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Dental
PLAQUE
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•
•
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Introduction - distinct habitats of oral cavity
Plaque – definition, types.
Structure and Composition of Dental Plaque
Plaque Formation At Ultra structural Level
– Formation of dental pellicle
– Initial adhesion and Attachment
– Colonization
• Supragingival & Subgingival Plaque Formation: Clinical
Aspects
• Physiologic Properties of Dental Plaque
• Plaque As a Bio Film
• Special Bacterial Behavior In Bio films
• Plaque hypothesis – specific and non – specific
• Virulence factors of periodontopathogens
• Future advances in periodontal microbiology
Microbial habitats within the mouth*
• On the basis of physical & morphologic criteria, oral
cavity can be divided in to 5 major ecosystems:
1. Intraoral, supragingival, hard surfaces (teeth,
implants, restorations & prosthesis)
2. Periodontal/periimplant pocket (with its crevicular
fluid, root cementum or implant surface, & the pocket
epithelium)
3. Buccal epithelium, palatal epithelium & epithelium of
floor of mouth.
4. Dorsum of tongue
5. Tonsils
Distribution of Resident Oral Micro
flora
Teeth
•Non shredding surfaces
•Stagnant sites; food
impaction possible
•Influenced by GCF & saliva
•Streptococcus, Actinomyces,
Veillonella, Fusobacteria,
Prevotella, Treponema,
unculturable organisms
Cheeks, Lips, Palate
•Microflora has low
diversity
•Some periodontal
pathogens persist by
invading buccal cells.
•Streptococcus spp.
predominate
Tongue
•Highly papillated surfaces
•Some anaerobic sites.
•Facultative & obligate anaerobes
•Diverse microflora Streptococcus,
Actinomyces, Rothia, Neisseria
Principal Bacterial Genera Found In
Oral Cavity
Gram
negative
Gram
positive
cocci
cocci
rods
rods
Gram Positive
Cocci
Rods
Abiotrophia
Actinobaculum
Enterococcus
Actinomyces
Gemella
Alloscardovia
Preptostreptococcus
Bifidobacterium
Streptococcus
Cornybacterium
Finegoldia
Eubacterium
Granulicatella
Filifactor
Lactobacillus
Propionibacterium
Rothia
solobacterium
Gram Negative
Cocci
Rods
Anaeroglobu
Aggregatibacter
Mega sphaera
Campylobacter
Moraxella
Cantonella
Neisseria
Capnocytophaga
Veillonella
Centipeda
Eikenella
Leptotrichia
Prevotella
Porphyromonas
Tanerella
Treponema
wolinella
Bacterial Composition of Dental
Plaque From Different Sites
Approximal
•Gram positive &
gram negative;
facultative &
obligate anaerobes:
1. Neisseria
2. Streptococcus
3. Prevotella
4. Actinomyces
5. veillonella
Fissure
•Gram positive;
•Facultative
anaerobes
1. Streptococcus
2. Actinomyces
Tooth
Gingival crevice
•Gram positive &
gram negative &
obligate anaerobes:
1. Streptococcus
2. Prevotella
3. Actinomyces
4. Treponema
5. Eubacterium
Dental plaque
Definitions
Definations
• Dental plaque is defined clinically as a
structured, resilient, yellow-grayish substance
that adheres tenaciously to intraoral hard
surfaces, including removable or fixed
restorations.
“Bowen WH: Nature of plaque, Oral science review 1976”
• Dental plaque is a general term for complex
microbial community that develops on the tooth
surface, embedded in a matrix of polymers of
bacterial & salivary origin.
“Philip D Marsh, Michael V Martin, Oral Microbiology, 5th Edition.”
• Dental plaque can be defined as the soft
deposits that form the biofilm adhering to the
tooth surface or other hard surfaces in the oral
cavity, including removable and fixed
restorations.
Carranza 9th edition
CHANGING VIEWS OF PLAQUE
Sp pathogens identified for
many diseases
Search begins for oral pathogens
in plaque
1880
1900
1930
Golden age of
microbiology
Non sp plaque
Hypothesis
Diseases linked to
constitutional
defects
1960
1990
Plaque control
Sp plaque
hypothesis
Treatment aimed at
Causative agent
Biofilm
2000
Biofilm
Classification of dental plaque –
Listgarten (1976) Classified Dental Plaque According to its
Location as
Marginal
plaque*
Supra
gingival*
Sub gingival*
• Tooth associated
• Tissue associated
• Dental plaque must be differentiated from other
tooth deposits, like materia alba and calculus.
• Materia Alba refers to soft accumulations of
bacteria and tissue cells that lack the organized
structure of dental plaque.
• Calculus is hard deposits that form by
mineralization of dental plaque and is generally
covered by a layer of un mineralised plaque.
• Material alba
• Calculus
Carranza 11th edition
• Plaque can be defined as a complex microbial community,
with greater than 1010 bacteria per milligram.
– Socransky SS et al “The micro biota of gingival
crevice area of man” JCP 25:134, 1998
• In addition to the bacterial cells, plaque contains a small
number of epithelial cells, leukocytes, and macrophages.
The cells are contained within an extracellular matrix,
which is formed from bacterial products and saliva.
• The extracellular matrix contains protein, polysaccharide,
lipids and glycoproteins.
Dental plaque
Composition –
organic and in - organic
CHEMICAL COMPOSITION OF DENTAL PLAQUE
 80% water
 20% solids, includes cells mainly bacteria making up 35%
of the dry weight and extracellular components making 65%
of the dry weight.
 Other than bacteria, non bacterial organisms include:
• Mycoplasma
• Yeast
• Protozoa
• Viruses
 Host cells in Dental plaque.
 Epithelial cells
 Macrophages
 Leukocytes
INTERCELLULAR MATRIX OF
DENTAL PLAQUE
Organic constituents
Inorganic constituents
Material from Saliva, GCF and bacteria
ORGANIC CONSTITUENTS
 Poly saccharides
- dextran 95% (adhesion), levan
5%, Sialic acid and fructose
 Proteins
- Albumin
 Glycoproteins
- saliva
 Lipid materials
- Membrane remnants of bacteria
and host cells.
INORGANIC CONSTITUENTS
Primarily
-
Calcium & Phosphate
Traces
-
Sodium, Potassium and Fluoride
Fluoride
is derived
-
From external sources like
tooth paste, mouth washes
Dental plaque
Formation
DEVELOPMENT OF DENTAL PLAQUE
The formation of the
pellicle on the tooth
surface
Initial adhesion and
attachment of bacteria
Colonization and plaque
maturation
Formation of the pellicle
• Within nanoseconds after a vigorously polishing
the teeth, a thin, saliva derived layer called the
acquired pellicle, covers the tooth surface.
• Consists of more than 180 peptides, proteins,
glyco proteins, including keratins, mucins, proline
– rich proteins, and other molecules can function
as adhesion sites( receptors) for bacteria.
ULTRA STRUCTURE OF DENTAL PELLICLE
 Thickness - 30 - 100 nm
 2 hr pellicle: Granular structures which form
globules, that connect to the Hydroxyapatite
surface via stalk like structures.
 24 hrs Later: Globular structures get covered up
by fibrillar particles : 500 - 900 nm thick
 36 hrs Later: The pellicle becomes smooth,
globular
• Studies shows ( 2 hours) enamel pellicle, its
amino acids composition differs from that of
saliva, indicating that the pellicle forms by
selective adsorption* of the environmental
macromolecules.
Scannapieo FA et al , “ saliva and dental
pellicles’” contemporary periodontics, 1990
• Mechanism involved are:
Electrostatic forces *
Van der waals *
Hydrophobic forces*
CHEMICAL COMPOSITION OF ACQUIRED PELLICLE
(Mayhell & Butller 1976, Sonju 1975)




4.6% amino acids
2.7% Hexosamine
14% Total carbohydrates
Lipids - in small amounts
Amino acids in the pellicle
Pellicle contains more hydrophobic and less neutral
amino acids than whole saliva (ie more leucine,
alamine, tyrosine and sereine than saliva)
Hexosamines in the pellicle
Glucosamine - 18%, Galactosamine -18%
Carbohydrates in the pellicle
Glucose
- 20%, Galactose - 27%
Mannose - 9%
Fructose - 18%
Salivary Molecules in the pellicle
Acinar cell families
Mucins
Proline rich proteins - statherins
Cystatins, Amylases
Ductal & stromal products
Lactoferrin & Lysozyme
Initial Adhesion & Attachment of
Bacteria
• This concept approaches microbial adhesion
to surfaces in aquatic environment as 4 stage
sequence:
Attachment
Initial
adhesion
Transport
to surface
Colonization
of surface &
biofilm
formation
Clean
substratum
Molecular
adsorption
(Phase 1)
Single
organisms
(Phase 2)
Multiplication
(Phase 3)
Sequential
adsorption
of organisms
(Phase 4)
Transport to the surface
• Random contacts occur through:
Brownian motion ( 40 µm/hour)*
Sedimentation of organisms*
Liquid flow
Active bacterial movement (chemotactic activity)*
Initial adhesion
• Reversible adhesion of the bacterium and the
surface
• The proteins and carbohydrates that are
exposed on the bacterial cell surface become
important once the bacterial are in loose
contact with the acquired enamel pellicle.
• It results in initial, reversible adhesion of bacteria,
initiated by interactions between bacterium & surface
through long range & short range forces, including Van
der Waals attractive forces & electrostatic repulsive
forces.
• Derjaguin, Landau, Verwey, & Overbeek (DLVO) theory
have been postulated that above a separation distance
of 1nm, the summation of previous two forces
describes total long range interaction, also called as
total Gibbs energy (GTOT).
• The result of (GTOT=GA+GE )summation is function of a
separation distance between negatively charged
particle & a negatively charged surface in a medium
ionic strength suspension medium.
• GTOT for most bacteria consists of secondary minimum
(reversible binding takes place: 5-20 nm from the
surface), a positive maximum (located at <2nm away
from surface), where irreversible adhesion is
established.
• If a particle reaches primary minimum a group of short
range forces dominates adhesive interaction &
determines strength of adhesion.
• Particles in aqueous suspension can acquire charge due
to preferential adsorption of ions from solution of
certain groups attached to pellicle or surface.
• The charge on surface is always exactly balanced by an
equivalent number of counter ions; the size of this
electrical double layer is inversely proportional to ionic
strength of environment.
• As particle approaches surface, it experiences a weak
van der Waals attraction induced by fluctuating
dipoles within the molecules of the two approaching
surfaces. This attraction increases as particles moves
closer to substratum.
• A repulsive force is encountered if the surface continue
to approach each other due to overlap of electrical
double layers.
attachment
Adhesins
Attachment
• A firm anchorage between bacterium and
surface will be established by specific
interactions ( ionic, covalent, or hydrogen
bonding)
Adhesins
• Adhesins can be subdivided into two major
classes:
– Fimbrial adhesins, including fimbriae, pili, curli and
type IV pili,
– Nonfimbrial adhesins, such as autotransporter, outer
membrane and secreted adhesins,
– Those associated with biofilm formation
Periodontology 2000, Vol. 52, 2010, 12–37
Fimbrial adhesins
• Fimbrial adhesins of gram-negative bacteria
are classified into five major classes –
– Chaperone–usher (CU) pili,
– Curli,
– Type IV pili,
– Type III secretion pili and
– Type IV secretion pili – based on their
biosyntheticpathway
Curli
• Curli are thin aggregative fimbriae identified as a
new type of fimbrial adhesin expressed on the
outer surfaces of some Enterobacteriaceae, such
as Escherichia and Salmonella spp.
• Curli promote bacterial adhesion to and invasion
of the host, as well as biofilm formation, and they
also function as a potent promoter of host proinflammatory responses.
Chaperone–usher pili
• Pili (from Latin for hairs) and fimbriae (from
Latin for threads) are thin, filamentous,
proteinaceous surface appendages (hair-like
organelles) that protrude from the surface of
many different bacterial species and are
especially prominent on gram-negative
bacteria where they are anchored within the
outer membrane.
Type IV pili
• Type IV pili are extruded across the outer membrane
and form long and flexible surface appendages
expressed by major human pathogens, such as
–
–
–
–
–
–
–
Neisseria gonorrhoeae,
Neisseria meningitidis,
Pseudomonas aeruginosa,
Vibrio cholerae,
Salmonella enterica,
Legionella pneumophila and
the enteropathogenic E. coli.
• It is quite remarkable that type IV pili assembly can be
reversed and retracted through the bacterial cell wall.
Fimbriae:
• Are proteinaceous hair like appendages
• Composed of protein subunits called fimbrillin
• Fimbriae also carry adhesins
Fimbriae of oral strain are thin, flexible and 2-3nm in
diameter, thus differing from larger more rigid filmbriae
found on other bacteria such as eschericia coli
•Fibrils are also found oral bacterial species
e.g. S. mitis, Prevotella intermedia,
Prevotella nigrescens and S. mutans.
•A naeslundi is one of the most imp colonizing species on tooth
surfaces.
Two major types of fimbriae are present
Type 1:- Are associated with adhesion of A.
naeslundi to salivary acidic rich protein and
to statherin deposited within salivary
pellicle.
Type 2: Are associated with attachment to of
A.naeslundi to glycosidic receptors an
epithelial cells PMNs and oral streptocci
•The lectinase like adhesion to these substrates is inhibited by
galactose and N. acetyl galactosamine
The best characterized fimbriae of the oral G-ve bacteria
are those of P-gingivalis
3 types are present
•
They
are upto 3m long and 5nm wide, the major class of
which is composed of fimbrillin
The fimbrillin polypeptide binds proline rich proteins
statherin, lactoferrin, oral epithelial cells, oral streptococci
Fimbrae of P.g exhibit chaemotactic properties and
demonstrate cytokine induction, both of which are necessary
for P.g to invade epithelial cells
Host Bacterial Interactions Involved In
Adhesion
Bacterium
Adhesin
Receptor
Streptococcus spp
Antigen 1/11
Salivary agglutinin
Streptococcus spp
LTA
Blood group reactive
proteins
Mutans streptococci
Glucan binding protein
Glucan
Streptococcus
parasanguinis
35 kDA lipoprotein
Fibrin, pellicle
Actinomyces naelslundii
Type 1 fimbriae
Proline-rich proteins
Porphyromonas gingivalis
150 kDA protein
Fibrinogen
Prevotella loescheii
70 kDA lectin
Galactose
Fusobacterium nucleatum
42 kDA protein
Coaggregation with P.
gingivalis
Oral microbiology 4th edition, Philip Marsh
Other factors that help in attachment of bacteria
•
Force generating movement is an important first
step in biofilm formation by G-ve bacteria
• Active motility due to the production of flagella or twitching
mobility due to type IV pili are thought to increase the no of
initial interactions between bacterial cells and solid surfaces
and to help overcome initial repulsive forces between bacteria
and the surface.
• Cell surface proteins of staphylococcus epidermidis and
Caulobacter crescentus are imp in initial attachment.
•Polysaccharide adhesion of S. epidermidis
colonization
Primary and secondary colonizers
Co aggregation
Test tube brush
Colonization and plaque maturation
• Co aggregation – cell to cell recognition of genetically distinct
partner cell types
Primary colonizers
• They provide new binding sites for adhesion
by other oral bacteria.
• The metabolic activity of the primary
colonizers modifies the local micro
environment which influences the ability of
other bacteria to survive in the dental plaque
biofilm.
Primary colonizers
Secondary colonizers
• They do not initially colonize the clean tooth
surface but adhere to bacteria already in the
plaque mass.
Secondary colonizers
•Primary colonization by
predominantly Gram-positive facultative
bacteria.
Ss: Streptococcus
sanguis is most dominant.
Av :
Actinomyces spp. are also found in 24h
plaque.
• Gram-positive facultative
cocci and rods co-aggregate and
Multiply.
Surface receptors on the
Gram-positive facultative cocci
and rods allow the subsequent
adherence of Gram-negative
organisms, which have a poor ability
to directly adhere to the pellicle.
Fn: Fusobacterium nucleatum.
BI: Prevotella intermedia.
The heterogeneity increases
as plaque ages and matures.
As a result of ecologic
changes, more Gram-negative
strictly anaerobic bacteria colonize
secondarily and contribute to an
increased pathogenicity of the
biofilm.
Co aggregation

It was described by Gibbsons & Nygaard
• Corncob formation - Streptococci adheres to
filaments of bacterionema matruchotti or
actinomyces species
• Test tube brush – composed of filamentous
bacteria to which gram negative rods adhere.
•
Significance of co aggregation has been highlighted
(Kollenbrander 1989, 1995, 1993) in various in vitro & in vivo
studies.
•
F.nucleatum is central to the mechanism - since this organism can
co aggregate with numerous other species.
•
Examples








F.nucleatumS.sanguis
P. loescheii
A.viscous
Capnocytophaga
P.gingivalis
B.forsythus
T.denticola
18 new genera from oral cavity show co aggregation
-Cell to cell recognition of genetically distinct partner cell
types (Kolen brander PE et al 1993)
-Through the highly specific steriochemical interaction of
protein and carbohydrate molecules located on the bacterial
cell surface.
-Mediated by lectinlike adhesins and can be inhibited by
lactose and other galactosides
-Coaggregation concept opens new perspectives, especially
for the use of probiotics
EA
RL
Y
C
OL
O
N
I
ZE
RS
S.mitis
S.oralis
S.sanguis
CLOSELY ASSOCIATED
V.parvula
COMPLEXES IN THE ORAL
A.odontolyticus
CAVITY
Streptococcus sps
S.gorondi,
S.intermedius
C.rectus
P.intermedia
P.nigrescens
P.micros
F.nucleatum
E.nodatum
P.gingivalis
T.forsythus
T.denticola
C.showae
E.corrodens
Capnocytophaga sps
A.actinomycetocomitans
LATE COLONIZERS
Socransky SS, Haffajee et al, “micro biel complexes in
subgingival plaque” JCP 14: 588, 1987
Physiologic properties of dental plaque
Early colonizers:
use oxygen and
lower the redox
potential, which
then favours
growth of
anaerobic
bacteria
• streptococci
• actinomyces
Gram positive
species:
• use sugars as an
energy sources
• and saliva as a
carbon source
Bacteria in
mature plaque:
use amino acids
and small
peptides as
energy sources
• anaerobic
• asaccharolytic
Bacteria like p.
gingivalis use by
products of
other bacteria
• Such as succinate
from
capnocytophaga
ochraceus
• Protocheme from
campylobacter
rectus
Host – as important source of
nutrients
Bacteria degrade
host proteins to
release ammonia
which is used by
another baceria
as a nitrogen
source.
p. Gingivalis uses
hemin iron from
the breakdown of
host
haemoglobin.
Prevotella
intermedia
proportions
increases with
steroid increase
in host.
Ecological plaque hypothesis
• In 1990, Marsh et al developed the ecologic
plaque hypothesis
• According to this, both the total no. of dental
plaque and the specific microbial composition of
plaque may contribute to the transition from
health to disease.
• A change in the nutrient status of a pocket or
chemical and physical changes to the habitat are
thus considered the primary cause for
overgrowth by pathogens
• New treatment concepts :
– Alter the local environment by reducing the
crevicular flow rate, or
– The site made less anaerobic by the use of redox
agents
De Novo Supragingival Plaque
Formation: Clinical Aspects
• During 1st 24 hrs, starting from a clean tooth
surface, plaque growth is negligible from clinical
view point.
• Following 3 days, plaque growth increases at a
rapid rate, then slows down.
• After 4 days, on average 30% of total tooth crown
area will be covered with plaque. Plaque does not
seem to increase substantially after 4th day.
• There will be a shift towards anaerobic & gram
negative flora, including an influx of Fusobacteria,
filaments, spiral forms & spirochetes.
Topography of supragingival plaque:
• Initial plaque formation takes place along the
gingival margin & from interdental space, later
further extension in coronal direction can be
observed.
• Plaque formation can also start from grooves,
cracks, perikymata, or pits
• Scanning electron microscopy reveals that early
colonization of enamel surface starts from
surface irregularities, where bacteria escape
shear forces allowing time needed to change
from reversible to irreversible binding.
Surface microroughness:
• Rough intraoral surfaces accumulate & retain
more plaque & calculus in terms of thickness,
area & colony forming unit.
• Smoothing intraoral surfaces decreases rate of
plaque formation.
• There seems to be threshold for surface
roughness {Ra 0.2 micrometers}, above which
bacterial adhesion is facilitated.
Variation within dentition:
• Early plaque formation occurs faster.
1. In lower jaw, compared to upper jaw.
2. In molars areas.
3. On buccal tooth surfaces, compared to oral
sites.
4. In interdental regions compared to strict
buccal or oral surface.
Impact of gingival inflammation:
• Plaque formation is more rapid on tooth
surfaces facing inflamed gingival margins, than
those facing healthy gingivae. Studies suggest
that increase in crevicular fluid production
enhances plaque formation, it favors initial
adhesion & colonization of bacteria.
Impact of patient age:
• Subject’s age does not influence de novo
plaque formation.
• Plaque developed in older patients resulted in
more severe gingival inflammation, which
indicates an increased susceptibility to
gingivitis with aging.
De Novo Subgingival Plaque Formation
• Early studies, using culturing techniques
examined changes in subgingival microbiota
during 1st week after mechanical debridement,
partial reduction followed by fast regrowth to
almost pre treatment levels within 7 days.
• This reveals that a high proportion of treated
tooth surfaces still harbored plaque & calculus
after scaling, these remaining bacteria were
considered primary source for subgingival
recolonization.
• Oral implants have been used as model to study
impact of surface roughness on subgingival
plaque formation.
• Bollen CM, et al “ The influence of abutment surface roughness on
plaque accumulation and peri – impalnt mucositis” clin oral
implants res 7: 201;1996
• Smooth abutments were found to harbor 25
times less bacteria than rough ones, with a
slightly higher density for coccoid cells.
• Subgingival microflora was largely dependent on
remaining presence of teeth & degree of
periodontitis in remaining natural teeth.
Ageing & Microflora
• Following tooth eruption the isolation frequency of
spirochetes & black pigmented anaerobes increases.
• Increased prevalence of spirochetes & black pigmented
anaerobes is found in teenagers, this is due to
hormones entering gingival crevice & acting as a novel
nutrient source.
• Rise in P. intermedia in plaque during 2nd trimester of
pregnancy has been ascribed due to elevated levels of
oestradiol & progesterone which supplies
napthoquinone for growth of this microorganism.
Effects on oral microflora
Indirect
effects
Direct effects
•Denture wearing
•Medication
•Cancer therapy
•Dietary changes
•Cell mediated immunity wanes
•Changes in salivary antibodies
•Hormonal changes
•Altered physiology of oral mucosa
Oral microflora
Plaque As a BioFilm
• The term biofilm describes the relatively undefinable
microbial community associated with a tooth surface or any
other hard, non-shedding material (Wilderer & Charaklis
1989)
• Biofilms have an organized structure.
• They are composed of micro colonies of bacterial cells non
randomly distributed in a shaped matrix or glycocalyx.
• In lower plaques layers microbes are bound together in
polysaccharide matrix with other organic & inorganic
materials.
• On top of lower layer, a loose layer appears that is often
irregular in appearance; it can extend into surrounding
medium.
In a pipe
Plaque on the teeth
In a Creek
In a membrane
Bacteria in bio - films
• Resistant of bacteria to antimicrobial agents is
increased in the biofilm.
• Almost 1000 to 1500times more resistant to antibiotics
than in their planktonic stage
• Why increased resistance?????
 Nutrional status
 Growth rate
 Temperature
 pH
 Prior exposure to sub – effective conc. Of antimicrobial
agents.
Bio film
• Certain properties that resists diffusion like;
strongly charged or chemically highly reactive
agents fail to reach the deeper part of bio film
because biofilm acts as an ion- exchange resin,
removing such molecules from solution.
• Recently “super resistant” bacteria were
identified; the cells have multidrug resistant
pumps that can extrude antimicrobial agents
from the cell.
• Genetic expression is different in biofilm
bacteria when compared to planktonic
(free floating) bacteria.
• Biofilm cells can coordinate behavior
via intercellular "communication“ using
biochemical signaling molecules.
• Involves the regulation of expression of
specific genes through the accumulation
of signaling compounds that mediate
intercellular communication
• Dependent on cell density and mediated
through signaling compounds
• Quorum sensing gives biofilms their
distinct properties
Quorum sensing is involved in the regulation of
genetic competence
mating
bacteriocin production
sporulation
stress responses
virulence expression
biofilm formation
bioluminescence
Competence is a physiological state in which bacteria
develop a capacity to take up exogenous DNA (Dubnau,
1991)
It is an elaborate process involving multiple protein
components and sophisticated regulatory networks
It is important to ensure that a DNA pool is available
when the cells become competent.
• In S.mutans ,quorum sensing is mediated
by a competence stimulating peptide
(CSP)
• This peptide also induces genetic
competence so that the transformation
frequency of biofilm grown S.mutans was
10 to 600 fold greater than for
planktonic cells
Principle of Bacterial Transmission,
Translocation OR Cross Infection
• Intraoral transmission of bacteria from one
niche to another is called translocation or
cross infection.
• Christersson et al. demonstrated translocation
of A.a by periodontal probes in patients with
localized aggressive periodontitis.
Translocation & Mechanical
Debridement
• To reduce the chance of intraoral translocation “one
stage mouth disinfection” was introduced by Leuven
group in 1990
• This strategy attempts to eradicate, or at least suppress
periodontal pathogens in a short time not only from
periodontal pocket, but also from their habitats.
• Several studies illustrate benefits of one stage full
mouth disinfection approach in relation to:
1. Gain in attachment
2. Pocket depth reduction
3. Microbiologic shifts
Microbial Specificity of Periodontal
Diseases
Non Specific Plaque Hypothesis
Specific Plaque Hypothesis
Non Specific Plaque Hypothesis
• The nonspecific and specific plaque hypotheses were delineated in
1976 by Walter Loesche
• The nonspecific plaque hypothesis maintains that periodontal
disease results from the "elaboration of noxious products by the
entire plaque flora.
• According to this thinking, when only small amounts of plaque are
present, noxious products are neutralized by the host.
• Similarly, large amounts of plaque would produce large amounts of
noxious products, which would essentially overwhelm the host's
defenses.
• Nonspecific plaque hypothesis is the concept that control of
periodontal disease depends on control of the amount of plaque
accumulation.
• Treatment of periodontitis by debridement (nonsurgical or surgical)
and oral hygiene measures focuses on the removal of plaque and its
products and is founded in the nonspecific plaque hypothesis.
Specific Plaque Hypothesis
• The specific plaque hypothesis states that only
certain plaque is pathogenic, and its
pathogenicity depends on the presence of or
increase in specific microorganisms.
• This concept predicts that plaque harboring
specific bacterial pathogens results in
periodontal disease because these organisms
produce substances that mediate the
destruction of host tissues.
Socransky's criteria for periodontal
pathogens
• ASSOCIATION: A pathogen should be found
more frequently and in higher numbers in
disease states than in healthy states
• ELIMINATION: Elimination of the pathogen
should be accompanied by elimination or
remission of the disease.
•
• HOST RESPONSE: There should be evidence of
a host response to a specific pathogen which
is causing tissue damage.
• VIRULENCE FACTORS: Properties of a putative
pathogen that may function to damage the
host tissues should be demonstrated.
• ANIMAL STUDIES: The ability of a putative
pathogen to function in producing disease
should be demonstrated in an animal model
system.
• The two periodontal pathogens that have most
thoroughly fulfilled Socransky's criteria are
Actinobacillus actinomycetemcomitans in the form of
periodontal disease known as Localized Juvenile
periodontitis (LJP), and Porphyromonas gingivalis in
the form of periodontal disease known as adult
periodontitis.
•
Evidence implicating as a periodontal
pathogen(Adapted from Socransky, 1992)
CRITERION OBSERVATIONS
• Association Elevated in lesions of Juvenile Periodontitis, and
some lesions of Adult Periodontitis
• Elevated in "active" Localized Juvenile Periodontitis (LJP) lesions
• Detected in apical region of periodontal pocket or in tissues of
LJP lesions
• Unusual in health or gingivitis
• Elimination Elimination associated with clinical resolution of
disease
• Species found in recurrent lesions
• Host Response Elevated systemic and local antibody levels in
Juvenile Periodontitis
• Virulence Factors Leukotoxin, collagenase, endotoxin,
epitheliotoxin, fibroblast inhibitory factor, bone resorptioninducing factor
• Animal Studies Disease induced in gnotobiotic rats
Evidence implicating P. gingivalis as a periodontal pathogen
(Adapted from Socransky, 1992)
CRITERION OBSERVATIONS
• Association Microorganism is elevated in periodontitis lesions
Unusual in health or gingivitis
• Elimination Suppression or elimination results in clinical
resolution
• Species found in recurrent lesions
• Host Response Elevated systemic and local antibody in
periodontitis
• Virulence Factors Collagenase, trypsin-like enzyme,
fibrinolysin, immunoglobulin degrading enzymes, other
proteases, phospholipase A, phosphatases, endotoxin,
hydrogen sulfate, ammonia, fatty acids and other factors that
compromise PMN function
• Animal Studies Onset of disease correlated with colonization
in monkey model
• Key role in mixed infections in animal models
PERIODONTAL HEALTH
 102 to 103 bacteria.
 Certain bacterial species have been proposed to be beneficial to the
host, including S. sanguis, Veilonella parvula, and C.
ochraceus(Carranza 10th)
 Bacteria associated with periodontal diseases are often found in the
subgingival microflora at healthy sites, although they are normally
present in small proportions(Rose & Maeley, 6th)
 Nonmotile nature.
GINGIVITIS
 104 to 106 bacteria.
 Gram-negative bacteria.
 Compared with healthy sites, noticeable increase also occur in the
numbers of motile bacteria, including cultivable and uncultivable
treponemas (spirochetes).
 Pregnancy associated gingivitis is accompanied by dramatic
increases in levels of P. intermedia, which uses the steroid as
growth factors(Carranza,10th )
CHRONIC PERIODONTITIS
 C. rectus, P. gingivalis, P. intermedia, F. nucleatum and T. forsythia
were found to be elevated in the active sites(Carranza,10th )
 Sites with chronic periodontitis will be populated with greater
proportions of gram-negative organisms and motile bacteria.
 Certain gram-negative bacteria with pronounced virulence properties
have been strongly implicated as etiologic agents e.g. P. gingivalis and
Tannerella forsythus.
LOCALIZED AGGRESSIVE PERIODONTITIS
 Gram -ve, and anaerobic rods.
 The most numerous isolates are several species from the
genera Eubacterium, A. naeslundii, F. nucleatum, C. rectus,
and Veillonella parvula.
 In some populations, a strong case can be made for Aa
playing a causative role in LAP, especially in cases in which
patients harbor highly leukotoxic strains of the organism.
 However, some populations of patients with LAP do not
harbor Aa, and in still others P. gingivalis may be etiologically
more important.
GENERALIZED AGGRESSIVE
PERIODONTITIS
 The sub-gingival flora in patients with generalized aggressive periodontitis resembles that in other forms of periodontitis.
 The predominant subgingival bacteria in patients with generalized
aggressive periodontitis are P. gingivalis, T. forsythis A.
actinomycetemcomitans, and Campylobacter species.
REFRACTORY CHRONIC
PERIODONTITIS
 Unusually diverse and may contain enteric rods, staphylococci,
and Candida.
 Persistently high levels are found of one or more of P.
gingivalis, T. forsythis, S. inter-medius, P. intermedia,
Peptostreptococcus micros, and Eikenella corrodens.
 Persistence of Streptococcus constellatus has also been
reported.
NECROTIZING ULCERATIVE
GINGIVITIS/PERIODONTITIS
 More than 50% of the isolated species were strict
anaerobes with P. gingivalis and F. nucleatum
accounting for 7-8% and 3.4%, respectively.
PERIODONTAL ABSCESSES
 The bacteria isolated from abscesses are similar to those
associated with chronic and aggressive forms of periodontitis.
 An average of approximately 70% of the cultivable flora in
exudates from periodontal abscesses are gram-negative and
about 50% are anaerobic rods.
 Periodontal abscesses revealed a high prevalence of the
following putative pathogens: F. nucleatum (70.8%), P. micros
(70.6%), P. intermedia (62.5%), P. gingivalis (50.0%), and T.
forsythis (47.1%).
 Enteric bacteria, coagulase-negative staphylococci, and
Candida albicans have also been detected.
PERIIMPLANTITIS
 High proportion of anaerobic gram negative rods, motile
organisms, and spirochetes).
 Species such as Aa, Pg, Tf, P. micros, C. rectus, Fusobacterium,
and Capnocytophaga are often isolated from failing sites.
 Other species such as Pseudomonas aeruginosa,
enterobacteriaceae, Candida albicans and staphylococci, are
also frequently detected around implants.
PEPTOSTREPTOCOCCUS MICROS
 P. micros is a Gram positive, anaerobic, small, asaccharolytic
coccus.
 Two genotypes can be distinguished with the smooth genotype
being more frequently associated with periodontitis lesions
than the rough genotype (Kremer et al. 2000).
 P. micros was found to be in higher numbers at sites of
periodontal destruction as compared with healthy sites
(Papapanou et al 2000, Riggio et al 2001).
 It was shown that P. micros in combination with either P.
intermedia or P. nigrescens could produce transmissible
abscesses (Van Dalen et al 1998).
 Produce protease(Grenier 2006)
SALMONELLAS SPECIES
 The salmonellas spp. are Gram negative, curved, saccharolytic
rods and may be recognized by their curved shape, tumbling
motility and, in good preparations, by the presence of a tuft of
flagella inserted in the concave side.
 Moore et al (1987) described six genetically and
phenotypically distinct groups isolated from oral cavity and
found S. noxia at a higher proportion of shallow sites
(PD>4mm) in chronic periodontitis.
EUBACTERIUM SPECIES
 Suggested as possible periodontal pathogens due to
their increased levels in disease sites. (Moore et al
1985).
 E. nodatum, Eubacterium brachy and Eubacterium
timidum are Gram positive, strictly anaerobic, small
somewhat pleomorphic rods.
 Some of these species elicited elevated antibody
responses in subjects with destructive periodontitis.
(Martin et al 1988)
MILLERI STREPTOCOCCI
 Some of the streptococcal species are
associated with and may contribute to disease
progression.
 Milleri streptococci, Streptococcus anginosus,
S. constellatus and S. intermidius might
contribute to disease progression in subsets of
periodontal patients.
 These species was found to be elevated at
sites which demonstrated recent disease
progression (Dzink et al 1988).
OTHER SPECIES
 Emphasis have been placed on enteric organisms, staphylococcal
species as well as other unusual mouth inhabitants.
 Slots et al (1990)
VIRUSES
Contreras & Slots 2000, Kamma et al 2001
• Viral diseases of the oral mucosa and the
perioral region are often encountered in
dental practice. Viruses are important
ulcerogenic and tumorigenic agents of the
human mouth.
• Four major viral families are associated with the main
viral oral diseases of adults, as follows:
• 1. The group of herpesviruses contains eight different
members that all are enveloped double-stranded DNA
viruses. In the oral cavity, they are related to different
ulcers, tumors, and other oral pathoses.
• 2.Human papillomaviruses are grouped within five
genera and are nonenveloped double-stranded DNA
viruses. In the oral cavity, they are related to ulcers,
tumors, and oral pathoses.
• 3. Picornaviruses are all nonenveloped, singlestranded RNA viruses. In the oral cavity, they
are related to ulcers and different oral
pathoses
• 4. Retroviruses are divided into seven genera
of which two are human pathogens. All
retroviruses are enveloped single-stranded
RNA viruses. In the oral cavity, they are related
to different tumors and oral pathoses.
 Herpesviruses are capable of infecting various types of cells,
including polymorphonuclear leukocytes, macrophages, and
lymphocytes.
 The diffuse invasion of Candida fungi and other opportunistic
organisms into the gingival tissue of AIDS patients has been
demonstrated to be a typical virus-mediated alteration of host
defense mechanisms.
 Shobha Prakash, Sushma Das (2006) concluded that HSV-1 and
EBV are significantly associated with destructive periodontal
disease including chronic and aggressive periodontitis. HSV-1
detected sites in relation to pocket depth and clinical attachment
level were found to be significant indicating that it is associated with
severity and progression of destructive periodontal disease.
FUNGI
 Hannula J, Dogan B, Slots (2001) showed
geographical differences in the subgingival
distribution of C. albicans serotypes and
genotypes and suggested geographic
clustering of C. albicans clones in
Subgingival samples of Chronic
Periodontitis patients.
 Reynaud AH (2001) found a weak
correlation between yeasts in periodontal
pockets.
MIXED INFECTIONS
 At the pathogenic end of the spectrum, it is conceivable
that different relationships exist between pathogens.
 The presence of two pathogens at a site could have no
effect or diminish the potential pathogenicity of one or
other of the species.
 Alternatively, pathogenicity could be enhanced either in
an additive or synergistic fashion.
 It is not clear whether the combinations suggested in the
experimental abscess studies are pertinent to human
periodontal diseases
ARCHAEA
• Single celled organism that are distinct from
the bacteria.
• Methanogenic archaea produce methane gas
from hydrogen gas, carbon dioxide
• Isolated from patients with periodontal
disease by enriching cultures with H2 and
CO2.
1.Dental Plaque: biological significance of a biofilm
and community life style
P.D.Marsh – JCP- 2005
2.Oral biofilms and Calculus – text book of Clinical periodontology
and Implant dentistry Jan Lindhe, Lang and Karring – 5th Edition
3.Periodontal microbial Ecology – Socransky and Haffajee
Periodontology 2000 – Volume 38 – 2005
4.Microbiology of Periodontal diseases: Genetics, Polymicrobial
communities, selected pathogens and treatment.
Haffajee and socransky - Peridontology 2000, Volume 42, 2006
5.Communication among Oral Bacteria
Paul E. Kolenbrander,* Roxanna N. Andersen, David S. Blehert,
G. Egland,Jamie S. Foster, and Robert J. Palmer Jr.
MICROBIOLOGY AND MOLECULAR BIOLOGY REVIEWS, Sept. 2002
6.Interspecies Interactions within Oral Microbial Communities
Howard K. Kuramitsu,1† Xuesong He,2† Renate Lux,2 Maxwell H.
Anderson,3 and Wenyuan Shi2*
MICROBIOLOGY AND MOLECULAR BIOLOGY REVIEWS, Dec. 2007
7.Microbial etiology of periodontitis
Tatsuji Nishihara & Takeyoshi Koseki
Periodontology 2000 Vol-36
8.Periodontal disease at the Biofilm-Gingival interface
Offenbacher et al J.P – Oct 2007
9.Impact of 16S rRNA Gene Sequence Analysis for Identification of
Bacteria on Clinical Microbiology and Infectious Diseases
Jill E. Clarridge III*`
CLINICAL MICROBIOLOGY REVIEWS, Oct. 2004
10.Interspecies interactions within Oral Microbial
Communities
Howard K.Kuramitsu, Xeusong He, Renate Lux, Maxwell H.Anderson
and Wenyuan Shi
Microbiology and Molecular Biology Reviews, Dec. 2007