Cementogenesis: Function, Tasks, Role & Diseases

During cementogenesis, the root cement of the tooth root is formed. The root cementum is part of the periodontium and assists it in embedding the tooth in the tooth socket. Both fibroblasts and cementoblasts are involved in cementogenesis.

What is cementogenesis?

Cementogenesis is the formation of the root cementum of the tooth root. Cementogenesis describes the entire process of tooth root cementum formation. It is part of embryonic tooth development, which is called odontogenesis. However, cementogenesis is not limited to embryonic tooth development. Tooth cementum formation occurs throughout life as long as the dental apparatus is undamaged. Root cementum surrounds the dentin of the root and is of bone-like consistency. Together with the dentin, it enables the tooth to be firmly anchored in the periodontium. Dentin and root cementum both consist of a mesh of collagen fibers and mineral components. The root cementum has a larger mineral content in the form of hydroxyapatite. Its composition is similar to that of bone. The mineral component hydroxyapatite contains large amounts of calcium and phosphates. Thus, root cementum consists of approximately 65 percent hydroxyapatite, 23 percent organic matrix of collagen fibrils and cementocytes, and 12 percent water. Cementoblasts are responsible for the formation of the root cement. The cementoblasts develop from the mesenchymal cells of the tooth sacs or jaws. The tooth sacs are made of connective tissue and surround the crown of the tooth during tooth development before tooth eruption.

Function and task

The goal of cementogenesis is to form tooth cementum. Tooth cementum only surrounds the tooth root to firmly anchor the tooth in the periodontium and is therefore also called root cementum. Cementogenesis begins at a later stage of tooth development. Two types of root cementum are formed. There is a cellular and an acellular form. Initially, the acellular variety develops. At the beginning of cementogenesis, fibroblasts and cementoblasts differentiate from the embryonic mesenchymal cells. The fibroblasts generate type I collagen fibers and use them to form the so-called Sharpey fibers of the root membrane. During cementogenesis, the root membrane becomes embedded in the root cementum. The cementoblasts differentiate from the follicular cells only after the dissolution of the Hertwig’s epithelial sheath. In the process, they secrete fine collagen fibrils. These fibrils move away from the tooth at right angles. As the process continues, more collagen is deposited to lengthen and thicken the fiber bundles. This is followed by further deposition of bone sialoprotein and osteocalcin. Thus, a secretory matrix of fibers and proteins is formed. After the start of mineralization, the cementoblasts leave the root cementum. As they do so, the fibers that remain behind bond with the periodontal ligaments of the root membrane at the surface. Only when tooth formation is almost complete, the cellular root cementum is formed. This is formed around the fiber bundles of the periodontal ligaments. However, the cementoblasts do not move away here, but are literally walled in the root cementum. These walled-in cementoblasts are then referred to as cementocytes. It is assumed that the cementoblasts for both types of cementogenesis originate from different sources. For example, the cells for acellular cementogenesis are thought to come from the tooth follicle, whereas in the formation of cellular root cement, cementoblasts from the adjacent bones initiate cementogenesis. However, in teeth with only one root, there is no cellular root cementum. It is found only in premolars and molars. In these, it is found at the root apex and between the roots of the teeth.

Diseases and ailments

In inflammatory processes of the entire periodontium, among other things, there is also a disturbance of cementogenesis. As a result, the jawbone, gums, tooth root and root cementum recede. The tooth loosens and dies. Overall, this process is called periodontitis. Periodontitis starts from a bacterial infection of the gums or tooth. First, the gums become detached from the jawbone. This allows more bacteria, fungi or viruses to enter the gum pockets.It is difficult to clean the gum pockets, so that a chronic process of decay of the entire periodontium often develops. Depending on the strength of the immune system, there is a more or less severe decline of the gums, jaw bones and tooth cementum. In untreated cases, the connective tissue fibers that hold the teeth in the periodontium are destroyed. At the same time, the tooth structure is also broken down by acidic breakdown products of the food pulp until the nerves are exposed. The result is severe toothache. In the further course, the nerves supplying the tooth also die. The tooth is no longer supplied and also dies. In the process, the processes of cementogenesis also come to a standstill. The protective layer of the tooth root in the form of root cementum continues to be degraded by the mechanical and chemical stresses, but no new root cementum is formed. As a result, the already dead tooth loses its hold in the periodontium over time, loosens and eventually falls out. Dental diseases can also lead to a variety of other ailments that are not initially thought to be caused by diseased teeth. These include rheumatic diseases and cardiovascular diseases. In connection with cementoblasts, these cells may also proliferate. This results in the formation of a benign cementoblastoma. This tumor is very rare and usually does not cause pain. It is associated with hypercementosis. Treatment is usually not necessary.