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The teeth of Arctodus pristinus transition between undulating to acute-angled Hunter-Schreger bands while Arctodus simus exhibited a transition between undulating to zigzag bands, demonstrating an evolution towards reinforced tooth enamel. This has been convergently evolved with giant pandas, agriotheriin bears, and Hemicyon. [9]
The enamel on primary teeth has a more opaque crystalline form and thus appears whiter than on permanent teeth. The large amount of mineral in enamel accounts not only for its strength but also for its brittleness. [6] Tooth enamel ranks 5 on Mohs hardness scale (between steel and titanium) and has a Young's modulus of 83 GPa. [4]
Ground apatite was used as a pigment for the Terracotta Army of 3rd-century BCE China, [28] and in Qing dynasty enamel for metalware. [29] During digestion of apatite with sulfuric acid to make phosphoric acid, hydrogen fluoride is produced as a byproduct from any fluorapatite content. This byproduct is a minor industrial source of hydrofluoric ...
Amelogenesis is the process of forming tooth enamel, the hard, protective outer layer of teeth. [1] This process begins during tooth development after the initial formation of dentin (dentinogenesis), the layer beneath the enamel. [2]
Tooth development begins at week 6 in utero, in the oral epithelium. The process is divided into three stages: Initiation; Morphogenesis and; Histogenesis [2]; At the end of week 7 i.u., localised proliferations of cells in the dental laminae form round and oval swellings known as tooth buds, which will eventually develop into mesenchymal cells and surround the enamel organ.
Enamel and dentin do not regenerate after they mineralize initially. Enamel hypoplasia is a condition in which the amount of enamel formed is inadequate. [59] This results either in pits and grooves in areas of the tooth or in widespread absence of enamel. Diffuse opacities of enamel does not affect the amount of enamel but changes its appearance.
This layer, along with the inner enamel epithelium, is responsible for the tooth enamel formation. It is a part of the dental (enamel) organ. Stratum intermedium stores glycogen. It is absent in the part of the tooth germ that outlines the root portions of the tooth which does not form enamel.
Produced during the second stage of enamel calcification, also known as the maturation stage, ameloblasts produce matrix and enamel at the rate of 4 micrometers per day; however every fourth day there is a change in development. Brownish lines, the striae of Retzius, develop as a result of a change in the growth process.