Development of Tooth – Part 3 : Root Formation

Today’s video is about the root
formation of a tooth, Before proceeding please make sure to subscribe and turn on the bell icon for upcoming videos. The development of root begins after
the enamel and dentin has reached the future cementoenamel junction. Since we said that hertwig’s epithelial root sheath which was an extension of the inner and outer enamel epithelium, turns medially before it grows vertically. – it now grows coronal to the diaphragm, It’s worth repeating that the epithelial diaphragm is constant and it will not grow at its free end into the
connective tissue but it may form tongue like extensions in multi rooted teeth. To understand this, imagine the root sheath as a collar or skirt hanging down from the enamel Organ and we are having an inferior view of it. If the entire circumference of the diaphragm grows evenly it will form single-rooted teeth. If two areas of the diaphragm opposite each other grows rapidly more than its other areas, it will form two columns of roots. if three areas grows rapidly and meet
they will form tri-rooted teeth or three columns of roots. For simplicity, let’s have a close-up of
this area only and understand that how root formation begins. As the root sheath begins to grow coronal to the diaphragm, it causes the differentiation of its nearby cells into preodontoblasts. The cells of the dental sac are still undifferentiated at this point, and they will differentiate only when the barrier between them and the dentinal matrix is removed. As soon as the immature odontooblasts converts to mature odontoblasts they lay down the dentinal matrix and this dentinal matrix will make the root sheet to perforate at certain sites, as a result of which the barrier between the
dentin and the dental follicular cells is removed. Some of the cells will differentiate into fibroblasts and they will make the collagen fibers of the PDL some of the cells will differentiate into cementoblasts and they will lay down the cemental matrix. Some cells will differentiate into osteoblasts, they will make the alveolar bone After the degeneration of the root sheet, some of its cells retains into the PDL. These cells are called epithelial rests of malassez. As the epithelial root sheath grows further beyond its degenerated zone, it causes the differentiation of the nearby dental papillar cells into preoodontoblasts and the process is repeated in the same manner. After the dentinal and cemental matrix are mineralized and the PDL fibers are organized, four layers may be found The odontoblastic layer, the dentin, the
cementum and the PDL fibers. The process is repeated as the root sheath grows into the next area and in this way the root formation is completed. If you think this video really helped you please like, subscribe, share and comment if you have any questions. Thank you for watching!

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