histology of enamel dr. shahzadi tayyaba hashmi. introduction enamel is a highly mineralized...

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HISTOLOGY OF ENAMEL Dr. Shahzadi Tayyaba Hashmi

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Page 1: HISTOLOGY OF ENAMEL Dr. Shahzadi Tayyaba Hashmi. INTRODUCTION Enamel is a highly mineralized structure covering the anatomic crown of tooth It is the

HISTOLOGY OF ENAMELDr. Shahzadi Tayyaba Hashmi

Page 2: HISTOLOGY OF ENAMEL Dr. Shahzadi Tayyaba Hashmi. INTRODUCTION Enamel is a highly mineralized structure covering the anatomic crown of tooth It is the

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

Page 3: HISTOLOGY OF ENAMEL Dr. Shahzadi Tayyaba Hashmi. INTRODUCTION Enamel is a highly mineralized structure covering the anatomic crown of tooth It is the

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

Page 4: HISTOLOGY OF ENAMEL Dr. Shahzadi Tayyaba Hashmi. INTRODUCTION Enamel is a highly mineralized structure covering the anatomic crown of tooth It is the

INTRODUCTIONCHEMICAL PROPERTIES: Enamel is composed of organic & inorganic substancesi. Organic --------4%(Mainly non collagenous proteins) Amelogenins ameloblastins

ii. Inorganic--------96%Mainly calcium phosphate crystals (hydroxyapatite crystals)

iii. Water

Page 5: HISTOLOGY OF ENAMEL Dr. Shahzadi Tayyaba Hashmi. INTRODUCTION Enamel is a highly mineralized structure covering the anatomic crown of tooth It is the

MICROSCOPIC STRUCTURE

1) Enamel rods(prisms)2) Rod sheaths3) Cementing inter-rod substance

Page 6: HISTOLOGY OF ENAMEL Dr. Shahzadi Tayyaba Hashmi. INTRODUCTION Enamel is a highly mineralized structure covering the anatomic crown of tooth It is the

1) ENAMEL RODS

1. Course2. Number3. Transverse striation 4. Direction5. Gnarled enamel

Page 7: HISTOLOGY OF ENAMEL Dr. Shahzadi Tayyaba Hashmi. INTRODUCTION Enamel is a highly mineralized structure covering the anatomic crown of tooth It is the

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

Page 8: HISTOLOGY OF ENAMEL Dr. Shahzadi Tayyaba Hashmi. INTRODUCTION Enamel is a highly mineralized structure covering the anatomic crown of tooth It is the

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

Page 9: HISTOLOGY OF ENAMEL Dr. Shahzadi Tayyaba Hashmi. INTRODUCTION Enamel is a highly mineralized structure covering the anatomic crown of tooth It is the
Page 10: HISTOLOGY OF ENAMEL Dr. Shahzadi Tayyaba Hashmi. INTRODUCTION Enamel is a highly mineralized structure covering the anatomic crown of tooth It is the

Direction of rods

Permanent teeth Deciduous teeth

Page 11: HISTOLOGY OF ENAMEL Dr. Shahzadi Tayyaba Hashmi. INTRODUCTION Enamel is a highly mineralized structure covering the anatomic crown of tooth It is the

GNARLED ENAMEL 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

Page 12: HISTOLOGY OF ENAMEL Dr. Shahzadi Tayyaba Hashmi. INTRODUCTION Enamel is a highly mineralized structure covering the anatomic crown of tooth It is the

Gnarled enamel

Page 13: HISTOLOGY OF ENAMEL Dr. Shahzadi Tayyaba Hashmi. INTRODUCTION Enamel is a highly mineralized structure covering the anatomic crown of tooth It is the

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

Page 14: HISTOLOGY OF ENAMEL Dr. Shahzadi Tayyaba Hashmi. INTRODUCTION Enamel is a highly mineralized structure covering the anatomic crown of tooth It is the

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

Page 15: HISTOLOGY OF ENAMEL Dr. Shahzadi Tayyaba Hashmi. INTRODUCTION Enamel is a highly mineralized structure covering the anatomic crown of tooth It is the