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Enamel
Dr. Mahmoud Bakr
School Of Dentistry and Oral health
Griffith University
Member of the Australian Dental Association (ADA),Australian Biology Institute Inc. (ABI), and theEgyptian Dental Union (EDU).
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ENAMEL
*PHYSICAL PROPERTIES:COLORTHICKNESS
HARDNESSBRITTLENESSPERMEABILITY
The hardest calcified tissue in the body
forms the protective covering of the crown
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GROUND SECTION DECALCIFIED SECTION
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CHEMICAL COMPOSITION:
CRYSTALLINE CALCIUM PHOSPHATE
HYDROXYAPATITE
Ca 10(PO4)6 (OH)2
96%
By weight
4%
AMELOGENINSENAMELINS and Water
INORGANIC
CONTENTORGANIC
CONTENT
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unit structure ofenamel
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7/39Enamel rods
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Wavy Course of Enamel Rods
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HUNTER-SCHREGER BANDS(optical phenomenon) dark and light bands
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Hunter Schreger bands
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Note that Hunter
Schreger bands
Start from the ADJ
an end beforereaching the outer
surface of enamel
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Cross Section : Hexagonal, fish scales,keyhole pattern
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HISTOLOGICAL STRUCTURES OFENAMEL
Incremental lines
Enamel lamellae
Enamel tufts Enamel spindle
Dentino-enamel junction
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STRUCTURAL FEATURES OF ENAMEL
CROSS
STRAIATIONS
(short increment)
INCREMENTAL LINES
OF RETZIUS
( long increment)
Incremental lines:
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INCREMENTAL LINES OF RETZIUS
( long increment)
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1
3
1
3 2
1. A.D.J
2. Brown striae of Retzius
3. Dentinal tubule
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Brown striae of Retzius A.D.J Dentinal tubules
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NEONATAL LINE
Postnatal
Enamel
Prenatal
Enamel
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Enamel lamella
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Enamel lamellae
In enamel
only
Extending in enamel and
dentin
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A: enamel tuft
B: enamel Lamella
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Enaml tufts
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Enamel Spindles
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THE AMELODENTINAL JUNCTION
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* OUTER STRUCTURELESS ENAMEL
*PERIKYMATA*ENAMEL ROD ENDS
* CRACKs*Afibrillar cementum
SURFACE STRUCTURESOF ENAMEL
SURFACE STRUCTURES
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SURFACE STRUCTURES
REMEMBER: THAT THERE IS AN INNER STRUCTURELESS
ENAMEL
1 OUTER STRUCTURELESS ENAMEL
30 um thick
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Perikymata
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Enamel Rod Ends
SHALLOWERCERVICALLYDEEPEROCCLUSALLY
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CRACKs
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AFIBRILLAR CEMENTUM
E
C
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SALIVARY PELLICLE
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Age changes of Enamel
Attrition
Decreased Permeability
Increased Hardness (ionic exchange)
Color changes
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Attrition
Dentin
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ASG
2 - PERMEABILITY
Main pathRecently
Erupted teeth
Old enamel
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