Dentin Properties Classification

1. DENTIN

2. Introduction
• Dentin is the mineralised tissue
that forms the bulk of the tooth
• It is present in the crown and in
the root portion of the tooth.
• It is covered by enamel in the
crown portion and cementum in
the root portion.
• It consists of mineralized
collagen matrix consisting of
closely packed dentinal tubules
which extends the entire
thickness of the dentin.

3. Physical
properties of
dentin
• Dentin is pale yellow contributes the color of
the tooth
• Dentin is harder than the bone and cementum
but softer than the enamel.
• Even though the dentin is rigid ,it is an elastic in
nature ,which permits slight deformation.
• The tubular structure of dentin makes it
permeable ;this permeability , however
decreases with increasing age.

4. Chemical
properties of
dentin
• 70% of inorganic material and 20% of
organic material and 10% water
• Inorganic portion –calcium hydroxy apetite
crystal
• Organic portion – collagen fibres mainly type
I collagen.
• Ground substance- non collagenous matrix
protein.

5. Histology of dentin
1. DENTINAL TUBULES
Odontoblast forms the dentin
matrix and move towards the
pulp.
shape of dentinal
tubules

6. • The thickness of dentin ranges from 3 to 10 mm.
• Buccal and lingual surfaces are bigger than the mesial and
distal surfaces.
• The tubules are closely packed towards pulp and widely
packed dentinoenamel junction.
• Dentinal tubules contains terminal branches and lateral
branches

7. Lateral and
terminal
branches of
dentinal
tubules

8. Predentin
• Predentin is the newly laid ,yet
to be mineralized dentin matrix.
• It is the innermost layer of the
dentin clos to the pulp.
• Width is 6 to 10micrometer.
• It becomes a part of mineralized
dentin when it starts undergoing
mineralization.

9. Peritubular dentin
• The dentin that present immediately
next to the dentinal tubules is the
peritubular dentin.
• The minerals are deposited in the
inner wall of tubule for the formation
of peritubular dentin so it is called as
INTRATUBULAR DENTIN.
• The thickness of peritubular dentin is
0.75micrometer in outer dentin and
0.4micrometer.
• The thick organic matter rich in
glycosaminoglycans called lamina
lamitants is seen in peri tubular dentin

10. Intertubular
dentin
• The dentin situated between the dentinal tubules is the intertubular
dentin which forms the major bulk of the dentin
• It is made up of type I collagen fibres.

11. Odontoblastic
process
• Odontoblastic process are the
cytoplasmic extensions of the
odontoblast which extend into
the dentinal tubules
• The process has a diameter of 3-
4 micrometer when it enters the
dentinal tubules and tapers to
1micrometer as it extends
further into the tubule.

12. Odontoblastic process

13. Primary dentin
• MANTLE DENTIN
Mantle dentin is a first formed dentin in
the crown.
It is less mineralised
It is composed of larger collagen fibre
It shows branching of dentinal tubules.

14. Circumpulpal
dentin
• Circumpulpal dentin constitutes
the remaining primary dentin
• When compared to mantle
dentin , circumpulpal dentin is
more mineralised and has
collagen fibres

15. Interglobular dentin
• During the mineralisation of dentin matrix the
minerals are deposited as globules
• In most areas these globules fuse to form a
uniformly calcified tissue .
• When some of the globules fails to fuse into a
homogenous mass hypomineralised area will form,
called as interglobular dentin.

16. Age and functional changes
• Secondary dentin
• Transluscent dentin
• Tertiary dentin
• Sclerotic dentin
• Dead tracts

17. Secondary Dentin
• Dentin formed after root completion
• Borders the pulp
• Formed by continuous , slow deposition of
dentin by odontoblasts
• Fewer dentinal tubules
• Function : Continuous deposition leads to
smaller pulp chamber and narrow root
canals in old patients
• Protects the pulp from exposure

18. Translucent dentin
• As a result of physiologic ageing, dentinal
tubules become completely occluded with
apatite crystals
• Common in the root
• Same refractive index as intertubular dentin
• Occluded dentinal tubules appear translucent
in ground section
• Formation starts apically, proceeds cervically
with age.
• Function: Used in Forensic dentistry for age
estimation

19. Tertiary dentin
• Dentin formed in response to various stimuli like attrition, caries or
restorative dental procedure
• Types
• Reactionary dentin
• Reparative dentin/Osteodentin

20. Reactionary dentin
• Formed by existing odontoblasts
which have survived severe
damage cause to them by
stimulus.
• Irregular appearance with fewer
tubules

21. Reparative dentin
• Formed by newly differentiated
odontoblast-like cells that replace
the original odontoblasts that
have been destroyed by stimulus
• Newly differentiated odontoblast
like cells arise from deeper regions
of the pulp
• Irregular with fewer , more
twisted tubules
• Newly differentiated odontoblast
like cells get entrapped in the
matrix they form to produce
osteodentin.

22. Possible origin of newly differentiated
odontoblast like cells
• Dormant odontoblast cells formed as a result of epithelial-
mesenchymal interaction during tooth development
• Odontoblast like cells that arise from stem cell population,without
epithelial-mesenchymal interaction, under the influence of cytokines
and growth factors

23. Sclerotic dentin
• Filling up of dentinal tubules with calcified
material in response to caries, attrition, erosion
• Defensive reaction
• Keeps the pulp vital for a longer time
• Fine meshwork of apatite crystals
• Transparent
• Appears light in transmitted light and dark in
reflected light.
• Mineral concentration is higher, crystal size is
smaller
• Harder

24. Dead tracts
• Empty dentinal tubules due to
retraction of odontoblastic
process or death of odontoblast.
• Occurs as a result of caries,
attrition, erosion
• In ground sections, appear dark
in transmitted light and white in
reflected light
• Commonly seen in narrow pulp
horns
• Common in older teeth

25. DENTIN SENSITIVITY
• DIRECT NEURAL STIMULATION THEORY
• FLUID OR HYDRODYNAMIC THEORY
• TRANSDUCTION THEORY

26. DENTINOGENESIS
• Dentin formation begins when the tooth germs has reached the
bell stage of development.