009.dental plaque

Dr Jaffar Raza Syed

Dental plaque

“WHO specific but highly variable structural entity resulting from

colonization and growing microorganisms on surfaces of teeth and consisting

of numerous

microbial species and strains embedded in an extracellular matrix”

“Dental Plaque is an adherent intercellular matrix consisting primarily of

proliferating microorganisms, along with a scattering of epithelial cells,

leukocytes and macrophages.”

Dr Jaffar Raza Syed

Composition of plaque.

A. Microorganisms: 500 distinct species:

• Bacterial

• Non-bacterial

(a) Mycoplasma

(b) Yeasts

(c) Protozoa

(d) Viruses

B. Host cells:

• Epithelial cells

• Macrophages

• Leukocytes

Dr Jaffar Raza Syed

C. Organic compounds:

• Polysaccharides

• Proteins

• Glycoproteins

• Lipid materials

D. Inorganic compounds:

• Calcium

• Phosphorous

• Fluoride

• Sodium

• Potassium

Dr Jaffar Raza Syed

DENTAL PLAQUE AS A BIOFILM

it is the biofilm of complex and dynamic microbial community. It contains

areas of high and low bacterial biomass interlaced with aqueous channels of

different sizes, which are the nutrient channels for bacterial colonization. The

intercellular matrix forms a hydrated gel in which bacteria can survive and

proliferate. Hence, biofilm adheres firmly to the tooth surface and is resistant

to mechanical removal, as well as antibiotics

Dr Jaffar Raza Syed

TYPES OF DENTAL PLAQUE

plaque is differentiated into two categories, supragingival and subgingival

Supragingival plaque Coronal plaque

Marginal plaque

Subgingival plaque Attached plaque

Unattached subgingival plaque

Attached plaque can be tooth, epithelium and/or

connective tissue associated.

Dr Jaffar Raza Syed

Supragingival Plaque

can be detected clinically only after it h

thickness.

Small amounts of plaque can be visuali

using disclosing agents.

The color varies from grey to

only after it has reached a certain

Small amounts of plaque can be visualized by

to yellowish-grey to yellow.

Dr Jaffar Raza Syed

Subgingival Plaque

usually thin,

contained within the gingival sulci or periodontal pocket and thus cannot be

detected by direct observation.

identified only by running the end of a probe around gingival margin

Dr Jaffar Raza Syed

Dr Jaffar Raza Syed

1..Tooth-associated Subgingival Plaque

similar to the supragingival plaque.

The flora is dominated by Gram

bacteria and some/few Gram

This flora is associated with

calculus formation,

root caries and

root resorption.

associated Subgingival Plaque

plaque.

Gram-positive cocci, rods, filamentous

w Gram-negative cocci and rods.

cocci, rods, filamentous

Dr Jaffar Raza Syed

2..Epithelium-associated Subgingival Plaque

loosely adherent because it

interbacterial matrix and is in direct association

with the gingival epithelium, extending from

the gingival margin to the junctional epithelium

This plaque predominantly contains

Gram-negative rods and cocci, flagellated

bacteria and Spirochetes.

associated Subgingival Plaque

because it lacks the

interbacterial matrix and is in direct association

gingival epithelium, extending from

the junctional epithelium.

contains

rods and cocci, flagellated

Dr Jaffar Raza Syed

3..Connective Tissue-associated Plaque

It is usually demonstrated in

Periodontitis (LAP) patients

associated Plaque

It is usually demonstrated in ANUG and localized aggressive

Dr Jaffar Raza Syed

Development Of Dental Plaque

Pellicle is the initial organic structure that forms on the surfaces of the teeth

and artificial prosthesis.

The first stage in pellicle formation involves adsorption of salivary proteins

to apatite surfaces.

The transition from pellicle to dental plaque is extremely rapid.

The first components include mainly cocci, epithelial cells and PMNL.

they form a monolayer within a few hours.

Dr Jaffar Raza Syed

the attached bacteria proliferate and form small colonies of cocci.

With time other types of microorganisms proliferate and form different

microcolonies.

Bacterial Adherence

During initial adherence, interactions occur mainly between specific bacteria

and the pellicle.

Dr Jaffar Raza Syed

1..Bacterial Attachment via Electrostatic Interactions

Oral bacteria bear an overall net negative charge

charged components of the bacterial surface and negatively

charged components of pellicle

such as calcium

Bacterial Attachment via Electrostatic Interactions

overall net negative charge, negatively

charged components of the bacterial surface and negatively

licle become linked by cations

Dr Jaffar Raza Syed

2..Bacterial Attachment via Specific Lectin

Lectins in the bacterial surfaces recognize specific

carbohydrate structure in the pellicle and become linked

Adhesion and attachment occurs between:

• Bacteria and clean tooth surface

• Bacteria and pellicle

• Bacteria and same species

• Bacteria and different species

• Bacteria and matrix.

Bacterial Attachment via Specific Lectin-like Substances

in the bacterial surfaces recognize specific

carbohydrate structure in the pellicle and become linked

occurs between:

• Bacteria and clean tooth surface

• Bacteria and same species

• Bacteria and different species (coaggregation)

Substances

Dr Jaffar Raza Syed

Growth and Accumulation of Bacteria

Once the bacteria is adhered to the pellicle,

Subsequent growth leads to bacterial accumulation

and increased plaque mass.

The initial bacteria that colonize

Are mostly gram-positive facultative microorganisms

such as Actinomyces viscosus

Streptococcus sanguis,

as the plaque matures, secondary colonization

Capnocytophaga, P.gingivalis

Growth and Accumulation of Bacteria

Once the bacteria is adhered to the pellicle,

growth leads to bacterial accumulation

mass.

colonize the pellicle surface

facultative microorganisms

Actinomyces viscosus and

secondary colonization of P.intermedia,

gingivalis takes place.

,

Dr Jaffar Raza Syed

Plaque hypothesis

1..Non-specific plaque hypothesis:

Described by Walter Loesche in 1976.

“Periodontal disease results from the elaboration of noxious products by the

entire plaque flora.”

Shortcomings:

Some individuals with constant amount of plaque and calculus

never developed destructive periodontitis.

Some sites were not affected, whereas advanced disease was

found in adjacent sites.

Dr Jaffar Raza Syed

2..Specific plaque hypothesis:

Described by Walter Loesche in 1976.

“only certain plaque is pathogenic and its pathogenicity depends on the

presence of or increase in specific microorganisms.”

Shortcomings:

There were occasions when either disease was diagnosed in

the absence of the putative pathogens or when pathogens are

present with no evidence of disease.

Dr Jaffar Raza Syed

3..Modern version of specific theory:

Described by Socransky in 1979.

According to this theory, 6-12 bacterial species may be responsible

for the majority of cases of destructive periodontitis and additional

species may be responsible for small number of other cases.

Dr Jaffar Raza Syed

4..Unified theory:

Described by Theilade in 1986.

It is the modern version of non–specific and specific plaque hypothesis.

According to this theory all bacterial plaque may contribute to the pathogenic

potential of the subgingival flora to a greater or lesser extent. This

is due to its ability to colonize and evade host defenses and provoke

inflammation and tissue damage.

Dr Jaffar Raza Syed

5..Ecological plaque hypothesis:

According to this, any change in the nutrient status of a pocket, i.e. physical

and chemical change to the habitat are considered the primary cause for

overgrowth of pathogens.

Dr Jaffar Raza Syed

Different complexes and their significance.

According to Socransky:

Dr Jaffar Raza Syed

Yellow complex:

Streptococcus sp., S. sanguis, S. mitis,

S. intermedius, S. oralis, S. gordonii

Purple complex:

Veillonella parvula and A. odontolyticus

Green complex:

Capnocytophaga sp., A.a

Eikenella corrodens

Dr Jaffar Raza Syed

Orange complex:

Campylobacter gracilus, F. nucleatum,

P. intermedia, P. micros, C. rectus

Red complex:

P. gingivalis, Tannerella forsythia, T. denticola.

Dr Jaffar Raza Syed

Significance:

Early colonizers include members of yellow complexes, purple

complexes and green complexes.

Orange complex members are thought to bridge early colonizers.

Red complex members are associated with bleeding on probing and more

dominant at late stages in plaque development.

Green and orange complexes include species recognized as pathogens in

periodontal and non–periodontal infection.

009.dental plaque

Health & Medicine