Peridontics : 5/microbial Interaction With The Host In Periodontal Diseases/ First Semester

Front 1

is the precense of the pathogne alone is suffiecnet for the inatiant of a tissue destrctuion ?

Back 1

The presence of periodontal pathogens alone is insufficient to cause the tissue destruction seen in periodontitis

It is the body’s response to the periodontal pathogens that is the cause of nearly all the destruction seen in periodontitis.

Front 2

Bacterial Virulence Factors

Back 2

Virulence factors—mechanisms that enable the bacteria to colonize and invade the tissues of the periodontium

Minor cause of periodontal destruction ( the virualnce factors )

they can be :
1) Characteristics of the bacteria, themselves
2) Products produced by the bacteria

Front 3

1) Characteristics of the bacteria, themselves

Back 3

1)Bacterial invasion factors—allow bacterium to actively penetrate the epithelium lining of the pocket wall and enter the gingival connective tissue

2) Peptides—found in the bacterial cell membrane

3) Exotoxins—harmful proteins (potent toxin) released from the bacterial cell

4) Enzymes—proteins that catalyze chemical reactions that are harmful to the body’s cells

Front 4

what's Coaggregation of the bacteria ?

Back 4

the cell-to-cell adherence of one oral bacterium to another.

Coaggregation is NOT random, each bacterial strain only has a limited set of bacteria to which they are able to adhere

Front 5

GENERAL : list the three Coaggregation of Bacteria

Back 5

•Early
•Intermediate
•Late

Front 6

Early Colonizers

Back 6

•The first bacteria to colonize the tooth surface are nonpathogenic.
•Periodontal pathogens are UNABLE to colonize the biofilm alone.

Early Gram-positive:
•Actinomyces viscosus
Attaches to fimbriae to proline rich proteins on saliva coated tooth surfaces.
•Streptococcus sanguis

Streptococcal Species—Early Colonizers :
•Many streptococcal species have the ability to attach to the tooth pellicle

-Other early colonizers coaggregate with the streptococcal species.

Front 7

The Importance of Early Colonizers

Back 7

Free-floating periodontal pathogens cannot cause disease.

Every time the biofilm is disrupted, the process must start all over again with the early colonizers.

Front 8

Intermediate and Late Colonizers

Back 8

Like the early colonizers, the intermediate and late bacterial colonizers must join the biofilm in the proper sequence.

Many of the periodontal pathogens are late colonizers of the biofilm IMPORTANT . THE ONES THAT CASUES THE DISEASE = LATE

Front 9

Intermediate Coaggregation

Back 9

Bacteria begin to multiply

Gram-negative bacteria join:
•Fusobacterium nucleatum
•Prevotella intermedia

Gram-negative bacteria colonize
• Porphyromonas gingivalis
• Capnocytophaga gingivalis

Front 10

Socransky’s Microbial Complexes

Back 10

slide 24

Front 11

Biochemical Mediators

Back 11

Biochemical mediators are biologically active compounds secreted by the immune cells that activate the body’s inflammatory response.

Released by the immune cells to activate the inflammatory response.

Inflammatory mediators of importance in periodontal disease are
–Cytokines
–Prostaglandins
–Matrix metalloproteinases (MMPs)

Front 12

Cytokines

Back 12

Cell signalling protein molecules

Powerful mediators produced by immune cells

Influence the behavior of other cells

Signal to the immune system to send more phagocytes to site of infection

Produced by many different cells—PMNs, macrophages, B lymphocytes, epithelial cells, gingival fibroblasts, and osteoblasts

Produced in response to tissue injury

Cytokines important in periodontal disease include IL-1, IL-6, IL-8, and TNF-alpha.

Functions of Cytokines :

Recruit cells (PMNs and macrophages) to infection site

Increase vascular permeability that increases movement of immune cells into the tissues

Can initiate tissue destruction and bone loss in chronic infections, such as periodontal disease

Front 13

Prostaglandins

Back 13

Potent inflammatory mediators

Series of prostaglandins—D, E, F, G, H, I

Most cells can produce prostaglandins (arachidonic acid in the cell membrane)

Macrophages and fibroblasts

Functions of Prostaglandins :
Increase permeability and dilatation of blood vessels to promote increased movement of immune cells and complement to the infection site

Trigger osteoclasts—bone-consuming cells—to destroy the alveolar bone

Promote the overproduction of destructive MMP enzymes

Front 14

Prostaglandins of the E series (PGE)

Back 14

initiate most of the alveolar bone destruction in periodontitis.

Front 15

Matrix Metalloproteinases (MMPs)

Back 15

•Family of at least 12 different enzymes
•Produced by various cells of the body—PMNs, macrophages, fibroblasts, JE cells
•Enzymes act together to breakdown connective tissue matrix (collagen,gelatin, elastin)

Function of MMPs in Health :
In health, MMPs facilitate normal turnover of the periodontal connective tissue matrix.

MMPs in chronic Bacterial Infection :
•MMPs are released
•Overproduction of MMPs results in breakdown of connective tissue of the periodontium.

High MMP levels result in extensive collagen destruction in the periodontal tissues

Gingival recession, pocket formation, and tooth mobility.

Front 16

Host Response in Periodontal Disease : Initial

Back 16

•Bacteria colonize the tooth near the gingival margin.
•Bacteria initiate host response.
•PMNs pass from bloodstream into the gingival connective tissue.
•PMNs release cytokines that destroy gingival connective tissue, allowing PMNs to move quickly through the tissue.
•PMNs migrate into the sulcus and phagocytize bacteria.

Front 17

Host Response in Periodontal Disease : Early

Back 17

•Bacteria penetrate into the connective tissue.
•PMNs release cytokines causing more localized destruction of the connective tissue.
•Macrophages release cytokines, PGE2, and MMPs.

Front 18

Host Response in Periodontal Disease :Established

Back 18

•Plaque biofilm extends subgingivally
•Host cells produce more toxic chemicals—cytokines, PGE2, and MMPs.
•Increase in proportions of gram-negative anaerobes.

Front 19

host Response in Periodontal Disease :Advanced

Back 19

•Cytokines destroy the connective tissue and PDL fibers.
•Cytokines, PGE2, and MMPs destroy the connective tissue and bone.
•PGE2 initiates bone destruction.
Specific microorganisms: P.gingivalis, T.forsythus, T.denticola, P.intermedia,
A.a,F.nucleatum, E.corroens,
C. rectus

Front 20

Mechanisms of Alveolar Bone Destruction

Back 20

•Macrophages produce cytokines, PGE2, and MMPs.
•This will stimulate fibroblasts to secrete PGE2 and MMP.
•Destruction of the connective tissue.
•PGE2 stimulates osteoclasts to resorb the alveolar bone.

Front 21

Let us remember that..

Back 21

•For the periodontium to remain healthy, the bacterial infection must be controlled so as not to trigger a chronic, exaggerated host immune response.
•The body’s immune response to the bacteria causes most of the tissue destruction in the periodontal tissues.