1. Dr. Shahzadi Tayyaba Hashmi
HISTOLOGY OF ENAMEL
Dr. Shahzadi Tayyaba Hashmi

2. introduction
Enamel is a highly mineralized structure covering the anatomic crown of tooth
It is the only tissue that is totally acellular
PHYSICAL PROPERTIES:
Colour:
Appears bluish white or grayish at the thick opaque areas & yellow-white at the thin areas reflecting underlying dentin
Thickness:
Thickness over the cusps of the molars where it measures 2.5 mm & incisal edges of incisors where it is 2.0 mm

3. introduction Hardness:
Enamel is the hardest calcified tissue in the body because of its high content of minerals
Enamel can withstand load of mastication and resist wear process

4. introduction CHEMICAL PROPERTIES:
Enamel is composed of organic & inorganic substances
Organic %
(Mainly non collagenous proteins)
Amelogenins
ameloblastins
ii. Inorganic %
Mainly calcium phosphate crystals
(hydroxyapatite crystals)
iii. Water

5. MICROSCOPIC STRUCTURE
Enamel rods(prisms)
Rod sheaths
Cementing inter-rod substance

6. 1) Enamel rods Course Number Transverse striation Direction
Gnarled enamel

7. 1. course
The enamel rod starts straight at dentino- enamel junction (D.E.J.) for about 30 µ then has a wavy course till near the outer surface of enamel where it become straight once more

8. 2. Number
The number of the enamel rods varies from 5 millions in lower lateral incisor to 12 millions in the upper first premolars
The number of the rods equals the number of the ameloblasts

10. Direction of rods
Permanent teeth
Deciduous teeth

11. Gnarled enamel Gnarled enamel Twisted course of enamel rods
Gnarled enamel is twisted and intertwined rod structure associated with increase strength of the enamel
Present mainly in the incisal edges and tip of the cusps D
Twisted course of enamel rods
Gnarled enamel

12. Gnarled enamel

13. 2) Rod sheath A thin peripheral layer Darker than the rod
Relatively acid-resistant
Less calcified and contains more organic matter than the rod itself
Electron Microscope :often incomplete

14. 3) Interprismatic substance
Cementing E. rods together
More calcified than the rod sheath
Less calcified than the rod itself
Appears to be minimum in human teeth