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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]
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.
When follistatin, a BMP inhibitor, is over expressed in the epithelium of developing teeth, the ameloblasts do not differentiate and no enamel forms. Another example includes the conditional deletion of dicer-1 in the epithelium of developing teeth, which may cause impaired differentiation of ameloblasts resulting in deficient enamel formation. [2]
The dental lamina is first evidence of tooth development and begins at the sixth week in utero. [5]: 101 This is responsible for the cap-like structure of the enamel organ. It is important to note that enamel is an ectodermal product as it is originally derived from ectoderm which is the outermost of the three germ layers of the forming embryo.
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.
Teeth affected by regional odontodysplasia nevAmelogenesis imperfecta is an autosomal dominant disease characterized by a defect in dental enamel formation. Teeth are often free of enamel, small, misshapen, and tinted brown. The cause of these deformities is due to a mutation in enamel in expression.
The dentinoenamel junction or dentin-enamel junction (DEJ) [1] is the boundary between the enamel and the underlying dentin that form the solid architecture of a tooth. It is also known as the amelo - dentinal junction, [ 2 ] or ADJ.
In vertebrates, an odontoblast is a 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 formation of dentin, the substance beneath the tooth enamel on the crown and the cementum on the root.