The formation of enamel on teeth, called amelogenesis, begins during the advanced bell stage when ameloblasts differentiate from the inner enamel epithelium and begin secreting enamel matrix proteins onto the underlying dentin layer. These ameloblasts secrete primarily amelogenins and non-amelogenins which undergo immediate partial mineralization as hydroxyapatite, unlike other calcified tissues. This unique property results in enamel, the hardest substance in the body, being formed.

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

7. 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)
•Proteins of this group are Enamelin,
Ameloblastin and Tuftelin (EAT)
V
S
Enamel Matrix Proteins

8. During formation, all other
calcified tissues have an
unmineralized layer:
1. Bone- osteoid
2. Cementum- cementoid
3. Dentin- pre-dentin)
No such layer is present
during enamel formation as
the secreted enamel matrix
proteins undergo
IMMEDIATE PARTIAL
MINERALIZATION
Enamel

9. 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

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

11. A QUICK SUMMARY…