Cementoblast
Encyclopedia
A cementoblast is a biological cell
Cell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....

 that forms from the follicular cells around the root of a tooth
Tooth
Teeth are small, calcified, whitish structures found in the jaws of many vertebrates that are used to break down food. Some animals, particularly carnivores, also use teeth for hunting or for defensive purposes. The roots of teeth are embedded in the Mandible bone or the Maxillary bone and are...

, and whose biological function is cementogenesis
Cementogenesis
Cementogenesis is the formation of cementum, one of the three mineralized substances of a tooth. For cementogenesis to begin, Hertwig's epithelial root sheath must fragment. Once the root sheath fragments, the dentin that later forms the tooth's root, comes in contact with the dental sac...

, which is the creation of cementum
Cementum
Cementum is a specialized calcified substance covering the root of a tooth. Cementum is excreted by cells called cementoblasts within the root of the tooth and is thickest at the root apex. These cementoblasts develop from undifferentiated mesenchymal cells in the connective tissue of the dental...

 (the hard tissue that covers the root of the tooth).
Cementoblasts lay down the organic matrix of cementum which later gets mineralised by minerals from oral fluids. Thus the cementoblasts lay down collagen and secrete osteocalcin and sialoprotein. They possess all the organelles associated with protein synthesis such as RER
Endoplasmic reticulum
The endoplasmic reticulum is an organelle of cells in eukaryotic organisms that forms an interconnected network of tubules, vesicles, and cisternae...

 and Golgi apparatus
Golgi apparatus
The Golgi apparatus is an organelle found in most eukaryotic cells. It was identified in 1898 by the Italian physician Camillo Golgi, after whom the Golgi apparatus is named....

.

The mechanism of differentiation of the cementoblasts is controversial but circumstantial evidence suggests that an epithelium or epithelial component may cause dental follicle cells to differentiate into cementoblasts, characterised by an increase in length.
The initially formed cementum in coronal two-thirds of the root is acellular, but when the cementoblasts get trapped in lacunae in their own matrix like bone cells, the cementum is called cellular or secondary cementum and is present only in the apical third of the root.

Once in this situation, the cementoblasts lose their secretory activity and become cementocytes.
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