Periodontium: Periodontal tissue and root development

• what Periodontal tissues originate from the dental follicle?

  - Cementum

  - PDL from fibroblasts

  - alveolar bone from osteoblasts
• describe the dental follicle

  a sac-like structure made of ectomesenchymal cells surrounding a developing tooth.
• root formation

  
  

  how is the cervical loop formed?

  • Extension of the inner and outer enamel epithelia and the stellate reticulum.
• root formation

  
  

  what happens to the cervical loops during crown formation?

  elongation
• root formation

  
  

  what happens to the cervical loops once crown formation is complete?

  the cervical loop collapses into a two layered epithelial structure, called Hertwig's Epithelial Root Sheath (HERS)

  
  

  • Extension of the inner and outer enamel epithelia that forms the tooth root.

  • Elongates and induces dentine formation on the pulp-side, but initially inhibits cementum formation on the follicle side.
• root formation

  
  

  what does HERS break up into?

  a network of epithelial cells -> the epithelial rests of Malassez
• root formation leading to cementum formation

  
  

  what does the breakup of HERS allow?

  This breakup of HERS allows the follicle cells to reach the dentine surface of the developing tooth root, initiating cementum formation ( it will differentiate into cementum-producing cells (cementoblasts))

  
  

  -> This also traps collagen fiber bundles from the developing PDL, forming Sharpey's fibers.