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Mohammad Muztaba Khan
Department of Pharmacology Bhavdiya
institute sibar Sohawal Ayodhya
Inflammation is defined as the local response of living
tissues to injury due to any agent.
inflammation, a process by which the body's immune
system malfunctions.( failure to function normally.
Eg. diseases, like arthritis, diabetes, myasthenia gravis
The causes of inflammation are many and varied:
Mechanic agents: fractures, foreign corps, sand, etc.
Thermal agents: burns, freezing
Chemical agents: toxic gases, acids, bases
Biological agents: bacteria, viruses, parasites
Circulation disorders: thrombosis, infarction, hemorrhage
Enzymes activation – e.g. acute pancreatitis
Metabolic products – uric acid, urea
CHEMICAL MEDIATORS OF INFLAMMATION
CELSUS in 1st century A.D named the famous 4 cardinal signs
of inflammation as:
To these, 5th sign functio laesa, or loss of function was later
added by VIRCHOW
SIGNS OF INFLAMMATION
Fluid accumulation, plasma protein exudation
Lymphocytes, macrophages, plasma cells as inflammatory
Pathogenesis: Three main processes occur at the site of
inflammation, due to the release of chemical mediators
● Increased blood flow (redness and warmth).
● Increased vascular permeability (swelling,
pain & loss of function).
● Leukocytic Infiltration.
Mechanism of Inflammation
2. Exudation ‐
3. Emigration of
1. HAEMODYNAMIC CHANGES:
1. TRANSIENT VASOCONSTRICTION
2. VASODILATATION (arterioles, venules and capillaries)
obvious within half an hour of injury
Increase blood volume in microvascular bed Redness
3. Elevation of HYDROSTATIC PRESSURE
Results in transudation of fluid in the extracellular space
4. Slowing or stasis
Increased vascular permeability
Increased concentration of RBCs
Raised blood viscosity
Slower blood flow
slowing followed by
LEUCOYTE MIGRATION (neutrophils mainly) to the
Leukocytes then move and migrate
through gaps between the endothelial
cells in the extravascular space.
2. ALTERED VASCULAR PERMEABILITY
In normal circumstances fluid balance is maintained by 2
opposing set of forces:
1.Forces that cause OUTWARD MOVEMENT of fluid from
microcirculation are intravascular hydrostatic pressure and
osmotic pressure of interstitial fluid.
2.Forces that cause INWARD MOVEMENT of interstitial fluid
into circulation are intravascular osmotic pressure and hydrostatic
pressure of interstitial fluid.
• Accumulation of fluid - interstitial compartment
which comes from blood plasma by its escape
through the endothelial wall of peripheral vascular
• Escape of fluid is due to vasodilatation and
consequent elevation in hydrostatic pressure -
• Subsequently, the characteristic inflammatory
oedema, appears by increased vascular
permeability of microcirculation – exudate.
1. Endothelial cell contraction
mediated by histamine, bradykinin, leukotrienes
short duration: 15-30 min.
2. Structural re-organisation of the
cytoskeleton of endothelial cells -
Reversible retraction at the intercellular
• Mediated by cytokines such as
interleukin-1 (IL-1) and tumour
necrosis factor (TNF)-α.c
3. Endothelial injury or Direct injury to endothelial cells
Cell necrosis and appearance of physical gaps.
Process of thrombosis is initiated at the site of damaged
Affects all levels of microvasculature.
immediate sustained response, lasts for
several hours or days
4. Leukocyte-mediated endothelial injury
• Adherence of leucocytes to the endothelium at the site of
• Activation of leucocytes - release proteolytic enzymes and
• Cause endothelial injury and increased vascular
• Newly formed capillaries under the influence of vascular
endothelial growth factor (VEGF).
• Process of repair and in tumours are excessively
5. Neo vascularisation
1. EXUDATION OF LEUCOCYTES
Most important feature of inflammatory response.
The escape of leucocytes from lumen of microvasculature to the
In acute inflammation, polymorphonuclear neutrophils comprise
the first line of defense, followed later by the monocytes and
CHANGES LEADING TO MIGRATION
1. CHANGES IN THE FORMED ELEMENTS OF BLOOD
subsequently, SLOWING of BLOOD STREAM
The central stream of cells widens and peripheral plasma zone
becomes narrower because of loss of plasma by exudation.
The neutrophils of the central column come close to the vessel
2. ROLLING ANDADHESION:
Peripherally marginated and pavemented neutrophils slowly roll
over the endothelial cells lining the vessel wall.
Transient bond between the leucocytes and the endothelial cells
(cytokine-activated Endothelial cells)
(Preformed and stored in endothelial cells)
L-selectin (expressed on surface of Lymphocytes and
Activated during the process of loose and transient adhesions
between the endothelial cells and leucocytes.
IMMUNOGLOBULIN SUPER FAMILYADHESION
Neutrophils move till a suitable site is reached
Subsequently, crosses the basement membrane by damaging it
locally with secreted collagenases and escape out into the
Simultaneously escape of RBCs takes place through the gaps
between the endothelial cells.
Diapedesis gives Hemorrhagic appearance to the inflammatory
The chemotactic factor mediated transmigration of leucocytes
after crossing several barriers to reach the interstitial tissues is
Well illustrated by BOYDEN’S CHAMBER EXPERIMENT.
In this, a millipore filter separates the suspension of leucocytes
from the test solution in tissue culture chamber.
If the test solution contains chemotactic agent, the leucocytes
migrate through the pores of filter towards the chemotactic agent.
It is a prolonged process in which tissue destruction and
inflammation occurs at the same time.
> 48 hours (weeks, months, years)
Mononuclear cells (Macrophages, Lymphocytes, Plasma cells)
Can be caused by 1 of the following 3 ways:
1. Chronic inflammation following acute inflammation
2. Recurrent attacks of acute inflammation
3. Chronic inflammation starting de novo
FEATURES OF CHRONIC INFLAMMATION
Infiltration with mononuclear
cells – macrophages,
lymphocytes & plasma cells
Healing by Proliferation &
connective tissue replacement of
Persistent macrophage accumulationby
following mechanisms :
1. )Recruitment from circulation–
Chemotactic stimuli include:
b) Platelet derived growthfactor
c) Transforming growthfactor
2.) Local proliferation of macrophage
3.) Immobilization of macrophages
Resulting in the formation of granulation tissue
REACTIONS OF PULP TO BACTERIAL INVASION
ᶲ Vascular changes take place
inside blood vessels.
ᶲ PMNLs reach the area of
ANATOMICAL FEATURES OF PULP THAT TEND TO
ALTER THE RESPONSE
Enclosure of pulp in rigid calcified walls - PREVENTS EXCESSIVE
SWELLING.. Thus more painful.
Pressure leads to decrease Blood supply and Ischaemia – does not get
corrected since collateral circulation cannot develop through tiny apical59
HISTOLOGIC FEATURES OF PULPITIS
PREDOMINATE - chiefly
plasma cells &
Fibroblastic activity is
collagen fibres seen in
• Continued vascular
• Accumulation of oedemal
fluid in connective tissue
• Pavementing of PMNLs
along endothelial wall
• Inflammation of periodontal ligament around root apex..
Changes localised around root
apex…..since richly vascular.
Vascular changes , infiltration of
PMNLs , and exudate
Resorption of bone –
1) Robbin’s & Cotron Pathological basis of diseases
2) Essential pathology for dental students - Harsh mohan
3) Text book of oral pathology - Shafers