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90-512: The site was discovered in 2000 during roadworks, that linked Phum Snay village with National Road 6. Investigations revealed the presence of a number of ancient burials associated with material including bronzes and semiprecious stones. Immediate widespread looting by the local inhabitants over an area of 24 km (9 sq mi) made a full assessment of the extent of the archaeological remains difficult. Excavations started in February 2001 on

180-602: A 15 x 5 m area. The site dates roughly between 500 BC and AD 500. These dates were not obtained from stratigraphy as many of the artifacts and burials were disturbed by looting . Chronology was therefore determined by comparison to other nearby sites with similar grave goods and mortuary rituals. A general analysis was done of the 134 individuals identified through the minimum number of individuals method . Twenty-one burials in total were exhumed that contained human remains. The researchers noted pathological lesions in photos and written descriptions. A few specimens were x-rayed but

270-423: 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

360-439: 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

450-457: 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

540-402: 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,

630-433: 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

720-437: 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

810-452: 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

900-607: A large quantity of animal bones. The proportion of left forelimbs of hooved animals suggest a very particular sacrificial practice of animals within the burials. Researchers found that the manner of the burials and the goods contained within were closest in relation to the Óc Eo culture of the Mekong Delta . Another major find within Phum Snay was the high percentage of burials containing weapons. The graves contained swords, daggers, spearheads, and projectile points. Due to

990-399: 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

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1080-419: 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

1170-410: 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

1260-436: A section. The samples are analyzed to determine their detrital remanent magnetism (DRM), that is, the polarity of Earth's magnetic field at the time a stratum was deposited. For sedimentary rocks this is possible because, as they fall through the water column, very fine-grained magnetic minerals (< 17  μm ) behave like tiny compasses , orienting themselves with Earth's magnetic field . Upon burial, that orientation

1350-426: A slingshot should also be considered as SFT objects or items. BFT lesions result from clubs, cudgels and hammers. Perimortem injuries were identified as separate from healed injuries because they often had bone flakes adhered to the edges of the fractures. Researchers were careful to distinguish between lesions caused by violence and those caused by infectious disease. Out of the sample discovered at Phum Snay, 23.4% of

1440-434: 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

1530-413: 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

1620-427: 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,

1710-519: 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

1800-412: 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

1890-431: Is also commonly used to delineate the nature and extent of hydrocarbon -bearing reservoir rocks, seals, and traps of petroleum geology . Chronostratigraphy is the branch of stratigraphy that places an absolute age, rather than a relative age on rock strata . The branch is concerned with deriving geochronological data for rock units, both directly and inferentially, so that a sequence of time-relative events that created

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1980-463: 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

2070-458: 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 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

2160-437: 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

2250-534: Is due to physical contrasts in rock type ( lithology ). This variation can occur vertically as layering (bedding), or laterally, and reflects changes in environments of deposition (known as facies change). These variations provide a lithostratigraphy or lithologic stratigraphy of the rock unit. Key concepts in stratigraphy involve understanding how certain geometric relationships between rock layers arise and what these geometries imply about their original depositional environment. The basic concept in stratigraphy, called

2340-453: 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

2430-559: 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

2520-432: 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

2610-418: 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

2700-416: 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

2790-425: 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

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2880-419: 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

2970-411: Is preserved. For volcanic rocks, magnetic minerals, which form in the melt, orient themselves with the ambient magnetic field, and are fixed in place upon crystallization of the lava. Oriented paleomagnetic core samples are collected in the field; mudstones , siltstones , and very fine-grained sandstones are the preferred lithologies because the magnetic grains are finer and more likely to orient with

3060-438: 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

3150-413: 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

3240-418: 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

3330-527: 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

3420-443: 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

3510-461: 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

3600-431: The law of superposition , states: in an undeformed stratigraphic sequence, the oldest strata occur at the base of the sequence. Chemostratigraphy studies the changes in the relative proportions of trace elements and isotopes within and between lithologic units. Carbon and oxygen isotope ratios vary with time, and researchers can use those to map subtle changes that occurred in the paleoenvironment. This has led to

3690-564: The natural remanent magnetization (NRM) to reveal the DRM. Following statistical analysis, the results are used to generate a local magnetostratigraphic column that can then be compared against the Global Magnetic Polarity Time Scale. This technique is used to date sequences that generally lack fossils or interbedded igneous rocks. The continuous nature of the sampling means that it is also a powerful technique for

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3780-573: The Iron Age. Furthering this idea is the general location of Phum Snay, right outside the Angkorian capital. Increasing competition over resources could have been the driving force behind the formation of a hierarchical society and organized state. The differences in morphological features between the human remains at Phum Snay and other modern Southeast Asian areas lends itself to the two-layer hypothesis. The people at Phum Snay were less affected by

3870-420: 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,

3960-615: The ambient field during deposition. If the ancient magnetic field were oriented similar to today's field ( North Magnetic Pole near the North Rotational Pole ), the strata would retain a normal polarity. If the data indicate that the North Magnetic Pole were near the South Rotational Pole , the strata would exhibit reversed polarity. Results of the individual samples are analyzed by removing

4050-425: 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

4140-423: 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

4230-667: 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

4320-408: 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,

4410-422: 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

4500-502: The context of burials with high rates of traumatic lesions, the presence of these weapons indicates possible military formation, and certainly an increased level of violence than is seen in other sites within Southeast Asia. The weapons and tools found within the site were made of iron with bronze adornments. This solidified the site's place within the Iron Age because iron weapons and tools had many advantages over bronze, such as

4590-444: 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

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4680-448: 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

4770-436: 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

4860-635: 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

4950-410: 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

5040-440: 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

5130-413: 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

5220-408: 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

5310-408: 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

5400-419: 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

5490-416: 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

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5580-464: The estimation of sediment-accumulation rates. 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 the tissue around the tooth , tooth loss and infection or abscess formation. Tooth regeneration

5670-483: 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

5760-512: The gap may be due to removal by erosion, in which case it may be called a stratigraphic vacuity. It is called a hiatus because deposition was on hold for a period of time. A physical gap may represent both a period of non-deposition and a period of erosion. A geologic fault may cause the appearance of a hiatus. Magnetostratigraphy is a chronostratigraphic technique used to date sedimentary and volcanic sequences. The method works by collecting oriented samples at measured intervals throughout

5850-457: The high abundance of iron within the Earth, which made the spread of iron very rapid. Also present in the burials of a number of young adult males were ornamental shoulder decorations , which further support the idea of a violence-oriented society. The lack of blunt objects within the burials is slightly puzzling due to the higher rate of BFT lesions than SFT lesions, but this could be explained if

5940-467: The images yielded limited results. The majority of the injuries listed were cranial lesions. These were categorized into two groups: those caused by sharp force trauma (henceforth referred to SFT) which left small focused circles or lines and those caused by blunt force trauma (BFT,) resulting in round depressions in the scalp. SFT lesions are generally caused by sharp edged weapons, such as knives, swords and axes. Projectiles, such as arrows or those used by

6030-442: The individuals at Phum Snay wore helmets for protection. The health of the people living at Phum Snay was also determined from the burials. Rates of attrition , caries, and abscesses in the teeth of the human remains gave an idea of their dietary habits. The main result from the dentition was the presence of a social structure regarding male and female roles within the community. Rates of dental caries in females were higher than

6120-493: The individuals at the site were much higher than the remains can represent because a majority of assaults probably caused soft-tissue injuries, which would not be preserved in the archaeological record. Within the Phum Snay site, two types of burials were found. These include bodies that were stretched out lying flat and pits where remains were simply in piles. The burials contained a variety of grave goods, including ceramic vessels, bronze ornaments (bangles, rings, and bells), and

6210-605: The individuals showed signs of traumatic lesions, a number that is much higher than any other site in Southeast Asia . Both BFT and SFT were present within the skeletal remains, but there was a much higher rate of healed lesions than perimortem lesions. Some individuals had more than one lesion present upon the cranium. Within a sample of fifteen individuals, seventeen BFT lesions could be seen. These BFT lesions were rounded in shape, ranging in diameter from roughly 4 to 22 mm. Estimations suggest that injuries acquired by

6300-523: 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,

6390-453: 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

6480-413: 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

6570-642: The males, which may be attributed to a sexual division of labor. If the men are out hunting, they are receiving a higher level of protein in the food they are consuming, while the females may be eating more cariogenic foods if they are back tending the fields and surrounded by starches and carbohydrates . Measurements were taken on the cranial and dental morphologies of the individuals found within Phum Snay to compare them with those of modern Cambodia , Vietnam , Thailand , and Laos . The morphological similarities were found from Q-mode correlation coefficients of cranial and dental metrics. The findings indicated that

6660-484: The morphology of individuals at Phum Snay were significantly different than any of the other groups being compared. Overall, the modern groups have less robusticity than is found in the Phum Snay morphologies. The high rates of traumatic lesions and weapons within the burials at Phum Snay suggest a society that values warriors. Fighting was an important part of life to the people, which could be indicative of increasing competition over access to exotic exchange items during

6750-401: 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

6840-414: 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

6930-421: 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

7020-457: 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

7110-491: 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

7200-437: The rock layers. Strata from widespread locations containing the same fossil fauna and flora are said to be correlatable in time. Biologic stratigraphy was based on William Smith's principle of faunal succession , which predated, and was one of the first and most powerful lines of evidence for, biological evolution . It provides strong evidence for the formation ( speciation ) and extinction of species . The geologic time scale

7290-432: The rocks formation can be derived. The ultimate aim of chronostratigraphy is to place dates on the sequence of deposition of all rocks within a geological region, and then to every region, and by extension to provide an entire geologic record of the Earth. A gap or missing strata in the geological record of an area is called a stratigraphic hiatus. This may be the result of a halt in the deposition of sediment. Alternatively,

7380-405: The significance of strata or rock layering and the importance of fossil markers for correlating strata; he created the first geologic map of England. Other influential applications of stratigraphy in the early 19th century were by Georges Cuvier and Alexandre Brongniart , who studied the geology of the region around Paris. Variation in rock units, most obviously displayed as visible layering,

7470-406: The specialized field of isotopic stratigraphy. Cyclostratigraphy documents the often cyclic changes in the relative proportions of minerals (particularly carbonates ), grain size, thickness of sediment layers ( varves ) and fossil diversity with time, related to seasonal or longer term changes in palaeoclimates . Biostratigraphy or paleontologic stratigraphy is based on fossil evidence in

7560-527: The substantial gene flow received by other areas of Southeast Asia. Stratigraphy Stratigraphy is a branch of geology concerned with the study of rock layers ( strata ) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks . Stratigraphy has three related subfields: lithostratigraphy (lithologic stratigraphy), biostratigraphy (biologic stratigraphy), and chronostratigraphy (stratigraphy by age). Catholic priest Nicholas Steno established

7650-508: 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

7740-434: 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

7830-557: 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

7920-429: The theoretical basis for stratigraphy when he introduced the law of superposition , the principle of original horizontality and the principle of lateral continuity in a 1669 work on the fossilization of organic remains in layers of sediment. The first practical large-scale application of stratigraphy was by William Smith in the 1790s and early 19th century. Known as the "Father of English geology", Smith recognized

8010-408: 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

8100-529: Was developed during the 19th century, based on the evidence of biologic stratigraphy and faunal succession. This timescale remained a relative scale until the development of radiometric dating , which was based on an absolute time framework, leading to the development of chronostratigraphy. One important development is the Vail curve , which attempts to define a global historical sea-level curve according to inferences from worldwide stratigraphic patterns. Stratigraphy

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