Amelogenesis (enamel) formation stage for my students

1. Haya Ghazan

2. AMELOGENESIS
What?
The formation of enamel on teeth
When?
Begins when the crown is forming during ADVANCED BELL STAGE
After dentinogenesis forms the 1st layer of Dentin
Where?
On top of the 1st layer of dentin
Who?
By AMELOBLASTS differentiated from the IEE

3. OVERVIEW
Amelogensis
Pre- Secretory Secretory Post- Secretory
Morphogenic Organizing Formative Maturative Protective Desmolytic

4. FORMATIVE STAGE

5. CELLULAR
CHANGES
Cell elongates further
Development of Tome’s Process:
• Blunt pyramidal cell process
• Penetrates the Basal lamina
• Enters the Pre- Dentin
• Incomplete septa separates it from the cell proper
• Contains secretory granules

6. • The ameloblasts start the synthesis and secretion of enamel matrix proteins
mRNA carries message
from nucleus to
cytoplasm
Ribosomes
translate mRNA
Protein synthesized in
RER and modified in
Golgi apparatus
Packed into secretory vesicles
and secreted via Tome’s Process
• Enamel matrix proteins
Amelogenins
• 90%
• Low molecular weight
• Hydrophobic
• Rich in Histidine, Glutamine,
Proline and Leucine
Non Amelogenins
• 10%
• High molecular weight
• Rich in Glycine, Aspartic acid and
Serine (GAS)
• Important proteins of this group are
Enamelin, Ameloblastin and Tuftelin
(EAT)
V
S

7. During formation, all
other calcified tissues (
bone, cartilages
cementum and dentin)
have an unmineralized
layer ( osteoid,
chondroid, cementoid
and pre-dentin)
No such layer is present
during enamel formation
as the secreted enamel
matrix proteins undergo
IMMEDIATE PARTIAL
MINERALIZATION

8. Occurs in Formative Stage, immediately after the matrix is laid down
Contributes 25%- 30% of eventual total mineral content of the enamel
Begins at the DEJ
First mineral molecule secreted is Octocalcium Phosphate, which is unstable and
hence converted to Hydroxyapatite form
IMMEDIATE PARTIAL MINERALIZATION

9. The Proximal Part releases interrod
The Distal Part releases enamel rod
1 Rod form 4 ameloblasts
Head is formed by 1, tail is formed by 3
ameloblasts
1 Ameloblast contributes to 4 different rods