Dentinogenesis is the creation, of dentin a substance that forms the inside of teeth. Dentinogenesis is performed by odontoblasts, which are a special type of biological cells on the ouside of dental pulps, and it begins at the late bell stage of a developing tooth. The different stages of dentin formation result in different types of dentin: mantle dentin, primary dentin, secondary dentin, and tertiary dentin. Parts of a tooth, including dentin Dentin (BE: dentine) is the substance between the enamel (substance in the crown) or cementum (substance in the root) of a tooth and the pulp chamber. ... Types of teeth Molars are used for grinding up foods Carnassials are used for slicing food. ... An odontoblast is a biological cell that is part of the outer surface of the dental pulp, and whose biological function is dentinogenesis, which is the creation of dentin, the substance under the tooth enamel and ivory. ... Cells in culture, stained for keratin (red) and DNA (green) The cell is the structural and functional unit of all living organisms, and are sometimes called the building blocks of life. ... The pulp of a tooth is the soft living tissue in the center of a tooth. ... Radiograph of lower right (from left to right) 3rd, 2nd, and 1st molars in different stages of development. ...

Odontoblasts differentiate from cells of the dental papilla. They begin secreting an organic matrix around the area directly adjacent to the inner enamel epithelium, closest to the area of the future cusp of a tooth. The organic matrix contains collagen fibers with large diameters (0.1-0.2 μm in diameter). The odontoblasts begin to move toward the center of the tooth, forming an extension called the odontoblast process. Thus, dentin formation proceeds toward the inside of the tooth. The odontoblast process causes the secretion of hydroxyapatite crystals and mineralization of the matrix. This area of mineralization is known as mantle dentin and is a layer usually about 150 μm thick. An odontoblast process is an extension of a cell called an odontoblast, which forms dentin in a tooth. ...

Whereas mantle dentin forms from the preexisting ground substance of the dental papilla, primary dentin forms through a different process. Odontoblasts increase in size, eliminating the availability of any extracellular resources to contribute to an organic matrix for mineralization. Additionally, the larger odontoblasts cause collagen to be secreted in smaller amounts, which results in more tightly arranged, heterogenous nucleation that is used for mineralization. Other materials (such as lipids, phosphoproteins, and phospholipids) are also secreted. Tropocollagen triple helix. ... Figure 1: Structure of a Lipid. ... Phosphoproteins are a group of proteins which are chemically attached to a substance containing phosphoric acid. ... Two schematic representations of a phospholipid. ...

Secondary dentin is formed after root formation is finished and occurs at a much slower rate. It is not formed at a uniform rate along the tooth, but instead forms faster along sections closer to the crown of a tooth. This development continues throughout life and accounts for the smaller areas of pulp found in older individuals. Tertiary dentin, also known as reparative dentin, forms in reaction to stimuli, such as attrition or dental caries. Attrition may have multiple meanings: From a military standpoint, attrition means a gradual, natural reduction in membership or personnel, as through retirement, resignation, or death. ...

The dentin in the root of a tooth forms only after the presence of Hertwig's epithelial root sheath (HERS), near the cervical loop of the enamel organ. Root dentin is considered different than dentin found in the crown of the tooth (known as coronal dentin) because of the different orientation of collagen fibers, the decrease of phosphoryn levels, and the less amount of mineralization. The Hertwigs epithelial root sheath (frequently abbreviated as HERS) is a proliferation of epithelial cells located at the cervical loop of the enamel organ in a developing tooth. ... The cervical loop is the location on an enamel organ in a developing tooth where the outer enamel epithelium and the inner enamel epithelium join. ...