineralized and

3700-494: Is typified by pottery in the form of small globular pots with everted rims. Phùng Nguyên-style pottery is found at Mán Bạc, with evidence of some localization. Regionally, the pottery at Mán Bạc appears to exhibit more similarities with those from Guangxi and Guangdong than those from the lower Mekong valley or northeastern Thailand . The Mán Bạc pottery also shows similarities to Assemblage F from Sham Wan in Hong Kong . One of

3800-418: Is weak; however, the anatomy of teeth may affect the likelihood of caries formation. Where the deep developmental grooves of teeth are more numerous and exaggerated, pit and fissure caries is more likely to develop (see next section). Also, caries is more likely to develop when food is trapped between teeth. Reduced salivary flow rate is associated with increased caries since the buffering capability of saliva

3900-549: The Ningxia Hui Autonomous Region , and parts of others. Loess deposits of varying thickness (decimeter to several tens of meters) are widely distributed over the European continent. The northern European loess belt stretches from southern England and northern France to Germany, Poland and the southern Ukraine and deposits are characterized by strong influences of periglacial conditions. South-eastern European loess

4000-683: The Pleistocene . Ancient soils, called paleosols , have developed on the top of the Sicily Island Loess and Crowley's Ridge Loess. The lowermost loess, the Crowley's Ridge Loess, accumulated during the late Illinoian Stage . The middle loess, Sicily Island Loess, accumulated during the early Wisconsin Stage . The uppermost loess, the Peoria Loess in which the modern soil has developed, accumulated during

4100-558: The Sus remains are thought to belong to domesticated pigs; however, the pig remains appear to maintain some features associated with wild boars, and were likely in the initial process of domestication. Additional mammalian fauna found at Mán Bạc include rats, dogs, Aonyx cinerea , civet , rhinoceros, Muntiacus muntjak , deer, Bos or water buffalo , and Cetacea . Compared to the number of taxa found at older Hoabinhian sites in northern Vietnam, which often included over 20 different taxa,

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4200-527: The cells in salivary glands, somewhat increasing the likelihood of caries formation. Susceptibility to caries can be related to altered metabolism in the tooth, in particular to fluid flow in the dentin. Experiments on rats have shown that a high-sucrose, cariogenic diet "significantly suppresses the rate of fluid motion" in dentin. The use of tobacco may also increase the risk for caries formation. Some brands of smokeless tobacco contain high sugar content, increasing susceptibility to caries. Tobacco use

4300-443: The cementum of root surfaces is more easily demineralized than enamel surfaces, a wider variety of bacteria can cause root caries, including Lactobacillus acidophilus , Actinomyces spp. , 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, for example, sites with

4400-461: The dental plaque . However, these four criteria are not always enough to cause the disease and a sheltered environment promoting development of a cariogenic biofilm is required. The caries disease 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

4500-664: The loess deposits which give the Yellow River its color have been farmed and have produced phenomenal yields for over one thousand years. Winds pick up loess particles contributing to the Asian Dust pollution problem. The largest deposit of loess in the United States which is the Loess Hills along the border of Iowa and Nebraska , has survived intensive farming and poor farming practices . For almost 150 years, this loess deposit

4600-551: The Austrian and Hungarian loess stratigraphy, respectively. Since the 1980s, thermoluminescence (TL), optically stimulated luminescence (OSL), and infrared stimulated luminescence (IRSL) dating have been available, providing the possibility for dating the time of loess (dust) depositions, i.e., the time elapsed since the last exposure of the mineral grains to daylight. During the past decade, luminescence dating has significantly improved by new methodological improvements, especially

4700-490: The Huangtu Plateau, is a plateau that covers an area of some 640,000 km around the upper and middle reaches of China's Yellow River . The Yellow River was so named because the loess forming its banks gave a yellowish tint to the water. The soil of this region has been called the "most highly erodible soil on earth". The Loess Plateau and its dusty soil cover almost all of Shanxi , Shaanxi , and Gansu provinces;

4800-556: The Rhine valley near Heidelberg . Charles Lyell (1834) brought the term into widespread usage, observing similarities between "loess" and its derivatives along the loess bluffs in the Rhine and in Mississippi . At the time, it was thought that the yellowish brown silt-rich sediment was of fluvial origin and had been deposited by large rivers. The aeolian origin of the loesses was recognized later (Virlet D'Aoust 1857), particularly due to

4900-420: The acid is neutralized by saliva or mouthwash . Fluoride toothpaste or dental varnish may aid remineralization. If demineralization continues over time, enough mineral content may be lost so that the soft organic material left behind disintegrates, forming a cavity or hole. The impact such sugars have on the progress of dental caries is called cariogenicity. Sucrose, although a bound glucose and fructose unit,

5000-496: The autumn and winter, when the melting of the ice sheets and ice caps ceased, the flow of meltwater down these rivers either ceased or was greatly reduced. As a consequence, large parts of the formerly submerged and unvegetated floodplains of these braided rivers dried out and were exposed to the wind. Because the floodplains consist of sediment containing a high content of glacially ground flour-like silt and clay , they were highly susceptible to winnowing of their silts and clays by

5100-587: The bacteria when they break down food debris or sugar on the tooth surface. Simple sugars in food are these bacteria's primary energy source and thus a diet high in simple sugar is a risk factor. If mineral breakdown is greater than buildup from sources such as saliva , caries results. Risk factors include conditions that result in less saliva, such as diabetes mellitus , Sjögren syndrome and some medications. Medications that decrease saliva production include antihistamines and antidepressants . Dental caries are also associated with poverty , poor cleaning of

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5200-425: The border between the pulp and dentin. Since odontoblasts are present, a stimulus, such as caries, can trigger a biologic response. These defense mechanisms include the formation of sclerotic and tertiary dentin . In dentin from the deepest layer to the enamel, the distinct areas affected by caries are the advancing front, the zone of bacterial penetration, and the zone of destruction. The advancing front represents

5300-423: The calcium ion and therefore exposure to them may promote tooth decay. Poverty is also a significant social determinant for oral health. Dental caries have been linked with lower socio-economic status and can be considered a disease of poverty. Forms are available for risk assessment for caries when treating dental cases; this system using the evidence-based Caries Management by Risk Assessment (CAMBRA). It

5400-667: The cementum enveloping the root surface is not nearly as durable as the enamel encasing the crown , root caries tend 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 cavities within months of tooth eruption. This can occur, for example, when children continuously drink sugary drinks from baby bottles (see later discussion). There are certain diseases and disorders affecting teeth that may leave an individual at

5500-408: The child's first 3 years such as mumps , diphtheria , scarlet fever , measles , hypoparathyroidism , malnutrition , malabsorption , hypo-vitaminosis D , chronic respiratory diseases , or undiagnosed and untreated coeliac disease , which usually presents with mild or absent gastrointestinal symptoms. Amelogenesis imperfecta , which occurs in between 1 in 718 and 1 in 14,000 individuals,

5600-422: The condition to others and also indicate the severity of tooth destruction. In some instances, caries is described in other ways that might indicate the cause. The G. V. Black classification is as follows: Early childhood caries (ECC), also known as " baby bottle caries ," " baby bottle tooth decay" or "bottle rot," is a pattern of decay found in young children with their deciduous (baby) teeth. This must include

5700-564: The convincing observations of loesses in China by Ferdinand von Richthofen (1878). A tremendous number of papers have been published since then, focusing on the formation of loesses and on loess/ paleosol (older soil buried under deposits) sequences as the archives of climate and environment change. These water conservation works have been carried out extensively in China, and the research of loesses in China has been ongoing since 1954. [33] Much effort

5800-444: The day. Another pattern of decay is "rampant caries", which signifies advanced or severe decay on multiple surfaces of many teeth. Rampant caries may be seen in individuals with xerostomia , poor oral hygiene, stimulant use (due to drug-induced dry mouth ), and/or large sugar intake. If rampant caries is a result of previous radiation to the head and neck, it may be described as radiation-induced caries. Problems can also be caused by

5900-448: The decay has progressed enough to allow the bacteria to overwhelm the pulp tissue in the center of the tooth, a toothache can result, and the pain will become more constant. Death of the pulp tissue and infection are common consequences. The tooth will no longer be sensitive to hot or cold but can be very tender to pressure. Dental caries can also cause bad breath and foul tastes. In highly progressed cases, an infection can spread from

6000-436: The demineralization of crystals in the enamel, caused by acids, over time until the bacteria physically penetrate the dentin. Enamel rods , 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 follows the direction of the enamel rods, the different triangular patterns between pit and fissure and smooth-surface caries develop in

6100-635: The demineralization process has stopped, leaving a stain. Active decay is lighter in color and dull in appearance. As the enamel and dentin are destroyed, the cavity becomes more noticeable. The affected areas of the tooth change color and become soft to the touch. Once the decay passes through the enamel, the dentinal tubules , which have passages to the nerve of the tooth, become exposed, resulting in pain that can be transient, temporarily worsening with exposure to heat, cold, or sweet foods and drinks. A tooth weakened by extensive internal decay can sometimes suddenly fracture under normal chewing forces. When

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6200-410: 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. Growth factors , especially TGF-β , are thought to initiate the production of reparative dentin by fibroblasts and mesenchymal cells of

6300-440: The dentin is considered sclerotic. According to hydrodynamic theory , fluids within dentinal tubules are believed to be the mechanism by which pain receptors are triggered within the pulp of the tooth. 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. In response to dental caries, there may be production of more dentin toward

6400-413: 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 brings immunoglobulins from the immune system to fight the bacterial infection. At the same time, there is an increase of mineralization of the surrounding tubules. This results in

6500-408: The development of dental caries relies heavily on the frequency of acid exposure. The carious process can begin within days of a tooth's erupting into the mouth if the diet is sufficiently rich in suitable carbohydrates. Evidence suggests that the introduction of fluoride treatments has slowed the process. Proximal caries take an average of four years to pass through enamel in permanent teeth. Because

6600-459: The development of single aliquot regenerative (SAR) protocols (Murray & Wintle 2000) resulting in reliable ages (or age estimates) with an accuracy of up to 5 and 10% for the last glacial record. More recently, luminescence dating has also become a robust dating technique for penultimate and antepenultimate glacial loess (e.g. Thiel et al. 2011, Schmidt et al. 2011) allowing for a reliable correlation of loess/palaeosol sequences for at least

6700-408: The direction of the pulp. This new dentin is referred to as tertiary dentin. 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. If the odontoblasts survive long enough to react to

6800-419: The disease) are present in dental plaque, but they are usually in too low concentrations to cause problems unless there is a shift in the balance. This is driven by local environmental change, such as frequent sugar intake or inadequate biofilm removal (toothbrushing). If left untreated, the disease can lead to pain, tooth loss and infection . The mouth contains a wide variety of oral bacteria , but only

6900-416: The enamel because the orientation of enamel rods are different in the two areas of the tooth. As the enamel loses minerals, and dental caries progresses, the enamel develops 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. The translucent zone

7000-476: The flow of saliva to an extreme degree. This is known as meth mouth . Tetrahydrocannabinol (THC), the active chemical substance in cannabis , also causes a nearly complete occlusion of salivation, known in colloquial terms as "cotton mouth". Moreover, 63% of the most commonly prescribed medications in the United States list dry mouth as a known side-effect. Radiation therapy of the head and neck may also damage

7100-411: The formation of loess: a dust source, adequate wind energy to transport the dust, a suitable accumulation area, and a sufficient amount of time. Periglacial (glacial) loess is derived from the floodplains of glacial braided rivers that carried large volumes of glacial meltwater and sediments from the annual melting of continental ice sheets and mountain ice caps during the spring and summer. During

7200-547: The last two interglacial/glacial cycles throughout Europe and the Northern Hemisphere (Frechen 2011). Furthermore, the numerical dating provides the basis for quantitative loess research applying more sophisticated methods to determine and understand high-resolution proxy data including the palaeodust content of the atmosphere, variations of the atmospheric circulation patterns and wind systems, palaeoprecipitation, and palaeotemperature. Besides luminescence dating methods,

7300-662: The late Wisconsin Stage. Animal remains include terrestrial gastropods and mastodons . Extensive areas of loess occur in New Zealand including the Canterbury Plains and on the Banks Peninsula . The basis of loess stratigraphy was introduced by John Hardcastle in 1890. Much of Argentina is covered by loess. Two areas of loess are usually distinguished in Argentina: the neotropical loess north of latitude 30° S and

7400-523: The likelihood of caries development. After meals or snacks , the bacteria in the mouth metabolize sugar, resulting in an acidic by-product that decreases pH. As time progresses, the pH returns to normal due to the buffering capacity of saliva and the dissolved mineral content of tooth surfaces. During every exposure to the acidic environment, portions of the inorganic mineral content at the surface of teeth dissolve and can remain dissolved for two hours. Since teeth are vulnerable during these acidic periods,

7500-453: The lower end of the socio-economic scale than people from the upper end of the socio-economic scale, due to lack of education about dental care, and lack of access to professional dental care which may be expensive. The most common bacteria associated with dental cavities are the mutans streptococci, most prominently Streptococcus mutans and Streptococcus sobrinus , and lactobacilli . However, cariogenic bacteria (the ones that can cause

7600-413: The maintenance of oral (and gastro-oesophageal) tissue integrity, and, on the other hand, iodine is effective in prevention of dental caries and oral health. Teeth are bathed in saliva and have a coating of bacteria on them ( biofilm ) that continually forms. The development of biofilm begins with pellicle formation. Pellicle is an acellular proteinaceous film which covers the teeth. Bacteria colonize on

7700-585: The most similarities with those from the Metal Period, modern Southeast Asians, and the Chinese Neolithic site at Weidun from the lower Yangtze River . The variance in dental morphology was also higher at Mán Bạc than at later sites associated with the Metal Period. The individuals at Mán Bạc display a very high frequency of dental caries , the highest of any ancient archaeological site in Southeast Asia;

7800-401: The mouth , and receding gums resulting in exposure of the roots of the teeth. Prevention of dental caries includes regular cleaning of the teeth, a diet low in sugar, and small amounts of fluoride . Brushing one's teeth twice per day, and flossing between the teeth once a day is recommended. Fluoride may be acquired from water , salt or toothpaste among other sources. Treating

7900-556: The neotropical loess. The pampean loess is sandy or made of silty sand. This article incorporates CC-BY-3.0 text from the reference "Loess in Europe: Guest Editorial". Dental caries Tooth decay , also known as cavities or caries , is the breakdown of teeth due to acids produced by bacteria . The cavities may be a number of different colors, from yellow to black. Symptoms may include pain and difficulty eating. Complications may include inflammation of

8000-534: The number of taxa hunted at Man Bac is clearly more limited. This suggests that hunting was likely less of a primary subsistence pursuit for the people of Man Bac. Many fish remains were also recovered from the site. The fish assemblage was dominated by the remains of marine and brackish water fish, with Acanthopagrus being the predominant species found. Other common species recovered from the site include sharks , rays, Lates calcarifer , Siluriformes and Serranidae . The remains of Trionychidae were also found at

8100-429: The only other site in Southeast Asia with dental carry frequencies approaching that at Man Bac is Khok Phanom Di  [ de ] . As is the case for Khok Phanom Di, the high prevalence of dental caries at Mán Bạc is partially skewed by the high frequencies of dental caries found in its female inhabitants; at both sites, the females were found to have over twice as many dental caries as the males. The individuals at

8200-512: The pampean loess. The neotropical loess is made of silt or silty clay. Relative to the pampean loess the neotropical loess is poor in quartz and calcium carbonate . The source region for this loess is thought by some scientists to be areas of fluvio-glacial deposits the Andean foothills formed by the Patagonian Ice Sheet . Other researchers stress the importance of volcanic material in

8300-414: The population. They have become more common in both children and adults in recent years. The disease is most common in the developed world due to greater simple sugar consumption, but less common in the developing world. Caries is Latin for "rottenness". A person experiencing caries may not be aware of the disease. The earliest sign of a new carious lesion is the appearance of a chalky white spot on

8400-423: The pottery vessels from Mán Bạc, in the shape of a drum, shows strong similarities to a bronze drum from the late Shang dynasty in China, which suggests that there was cultural contact with the bronze cultures from China at that time at Mán Bạc. The faunal assemblage at the site consists primarily of fish and mammalian remains. The mammalian faunal assemblage is dominated by the remains of Sus scrofa . Most of

8500-421: The presence of at least one carious lesion on a primary tooth in a child under the age of 6 years. The teeth most likely affected are the maxillary anterior teeth, but all teeth can be affected. 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

8600-457: The pulp. 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 that may not line up with existing dentinal tubules. This diminishes the ability for dental caries to progress within the dentinal tubules. The incidence of cemental caries increases in older adults as gingival recession occurs from either trauma or periodontal disease. It

8700-491: The risk factors and stages of development are similar. Initially, it may appear as a small chalky area (smooth surface caries), which may eventually develop into a large cavitation. Sometimes caries may be directly visible. However other methods of detection such as X-rays are used for less visible areas of teeth and to judge the extent of destruction. Lasers for detecting caries allow detection without ionizing radiation and are now used for detection of interproximal decay (between

8800-444: The sediment to fracture and form vertical bluffs . Loesses are homogeneous ; porous ; friable ; pale yellow or buff ; slightly coherent ; typically, non- stratified ; and often calcareous . Loess grains are angular , with little polishing or rounding, and composed of quartz , feldspar , mica , or other mineral crystals. Loesses have been described as rich, dust-like soil. Loess deposits may become very thick: at more than

8900-719: The site, especially the children, show extremely high frequencies of porotic hyperostosis , a condition generally associated with poor health. In 2018, researchers successfully extracted low coverage nuclear DNA from the petrous bone of 8 of the individuals from the cemetery at Mán Bạc. The individuals at Mán Bạc appear to be genetically homogeneous. The individuals at Mán Bạc show a mix of East Asian farmer and east Eurasian hunter-gatherer ancestry, with close genetic affinity for modern Austroasiatic speakers. Loess A loess ( US : / ˈ l ɛ s , ˈ l ʌ s , ˈ l oʊ . ə s / , UK : / ˈ l oʊ . ə s , ˈ l ɜː s / ; from German : Löss [lœs] )

9000-479: The site. Craniometric data suggests that the population at Mán Bạc was composed of a heterogeneous population. Several of the Mán Bạc craniums exhibit morphological similarities to the craniums found at later Dong Son culture sites from the Metal Period, while some retained morphological similarities to earlier craniums from Hoabinhian or Bacsonian sites. Overall, the cranial morphologies at Man Bac appear to share

9100-508: The surface of the tooth, indicating an area of demineralization of enamel . This is referred to as a white spot lesion, an incipient carious lesion, or a "micro-cavity". As the lesion continues to demineralize, it can turn brown but will eventually turn into a cavitation ("cavity").  Before the cavity forms, the process is reversible, but once a cavity forms, the lost tooth structure cannot be regenerated . A lesion that appears dark brown and shiny suggests dental caries were once present, but

9200-434: The teeth by adhering to the pellicle-coated surface. Over time, a mature biofilm is formed, creating a cariogenic environment on the tooth surface. The minerals in the hard tissues of the teeth – enamel, dentin and cementum – are constantly undergoing demineralization and remineralization. Dental caries result when the demineralization rate is faster than the remineralization, producing net mineral loss, which occurs when there

9300-557: The teeth). Primary diagnosis involves inspection of all visible tooth surfaces using a good light source, dental mirror and explorer . Dental radiographs ( X-rays ) may show dental caries before it is otherwise visible, in particular caries between the teeth. Large areas of dental caries are often apparent to the naked eye, but smaller lesions can be difficult to identify. Visual and tactile inspection along with radiographs are employed frequently among dentists, in particular to diagnose pit and fissure caries. Early, uncavitated caries

9400-408: The tissue around the tooth , tooth loss and infection or abscess formation. Tooth regeneration is an ongoing stem cell–based field of study that aims to find methods to reverse the effects of decay; current methods are based on easing symptoms. The cause of cavities is acid from bacteria dissolving the hard tissues of the teeth ( enamel , dentin and cementum ). The acid is produced by

9500-408: The tooth to the surrounding soft tissues . Complications such as cavernous sinus thrombosis and Ludwig angina can be life-threatening. Four things are required for caries to form: a tooth surface (enamel or dentin), caries-causing bacteria, fermentable carbohydrates (such as sucrose ), and time. This involves adherence of food to the teeth and acid creation by the bacteria that makes up

9600-506: The use of radiocarbon dating in loess has increased during the past decades. Advances in methods of analyses, instrumentation, and refinements to the radiocarbon calibration curve have made it possible to obtain reliable ages from loess deposits for the last 40–45 ka. However, the use of this method relies on finding suitable in situ organic material in deposits such as charcoal, seeds, earthworm granules, or snail shells. According to Pye (1995), four fundamental requirements are necessary for

9700-632: The wind. Once entrained by the wind, particles were then deposited downwind. The loess deposits found along both sides of the Mississippi River alluvial valley are a classic example of periglacial loess. During the Quaternary , loess and loess-like sediments were formed in periglacial environments on mid-continental shield areas in Europe and Siberia as well as on the margins of high mountain ranges like in Tajikistan and on semi-arid margins of some lowland deserts as in China. In England, periglacial loess

9800-526: Was farmed with mouldboard ploughs and tilled in the fall, both intensely erosive practices. At times it suffered erosion rates of over 10 kilograms per square meter per year. Today this loess deposit is worked as low till or no till in all areas and is aggressively terraced . An area of multiple loess deposits spans from southern Tajikistan up to Almaty , Kazakhstan . The Loess Plateau ( simplified Chinese : 黄土高原 ; traditional Chinese : 黃土高原 ; pinyin : Huángtǔ Gāoyuán ), also known as

9900-665: Was introduced into English from the German Löss , which can be traced back to Swiss German and is cognate with the English word loose and the German word los . It was first applied to the Rhine River valley loesses around 1821. The term "Löß" was first described in Central Europe by Karl Cäsar von Leonhard (1823–1824), who had reported yellowish brown, silty deposits along

10000-407: Was put into setting up regional and local loess stratigraphies and their correlations (Kukla 1970, 1975, 1977). However, even the chronostratigraphical position of the last interglacial soil correlating with marine isotope substage 5e was a matter of debate, due to the lack of robust and reliable numerical dating, as summarized, for example, by Zöller et al. (1994) and Frechen et al. (1997) for

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