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DENTINOGENESIS

Dr. Asmat Jameel

Assistant Professor

B.D.S, F.C.P.SHead Department of Oral Biology

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Begins at bell stage.Odontoblast differentiated from

ectomesenchymal cells of dental papilla

after receiving stimulus from IDE.

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DIFFERENTIATION

Dental papilla cells are small andundifferentiated with central nucleus andfew organelles.

Seperated from IDE by an acellular zonet at conta ns some ne co agen r s.

When cells of IDE reverse polarity,

c anges a so occurs n a acen en apapilla.

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DIFFERENTIATION

Cells enlarge ----preodontoblast---odontoblast as their cytoplasm increasesin volume to contain increase amount of

protein synthesizing organelles. ce uar zone s e mnate y

odontoblast.

on o as are g y po arze wnucleus located away from IDE.

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DENTINE

First collagen synthesized is deposited inthe ground substance of dental papilla.

VON KORFFS FIBERS: large diameter

0.1-0.2 micron meter collagen fibrilstype .

Originate deep among the odontoblast

ex en owar an an ou n estructureless ground substance

.

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DENTINE

Odontoblast continue to increase in size,produce smaller type I collagen thatorient themselves parallel to future DEJ .

Plasma membrane of odontoblasta acent to exten s stu yprocesses into the forming extracellular

.

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DENTINE

Budds off small matrix vesicles which liesuperficially near the basementmembrane.

Mineral phase first appears within thematrx ves c es as s nge crysta s.

Crystal grow and rupture and fuse with

a acen crys a s o orm a con nuouslayer of mineralized matrix.

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At mantle dentine formation capillariesfound in the subodontoblast layer.

As circumpulpal dentinogenesis is

initiated these capillaries migrateetween t e o onto ast.

After dentinogenesis retreat from the

o on o as .

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MINERALIZATION

Globular Linear.

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Mantle dentine region.Deposition of crystals in several discrete

areas o matrx.

Continued crystal growth, globular

enlarge and eventually fused to form asingle calcified mass.

Size depends upon rate of deposition ofdentine.

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Circumpulpal.When rate of formation ro ress slowl ,

mineralization front appears more

uniform.

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DENTINE

Hertwigs root sheath initiate thedifferentiation of odontoblast that formroot dentine.

Collagen fibers align parallel to basalamna n mante entne.

Degree of mineralization is less.

Rate of deposition is slower.

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DENTINOGENESIS

Demarcation line present betweenprimary and secondary dentine onhistological sections.

Less regular organization of dentinaltu ues or may e a sent.

Crowding or death of odontoblast.