Parts of a tooth, including dentin

Dentin (BE: dentine) is a calcified tissue of the body, and along with enamel, cementum, and pulp is one of the four major components of teeth. Usually, it is covered by enamel on the crown and cementum on the root and surronds the entire pulp. By weight, seventy percent of dentin consists of the mineral, hydroxylapatite, twenty percent is organic material, and ten percent is water.^[1] Yellow in appearance, it greatly affects the color of a tooth due to the translucency of enamel. Dentin, which is less mineralized and less brittle than enamel, is necessary for the support of enamel.^[2] Image File history File links Tooth_Section. ... Image File history File links Tooth_Section. ... British English (BrE, BE, en-GB) is the broad term used to distinguish the forms of the English language used in the United Kingdom from forms used elsewhere in the Anglophone world. ... Biological tissue is a group of cells that perform a similar function. ... Tooth enamel is the hardest and most highly mineralized substance of the body , and with dentin, cementum, and dental pulp is one of the four major parts of the tooth. ... Cementum is a specialized bony substance covering the root of a tooth. ... The dental pulp is the part in the center of a tooth made up of living soft tissue and cells called odontoblasts and others. ... A mans visible teeth. ... Hydroxylapatite is a naturally occurring form of calcium apatite with the formula Ca5(PO4)3(OH), but is usually written Ca10(PO4)6(OH)2 to denote that the crystal unit cell comprises two molecules. ... In optics, transparency is the property of being transparent, or allowing light to pass. ...

Dentin consists of microscopic channels, called dentinal tubules, which radiate outward through the dentin from the pulp to the exterior cementum or enamel border.^[3] These tubules contain fluid and cellular structures. As a result, dentin has a degree of permeability which can increase the sensation of pain and the rate of tooth decay. Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell being used to describe the smallest unit of a living organism Cells in culture, stained for keratin (red) and DNA (green) The cell is the... This article is about dental caries in humans. ...

The formation of dentin, known as dentinogenesis, begins prior to the formation of enamel and is initiated by the odontoblasts of the pulp. Unlike enamel, dentin continues to form throughout life and can be initiated in response to stimuli, such as tooth decay or attrition. Dentinogenesis is the creation, of dentin a substance that forms the inside of teeth. ... An odontoblast is a biological cell of neural crest origin that is part of the outer surface of the dental pulp, and whose biological function is dentinogenesis, which is the creation of dentin, the substance under the tooth enamel. ... Attrition is the loss of tooth structure due to by mechanical forces from opposing teeth. ...

There are different types of dentin, differentiated by appearance and stage of development. Primary dentin forms most of the tooth. Secondary dentin develops after root formation is complete and forms much slower than primary dentin. Tertiary dentin forms as a biological response to stimuli.

Structure

Dentinal tubules are structures that span the entire thickness of dentin and form as a result of the mechanism of dentin formation. From the outer surface of the dentin to the area nearest the pulp, these tubules follow an S-shaped path. The diameter and density of the tubules are greatest near the pulp.^[4] Tapering from the inner to the outermost surface, they have a diameter of 2.5 μm near the pulp, 1.2 μm in the middle of the dentin, and 900 nm at the dentino-enamel junction. Their density is 59,000 to 76,000 per square millimeter near the pulp, whereas the density is only half as much near the enamel. The dental-enamel junction, abbreviated DEJ, is the boundary between the enamel and dentin materials that form a tooth. ...

Within the tubules, there is an odontoblast process, which is an extension of an odontoblast, and dentinal fluid, which contains a mixture of albumin, transferrin, tenascin and proteoglycans.^[5] In addition, there are branching canalicular systems that connect to each other. These branches have been categorized by size, with major being 500-1000 μm in diameter, fine being 300-700 μm, and micro being less than 300 μm.^[6] The major branches are the terminal ends of the tubules. About every 1-2 μm, there are fine branches diverging from dentinal tubules at 45 degree angles. The microtubules diverge at 90 degree angles. An odontoblast process is an extension of a cell called an odontoblast, which forms dentin in a tooth. ... Albumin can refer to ovalbumin, the principal protein in egg white albumins, a group of proteins including serum albumin and together constituting roughly 60% of the protein in blood plasma. ... Transferrin is a plasma protein for iron ion delivery. ... Tenascins are extracellular matrix glycoproteins. ... Proteoglycans represent a special class of glycoprotein that are heavily glycosylated. ...

The porous, yellow-hued material is made up of 70% inorganic materials (mainly hydroxylapatite and some non-crystalline amorphous calcium phosphate), 20% organic materials (90% of which is collagen type 1 and the remaining 10% ground substance, which includes dentine-specific proteins), and 10% water (which is absorbed on the surface of the minerals or between the crystals). Because it is softer than enamel, it decays more rapidly and is subject to severe cavities if not properly treated, but dentin due to its elastic properties it is a good support for enamel. Its flexibility prevents the brittle enamel fracturing. Hydroxylapatite is a naturally occurring form of calcium apatite with the formula Ca5(PO4)3(OH), but is usually written Ca10(PO4)6(OH)2 to denote that the crystal unit cell comprises two molecules. ... Calcium phosphate is the name given to a family of minerals containing calcium ions (Ca2+) together with orthophosphates (PO43-), metaphosphates or pyrophosphates (P2O74-) and occasionally hydrogen or hydroxide ions. ... Tropocollagen triple helix. ... A representation of the 3D structure of myoglobin showing coloured alpha helices. ...

The three dimensional configuration of the dentinal tubules is under genetic control and is therefore a characteristic unique to the order, although in many mammalian species the tubules follow a gentle helical course through the solid matrix. This article is about the shape. ...

Types

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There are three types of dentine, primary, secondary and tertiary^[7][8]. Primary dentine is the most prominent dentine in the tooth, it outlines the pulp chamber. The outer layer is mantle dentine, it is formed by newly differentiated odontoblasts and is approximately 150 micrometer. It is different from the rest of primary dentine in that it lacks phosphoryn, has loosely packed collagen fibrils and is less mineralized. Image File history File links Question_book-3. ...

Newly secreted dentine is unmineralised and is called predentine. It is easily identified in haematoxylin and eosin stained section since it stains less intensely then dentine. It is usually 10-47 micrometer and lines the innermost region of the dentine. It is unmineralized and consists of collagen, glycoproteins and proteoglycans. It is similar to osteoid in bone and is thickest when dentinogenesis is occurring.

Secondary dentine is dentine that is formed after root formation is complete and the tooth is functional. It continues at a slower rate in incremental growths. It has a similar structure to primary dentine. Deposition is not always even around pulp chamber. Deposition causes a decrease in pulp chamber size, this means cavity preparation in young patients greater risk of exposing pulp.

Tertiary dentine is dentine formed as a reaction to external insult such as caries. It is of two type, either reactionary, where dentine is formed from pre-existing odontoblast or is it reparative, where newly differented odontoblast like cells are formed. Tertiary dentine is only formed by odontoblast directly affected by stimulus, the architecture and structure depends on intensity and duration of the stimuli e.g. if the stimulus is a carious lesion, there would be extensive destruction of dentine and damage to the pulp. Thus tertiary dentine would be deposited rapidly, with a sparse and irregular tubular pattern with cellular inclusion know as osteodentine. However if the stimuli is less active, it would be laid down less rapidly with a more regular tubular pattern and hardly any in any cellular inclusions.

Elephant ivory is solid dentin. The structure of the dentinal tubules contributes both to its porosity (useful for piano keys) and its elasticity (useful for billiard balls.) Elephant tusks are formed with a thin cap of enamel, which soon wears away, leaving the dentin exposed. Exposed dentin in humans causes the symptom of sensitive teeth. Genera and Species Loxodonta Loxodonta cyclotis Loxodonta africana Elephas Elephas maximus Elephas antiquus † Elephas beyeri † Elephas celebensis † Elephas cypriotes † Elephas ekorensis † Elephas falconeri † Elephas iolensis † Elephas planifrons † Elephas platycephalus † Elephas recki † Stegodon † Mammuthus † Elephantidae (the elephants) is a family of pachyderm, and the only remaining family in the order Proboscidea... This article or section does not cite its references or sources. ... Porosity is a measure of the void spaces in a material, and is measured as a fraction, between 0–1, or as a percentage between 0–100%. The term porosity is used in multiple fields including manufacturing, earth sciences and construction. ... A short grand piano, with the lid up. ... Elasticity is a branch of physics which studies the properties of elastic materials. ... A close-up picture of pool balls // US Billiard balls In the US, Billiard balls are balls used to play the game of US billiards. ... Dentine hypersensitivity is an intense pain felt when the dentin of the teeth are exposed to hot or cold foods or drinks. ...

Because dentin is softer than enamel, it wears away more quickly than enamel. Some mammalian teeth exploit this phenomenon, especially herbivores such as horses, deer or elephants. In many herbivores, the occlusal (biting) surface of the tooth is composed of alternating areas of dentin and enamel. Differential wearing causes sharp ridges of enamel to be formed on the surface of the tooth (typically a molar), and to remain during the working life of the tooth. Herbivores grind their molars together as they chew (masticate), and the ridges help to shred tough plant material. In zoology, an herbivore is an animal that is adapted to eat primarily plants (rather than meat). ... Who ever deleted my page is a prat and i wil hunt them down on lucy and shout at them loudly! RAAAAARRR! connie sansom ... This article is about the ruminent animal. ... For other uses, see Elephant (disambiguation). ... Molars are the rearmost and most complicated kind of tooth in most mammals. ...

Dentin may be demineralized and stained for histological study, unlike enamel. Dentin rates approximately 3 on the Mohs scale of mineral hardness. A thin section of lung tissue stained with hematoxylin and eosin. ... Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer. ...

A material similar to dentin forms the hard material that makes up dermal denticles in sharks and other cartilaginous fish. Denticles or placoid scales are small outgrowths which cover the skin of many cartilaginous fish including sharks. ... For other uses, see Shark (disambiguation). ...

References