Hydroxyapatite and Related Topics

Tooth enamel

One of the four major tissues that make up the tooth in humans and many other animals, including some species of fish.

Parts of a tooth, including the enamel (cross section).

Histologic slide showing a developing tooth. The mouth would be in the area of space at the top of the picture.

Histologic slide showing enamel formation

The effects of bruxism on an anterior tooth, revealing the dentin and pulp which are normally hidden by enamel

Common dentistry trays filled with fluoride foam

An X-ray showing enamel and dentin replaced by an amalgam restoration

Irreversible enamel defects caused by an untreated celiac disease. They may be the only clue to its diagnosis, even in absence of gastrointestinal symptoms, but are often confused with fluorosis, tetracycline discoloration, or other causes. The National Institutes of Health include a dental exam in the diagnostic protocol of celiac disease.

The primary mineral is hydroxyapatite, which is a crystalline calcium phosphate.

Destruction of a tooth by dental caries and disease.

Tooth decay

Breakdown of teeth due to acids produced by bacteria.

(A) A small spot of decay visible on the surface of a tooth. (B) The radiograph reveals an extensive region of demineralization within the dentin (arrows). (C) A hole is discovered on the side of the tooth at the beginning of decay removal. (D) All decay removed; ready for a filling.

Diagrammatic representation of acidogenic theory of causation of dental caries. Four factors, namely, a suitable carbohydrate substrate (1), micro-organisms in dental plaque (2), a susceptible tooth surface (3) and time (4); must be present together for dental caries to occur (5). Saliva (6) and fluoride (7) are modifying factors.

A Gram stain image of Streptococcus mutans.

"Stephan curve", showing sudden decrease in plaque pH following glucose rinse, which returns to normal after 30–60 min. Net demineralization of dental hard tissues occurs below the critical pH (5.5), shown in yellow.

Microbe communities attach to tooth surface and create a biofilm. As the biofilm grows an anaerobic environment forms from the oxygen being used up. Microbes use sucrose and other dietary sugars as a food source. The dietary sugars go through anaerobic fermentation pathways producing lactate. The lactate is excreted from the cell onto the tooth enamel then ionizes. The lactate ions demineralize the hydroxyapatite crystals causing the tooth to be degraded.

The progression of pit and fissure caries resembles two triangles with their bases meeting along the junction of enamel and dentin.

The faster spread of caries through dentin creates this triangular appearance in smooth surface caries.

The tip of a dental explorer, which is used for caries diagnosis

A dental infection resulting in an abscess and inflammation of the maxillary sinus

Tooth samples imaged with a non-coherent continuous light source (row 1), LSI (row 2) and pseudo-color visualization of LSI (row 3).

G. V. Black Classification of Restorations

Rampant caries caused by methamphetamine abuse.

Toothbrushes are commonly used to clean teeth.

Annual caries incidence increases exponentially with annual per capita sugar consumption. Data based on 10,553 Japanese children whose individual lower first molar teeth were monitored yearly from the age of 6 to 11 years of age. Caries plotted on a logarithmic scale, so line is straight.

Common dentistry trays used to deliver fluoride.

Fluoride is sold in tablets for cavity prevention.

An amalgam used as a restorative material in a tooth.

A tooth with extensive caries eventually requiring extraction.

An image from Omne Bonum (14th century) depicting a dentist extracting a tooth with forceps.

These minerals, especially hydroxyapatite, will become soluble when exposed to acidic environments.

Apatite

Apatite in photomicrographs of a thin section from the Siilinjärvi apatite mine. In cross-polarized light on left, plane-polarized light on right.

An apatite mine in Siilinjärvi, Finland.

Apatite is a group of phosphate minerals, usually hydroxyapatite, fluorapatite and chlorapatite, with high concentrations of OH−, F− and Cl− ions, respectively, in the crystal.

Mild fluorosis: in its usual mildest form, fluorosis appears as opaque white patches on the enamel

Dental fluorosis

Common disorder, characterized by hypomineralization of tooth enamel caused by ingestion of excessive fluoride during enamel formation.

Amelogenesis imperfecta: this condition can be mistaken for fluorosis

Enamel hypoplasia caused by untreated celiac disease: this condition is often confused with fluorosis

Severe fluorosis: brown discolored and mottled enamel of an individual from a region with high levels of naturally occurring fluoride

Severe fluorosis: the enamel is pitted and discolored

Hydroxyapatite is converted to fluoroapatite in a three step process.

Dentin

Calcified tissue of the body and, along with enamel, cementum, and pulp, is one of the four major components of teeth.

By volume, 45% of dentin consists of the mineral hydroxyapatite, 33% is organic material, and 22% is water.

Fluorapatite

Phosphate mineral with the formula Ca53F (calcium fluorophosphate).

Fluorapatite grains in carbonate groundmass. Photomicrographs of thin section from Siilinjärvi apatite ore.

Fluorapatite. São Geraldo do Baixio, Doce valley, Minas Gerais, Brazil.

Along with hydroxylapatite, it can be a component of tooth enamel, but for industrial use both minerals are mined in the form of phosphate rock, whose usual mineral composition is primarily fluorapatite but often with significant amounts of the other.

Tooth

Hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food.

Section through the ivory tusk of a mammoth

Buccal view of top incisor from Rattus rattus. Top incisor outlined in yellow. Molars circled in blue.

Buccal view of the lower incisor from the right dentary of a Rattus rattus

Lingual view of the lower incisor from the right dentary of a Rattus rattus

Midsagittal view of top incisor from Rattus rattus. Top incisor outlined in yellow. Molars circled in blue.

Lingual view of top incisor from Rattus rattus. Top incisor outlined in yellow. Molars circled in blue.

The European medicinal leech has three jaws with numerous sharp teeth which function like little saws for incising a host.

The limpet rasps algae from rocks using teeth with the strongest known tensile strength of any biological material

Dentine can be as hard as the rest of teeth and is composed of collagen fibres, reinforced with hydroxyapatite.

Calcium

Chemical element with the symbol Ca and atomic number 20.

One of the 'Ain Ghazal Statues, made from lime plaster

Travertine terraces in Pamukkale, Turkey

As an example of the wide range of solubility of calcium compounds, monocalcium phosphate is very soluble in water, 85% of extracellular calcium is as dicalcium phosphate with a solubility of 2.0 mM and the hydroxyapatite of bones in an organic matrix is tricalcium phosphate at 100 μM.

Remineralisation of teeth

Demineralised by acid in plaque and becomes partly dissolved crystal. This in turn is remineralised by fluoride in plaque to become a fluorapatite-like coating on remineralised crystal.|Example: Demineralization and remineralization of dental enamel in the presence of acid and fluoride in saliva and plaque fluid.

When enough acid is produced so that the pH goes below 5.5, the acid dissolves carbonated hydroxyapatite, the main component of tooth enamel.

Bone

For other uses, see Bone (disambiguation) or Bones (disambiguation).

Light micrograph of decalcified cancellous bone tissue displaying osteoblasts actively synthesizing osteoid, containing two osteocytes.

Transmission electron micrograph of decalcified woven bone matrix displaying characteristic irregular orientation of collagen fibers

One way to classify bones is by their shape or appearance.

Light micrograph of a section through a juvenile knee joint (rat) showing the cartilagineous growth plates

$Radiography used to identify possible bone fractures after a knee injury$

$Reduced bone mineral density in Osteoporosis (R), increasing the likelihood of fractures$

$Human femurs and humerus from Roman period, with evidence of healed fractures$

Skeletal fluorosis in a cow's leg, due to industrial contamination

Bones of slaughtered cattle on a farm in Namibia

Scanning electron microscope of bone at 100× magnification

The matrix is hardened by the binding of inorganic mineral salt, calcium phosphate, in a chemical arrangement known as bone mineral, a form of calcium hydroxylapatite.