Endo 02histo Pulp

8/6/2019 Endo 02histo Pulp

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Dental pulp is a soft tissue located in the

centre of tooth.

Pulp is originated from ecto-mesenchymal

cells of dental papilla


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1) Odontoblastic Layer

2) Cell Poor Zone

3) Cell Rich Zone


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a) ODONTOBLASTS

Form as a single layer at periphery of pulp

In coronal part are Numerous and large columnar

shape

In cervical and midroot portion appear fewer and

flattened shapeContains large nucleus which contain upto 4

nucleoli

Nucleus situated at basal end


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Golgi bodies located centrally

Mitochondria ,rough endoplasmic

reticulum, ribosome all distributed

throughout the cell body

Synthesize type I collagen

Secrete sialoproteins, alkalinephosphatase

Control mineralization of dentin

Irritated odontoblast secrets

collagen, amorphous material, large

crystals into lumen which results in

dentin permeability.


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b) HISTOCYTES AND MACROPHAGES:

y Originate from undifferentiated mesenchymal cells

y Appear as large oval or spindle shaped cells

y Involved in elimination of dead cells. Debris, bacteria

and foreign bodies

c) POLYMORPHONUCLEAR LOUKOCYTES:

y Common form is neutrophil

y Major cell type in abscess formation and effective in

destroying and phagocytising bacteria and dead cells


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d) LYMPHOCYTES

Types-

T-lymphocytes,

B- lymphocytes

Appear at site of injury after invasion by neutrophils

There presence indicates presence of persistent

irritation

e) MastcellsCauses vasodialation


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Found in greatest number in pulp

They form the cell rich zone

They are spindle shaped cells

Secrete extracellular components like type-I &

III collagen and ground substance

They never grow, remain undifferentiated state.


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Newly differentiated odontoblast that develop

after an injury to the existing odontoblast


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a) FIBRES

y Predominant collagen fiber in dentin is type-I; where as

type-I and type-III are found within pulp

y Pulpal collagen is present as fibrils

y They form as bundles ,irregularly arranged, except in

periphery where they lie parallel to predentin surface

y Apical portion of pulp contains more collagen fibers

than coronal pulp.


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b) GROUND SUBSTANCE

Its a structureless mass with gel like consistency

forming bulk of pulp.

Components are:

Glycosaminoglycans

Glycoproteins

Water

Functions:

Forms the bulk of pulp

Supports the cells

Acts as a medium of transport of nutrients from

vasculature to cells, and metabolites from cells to

vasculature


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c) CALCIFICATIONSPulp stones


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a) ARTERIOLES (AFFERENT BLOOD VESSELS)

Largest vessels to enter the apical foramen

Once inside the canal , the arterioles travel toward

the crown, and narrow, then branch and lose there

muscle sheath before forming a

capillary bed.

These muscle fibres form precapillary

sphincters which control blood flow

and pressure.


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b) EFFERENT BLOOD VESSELS

These venules constitute the outer side of pulpal

circulation and are slightly larger than arterioles.

They run with the

arterioles and exit

at the apical

foramen.


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80% of nerves of pulp are C-type fibres and rest areA- delta fibres.

a) C- FIBRES

They are unmyelinated and have

diameter of0.3 to 1.2 m

Conduction is slow

They conduct throbbing and achingpain associated with pulp tissue

damage

b) A-DELTA FIBRESThey are myelinated and with diameter of 2 to 5 m

Conduction is faster

Conduct sharp and pricking pain


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LYMPHATICS

They are thin walled vessels at the periphery of pulp

They pass through the pulp to exit as one or two larger

vessels through apical foramen.

The lymphatic vessel is composed of endothelium rich in

organelles and granules. There are discontinuity in the

walls of these vessels. These discontinuities helps in

passage of interstitial tissue fluid and lymphocytes into

the negative pressure lymph vessel.


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Lymphatic's help in removal of inflammatory

exudates, cellular debris.

After exiting from pulp, some vessels join similar

vessels in PDLand drain to regional lymph glands.


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a) Induction:

Induce oral epithelial differentiation into dental

lamina and enamel organ formation .

Induce developing enamel organ to become

particular tooth


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b) Formation ofdentin

Odontoblasts participate in dentin formation by:

Synthesizing and secreting inorganic matrix

Initially transporting inorganic components to newly

formed matrix

By creating an environment that permits

mineralization of matrix.

Also from response to injury like caries, trauma

etc.. called tertiary dentin.


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c) Nutritive

Supplies nutrients for dentin formation and

maintaining integrity of pulp.


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d) Defense

y Odontoblast form dentin in response to injury ,

originally when dentin thickness is lost by caries,

trauma etc.

y Also formed in area where continuity has been lost

by pulp exposure

y Has ability to process and identify toxins by

bacteria , dental caries etc and elicit an immune

response.


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e) Sensation

It transmits sensations mediated throughenamel or dentin

Transmits pain, and senses temperature

differences.


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When there is inflammatory reaction, there is

release of lysosomal enzymes which causes

hydrolysis of collagen and release of kinins which

causes increased vascular permeability. This

escaping fluid accumulates in pulp interstitial

space, but space in pulp is so confined that causes

increase in pulpal pressure. This causes pulpal

necrosis.


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In normal upright position, there is less

pressure effect on structures of head.

On lying down gravitational effect

disappears, there is sudden increase in

pulpal blood pressure, which leads to pain

in lying down.


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Decrease in cellular components

Dentinal sclerosis

Decrease in quality and number of blood

vessels and nervesReduction in size and volume of pulp due to

secondary and reparative dentin formation.

Increase in number and thickness of collagen

fibers.Increase in pulp stones and dystrophic

mineralization.


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REFERENCE:REFERENCE:ENDODONTICSENDODONTICS

PRINCIPLES AND PRACTICE (M. TORABINEJAD)PRINCIPLES AND PRACTICE (M. TORABINEJAD)

44THTHEDITIONEDITION

CHAPTERCHAPTER 1 ;1 ;

Pg:Pg: 11 -- 2020

Endo 02histo Pulp

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