2. DENTINOGENESIS
PROCESS OF FORMATION OF DENTIN BY
ODONTOBLASTS
Dental papilla cells small, undifferentiated,exhibit
central nucleus
Separated from inner enamel epithelium by
acellular zone
Cells of IEE reverse polarity & express
signaling molecules & growth factors
3. Ectomesenchymal cell adjoining acellular
zone enlarge to proliferate into
proodontoblasts
In proodontoblasts cytoplasm + amount of
protein synthesising organelles increase
to diff. them into odontoblasts
In odontoblast nuclei positioned away
from IEE
4. FORMATION OF MANTLE DENTIN
- After diff. odontoblasts synthesise first
dentin collagen of organic matrix
- This collagen deposited in ground
substance of dental papilla
- Appearance of distinct, large diameter
collagen k/a VON KORFF’S fibres is
first sign of dentin formation
• VON KORFF’S fibres mainly consist of
TYPE III collagen
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16. VASCULAR SUPPLY
• Provided by the Capillaries found in the
subodontoblastic
layer of the pulp.
• Migrate between odontoblasts, and later -
Regress
17. INNERVATION OF DENTIN
• Numerous Nerve Endings in
Predentin and Inner Dentin.
• 100-150μm from pulp.
• % of tubules innerveted Near Pulp
Horns –(40%)
• ↓ near CEJ- 1%
• Closely Associated with Odontoblast
Process.
• Arise from myelinated nerve fibers of
Dental Pulp- (Aδ fibres) Reach Brain
via Trigeminal N.
19. DIRECT NEURAL STIMULATION
• It was proposed by Scott
Stella in 1963
• Nerve endings in Tubules
are Directly Activated by
External Stimuli
• This view rests on the
assumption that Nerve
fibres Extend to DEJ.
• Not accepted
20. TRANSDUCTION THEORY
• Odontoblastic Processes are
primary structures excited by
stimulus.
• Transmit impulse to Nerve
Endings
• Supported by evidence that
odontoblasts → Neural Crest
Origin
• Discarded -No synaptic
Contacts
or vesicles - b/n odontoblasts
and
axons.
21. HYDRODYNAMIC THEORY
• Most popular Theory
• Gysi (1900), Brannstrom
• Various stimuli such as Heat,
Cold, Air, Mechanical
Pressure →Movement
of Fluid Within Tubule
↓
• Activating the Free Nerve
Endings Associated with
Odontoblast and its Process
• Act as Mechanoreceptors-
Sensation is felt as pain.