RATIONALE OF ENDODONTIC RATIONALE OF ENDODONTIC TREATMENTTREATMENT

The aim of the treatment is to remove all The aim of the treatment is to remove all infected hard or soft tissue and to restore the infected hard or soft tissue and to restore the tooth with a bacteria-tight restoration in order to tooth with a bacteria-tight restoration in order to preserve the health of the residual pulp tissue.preserve the health of the residual pulp tissue.

INFLAMMATIONINFLAMMATION

Inflammation is the local physiologic reaction of Inflammation is the local physiologic reaction of the body to noxious stimuli or irritants.the body to noxious stimuli or irritants.

Any irritant, whether of traumatic, chemical or Any irritant, whether of traumatic, chemical or bacterial origin, produces a sequence of basic bacterial origin, produces a sequence of basic physiologic and morphologic reactions in physiologic and morphologic reactions in vascular, lymphatic and connective tissues.vascular, lymphatic and connective tissues.

Objectives of inflammationObjectives of inflammation

Remove or destroy the irritant Remove or destroy the irritant Repair the damage to the tissue.Repair the damage to the tissue.

Injurious agent may cause reversible or Injurious agent may cause reversible or irreversible changes to the tissues.irreversible changes to the tissues.

Irreversible damage leads to tissue necrosis Irreversible damage leads to tissue necrosis whereas reversible damage leads to repair.whereas reversible damage leads to repair.

Inflammatory process resolves when the repair Inflammatory process resolves when the repair has been completed.has been completed.

Symptoms :Symptoms : Pain (due to action of cytotoxic agents released from Pain (due to action of cytotoxic agents released from

humoral, cellular and microbial elements on nerve humoral, cellular and microbial elements on nerve endings).endings).

Swelling (due to infiltration of macromolecules and Swelling (due to infiltration of macromolecules and fluids into the affected tissues).fluids into the affected tissues).

RednessRedness Heat (produced by vasodilatation of vessels and rushing Heat (produced by vasodilatation of vessels and rushing

of blood to affected tissues.of blood to affected tissues. Disturbance of function, resulting from changes in Disturbance of function, resulting from changes in

affected tissues.affected tissues.

Types of inflammation :Types of inflammation : Acute Acute ChronicChronic Predominant cell in acute inflammation is Predominant cell in acute inflammation is

polymorphonuclear neutrophil.polymorphonuclear neutrophil. Predominant cells in chronic inflammation are Predominant cells in chronic inflammation are

lymphocytes, plasma cells, monocytes and lymphocytes, plasma cells, monocytes and macrophages.macrophages.

Polymorphonuclear neutrophilsPolymorphonuclear neutrophils

Contain nucleus with 3 or more interconnected Contain nucleus with 3 or more interconnected lobules and cytoplasm containing lysosomal and lobules and cytoplasm containing lysosomal and specific granules.specific granules.

Functions :-Functions :- Phagocytize bacteriaPhagocytize bacteria Phagocytize and lyse fibrin, cellular debris.Phagocytize and lyse fibrin, cellular debris.

They are the first cells to migrate from vessels.They are the first cells to migrate from vessels. The PMNs, along with the products of cellular The PMNs, along with the products of cellular

lysis and nuclear debris, are the principal lysis and nuclear debris, are the principal constituents of pus.constituents of pus.

MACROPHAGESMACROPHAGES

These cells are derived from circulating These cells are derived from circulating monocytes.monocytes.

Immature monocytes in the extravascular areas, Immature monocytes in the extravascular areas, such as inflammation, differentiate into such as inflammation, differentiate into macrophages.macrophages.

They are mononucleated cells that, in periods of They are mononucleated cells that, in periods of great activity, fuse with other macrophages to great activity, fuse with other macrophages to produce multinucleated giant cell.produce multinucleated giant cell.

FUNCTIONS:FUNCTIONS:

They are phagocytic cells that ingest cellular They are phagocytic cells that ingest cellular debris, microorganisms and particulate matter.debris, microorganisms and particulate matter.

They enhance the immunologic reaction by They enhance the immunologic reaction by ingesting, processing and degrading antigen ingesting, processing and degrading antigen before it is presented to the lymphocytes.before it is presented to the lymphocytes.

There ability to remove debris from the area There ability to remove debris from the area facilitates repair.facilitates repair.

LYMPHOCYTESLYMPHOCYTES

Lymphocytes appear in chronic stage of Lymphocytes appear in chronic stage of inflammatory reaction.inflammatory reaction.

They have a large, spherical, or slightly indented They have a large, spherical, or slightly indented nucleus surrounded by a thin band of cytoplasm nucleus surrounded by a thin band of cytoplasm containing small granules.containing small granules.

Two types of small lymphocytes: B-cells and T-Two types of small lymphocytes: B-cells and T-cells.cells.

T-cellsT-cells T-cells are responsible for cell mediated T-cells are responsible for cell mediated

immunity & for immunosurveillance of the immunity & for immunosurveillance of the human organisms..human organisms..

when T-cells are stimulated by an antigens , when T-cells are stimulated by an antigens , foreign substances , they develop in to t foreign substances , they develop in to t lymphocytes ; they have following lymphocytes ; they have following manifestation……manifestation……

1.1. Memory T-cells : which speeds the Memory T-cells : which speeds the immunologic reaction in subsequent immunologic reaction in subsequent encounters with the same antigen.encounters with the same antigen.

2. Helper or suppressor T-cells : which stimulate 2. Helper or suppressor T-cells : which stimulate or supress the development of effector t or b or supress the development of effector t or b cellscells

3 . Effector T-cells : which may produce cell – 3 . Effector T-cells : which may produce cell – madiated immune reactions , such as delayed madiated immune reactions , such as delayed hypersensitivity.hypersensitivity.

Lymphokines : released by T lymphokinesLymphokines : released by T lymphokines

- activate macrophages , PMNs , non - activate macrophages , PMNs , non sensitised T-cellssensitised T-cells

Interferon : inhibit viral replicationInterferon : inhibit viral replication

B-cellsB-cells Shorter life span than T-cells & lesser in no.Shorter life span than T-cells & lesser in no. When activated by an antigen , B-cells When activated by an antigen , B-cells

becomebecome PLASMABLAST PLASMABLAST which devide to formwhich devide to form

1.plasma cells 2. memory cells..1.plasma cells 2. memory cells..

1. memory cells – 1. memory cells – speed the immunologic speed the immunologic reactions in subsequent encounters with the reactions in subsequent encounters with the same antigens. same antigens.

2. plasma cells - 2. plasma cells - large , oval or round cells with large , oval or round cells with eccentric nuclei containing chromatin in eccentric nuclei containing chromatin in cartwheel form cartwheel form

- produce Ig..- produce Ig..

Ig - types Ig - types

Ig M , Ig G , Ig A , Ig D , Ig EIg M , Ig G , Ig A , Ig D , Ig E

includes various reaction includes…includes various reaction includes…

1.1. Neutralisation of bacterial toxins by antitioxinsNeutralisation of bacterial toxins by antitioxins

2.2. Coating of bacteria by antibodies , or Coating of bacteria by antibodies , or opsonisation , to facilitate phagocytosis..opsonisation , to facilitate phagocytosis..

3.3. Lysis of bacteria by complement activationLysis of bacteria by complement activation

4.4. Agglutination of bacteriaAgglutination of bacteria

5.5. Combining of antibody with viruses to prevent Combining of antibody with viruses to prevent their entry into the cells..their entry into the cells..

eosinophilleosinophill Found during allergic & parasitic reactions..Found during allergic & parasitic reactions.. Involved in phagocytosis of antigen- antibody Involved in phagocytosis of antigen- antibody

complexes…, in detoxification of histamine… complexes…, in detoxification of histamine…

Basophill & mast cellsBasophill & mast cells Found in hemopoitic system & tissueFound in hemopoitic system & tissue Contain granules Contain granules Stimulated by tissue injury or antigen ; Stimulated by tissue injury or antigen ;

degranulate & release chemical mediators such degranulate & release chemical mediators such as histamine , vasodilator , heparin…. as histamine , vasodilator , heparin….

VASCULAR CHANGESVASCULAR CHANGES

1.1. VASODILATIONVASODILATION

2.2. INCREASED CAPILLARY INCREASED CAPILLARY PERMEABILITY, FOLLOWING PERMEABILITY, FOLLOWING INFLAMMATORY CHANGESINFLAMMATORY CHANGES

initially brief VASOCONSTRICTION followed initially brief VASOCONSTRICTION followed by VASODILATATION of arterioles & by VASODILATATION of arterioles & capillary sphincter…..due to capillary sphincter…..due to histaminehistamine released released from mast cellsfrom mast cells

so ,increased blood flow through vessels & so ,increased blood flow through vessels & reduction in vascular reactivity ; opening of reduction in vascular reactivity ; opening of dormant capillary bed that increases the dormant capillary bed that increases the blood supply to the tissues…blood supply to the tissues…

These changes increase intravascular pressure , These changes increase intravascular pressure , blood flowblood flow

HISTAMINE : increase contracting the HISTAMINE : increase contracting the endothelial cells & produce intracellular gap..endothelial cells & produce intracellular gap..

--- filtration of plasma & macromolecules from --- filtration of plasma & macromolecules from venules venules

--- plasma --- plasma less viscous & less protein less viscous & less protein

contain than blood plasmacontain than blood plasma

proteins like albumin ,proteins like albumin ,

fibrinogen, Igs.. fibrinogen, Igs..

chemical mediators & cells ofchemical mediators & cells of

inflammation inflammation

is called as inflammatoryis called as inflammatory

exudate exudate

it dilutes bacterial toxins , so reduce potential it dilutes bacterial toxins , so reduce potential for tissue damage. , helps to form fibrin to contain the for tissue damage. , helps to form fibrin to contain the inflammatory reaction…inflammatory reaction…

HEGMAN FACTOR ( factor xii ) : HEGMAN FACTOR ( factor xii ) :

-- released in infl.. Exudate-- released in infl.. Exudate

-- activate by collagen ; by damaged -- activate by collagen ; by damaged

basement membrane of blood vessels ; or basement membrane of blood vessels ; or

by Ag-Ab complexesby Ag-Ab complexes

-- reacts with prekallikrein of plasma or tissus-- reacts with prekallikrein of plasma or tissus

to produce to produce kinins kinins ( vasodilator )( vasodilator )

-- also activates the fibrinolytic & blood-- also activates the fibrinolytic & blood

coagulating systemcoagulating system

Also PLASMINOGEN in infl. Exudate Also PLASMINOGEN in infl. Exudate activated to plasmin..activated to plasmin..

-- activate complement system-- activate complement system

-- digest fibrin (fibrinogen) & aid in removal-- digest fibrin (fibrinogen) & aid in removal

of blood clotsof blood clots Ig Ig actvate complement & produce actvate complement & produce

anaphylatoxin anaphylatoxin act on mast cells act on mast cells release release histamine..histamine..

Also some chemotactic factor Also some chemotactic factor aid in aid in leucocytosis & lysis of bacteria…leucocytosis & lysis of bacteria…

Inflammatory exudate Inflammatory exudate edema edema increase increase pressure on venules to collapse pressure on venules to collapse reduce reduce venous drainage & blood flow.. venous drainage & blood flow.. stasis of stasis of blood in venules ( due to increase viscosity of blood in venules ( due to increase viscosity of blood) blood) leucocytic migration from center to leucocytic migration from center to periphery periphery adhere to vessel wall called adhere to vessel wall called pavementation of leucocytes pavementation of leucocytes emigration of emigration of leucocytes leucocytes migration to site called chemotaxis.migration to site called chemotaxis.

first PMNs , followed by monocytes & first PMNs , followed by monocytes & lymphocytes..lymphocytes..

Vascular responses continues with aggregation of Vascular responses continues with aggregation of RBC in vessels. RBC in vessels. increase resistance of blood increase resistance of blood to flow to flow decrease in O2 conc. ; increase in CO2 decrease in O2 conc. ; increase in CO2 conc. & iower the pH at infl. Site conc. & iower the pH at infl. Site decrease decrease removal of metabolites..removal of metabolites..

The aforementioned changes may spread The aforementioned changes may spread inflammation to adjacent tissue ; this viscious inflammation to adjacent tissue ; this viscious cycle of inflammation may lead to total necrosis cycle of inflammation may lead to total necrosis of pulp..of pulp..

At inflammatory sites ….At inflammatory sites …. PMNsPMNs Monocytes & lymphocytesMonocytes & lymphocytes MacrophagesMacrophages Plasmacells from b-cellsPlasmacells from b-cells IgsIgs Lymphocyte mediatorsLymphocyte mediators

Recovery of pulpRecovery of pulp

--- arteriovenous anastomoses & U-turn loops --- arteriovenous anastomoses & U-turn loops open in pulpal vasculature to reduce the flow the open in pulpal vasculature to reduce the flow the area of inflammation ; so decrease vascular area of inflammation ; so decrease vascular pressure..pressure..

--- increased tissue pressure plays a role in the --- increased tissue pressure plays a role in the recovery of pulp by allowing return of recovery of pulp by allowing return of macromolecules & fuids to venules..macromolecules & fuids to venules.. return return the vascular pressure & tissu pressure to normal the vascular pressure & tissu pressure to normal & stimulate the repair process..& stimulate the repair process..

Periradicular manifestationsPeriradicular manifestations

Root canal pathway Root canal pathway noxious products of noxious products of tissue necrosis & antigenic agent tissue necrosis & antigenic agent periradicular area periradicular area inflammatory & inflammatory & immunologic responses immunologic responses if more quantity if more quantity bone resorption ( by OAF factor ) & granulation bone resorption ( by OAF factor ) & granulation tissue formatoin tissue formatoin abscss formation abscss formation

Tissue changes following Tissue changes following inflammationinflammation

Either degenerative changes or proliferative Either degenerative changes or proliferative changeschanges

Degenrative changes :-Degenrative changes :- FibrousFibrous ResorptiveResorptive CalcificCalcific Necrosis Necrosis

Suppuration Suppuration Reqiurements for suppuration :-Reqiurements for suppuration :- Necrosis of tissue cellsNecrosis of tissue cells Sufficient number of ploymorphonuclear Sufficient number of ploymorphonuclear

leucocytesleucocytes Digestion of dean material by proteolytic Digestion of dean material by proteolytic

enzymesenzymes

Proliferative changes :-Proliferative changes :-

Produced by irritants mild enough to act as Produced by irritants mild enough to act as stimulants.stimulants.

In the center of inflammatory area, irritant may In the center of inflammatory area, irritant may be strong enough to produce destrcution be strong enough to produce destrcution whereas at the peiphery irritant may be mild whereas at the peiphery irritant may be mild enough to stimulate proliferation.enough to stimulate proliferation.

Endodontic implications:Endodontic implications:

Fish established experimental foci of infection in Fish established experimental foci of infection in the jaws of guinea pigs by drilling openings in the jaws of guinea pigs by drilling openings in the bone and packing in wool fibers saturated the bone and packing in wool fibers saturated with broth culture of microorganisms.with broth culture of microorganisms.

4 well defined zones of reaction found are :-4 well defined zones of reaction found are :- Zone of infection Zone of infection Zone of contaminationZone of contamination Zone of irritationZone of irritation Zone of stimulation Zone of stimulation

Zone of InfectionZone of Infection

Characterized by polymorphonuclear leucocytes.Characterized by polymorphonuclear leucocytes. Infection present in the center of lesion and Infection present in the center of lesion and

microorganisms were found only in that area.microorganisms were found only in that area.

Zone of contaminationZone of contamination

Surrounding the zone of infection.Surrounding the zone of infection. Characterized by round cell infiltration.Characterized by round cell infiltration. Cellular destruction observed in this zone.Cellular destruction observed in this zone. Bone cells die due to toxins released from zone Bone cells die due to toxins released from zone

of infection. Thus, lacunae appear empty.of infection. Thus, lacunae appear empty. Radigraphically seen as initial radiolucency Radigraphically seen as initial radiolucency

around the periapical region of infected tooth.around the periapical region of infected tooth. Prevalence of lymphocytes is seen.Prevalence of lymphocytes is seen.

Zone of IrritationZone of Irritation

Characterized by macrophages and osteoclasts.Characterized by macrophages and osteoclasts. Irritation due to dilution of toxins.Irritation due to dilution of toxins. Distinguished by small, round cells, normal bone Distinguished by small, round cells, normal bone

cells and osteoclasts could just above survive.cells and osteoclasts could just above survive. Collagen framework digested by phagocytes, Collagen framework digested by phagocytes,

macrophages while osteoclasts attack bone macrophages while osteoclasts attack bone tissue.tissue.

Overall histologic picture is one of much activity Overall histologic picture is one of much activity preparatory to repair.preparatory to repair.

Zone of StimulationZone of Stimulation

Characterized by fibroblasts and osteoblasts.Characterized by fibroblasts and osteoblasts. FibroblastFibroblast – laid down collagen fibers – laid down collagen fibers

- which act as - wall of defence around- which act as - wall of defence around

zone of irritationzone of irritation

- as a scaffolding aroud - as a scaffolding aroud

which new bonewhich new bone

formation occures.formation occures. Osteoblast Osteoblast – laid down new bone which is in– laid down new bone which is in

irrregular fashionirrregular fashion

Root canal is site of infection through which Root canal is site of infection through which

- micro organisms (in sufficient quantity)- micro organisms (in sufficient quantity)

- metabolic product of microorganisms- metabolic product of microorganisms

- toxic product of tissue necrosis…….- toxic product of tissue necrosis…….

may be diffused to the periradicular tissue.may be diffused to the periradicular tissue. They are destroyed by PMNs. But when They are destroyed by PMNs. But when

microorganisms are sufficiently virulant or in microorganisms are sufficiently virulant or in enough quantity……. They overwhelm the enough quantity……. They overwhelm the defensive mechanismdefensive mechanism

And they causes periradicular lesions. (abscess) And they causes periradicular lesions. (abscess)

Thus toxins ( pus ) may diluted enough to act Thus toxins ( pus ) may diluted enough to act as stimulant & form granulomaas stimulant & form granuloma

fibroblast form fibrous tissue & fibroblast form fibrous tissue & osteoblast delimit the area with wall of sclerotic osteoblast delimit the area with wall of sclerotic bone…bone…

If in addition, the epithelial rest of malasses If in addition, the epithelial rest of malasses are stimulated , a cyst will form…are stimulated , a cyst will form…

When root canal has been treated , the When root canal has been treated , the reservoir of bacteria or noxious products gets reservoir of bacteria or noxious products gets eliminated ; when the root canal is cleaned eliminated ; when the root canal is cleaned and obturated , the destroyed periapical bone and obturated , the destroyed periapical bone will undergo repair…will undergo repair…

thanks a lot….thanks a lot….