1. DENTIN

2. Dentin, the most voluminous mineralized connective
tissue of the tooth which is hard tissue and also mildly
elastic in nature and forms the pulp and provides
general form and shape to the tooth, and is also
called Substantia eburnea.
It considered as a vital tissue.
The hardness 1/5th of enamel and increase with age
Determine the shape of the crown , the number and
size of the root.
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3. Dentin
Enamel
Cementum

4. PHYSICAL PROPERTIES
 Color of dentin varies from light yellow in
deciduous teeth to pale yellow in permanent
dentition, becoming darker with age.
 It is elastic and subject to slight deformation.
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5. PHYSICAL PROPERTIES
Harder than bone but softer than enamel.
 Lower content of mineral salts in dentin
renders it more radiolucent than enamel.
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6. CHEMICAL PROPERTIES
Consists of 20% organic matter and 10% water & 70%
inorganic material.
The organic substance consists of collagenous fibrils
and a ground substance of mucopolysaccharides
(proteoglycans and glycosaminoglycan).
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7. CHEMICAL PROPERTIES
The inorganic component consists of hydroxyapatite
as in bone, cementum & enamel.
Organic constituents can be removed from the mineral
by incineration or organic chelation.
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8. STRUCTURES OF DENTIN
1. Dentinal tubules
2.Peritublar dentin
3.Intertublar dentin
4.Predentin
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9. DENTINAL TUBULES
 The dentinal tubules follow a gentle ‘S’-shaped
curve in the tooth crown and are straighter in the
incisal edges, cusps and root areas.
 Starting at right angles from the pulpal surface, the
first convexity of this doubly curved course is
directed toward the apex of the tooth.
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10. DENTINAL TUBULES
 These tubules end perpendicular to the
dentinoenamel and dentinocementum junctions.
 Dentinal tubule is lined with a layer of peritubular
dentin , which is much more mineralized than the
surrounding intertubular dentin.
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11. DENTINAL TUBULES
There are more tubules per unit area in the crown
than in the root.
The dentinal tubules have lateral branches throughout
dentin, which are termed canaliculi or microtubules.
A few dentinal tubules extend through the
dentinoenamel junction into the enamel. These are
termed enamel spindles.
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13. PERITUBULAR DENTIN
 Peritubular dentin has more mineral content and less
collagen fibers than the intertubular dentin.
 The peritubular dentin forms the walls of the tubules in
all the dentin.
 The continuous deposition of peritubular dentin
causes reduction in the size of tubular lumen.
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16. INTERTUBULAR DENTIN
 Forms the main body of dentin.
 It is located between the dentinal tubules or, more
specifically, between the zones of peritubular dentin.
 Intertubular dentin determine the elasticity of the
dental matrix and it’s less mineralized than peritubular
dentin.
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17. PREDENTIN
Is located adjacent to the pulp tissue which is
next to cell bodies of odontoblasts.
Is 2 to 6 microns thick, depending on the activity
of the odontoblast.
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18. PREDENTIN
It is the first formed dentin and is not
mineralized.
As the collagen fibers undergo mineralization at
the predentin - dentin front, the predentin then
becomes dentin and a new layer of predentin
forms circumpulpally.
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20. TYPES OF DENTIN
1. Primary dentin
a. Mantle
b. Circumpulpal
2.Secondary dentin
3.Reparative dentin
4.Sclerotic dentin
5. Interglobular dentine
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21. PRIMARY DENTIN
This type of dentin is formed before root
completion, gives initial shape of the tooth, it
continuous to grow tell 3 years after tooth eruption
and forms the major bulk of the dentin.
Mantle dentin
It is the outer or most peripheral part of the primary
dentin & is about 20um thick.
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22. PRIMARY DENTIN
Circumpulpal dentin
forms the remaining primary dentin or bulk of the
tooth, represents all of the dentin formed prior to
root completion.
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24. SECONDARY DENTIN
formed after root completion.
Contains fewer tubules than primary dentin.
There is usually a bend in the tubules where
primary and secondary dentin interface.
Secondary dentin forms at a slower rate then
primary dentin.
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25. REPARATIVE DENTIN
Known as reactionary, reparative or irregular
secondary dentin.
Produces in response to various stimuli such
attrition, caries, restorative dentinal procedure.
Tertiary dentin deposited rapidly.
Produced only at the site of odontoblast activation by
stimuli.
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27. SCLEROTIC OR TRANSPARENT DENTIN
Collagen fibers and apatite crystals begin appearing in
the dentinal tubules.
Apatite crystals are initially only sporadic in a dentinal
tubule but gradually fill it with a fine meshwork of
crystals.
Found specially in roots.
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28. Gradually, the tubule lumen is obliterated with
mineral, which appears very much like the peritubular
dentin.
Sclerotic dentine is generally observed in the teeth of
elderly people.
Transparent or light in transmitted and dark in
reflected light.
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SCLEROTIC OR TRANSPARENT DENTIN
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29. INTERGLOBULAR DENTIN
Sometimes mineralization of dentin begins in small
globular areas that fail to fuse into a homogenous
mass. This results in formation of hypocalcified
matrix , These are called interglobular dentin.
Forms in crowns of teeth in the circumpulpal dentin
just below the mantle dentin.
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30. INTERGLOBULAR DENTIN
Follows an incremental pattern.
In dry ground section, a small amount of interglobular
dentin may be lost and a space appears black in
transmitted light .
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31. STRUCTURAL LINES
Two types of structural lines can be found in
dentine :
The structural lines related to the formation of the
dentin are called incremental lines .
The other types of lines are related to the curvature of
the dentinal tubules. (Neonatal line)
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32. INCREMENTAL LINES
The incremental lines (von ebner), or imbrication
lines, appear striations or as fine lines at right angles to
the dentinal tubules.
The distance between these lines varies between 4 and
8 microns, which is the amount of dentin formed in 24
hours.
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33. INCREMENTAL LINES
When the tooth comes into functional occlusion, the
daily increment decreases.
The course of the lines indicates the growth pattern of
the dentin.
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35. NEONATAL LINE
These lines represent hypocalcified bands.
In the deciduous teeth and in the first permanent
molars, the prenatal and postnatal dentin is
separated by an accentuated contour line. This is
termed the neonatal line.
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36. NEONATAL LINE
This line represent the disturbance in
mineralization due to the abrupt change in
environment that occurs at birth.
The Neonatal line is present in both enamel and
dentine
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38. GRANULAR LAYER
This is a granular layer seen under transmitted light
adjacent to cementum. this is known as Tomes’
granular layer.
Slightly increases in amount from the cementoenamel
junction to the root apex.
The odontoblast initially interacts with ameloblasts or
root sheath cells through the basal lamina.
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40. AGE AND FUNCTIONAL CHANGES
With advancing and for functional requirements
number of changes are seen in dentin , the following
important are:
 Formation of secondary dentin.
 Sclerotic dentin.
 Formation of reparative dentin.
 Dead tract.
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41. DEAD TRACTS
The odontoblast processes disintegrate, & the empty
tubules are filled with air.
Appear black in transmitted light & white in reflected
light.
Often observed in the area of narrow pulpal horns
because of crowding of odontoblasts.
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42. Demonstrate decreased sensitivity.
Appear to a greater extent in older teeth.
Probably the initial step in the formation of sclerotic
dentin.
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DEAD TRACTS
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44. AFFECTED & INFECTED DENTIN
Infected dentine is the outer layer and is softened and
contaminated with bacteria. It is irreversibly denatured
and not remineralized
Affected dentine has a demineralized phase, but not
yet invaded by bacteria. It can be remineralized.
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45. AFFECTED & INFECTED DENTIN
In clinical restorative treatment of dentine during cavity
preparation it is infected dentine which is
completely removed. The affected dentine, which may
be remineralized after the completion of restorative
treatment, is not removed and is preserved.
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46. INNERVATIONS OF DENTIN
The nerve will loose its
schwann caoting then
pass between the
odontoblasts bodies and
enter the dentinal
tubules ( In crown and
fewer in the root )
Plexus of Raschkow
(suodontoblastic layer)
High at D E J
Less sensitive
area
High near the
pulpal surface