Pathogenesis of periodontal disease - PowerPoint Presentation

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Pathogenesis of periodontal disease

Dr

. Enas Razzoqi

B.D.S., M.Sc., Ph.D

in

Periodontics

Pathogen:

-

is any disease producing microorganism or material.Pathogenesis:

- Is the biologic and histologic events that occur in the tissues during the process of conversion from a healthy state to the diseased state.

Periodontal disease

:-

Periodontal diseases are a heterogeneous group of pathologies affecting the

periodontium. They include the major conditions gingivitis and periodontitis.

Gingivitis:

-

Is the inflammation of the

gingiva

which has many types. (No loss of attachment is associated with this condition

Periodentitis

: -

Is the inflammation of the supporting tissues of the teeth which is characterized by apical migration of

junctional

epithelium with associated loss of

attachment

.

Usually

progressively destructive changes leading to loss of bone and Periodontal ligament. In other word, it is an extension of inflammation from the

gingiva

into the adjacent bone and ligament.

Periodontal disease

Periodentitis

Gingivitis and

periodontitis are caused by bacteria that colonize the gingival crevice and attach to the tooth surfaces.

The pathogenic potential of bacteria within the plaque varies from individual to individual and from gingival site to gingival site.

Small amounts of plaque in a healthy person can be tolerated without causing

P.d.disease

., probably because of the control exerted by

host defense mechanisms

.

When specific bacteria within the plaque increase to significant numbers and produce virulence factors beyond the patient’s control threshold, the balance shifts form health to disease.

Mechanisms of

pathogenicity

:-

The acute phases of certain forms of P.D.

disease can be alleviated by any of a number of antibiotics.

intensive plaque control procedures eradicated clinical gingivitis

withdrawal of such procedures

increase in bacterial

plaque gingivitis.

subjects with destructive periodontal diseases show an elevated serum antibodies against specific

subgingival

organisms.

Evidence for a

pimary

role of bacteria in the etiology of periodontal (

p.d

.) disease:

In general G-

ve, facultative, capnophilic

or anaerobic microorganisms are the principal bacteria associated with P.d.d.

P.GingivalisA.actinomycetem

comitans

Prevotella

intermedia

Fusobacterium

nucleatum

Campylobacter rectus

Treponema

denticola

Eikenella

species

These are some of the most common bacteria associated with disease, because of

their pathogenic capabilities and their increased numbers in disease.

Aggregatibacter

actinomycetemcomitans

(Aa):-

small, non motile, G-

ve

,

saccharolytic

, round- ended rod and forms small, convex colonies.

-presence in higher numbers in lesions of

localized aggressive

periodontitis

(localized juvenile

periodontitis

previously (LJP)).

Soon thereafter, it was demonstrated that the majority of subjects with LAP had an elevated serum antibody response to this species.

The species has been isolated from adult

periodontitis

lesions, but less frequently and in lower numbers than from lesions in LAP subjects.

Suspected periodontal pathogens:

-

Actinobacillus

actinomycetemcomitans

Porphyromonas

gingivalis

(P. gingivalis):-

G-ve anaerobic, non motile,

asaccharolytic

rods that usually exhibit

coccal

to short rod morphologies.

P.gingivalis is a member of much investigated “

black pigmented

bacteroids

”

group. Organisms of this group form brown to black colonies on blood agar plates.

P.gingivalis

has been shown to induce elevated systemic and local immune responses in subjects with various forms of

periodontitis

; this is demonstrated by elevated antibody in serum or saliva of subjects with various forms of

periodontitis

.

Bacteroides

gingivalis

Virulence factors

The periodontopathogen

possess numerous factors that enable them to colonize and invade host tissue and permit them to damage the periodontium directly or to trigger a pathogenic host response indirectly, these factors also referred to

as (virulence factors).

The possible pathogenic mechanisms are

:

Bacteria were first identified by transmission electron microscopy within the gingival tissues and close to resorbing

bone surfaces in

mny

cases of advanced human

periodontitis

.

In 1965

Listgaarten

demonstrated with an electron microscope the invasive nature of spirochetes in acute necrotizing ulcerative gingivitis (ANUG).

In

localized aggressive

periodontitis

,

A.

actinomycetem

comitans

has been identified within the gingival connective tissue;

the presence of this organism within tissues appears to make the disease more resistant to treatment and may necessitate the use of antibiotics or other chemotherapeutic agents in refractory cases.

Bacterial invasion

Exotoxins

A.A.

(

leukotoxin

)

because of its toxic effect on human

polymorphonuclear

neutrophils

(PMNs).

The production of

exotoxins

by some plaque microorganisms has been described.