Search results
Results from the WOW.Com Content Network
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.
The odontoblasts secrete dentin throughout life, unlike enamel, which is considered secondary dentin once root formation is complete, which may be an attempt to compensate for natural wear of the enamel. This is because of the retention of the odontoblasts within the tooth, along the outer pulpal wall.
Cross-section of a tooth. B is dentin. Dentin (/ ˈ d ɛ n t ɪ n / DEN-tin) (American English) or dentine (/ ˈ d ɛ n ˌ t iː n / DEN-teen or / ˌ d ɛ n ˈ t iː n / DEN-TEEN) (British English) (Latin: substantia eburnea) is a calcified tissue of the body and, along with enamel, cementum, and pulp, is one of the four major components of teeth.
Enamel mineralization only occurs once (as ameloblasts are lost with eruption within the reduced enamel epithelium); therefore after amelogenesis, enamel production has been finalized. [4] This is in contrast to dentin formation which occurs throughout life (secondary dentin production).
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.
The dentinoenamel junction is the surface at which the enamel and the dentin of the crown of a tooth are joined. [7] The existing ectomesenchyme around the outside of the cap of the enamel organ then condenses into the dental sac. A basement membrane separate the enamel organ and the dental sac.
After the formation of enamel matrix, mineralisation of enamel takes place which is known as maturation. During this stage, the ameloblasts are slightly reduced in length. The stratum intermedium cells lose their cuboidal shape and assumed to be as spindle shape. During this stage, ameloblasts also exhibit microvilli at their distal extremities.
Dentin, less mineralized and less brittle, 3–4 in hardness, compensates for enamel and is necessary as a support. [7] On radiographs, the differences in the mineralization of different portions of the tooth and surrounding periodontium can be noted; enamel appears lighter than dentin or pulp since it is denser than both and more radiopaque. [8]