2. 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
12/27/2011 DENTAL PAQUE 2
3. 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
12/27/2011 DENTAL PAQUE 3
10. 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.”
12/27/2011 DENTAL PAQUE 10
11. 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
12/27/2011 DENTAL PAQUE 11
12. CHANGING VIEWS OF PLAQUE
Sp pathogens identified for Non sp plaque
many diseases Hypothesis Biofilm
Sp plaque
Search begins for oral Diseases linked
hypothesis
pathogens in plaque to constitutional
Treatment aimed
defects
at
Causative agent
1880 1900 1930 1960 1990 2000
Biofilm
Golden age of Plaque control
microbiology
12/27/2011 DENTAL PAQUE 12
13. Marginal
plaque*
Supra
gingival*
Sub •Tooth associated
gingival* •Tissue associated
12/27/2011 DENTAL PAQUE 13
15. 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.
12/27/2011 DENTAL PAQUE 15
16. Material alba Calculus
12/27/2011 DENTAL PAQUE 16
18. 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.
12/27/2011 DENTAL PAQUE 18
19. Composition –
organic and in - organic
12/27/2011 DENTAL PAQUE 19
20. 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
12/27/2011 DENTAL PAQUE 20
21. INTERCELLULAR MATRIX OF
DENTAL PLAQUE
Organic constituents
Inorganic constituents
Material from Saliva, GCF and bacteria
12/27/2011 DENTAL PAQUE 21
22. 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.
12/27/2011 DENTAL PAQUE 22
23. INORGANIC CONSTITUENTS
Primarily - Calcium & Phosphate
Traces - Sodium, Potassium and Fluoride
Fluoride - From external sources like
is derived tooth paste, mouth washes
12/27/2011 DENTAL PAQUE 23
25. The formation of the
pellicle on the tooth
surface
Initial adhesion and
attachment of bacteria
Colonization and plaque
maturation
12/27/2011 DENTAL PAQUE 25
26. 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.
12/27/2011 DENTAL PAQUE 26
27. 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
12/27/2011 DENTAL PAQUE 27
28. 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*
12/27/2011 DENTAL PAQUE 28
30. 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
12/27/2011 DENTAL PAQUE 30
31. This concept approaches microbial adhesion to
surfaces in aquatic environment as 4 stage
sequence:
Colonization
of surface &
Attachment biofilm
formation
Initial
adhesion
Transport to
surface
12/27/2011 DENTAL PAQUE 31
33. Random contacts occur through:
Brownian motion ( 40 µm/hour)*
Sedimentation of organisms*
Liquid flow
Active bacterial movement (chemotactic activity)*
12/27/2011 DENTAL PAQUE 33
34. 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.
12/27/2011 DENTAL PAQUE 34
35. 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).
12/27/2011 DENTAL PAQUE 35
36. 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.
12/27/2011 DENTAL PAQUE 36
37. 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.
12/27/2011 DENTAL PAQUE 37
39. A firm anchorage between bacterium and
surface will be established by specific
interactions ( ionic, covalent, or hydrogen
bonding)
12/27/2011 DENTAL PAQUE 39
40. 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
12/27/2011 DENTAL PAQUE 40
41. 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
12/27/2011 DENTAL PAQUE 41
42. 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 pro-inflammatory responses.
12/27/2011 DENTAL PAQUE 42
43. 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.
12/27/2011 DENTAL PAQUE 43
44. 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.
12/27/2011 DENTAL PAQUE 44
45. 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.
12/27/2011 DENTAL PAQUE 45
46. •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
12/27/2011 DENTAL PAQUE 46
47. 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
12/27/2011 DENTAL PAQUE 47
48. Bacterium Adhesin Receptor
Streptococcus spp Antigen 1/11 Salivary agglutinin
Streptococcus spp LTA Blood group reactive
proteins
Mutans streptococci Glucan binding protein Glucan
Streptococcus 35 kDA lipoprotein Fibrin, pellicle
parasanguinis
Actinomyces naelslundii Type 1 fimbriae Proline-rich proteins
Porphyromonas 150 kDA protein Fibrinogen
gingivalis
Prevotella loescheii 70 kDA lectin Galactose
Fusobacterium 42 kDA protein Coaggregation with P.
nucleatum gingivalis
Oral microbiology 4th edition, Philip Marsh
12/27/2011 DENTAL PAQUE 48
49. 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
12/27/2011 DENTAL PAQUE 49
50. Primary and secondary colonizers
Co aggregation
Test tube brush
12/27/2011 DENTAL PAQUE 50
51. Co aggregation -
cell to cell recognition of genetically distinct partner
cell types
12/27/2011 DENTAL PAQUE 51
52. 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.
12/27/2011 DENTAL PAQUE 52
56. •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.
12/27/2011 DENTAL PAQUE 56
57. 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.
12/27/2011 DENTAL PAQUE 57
58. 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.
12/27/2011 DENTAL PAQUE 58
59. 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.
12/27/2011 DENTAL PAQUE 59
60. • 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.nucleatum-
S.sanguis
P. loescheii
A.viscous
Capnocytophaga
P.gingivalis
B.forsythus
T.denticola
12/27/2011 DENTAL PAQUE 60
61. 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
12/27/2011 DENTAL PAQUE 61
64. Socransky SS, Haffajee et al, “micro biel complexes in
subgingival plaque” JCP 14: 588, 1987
12/27/2011 DENTAL PAQUE 64
65. Early colonizers: Gram positive Bacteria in Bacteria like p.
use oxygen and species: mature plaque: gingivalis use by
lower the redox •use sugars as an use amino acids products of
potential, which energy sources and small other bacteria
then favours •and saliva as a peptides as •Such as succinate
growth of carbon source energy sources from
anaerobic capnocytophaga
•anaerobic ochraceus
bacteria •asaccharolytic •Protocheme from
•streptococci campylobacter
•actinomyces rectus
12/27/2011 DENTAL PAQUE 65
66. Bacteria degrade
p. Gingivalis Prevotella
host proteins to
uses hemin iron intermedia
release ammonia
from the proportions
which is used by
breakdown of increases with
another baceria
host steroid increase
as a nitrogen
haemoglobin. in host.
source.
12/27/2011 DENTAL PAQUE 66
67. 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
12/27/2011 DENTAL PAQUE 67
68. 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
12/27/2011 DENTAL PAQUE 68
69. 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.
12/27/2011 DENTAL PAQUE 69
70. 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.
12/27/2011 DENTAL PAQUE 70
71. 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.
12/27/2011 DENTAL PAQUE 71
72. 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.
12/27/2011 DENTAL PAQUE 72
73. 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.
12/27/2011 DENTAL PAQUE 73
74. 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.
12/27/2011 DENTAL PAQUE 74
75. 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.
12/27/2011 DENTAL PAQUE 75
76. 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.
12/27/2011 DENTAL PAQUE 76
77. 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.
12/27/2011 DENTAL PAQUE 77
78. Effects on oral microflora
Direct effects Indirect
effects
•Cell mediated immunity wanes •Denture wearing
•Changes in salivary antibodies •Medication
•Hormonal changes •Cancer therapy
•Altered physiology of oral mucosa •Dietary changes
Oral microflora
12/27/2011 DENTAL PAQUE 78
79. 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.
12/27/2011 DENTAL PAQUE 79
82. 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.
12/27/2011 DENTAL PAQUE 82
83. 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.
12/27/2011 DENTAL PAQUE 83
86. • 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.
87. • 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
88. Quorum sensing is involved in the regulation of
genetic competence
mating
bacteriocin production
sporulation
stress responses
virulence expression
biofilm formation
bioluminescence
89. 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.
90. • 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
91. 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.
12/27/2011 DENTAL PAQUE 91
92. 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
12/27/2011 DENTAL PAQUE 92
93. Non Specific Plaque Hypothesis
Specific Plaque Hypothesis
12/27/2011 DENTAL PAQUE 93
94. 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.
12/27/2011 DENTAL PAQUE 94
95. 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.
12/27/2011 DENTAL PAQUE 95
96. 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.
12/27/2011 DENTAL PAQUE 96
97. 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.
12/27/2011 DENTAL PAQUE 97
98. 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.
12/27/2011 DENTAL PAQUE 98
99. 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 resorption-
inducing factor
Animal Studies Disease induced in gnotobiotic rats
12/27/2011 DENTAL PAQUE 99
100. 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
12/27/2011 DENTAL PAQUE 100
101. 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.
12/27/2011 DENTAL PAQUE 101
102. 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 )
12/27/2011 DENTAL PAQUE 102
103. 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.
12/27/2011 DENTAL PAQUE 103
104. 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.
12/27/2011 DENTAL PAQUE 104
105. The sub-gingival flora in patients with generalized aggressive
peri-odontitis 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.
12/27/2011 DENTAL PAQUE 105
106. 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.
12/27/2011 DENTAL PAQUE 106
107. More than 50% of the isolated species were strict
anaerobes with P. gingivalis and F. nucleatum
accounting for 7-8% and 3.4%, respectively.
12/27/2011 DENTAL PAQUE 107
108. 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.
12/27/2011 DENTAL PAQUE 108
109. 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.
12/27/2011 DENTAL PAQUE 109
110. 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)
12/27/2011 DENTAL PAQUE 110
111. 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.
12/27/2011 DENTAL PAQUE 111
112. 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)
12/27/2011 DENTAL PAQUE 112
113. 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).
12/27/2011 DENTAL PAQUE 113
114. Emphasis have been placed on enteric organisms, staphylococcal
species as well as other unusual mouth inhabitants.
Slots et al (1990)
12/27/2011 DENTAL PAQUE 114
115. Contreras & Slots 2000, Kamma et al 2001
12/27/2011 DENTAL PAQUE 115
116. 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.
12/27/2011 DENTAL PAQUE 116
117. 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.
12/27/2011 DENTAL PAQUE 117
118. 3. Picornaviruses are all nonenveloped, single-
stranded 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.
12/27/2011 DENTAL PAQUE 118
119. 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.
12/27/2011 DENTAL PAQUE 119
121. 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.
12/27/2011 DENTAL PAQUE 121
122. 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
12/27/2011 DENTAL PAQUE 122
123. 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.
12/27/2011 DENTAL PAQUE 123
124. 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
12/27/2011 DENTAL PAQUE 124
125. 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
12/27/2011 DENTAL PAQUE 125
126. 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
12/27/2011 DENTAL PAQUE 126
