Dentin is the hard, yellowish tissue that makes up the bulk of teeth beneath the enamel. It encloses the dental pulp and is covered by enamel on the crown and cementum on the root. Dentin is composed primarily of hydroxyapatite crystals and collagen fibers, making it harder than bone but softer than enamel. It contains dentinal tubules that extend from the pulp cavity to the outer surface and contain odontoblastic processes and nerves. There are three types of dentin: primary, secondary, and tertiary, which differ in their rates of formation and permeability. Dentin functions to protect the pulp, affect enamel color, absorb shock, and determine tooth shape.

1. DENTIN
Dentin

3. Dentin is a crystalline material that
enclose the pulp , formed by
odontoblast and it is mesenchymal in
origin.
Dentin is coverd by enamel on the
chrown and cementum on the root.

4. Dentin is the most voluminous
mineralized conective tissue of
the tooth.
Forms the hard tissue portion of
the dentino-pulp complex.

5. COMPOSITION

6. PHYSICAL PROPERTIES
Hard tissue forming the bulk of
the tooth.
Softer than enamel but harder
than bone and cementum.
It has a yellow color.
It has a rough surface texture
than the enamel.

7. PHYSICAL PROPERTIES
Vital and has nerve fibers but
avascular.
Less dense than enamel on
radiograph and appear
radiolucent.
It is permeable.
Has elastic quality.

8. BASIC COMPONENTS
1. DENTINAL TUBULES
 A long tubule extend from DEJ in
the crown or DCJ in the root to outer
wall of the pulp.
 Follow a gentle ,S, -shaped curve
in the tooth crown and are straight in
the incisal edges, cusps and root areas.
COMPONENTS OF DENTINAL
TUBULE
a. Odontoblastic cytoplasmic process.
b. Dentinal fluid.
c. Nerve fibers.

9. Dentinal tubules
{
Cross section
Longitudinal section

11. BASIC COMPONENTS
2. PERITUBULAR DENTIN
 Immediately surround and
forms the wall of detinal
tubules
 More highly calcified than
intertubular dentin
3.INTERTUBULAR DENTIN
-Is the dentin found
between the peritubular
dentin and it forms the most
bulk of dentin.

12. TYPES OF DENTIN
PRIMARY DENTIN
 Formed before root completion.
 Formed by primary odontoblast.
 Formed in faster rate.
 Gives initial shape of the tooth.
 It continues to grow till 3 years after tooth
eruption.
 It is more permeability.
a. Mantle dentin.
b. Circumpulpal dentin

13. Mentle
dentin
Primary dentin
{ Circumpulpal dentin
Irregular
Secondary
dentin
Secondary dentin
Predentin

15. SECONDARY DENTIN (Regular
secondary dentin)
 Formed after completion of root formation.
 Formed at a slower rate than primary dentin.
 Thickness increase with advacing age.
 Formed by primary odontoblast.
 Less permeability.
TERTIARY DENTIN
Known as (Irregular secondary or
Reparative or sclerotic dentin)
 -Frequently formed as a response to external
stimuli such as (dental caries, attrition).
 -Formed only at the site of odontoblast activation.
 Formed by secondary odontoblast.
 Thickness increase with advacing age.
 The least permeability of dentin, therefore
helping in prevention of diffusion of noxious
agent from the tubules.

19. FUNCTIONS OF DENTIN
1. Protection of the pulp.
2. Affects the color of enamel.
3. Shoch absorber and prevent
fracture of enamel.
4. Determine the shap of the crown.

20. Microscopic feature Of Dentin
1. Imbrication line of Von Ebner,s
2. Counter line of Owen
3. DEJ
4.CEJ
5.Neonatal line
6.Tome,s granular layers
7.Interglobular dentin
8.Age changes

21. Lines of Owen Neonatal line
{

22. {
Incremental lines

23. Tomes granular layer
{
Tomes granular layer

25. Age changes
sclerotic dentin
Dead tract

26. CLINICAL CONSIDERATION OF
DENTIN
1. As dentin is known to provide strength
and rigidity to the tooth,care should be
taken during tooth preparation.
2. Tooth preparation should be done
under constant air water spray to avoid
build up of heat formation.

27. CLINICAL CONSIDERATION
OF
DENTIN
3. Dentin should always be protected by
liners,bases or dentin bonding agents.
4. Smear layer is formed as a result of
tooth cutting(quantities of cutting
debris) for bonding of restorative
materials to tooth structue,this smear
layer has to be removed by etching
process.
.