1) Dentinogenesis is the process of dentin formation by odontoblasts. Undifferentiated dental papilla cells proliferate and differentiate into proodontoblasts and then into odontoblasts. 2) Odontoblasts synthesize and deposit the organic matrix of mantle dentin, which consists mainly of Type III collagen. This is the first sign of dentin formation. 3) The hydrodynamic theory is currently the most accepted explanation for how dentin transmits pain signals. According to this theory, external stimuli cause movement of fluid within dentin tubules, activating nerve endings associated with odontoblasts and transmitting pain sensations.

1. DENTINOGENESIS
DR Monika Negi
MDS
ORAL PATHOLOGY MICROBIOLOGY AND FORENSIC ODONTOLOGY

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

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.

18. PAIN TRANSMISSION THROUGH
DENTIN
• DIRECT NEURAL
STMULATION
• TRANSDUCTION THEORY
• HYDRODYNAMIC THEORY

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.