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Uploaded byDr Monika Negi
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Dentinogenesis

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.

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DENTINOGENESIS DR Monika Negi MDS ORAL PATHOLOGY MICROBIOLOGY AND FORENSIC ODONTOLOGY
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
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
 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
VASCULAR SUPPLY • Provided by the Capillaries found in the subodontoblastic layer of the pulp. • Migrate between odontoblasts, and later - Regress
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.
PAIN TRANSMISSION THROUGH DENTIN • DIRECT NEURAL STMULATION • TRANSDUCTION THEORY • HYDRODYNAMIC THEORY
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
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.
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.
Dentinogenesis