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Enamel (history of ameloblasts (differentiating stage (in early bell stage…

- - - - responsible for the different orientation of crystal
  - - - reduction in height
      - decrease in its organelle content
      - withdrawal of tomes process
      - decrease in the cell population
  - - - two type of ameloblasts in this stage
        
        a. ruffled ended ameloblast (80%)
        
        induction of minerals
        
        tight distal junction
        
        leaky proximal junction
        
        b. smooth ended ameloblast (20%)
        
        removal of water and protein
  - - - protects enamel from resorption from dental sac
- - - - short incremental lines
        
        4 microns
    - - long incremental lines
        
        16 microns
        
        weekly rest
    - - accentuated incremental line separating before and after birth
      - only deciduous teeth and permanent first molars
      - quality : prenatal is better than postnatal
        
        constant nutrition and more protection
  - - - never extend to dentin
      - true lamellae
    - - unmineralised area after enamel formation
      - type B crack occurs before the tooth eruption
      - type C crack occurs after tooth eruption
- - - - Defect in the quantity of Enamel matrix
    - - it is a defect in the quality of the calcified Enamel Matrix
- - - - enamel rods have complex course to withstand masticatory forces