Tooth enamel

The enamel ( Neulateinisch filmstrip final, formerly substantia adamantinea ) is the outer layer of the teeth of land vertebrates ( Tetrapoda ) and is situated in the area of ​​the tooth crown dentin.

In the body of the human tooth enamel is the hardest tissue with a Mohs hardness 5 It contains compounds of calcium, phosphorus, magnesium, sodium next to proteins and fats are involved in the structure. Enamel is inorganic to 95% and consists largely of the phosphate [ Ca 5 (PO4) 3OH ] x2 ( hydroxyapatite). This substance is soluble in acid. When viewed with the electron microscope, consists of enamel ribbon-like crystallites clustered in bunches. These are called prisms and usually run perpendicularly ( at a 90 ° angle) to the enamel surface. Enamel prisms are limited to the teeth of mammals. Melting shows according to its construction a color spectrum that ranges from reddish to bluish gray. By the light diffraction at the smallest components there is an iridescence. Furthermore, he shows opalescence.

Enamel is ontogenetically formed in the ectoderm in a special enamel organ of ameloblasts through biomineralization, cells of epithelial origin, which come from the Hertwig's epithelial root.

The melting point of the enamel is at 1620 ° C.

Dentistry

Tooth enamel is not crossed by nerves and can not be simulated. Therefore, tooth decay causes no pain, as long as it is not penetrated through the dentin to the pulp, the degraded material must, however, be removed and the tooth with other materials are "repaired". An enamel caries can through diet Steering and frequent administration of low-dose fluoride ( the so-called fluoridation ) remineralize again, while the hydroxide ions are replaced by fluoride in the apatite to fluorapatite. Only when the decay has broken through the enamel layer and propagates in the underlying dentin, is displayed a restorative therapy for the purposes of minimally invasive dentistry.

The reduction of the enamel can be carried out by mechanical means, usually. By abrasion in too frequent and vigorous brushing in the dentifrice The chemical process by acidic foods causes the enamel to erosion.