2. - Dentin is a crystalline material that enclose
the pulp.
- formed by odontoblast and it is mesenchymal
in originated consists of tiny tubules or tubes.

3. - It is the second layer of the tooth and is
normally coverd by enamel on the chrown and
cementum on the root, making up the
majority of the tooth's structure

4. 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.

5.  Vital and has nerve fibers but avascular.
 Less dense than enamel on radiograph and
appear radiolucent.
 It is permeable.
Has elastic quality.

6. - Consists of 70% inorganic material mainly calcium
hydroxyapitate crystals which appear plate like and
smaller than that of enamel.
- 20% organic matter mainly collagen.
- 10% water.

7. Inorganic material 70%
Organic material 20%
Water 10%

8. 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. 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.

10.  Support the enamel.
 Protect the pulp.
 Determines the shape of the crown.
 Provide The Color of Tooth.

12. 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.

13. PRIMARY DENTIN
Mentle dentin Circumpulpal dentin
First dentin formed against DEJ Large collagen fibers perpendicular
Fine collagen fibers parallel to DEJ
Large collagen fibers perpendicular
To DEJ
Ground subestance from
odontoblast only
Ground subestance from dental
Papilla and odontoblast

14. 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.

15. TERTIARY DENTIN:
(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.

18. 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.

19. 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.

22. ؟
Mhammed Ali Al gnaidy (32) Mohammed Taleb Basarda (33) Shaikh Ahmed Bajaber (35)