Sharpey fiber
Sharpey fibers are fibers belonging to the periosteum and consisting of collagen type I fiber bundles (28,000 fibers / mm 2 ). They are named after the anatomist William Sharpey , who first described them in 1846. These fibers are not stretchable, but rather stretch out of their wavy shape in order to transmit the tensile forces.
Occurrence
Sharpey's fibers are in the periosteum (periosteum) of the bone, in bone-tendon junction and the periodontal ligament (PDL) of the tooth before.
Periosteum
Sharpey fibers of the periosteum arise from the outer layer of connective tissue (stratum fibrosum) of the periosteum. They run through the osteogenic stratum and penetrate the substantia compacta of the bone. They are used to fix the periosteum to the bone. Through additional connective tissue contacts between the stratum fibrosum and the overlying tendons and ligaments, they establish a connection between bones and muscles. In the periosteum itself, they run as collagenous fibrils in a tangential direction. They are called "spiculae" if they calcify in the course of malignant processes and appear as sunbeam-like bone threads.
Bone-tendon transition
The Sharpey fibers transmit the force via the attachment points of the bone for ligaments and tendons. The tendon attachment zone occurs as a diaphyseal attachment. Here the damping is achieved by interweaving the collagen fibers of the tendon with elastic fibers of the stratum fibrosum of the periosteum.
Root skin
The Sharpey fibers are attached to the basic bone substance and form the connection to the root cement of the tooth, the alveolodental fibers . They are also known as periodontal ligament or periodontal ligament . The tooth is resiliently attached to them. Thus the tooth root is "suspended" in the tooth socket. The bone can cope with these tensile forces, whereas it would react with bone degradation in the absence of periodontal pressure. In addition, the collagen fibers of the periodontium prevent the tooth from being pulled out, tilting and rotating about its longitudinal axis.
The connection between the cement of the tooth root on the one hand and the bone of the alveolus on the other hand is a special form of syndesmosis .
Classification on the tooth
| Fiber bundle | function |
|---|---|
| Descending fiber bundles | prevent the tooth from being pulled out of the socket |
| Horizontal bundles of fibers | fix the most coronal part of the tooth root |
Fiber bundles ascending from the root cement to the alveolar bone |
transform pressure into tensile load |
| Interradicular fiber bundles | occur in multi-rooted teeth; run horizontally or descending from the point where the roots branch to the interradicular bone septum. |
| Apical fiber bundles | run horizontally or descending from the tip of the root to the alveolar bone and prevent the tip of the root from moving and the tooth being pulled out. |
biosynthesis
During the hydroxylation of the amino acids proline to hydroxyproline by the enzyme prolyl-4-hydroxylase ( EC 1.14.11.2 ) and lysine to hydroxylysine by the enzyme lysyl hydroxylase ( EC 1.14.11.4 ), during collagen synthesis only one oxygen atom is required from the oxygen molecule. The other is done by the cofactor ascorbic acid (vitamin C), which is oxidized to dehydroascorbic acid and water.
scurvy
A disturbed collagen synthesis and thus a disturbed formation of the Sharpey fibers occurs with a persistent lack of vitamin C in the food, which cannot fulfill its function as structural protein , which among other things leads to bleeding gums , gingival hyperplasia and tooth loss in scurvy . Numerous serious symptoms of this deficiency disease appear several months after the onset of the vitamin C deficiency. If left untreated, scurvy leads to death.
Tooth extraction
The removal of a tooth (extraction) is effected by a relaxation of the tooth in its tooth socket (alveolus). For this purpose, the tooth is moved back and forth slowly and with measured force by means of a lever or pliers, whereby the alveolar bone is stretched and the alveolus is expanded. In the case of single-root teeth, a rotary movement can also be carried out. The dislocation movements tear the Sharpey fibers, whereupon the tooth can be removed.
Periodontal disease
In periodontitis , the connection between periodontal and dental cement is broken down, i.e. the Sharpey fibers, which irreversibly destroys the teeth holding apparatus . When the periodontium is inflamed, the tissue in the periodontal gap (gap between the root of the tooth and the bone compartment) swells , lifting the tooth slightly out of its alveolus and giving you the feeling that "the tooth has become too long" when you bite open.
Individual evidence
- ^ Walter Hoffmann-Axthelm : Lexicon of Dentistry , Quintessenz-Verlag, Berlin, 1995
- ↑ Leonardo Dude, Extraction Forceps of the Roman Empire , Dissertation, 2006.
- ↑ Frans van den Berg: Applied Physiology: Volume 1: Understanding and influencing the connective tissue of the musculoskeletal system . Georg Thieme, 2010, ISBN 978-3-13-163053-7 , pp. 89- ( google.com ).
- ↑ Frans van den Berg: Applied Physiology: Volume 1: Understanding and influencing the connective tissue of the musculoskeletal system . Georg Thieme, 2010, ISBN 978-3-13-163053-7 , pp. 212 ( google.com ).
- ↑ Birte Steiniger, Hans Schwarzbach, Vitus Stachniss: Microscopic anatomy of the teeth and the parodont . Georg Thieme, 2010, ISBN 978-3-13-160391-3 , p. 35-45 ( google.com ).
- ↑ Klaus Kühn : Structure and biochemistry of collagen. In: Chemistry in Our Time . Volume 8, 1974, pp. 97-103. doi: 10.1002 / ciuz.19740080402 .
- ↑ Eckhart Buddecke: Biochemical basics of dentistry . Walter de Gruyter, 1981, ISBN 978-3-11-085820-4 , pp. 61 ( google.com ).
- ↑ Jarg-Erich Hausamen, Egbert Machtens, Jürgen F. Reuther, Harald Eufinger, Alexander Kübler, Henning Schliephake: Oral and maxillofacial surgery . Springer, 2012, ISBN 978-3-642-17801-6 , pp. 46 ( google.com ).
- ↑ Werner Linß, Jochen Fanghänel: Histology: cytology, general histology, microscopic anatomy . Walter de Gruyter, 1998, ISBN 978-3-11-014032-3 , p. 164 ( google.com ).
