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Cementum situated around a human molar The cementum is the surface layer of the tooth root, covering the dentin (which is labeled B). Rather than being a passive entity like paint on a wall, cementum is a dynamic entity within the periodontium .
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. It is usually covered by enamel on ...
The cementum is light yellow and slightly lighter in color than dentin. It has the highest fluoride content of all mineralized tissue. Cementum also is permeable to a variety of materials. It is formed continuously throughout life because a new layer of cementum is deposited to keep the attachment intact as the superficial layer of cementum ages.
Dentin has microscopic channels, called dentinal tubules, which radiate outward through the dentin from the pulp cavity to the exterior cementum or enamel border. [17] The diameter of these tubules range from 2.5 μm near the pulp, to 1.2 μm in the midportion, and 900 nm near the dentino-enamel junction. [ 18 ]
Coronal cementum - where the enamel overlaps the cement. Abutment - It is also known as vis a vis relation, where the cement and enamel meet at the butt joint, occurring in 30% of sections, and the least common, occurring in 10% of sections. Gap between cementum and enamel exposing the dentin. [5]
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]
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.
Dentin formation, known as dentinogenesis, is the first identifiable feature in the crown stage of tooth development. The formation of dentin must always occur before the formation of enamel. The different stages of dentin formation result in different types of dentin: mantle dentin, primary dentin, secondary dentin, and tertiary dentin. [31]