dentinogenesis

• Dentinogenesis

  The process of dentine formation and mineralisation

  
• Differentiation of odontoblasts

  1. Signalling molecules expressed by IEE induce the differentiation of odontoblasts from dental papilla cells

  2. Dental papilla cells are separated from preameloblasts by an acellular zone containing fine collagen fibrils

  3. Each dental papilla cell divides to two cells: one becomes a terminally differentiated odontoblast and the other remains undifferentiated

  4. The undifferentiated cells are a reservoir for differentiation into odontoblast-like cells in case the odontoblasts are lost

  
• Differentiation of odontoblasts


  1. Immediately after the change in polarity of inner enamel epithelium, dental papilla cells adjacent to IEE elongate and become preodontoblasts

  2. The preodontoblasts differentiate into odontoblasts which have increasing amounts of protein-synthesising organelles

  3. The odontoblasts are polarised nuclei located away from the IEE

  
• Formation of mantle dentine


  1. Odontoblasts produce the organic matrix

  2. von Korff's fibres signal the initial dentin formation

  3. They are large-diameter collagen fibrils (0.1 – 0.2 um in diameter)

  4. Type III collagen associated in the early stages with fibronectin

  5. Odontoblasts also produce collagen type I oriented parallel to the future DEJ

  
• Reciprocal induction

  1. Preameloblasts induce dental papilla cells to differentiate into odontoblasts

  2. Predentine (organic dentine matrix) is secreted by odontoblasts

  3. The basal lamina between the two cell layers disintegrates

  4. The contact between predentine and preameloblasts leads to the complete differentiation of preameloblasts to secretory ameloblasts

  5. The process starts from cusp tips/incisal edges and extends laterally

  
• Formation of mantle dentine


  1. Odontoblasts also develop stubby processes into the forming extracellular matrix

  2. These occasionally penetrate the basal lamina adjacent to IEE and become enamel spindles

  3. The odontoblast process (Tome's fibre) is also formed

  4. Matrix vesicles appear and signal the beginning of mineralisation

  5. The mantle dentine is 15-20 um thick

  
• Vascular supply during dentinogenesis

  1. During mantle dentinogenesis: beneath the odontoblasts

  2. During circumpulpal dentinogenesis: some capillaries are found between odontoblasts

  
• Patterns of dentine mineralisation


  • Globular (calcospheric)
  • Linear

  
• Globular (calcospheric) mineralisation occurs in mantle and circumpulpal dentine, with discrete areas of matrix with continued crystal growth, where the globular masses enlarge and fuse. The size of the globules depends on the speed of dentine deposition
• Linear mineralisation occurs in circumpulpal dentine