ORAL MICROFLORA
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com
CONTENTS OF THE SEMINAR
Introduction.
Ecological Terminologies.
Mouth as a habitat for microbial growth.
Factors affec...
Introduction
The mouth is continually exposed to organisms
from the external environment ,beginning with
the passage throu...
In general, these microflora’s live in harmony
with humans and, indeed, all parties benefit from the
association. It has b...
It has been estimated that the human body is
made up of over 1014 cells of which only around 10%
are mammalian. The remain...
ECOLOGICAL TERMINOLOGIES
THE INDIGENOUS (RESIDENT) FLORA
The indigenous flora comprise those indigenous
species that are almost always present in h...
TRANSIENT FLORA
Transient flora comprise organisms "just passing
through" a host. At any given time a particular
species m...
SYMBIOSIS
When both the host and the bacteria benefit from
their inter-relationship it is termed "symbiotic."
ANTIBIOSIS
A...
PATHOGENS
Micro-organisms that have the potential to cause
disease are termed pathogens.
OPPORTUNISTIC PATHOGENS
Micro-org...
AEROBIC
Micro-organisms that require oxygen for growth.
ANAEROBIC
Micro-organisms that require reduced condition for
growt...
MICRO- AEROPHILIC
Micro-organisms that require low concentration of
oxygen for their growth.
FACULTATIVE
Micro-organisms t...
The Mouth As a Habitat For Microbial Growth
Not all of the micro-organisms that enter the mouth
are able to colonize. The ...
Ecological conditions within the mouth will also
vary during the change from the primary to the
permanent dentition. and f...
Transient fluctuations in the stability of the
oral ecosystem may be induced by the frequency
and type of food ingested, v...
Four features that make the oral cavity distinct
from other areas of the body are:
 Teeth
 Specialized mucosal surfaces
...
TEETH
Is the only normally accessible site in the body
that has hard non-shedding surface for microbial
colonization.

The...
Plaque is an example of a biofilm, and, while it
is found naturally in health, it is also associated with
dental caries an...
The ecological complexity of the mouth is
increased still further by the range of habitats
associated with the tooth surfa...
MUCOSAL SURFACES
Although the mouth is similar to other ecosystems in
the digestive tract in having mucosal surfaces for
m...
The papillary structure of the dorsum of the
tongue provides refuge for many micro-organisms
which would otherwise be remo...
The mouth also contains keratinized (e.g. the
palate)

as

well

as

non-keratinized,

stratified

squamous epithelium whi...
Distinct microbial habitats within the mouth
Site

Comments

Lips, cheek, palate Biomass restricted by desquamation;
diffe...
SALIVA
The mouth is kept moist and lubricated by
saliva which flows over all the internal surfaces of
the oral cavity. Sal...
There

are

differences

in

the

chemical

composition of the secretions from each gland, but the
complex mixture is term...
Some of these ions contribute to the buffering
property of saliva which can reduce the cariogenic
effect

of

acids

produ...
The mean pH of saliva is between pH 6.75 and
7.25, although the pH and buffering capacity will vary
with the flow rate. Wi...
Whole Saliva
Constituents
Protein
IgA
IgG
IgM
C3
Amylase

Resting
220
19
1
<1
tr
38

Stimulated GCF
280
7x103
110*
350*
25...
Sodium

15

60

204

Potassium

80

80

70

Calcium

6

6

20

Magnesium

<1

<1

1

Phosphate

17

12

4

Bicarbonate

31...
GINGIVAL CREVICULAR FLUID (GCF)
Serum components can reach the mouth by
the flow of a serum-like fluid through the junctio...
GCF can influence the site by acting as a novel
source of nutrients, while its flow will remove nonadherent microbial cell...
GCF also contains components of the host
defenses which play an important role in regulating
the microflora of the gingiva...
Factors affecting the growth of
micro-organisms in the oral
cavity
Temperature

Redox potential
pH
Nutrients
Adherence and...
TEMPERATURE
The human mouth is kept at a relatively
constant temperature (35-36

C), which provides

◦

conditions suitabl...
Periodontal pockets with active disease have a higher
temperature (up to 390 C) compared with healthy
sites (mean value 36...
A

large

rise

in

temperature

down-regulates

expression of fimbriae (which mediate attachment of
the bacterium to host...
Temperature has been shown to vary between
different sub gingival sites, even within the same
individual, and may influenc...
REDOX POTENTIAL
It is the level of the electrical potential of a site
relative to a standard hydrogen electrode. This
pote...
Tissues or microbes that need a positive Eh for
viability are termed "aerobes," and those that need a
negative Eh are "ana...
The

majority

facultatively anaerobic

of

organisms

are

either

or obligately anaerobic .

Anaerobic species require r...
Some anaerobes can survive at aerobic
habitats by existing in close partnership with oxygen
consuming

species.

Obligate
...
The development of plaque in this way is
associated with a specific succession of microorganisms . Early colonizers will u...
Thus, as the redox potential is gradually
lowered, sites become suitable for the survival and
growth of a changing pattern...
Periodontal pockets are more reduced ( - 48
m V) than healthy gingival crevices in the same
individuals (+ 73 m V). Approx...
Thus, plaque will be suitable for the growth of
bacteria with a range of oxygen tolerances. The
redox potential at various...
Similarly, the redox potential will also affect
bacterial metabolism, e.g. the activity intracellular
glycolytic enzymes a...
pH
Many micro-organisms require a pH around
neutrality for growth, and are sensitive to extremes
of acid or alkali. The pH...
Bacterial population shifts within the plaque
microflora can occur following fluctuations in
environmental pH After sugar ...
Depending on the frequency of sugar intake, the
bacteria in plaque will be exposed to varying
challenges of low pH. Many o...
This can result in the enhanced growth of, or
colonization by, acid-tolerant

species, especially

mutans streptococci and...
In contrast, the pH of the gingival crevice becomes
alkaline during the host inflammatory response in
periodontal disease,...
This degree of change may perturb the balance of
the resident microflora of gingival crevice by
favouring the growth and m...
NUTRIENTS
The association of an organism with a particular
habitat is direct evidence that all of the necessary
growth-req...
ENDOGENOUS NUTRIENTS
The persistence and diversity of the resident oral
microflora is due primarily to the metabolism of t...
In addition, the gingival crevice is supplied with GCF
which, in addition to delivering components of the
host defences, c...
Plaque

bacteria

proteases,

and

produce

glycosidase

interact

synergistically

and
to

breakdown these endogenous nut...
E
X
O
G
E
N
O
U
S

N
U
T
R
I
E
N
T
S
Superimposed upon these endogenous nutrients is
the

complex

array

of

food

stuffs

ingested

periodically in the diet....
sucrose can be converted by bacterial enzymes into
two classes of polymer (glucans and fructans)
which can be used to cons...
The ingestion of milk or milk products can
protect the teeth of animals against caries This
may be due to the buffering ca...
Sugar

substitutes

are

sweet-tasting

compounds that cannot be metabolized to acid by
oral bacteria. Xylitol, for exampl...
ADHERENCE AND AGGLUTINATION
Chewing and the natural flow of saliva (mean rate =
19 ml/h) will detach microorganisms not fi...
Salivary components can aggregate certain bacteria
which facilitates their removal from the mouth by
swallowing.

Bacteria...
The molecules responsible for agglutination
are mucins. Mucins are high molecular weight
glycoprotein's. These Mucins not ...
Dental plaque formation involves an ordered
colonization by a range of bacteria. The early
colonizers interact with, and a...
ANTIMICROBIAL AGENTS AND INHIBITORS
Anti-plaque

agents

are

distinguished

from

antimicrobials on the basis of their mo...
Both types of agent can be delivered from
toothpastes

(dentifrices)

and

mouthwashes.

Antibiotics given systemically or...
Within a few hours of taking prophylactic high
doses of penicillin's, the salivary microflora can be
suppressed permitting...
Host defences
The health of the mouth is dependent on the integrity
of the mucosa (and enamel) which acts as a physical
ba...
HOST GENETICS
Gender

and

race

can

influence

disease

susceptibility, and possibly also affect the microflora.
In an a...
The reasons for this are unknown, but may
reflect some variation in the local immune response.
The microflora of twin chil...
ACQUISITION
ACQUISITION OF THE RESIDENT ORAL
MICROFLORA
The foetus in the womb is normally sterile.
During delivery the baby comes into contact with
the normal microflora of the ...
Despite

the

widespread

possibility

of

contamination, the mouth of the new born baby is
usually sterile. From the firs...
Acquisition

depends

on

the

successive

transmission of micro-organisms to the site of
potential colonization. Initiall...
Mutans streptococci found in children appeared
identical to those of their mothers in 71 % of 34
infant-mother
father

to
...
The first micro-organisms to colonize are termed
pioneer species, and collectively they make up the
pioneer

microbial

co...
In the oral cavity, physical factors include the
shedding of epithelial cells (desquamation), and the
shear forces from ch...
The pioneer micro-organisms are S. salivarius, S.
mitis and S. oralis. With time, the metabolic activity
of the pioneer co...
Eventually a stable situation is reached with a high
species

diversity;

this

is

termed

the

climax

community. A clim...
When the infants were followed longitudinally during
the eruption of the primary dentition, gram-negative
anaerobic bacter...
These findings confirmed that the eruption of
teeth has a significant ecological impact on the oral
environment, and its r...
Studies of the transmission of mutans streptococci
to children have identified a specific 'window of

infectivity' between...
ALLOGENIC AND AUTOGENIC SUCCESSION
The development of a climax community at an
oral site can involve examples of both allo...
For

example,

species

such

as

mutans

streptococci and S. sanguis only appear in the
mouth once teeth have erupted .Th...
AGEING AND THE ORAL
MICROFLORA
Birth
Infancy and early childhood
Adolescence
Adulthood
DECIDUOUS
DENTITION

PERMANENT
DENTITION
HUMAN ORAL FLORA
Gram-positive facultative
cocci

Gram-negative facultative
rods

Staphylococcus
epidermidis
Staph. aureus...
Gram-positive
anaerobic cocci

Gram-positive anaerobic
rods

Peptostreptococcus sp

Actinomyces israelii
A. odonotolyticus...
Gram-negative
anaerobic cocci

Gram-negative anerobic rods

Veillonella alcaescens Bacteroides asaccharolyticus
V. parvula...
Spirochetes

Yeasts

Treponema denticola
T. Microdentium

Candida albicans
Geotrichum sp.

Protozoa

Mycoplasma

Entamoeba...
DISTRIBUTION OF THE RESIDENT
ORAL MICROFLORA
FACTORS AFFECTING THE DISTRIBUTION OF
ORAL MICRO-ORGANISMS
Host receptors
Bacterial adhesins
CELL WALL OF STREPTOCOCCUS
METABOLISM OF ORAL BACTERIA
PLAQUE
DEFENITION
Dental plaque can be defined as the soft deposits
that form the biofilm adhering to the tooth surfaces
or other...
Steps in formation of
plaque
Bacteria attached to Enamel Pellicle
Initial colonization
Biofilm Formation
Colonies of Rods and Filamentous Bacteria
Mature plaque (Corncob Formation)
PLAQUE AS SEEN
WITH NAKED EYES

AFTER STAINING WITH
ERYTHROCINE
MICRO-ORGANISMS FOUND IN
PLAQUE
Predominant microflora of the dental plaque
CLASSIFICATION OF PLAQUE BASED
ON THE SITE
Supra gingival (Smooth surface) plaque.
Sub gingival plaque.
Approximal plaque
...
Gradients in dental Plaque
Microbial homeostasis in dental plaque
Factors involved in break down of microbial
homostasis
Factors involved in microbial interaction in dental
plaque
MICROFLORA IN DISEASE
INFECTIONS OF THE MOUTH
Infection
Dental caries
Periodontal diseases
Surgical infection
a) Dry socke...
INFECTIONS OF THE MOUTH
Infection
Organism
Soft tissue infections
a) Diphtheria
C. Diphtheriae
b) ANUG
Fuso-spirochaetes
c...
INFECTIONS OF THE MOUTH
Infection
Organism
Fungal infections
a) Candidosis
Candida albicans
b) Histoplasmosis
H. Capsulatu...
MICROFLORA IN DISEASE
Interrelationship that leads to dental disease
Dental caries

Property
Acids produced in caries
Bacteria in caries
PLAQUE HYPOTHESIS
PERIODONTAL DISEASE
Hypothesis in periodontal
disease
Mechanism of tissue distruction in periodintal disease
BACTERIA IN GINGIVITIS
GINGIVITIS
BACTERIA IN CHRONIC PERIODONTITIS
PERIODONTITIS
Bacterial invasion
OPPORTUNISTIC INFECTIONS
Virulance factor of candida albicans
Predisposing factors of oral candidosis
Classification of primary oral candidiasis
Principal fungi affecting the oral cavity
REVIEW OF LITTERATURE
Budtz-Jorgensen E, Theilade. E, Theilade J:
Quantitative

relationship

between

yeasts

and

bacteria in denture induced ...
Further he concluded that denture plaque may be
present without clinically demonstrable signs of
stomatitis.
He also state...
Thomas E Rams, Thomas W, Roberts, Helt
tatun & Paul H.Keyer(1984) conducted a
study

on

the

subgingival

microbial

flor...
FRANK R. M. et. aI, Transmission electron
microscopy of plaque accumulations in denture
stomatitis(1985)
They found that i...
R.Holt,M.G.Newman,F.Kratochvil,S.Jeswani,
M.Bugler,S.Khorsandi and

M.Sanz,1986

Implants are subjected to many of the sam...
Michael G, Newman ThomasF, Flemig 1988
The microbiota associated with stable and
failing implants is similar to the microb...
Quirynen M, Listgarten MA, 1990
No
significant changes in the distribution of bacterial
morphotypes could be found between...
Hajishengallis G, Michalek SM.( 1999)
Current status of a mucosal vaccine against dental caries
Research efforts towards d...
Cell-surface fibrillar proteins, which mediate
adherence

to

the

salivary

pellicle,

and,

glycosyltransferase enzymes,...
Ueta E, Tanida T, Yoneda K, Yamamoto T, Osaki T
(2001)
Increase of Candida cell virulence by anticancer drugs
and irradiat...
Correspondingly,

surviving

Candida

cells

after

these

treatments were resistant to nentrophils, with a reduction to
h...
Ling L-J, Hung S-L, Tseng S-C, Chen Y-T, Chi LY, Wu K-M, Lai Y-L. (2001)
Association between betel quid chewing,
periodont...
This

investigation

examined

whether

an

association exists between betel quid chewing and
signs of periodontal disease...
A significantly higher prevalence of bleeding
on probing was found in betel quid chewers
than non-chewers among the subjec...
Vitkov L, Krautgartner WD, Hannig M, Weitgasser R,
Stoiber W (2002)
Candida attachment to oral epithelium.
Inflamed oral m...
Ersin NK, Kocabas EH, Alpoz AR, Uzel A.(2004 )
Transmission of Streptococcus mutans in a group
of Turkish families
.

Eigh...
CONCLUSION
The mouth has a resident microflora with a
characteristic composition that exists, for the most
part, in harmony with the ...
Emphasis has to be given for
maintenance of good oral
hygiene
“PREVENTION IS BETTER THAN CURE”
References –
1.Oral Microbiology 4 th edition
Philip Marsh, Michael V Martin.
2. Oral Microbiology and Immunology
Newman a...
6. Kees Mcyoledjh, Menny J.A Merija, Wila
A.Vas der rcijcles Gerry M.Raghobar, Arjan
Vissis, Boundwijn stegesga “Microbiot...
9. Sreenivas Koka, Michael Razziig, Thomas
J.Bolem, Salam Syed , “ Microbial colonization
of dental implants in partially ...
12. Frank RM et al Transmission electron
microscopy of plaque accumulation in denture
stomatitis. JPD 1985 ; 53: 115-124
THANK YOU
Oral microflora /certified fixed orthodontic courses by Indian dental academy
Oral microflora /certified fixed orthodontic courses by Indian dental academy
Oral microflora /certified fixed orthodontic courses by Indian dental academy
Oral microflora /certified fixed orthodontic courses by Indian dental academy
Oral microflora /certified fixed orthodontic courses by Indian dental academy
Oral microflora /certified fixed orthodontic courses by Indian dental academy
Oral microflora /certified fixed orthodontic courses by Indian dental academy
Oral microflora /certified fixed orthodontic courses by Indian dental academy
Oral microflora /certified fixed orthodontic courses by Indian dental academy
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The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.

Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
0091-9248678078

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Oral microflora /certified fixed orthodontic courses by Indian dental academy

  1. 1. ORAL MICROFLORA INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com
  2. 2. CONTENTS OF THE SEMINAR Introduction. Ecological Terminologies. Mouth as a habitat for microbial growth. Factors affecting the growth of the microorganisms in the oral cavity. Distribution of the resident oral micro flora. Adhesion, acquisition, metabolism. Dental plaque. Microflora in disease. Opportunistic infections. Conclusion.
  3. 3. Introduction The mouth is continually exposed to organisms from the external environment ,beginning with the passage through the birth canal. In time a ecological balance is reached that serves to establish a resident microbial flora that remains fairly stable throughout life.
  4. 4. In general, these microflora’s live in harmony with humans and, indeed, all parties benefit from the association. It has been proposed recently that this harmonious relationship is a result of complex molecular signaling between resident microflora and host cells. members of the
  5. 5. It has been estimated that the human body is made up of over 1014 cells of which only around 10% are mammalian. The remainder are the microorganisms that comprise the resident microflora of the host. This resident microflora does not have merely a passive relationship with its host.
  6. 6. ECOLOGICAL TERMINOLOGIES
  7. 7. THE INDIGENOUS (RESIDENT) FLORA The indigenous flora comprise those indigenous species that are almost always present in high numbers, that is, greater than 1 percent of the total viable count . SUPPLEMENTAL FLORA The supplemental flora are those bacterial species that are nearly always present, but in low numbers, that is, less than 1 percent of the total viable count .
  8. 8. TRANSIENT FLORA Transient flora comprise organisms "just passing through" a host. At any given time a particular species may or may not be represented in the flora. AUTOCHTHONOUS Species found characteristically habitat. in a particular ALLOCHTHONOUS organisms which originate from elsewhere and are generally unable to colonize successfully unless the ecosystem is severely disturbed.
  9. 9. SYMBIOSIS When both the host and the bacteria benefit from their inter-relationship it is termed "symbiotic." ANTIBIOSIS An antibiotic relationship is the opposite of a symbiotic relationship. Instead of helping each other, the bacteria and the host are antagonistic to, each other.
  10. 10. PATHOGENS Micro-organisms that have the potential to cause disease are termed pathogens. OPPORTUNISTIC PATHOGENS Micro-organisms that cause disease only under exceptional circumstances . TRUE PATHOGENS Micro-organisms that are consistently associated with a particular disease .
  11. 11. AEROBIC Micro-organisms that require oxygen for growth. ANAEROBIC Micro-organisms that require reduced condition for growth . CAPNOPHILIC Micro-organisms that require carbon dioxide for growth. HABITAT Site where the micro-organisms grow.
  12. 12. MICRO- AEROPHILIC Micro-organisms that require low concentration of oxygen for their growth. FACULTATIVE Micro-organisms that can grow in the presence or absence of a specific environment E.g. facultative aerobes OBLIGATORY Micro- organisms that require a specific environment for growth. E.g. obligatory anaerobes
  13. 13. The Mouth As a Habitat For Microbial Growth Not all of the micro-organisms that enter the mouth are able to colonize. The properties of the mouth make it ecologically distinct from all other surfaces of the body, and dictate the types of microbe able to persist. Habitats that provide obviously different. ecological conditions include mucosal surfaces (such as the lips, cheek, palate and tongue) and teeth.
  14. 14. Ecological conditions within the mouth will also vary during the change from the primary to the permanent dentition. and following the extraction of teeth, the insertion of prostheses such as dentures, and any dental treatment, including scaling, polishing and fillings.
  15. 15. Transient fluctuations in the stability of the oral ecosystem may be induced by the frequency and type of food ingested, variations in saliva flow and periods of antibiotic therapy.
  16. 16. Four features that make the oral cavity distinct from other areas of the body are:  Teeth  Specialized mucosal surfaces  Saliva  Gingival crevicular fluid (GCF).
  17. 17. TEETH Is the only normally accessible site in the body that has hard non-shedding surface for microbial colonization. These unique tissues allow the accumulation of large masses of micro-organisms (predominantly bacteria) and their extra cellular products, termed dental plaque.
  18. 18. Plaque is an example of a biofilm, and, while it is found naturally in health, it is also associated with dental caries and periodontal disease. In disease, there is a shift in the composition of the plaque microflora away from the species that predominate in health.
  19. 19. The ecological complexity of the mouth is increased still further by the range of habitats associated with the tooth surface. Teeth do not provide a uniform habitat but possess several distinct surfaces, each of which is optimal for colonization and growth by different populations of micro-organisms.
  20. 20. MUCOSAL SURFACES Although the mouth is similar to other ecosystems in the digestive tract in having mucosal surfaces for microbial colonization, the oral cavity does have specialized surfaces which contribute to the diversity of the microflora at certain sites.
  21. 21. The papillary structure of the dorsum of the tongue provides refuge for many micro-organisms which would otherwise be removed by mastication and the flow of saliva. Such sites on the tongue can also have a low redox potential, which enables obligatory anaerobic bacteria to grow. Indeed, the tongue may act as a reservoir for some of the Gramnegative anaerobes.
  22. 22. The mouth also contains keratinized (e.g. the palate) as well as non-keratinized, stratified squamous epithelium which may affect the intra-oral distribution of micro-organisms.
  23. 23. Distinct microbial habitats within the mouth Site Comments Lips, cheek, palate Biomass restricted by desquamation; different surfaces have specialized host cell types. Tongue Highly papillated surface; acts as a reservoir for anaerobes. Teeth Non-shedding surface enabling large masses of microbes to accumulate (e.g. biofilms such as dental plaque). Teeth have distinct surfaces for microbial colonization; each surface (e.g. fissures, smooth surfaces, approximal, gingival crevice) will support a distinct microflora because of their intrinsic biological properties.
  24. 24. SALIVA The mouth is kept moist and lubricated by saliva which flows over all the internal surfaces of the oral cavity. Saliva enters the oral cavity via ducts from the major paired parotid, submandibular and sublingual glands as well as from the minor glands of the oral mucosa (labial, lingual, buccal and palatal glands) where it is produced.
  25. 25. There are differences in the chemical composition of the secretions from each gland, but the complex mixture is termed 'whole saliva'. Saliva contains several ions including sodium, potassium, calcium, chloride, bicarbonate and phosphate .
  26. 26. Some of these ions contribute to the buffering property of saliva which can reduce the cariogenic effect of acids produced from the bacterial metabolism of dietary carbohydrates. Bicarbonate is the major buffering system in saliva but phosphates, peptides and proteins are also involved.
  27. 27. The mean pH of saliva is between pH 6.75 and 7.25, although the pH and buffering capacity will vary with the flow rate. Within a mouth, the flow rate and the concentration of components such as proteins and calcium and phosphate ions have circadian rhythms, with the slowest flow of saliva occurring during sleep.
  28. 28. Whole Saliva Constituents Protein IgA IgG IgM C3 Amylase Resting 220 19 1 <1 tr 38 Stimulated GCF 280 7x103 110* 350* 25* tr 40 - Lysozyme 22 11 + Albumin tr tr +
  29. 29. Sodium 15 60 204 Potassium 80 80 70 Calcium 6 6 20 Magnesium <1 <1 1 Phosphate 17 12 4 Bicarbonate 31 200 -
  30. 30. GINGIVAL CREVICULAR FLUID (GCF) Serum components can reach the mouth by the flow of a serum-like fluid through the junctional epithelium of the gingivae .The flow of GCF is relatively slow at healthy sites, but increases during inflammation.
  31. 31. GCF can influence the site by acting as a novel source of nutrients, while its flow will remove nonadherent microbial cells. Many bacteria from subgingival plaque are proteolytic and interact synergistically to break down the host proteins and glycoprotein's to provide peptides, amino acids and carbohydrates for growth.
  32. 32. GCF also contains components of the host defenses which play an important role in regulating the microflora of the gingival crevice in health and disease. The neutrophils in GCF are viable and can phagocytose bacteria within the crevice.
  33. 33. Factors affecting the growth of micro-organisms in the oral cavity Temperature Redox potential pH Nutrients Adherence and agglutination Anti-microbial agents. Host defence Host genetics
  34. 34. TEMPERATURE The human mouth is kept at a relatively constant temperature (35-36 C), which provides ◦ conditions suitable for the growth and metabolism of a wide range of micro-organisms. Temperature can also affect key parameters associated with the habitat, such as pH, ion activity, aggregation of macro-molecules and gas solubility.
  35. 35. Periodontal pockets with active disease have a higher temperature (up to 390 C) compared with healthy sites (mean value 36.80 C). Such changes in temperature affect gene expression in periodontal pathogens, such as Porphyromonas gingivalis.
  36. 36. A large rise in temperature down-regulates expression of fimbriae (which mediate attachment of the bacterium to host cells) and the major proteases of this micro-organism, and up regulates synthesis of superoxide dismutase, oxygen metabolites. which neutralizes toxic
  37. 37. Temperature has been shown to vary between different sub gingival sites, even within the same individual, and may influence the proportions of certain bacterial species, such as the putative periodontal pathogens P. gingivalis, Bacteroides forsythus' and Campylobacter rectus.
  38. 38. REDOX POTENTIAL It is the level of the electrical potential of a site relative to a standard hydrogen electrode. This potential, called the Eh, is the tendency for a medium or compound to oxidize or reduce an introduced molecule by the removal or addition of electrons..
  39. 39. Tissues or microbes that need a positive Eh for viability are termed "aerobes," and those that need a negative Eh are "anaerobes”. Despite the easy access to the mouth of air with an oxygen concentration of approximately 20%, it is perhaps surprising that the oral microflora comprises few, if any, truly aerobic species
  40. 40. The majority facultatively anaerobic of organisms are either or obligately anaerobic . Anaerobic species require reduced conditions for their normal metabolism; therefore, it is the degree of oxidation-reduction (redox potential, Eh) at a site that governs their survival.
  41. 41. Some anaerobes can survive at aerobic habitats by existing in close partnership with oxygen consuming species. Obligate anaerobes also possess specific molecular defence mechanisms that enable them to cope with low redox potential (highly reduced).
  42. 42. The development of plaque in this way is associated with a specific succession of microorganisms . Early colonizers will utilize O 2 and produce CO2; later colonizers may produce H2 and other reducing agents such as sulphur containing compounds and volatile fermentation products,
  43. 43. Thus, as the redox potential is gradually lowered, sites become suitable for the survival and growth of a changing pattern of organisms, and particularly anaerobes. Differences have been found between the Eh of the gingival crevice in health and disease.
  44. 44. Periodontal pockets are more reduced ( - 48 m V) than healthy gingival crevices in the same individuals (+ 73 m V). Approximal areas (between teeth) will also have a low Eh although values for the redox potential at these sites have not been reported. Gradients of O2 concentration and Eh will exist in the oral cavity, particularly in a thick biofilm such as plaque.
  45. 45. Thus, plaque will be suitable for the growth of bacteria with a range of oxygen tolerances. The redox potential at various depths will be influenced by the metabolism of the organisms present and the ability of gases to diffuse in and out of plaque.
  46. 46. Similarly, the redox potential will also affect bacterial metabolism, e.g. the activity intracellular glycolytic enzymes and the pattern of fermentation products of Streptococcus mutants varies under strictly anaerobic conditions. Thus, modifications to the habitat that disturb such gradients may influence the composition and metabolism of the microbial community.
  47. 47. pH Many micro-organisms require a pH around neutrality for growth, and are sensitive to extremes of acid or alkali. The pH of most surfaces of the mouth is regulated by saliva so that, in general, optimum pH values for microbial growth are provided at sites bathed by this fluid.
  48. 48. Bacterial population shifts within the plaque microflora can occur following fluctuations in environmental pH After sugar consumption, the pH in plaque can fall rapidly to below pH 5.0 by the production of acids (predominantly lactic acid) by bacterial metabolism slowly to base-line values. the pH then recovers
  49. 49. Depending on the frequency of sugar intake, the bacteria in plaque will be exposed to varying challenges of low pH. Many of the predominant plaque bacteria from healthy sites can tolerate only brief conditions of low pH, and are inhibited or killed by more frequent or prolonged exposures to acidic conditions.
  50. 50. This can result in the enhanced growth of, or colonization by, acid-tolerant species, especially mutans streptococci and Lactobacil­lus species, which are normally absent or only minor components in dental plaque at healthy sites. Such a change in the bacterial composition of plaque predisposes a surface to dental caries.
  51. 51. In contrast, the pH of the gingival crevice becomes alkaline during the host inflammatory response in periodontal disease, e.g. following deamination of amino acids and ammonia production. The mean pH may rise to between pH 7.2 and 7.4 during disease, with a few patients having pockets with a mean pH of around 7.8.
  52. 52. This degree of change may perturb the balance of the resident microflora of gingival crevice by favouring the growth and metabolism of periodontal pathogens, such as Porphyromonas gingivalis, that have pH optima for growth above pH 7.5.
  53. 53. NUTRIENTS The association of an organism with a particular habitat is direct evidence that all of the necessary growth-requiring nutrients are present. The mouth can support a microbial community of great diversity and satisfy the requirements of many nutritionally demanding bacterial population.
  54. 54. ENDOGENOUS NUTRIENTS The persistence and diversity of the resident oral microflora is due primarily to the metabolism of the endogenous nutrients provided by the host, rather than by exogenous factors in the diet. The main source of endogenous nutrients saliva, which contains amino acids, peptides, proteins and glycoproteins, vitamins and gases.
  55. 55. In addition, the gingival crevice is supplied with GCF which, in addition to delivering components of the host defences, contains potential sources of novel nutrients, such as albumin and other host proteins and glycoproteins, including haeme containing molecules. The difference in source of endogenous nutrients is one of the reasons for the variation in the microflora of the gingival crevice compared with other oral sites .
  56. 56. Plaque bacteria proteases, and produce glycosidase interact synergistically and to breakdown these endogenous nutrients as no single species has the full enzyme complement to totally metabolize these nutrients.
  57. 57. E X O G E N O U S N U T R I E N T S
  58. 58. Superimposed upon these endogenous nutrients is the complex array of food stuffs ingested periodically in the diet. Fermentable carbohydrates are the main class of compounds that influence markedly the ecology of the mouth. Such carbohydrates can be broken down to acids while, additionally,
  59. 59. sucrose can be converted by bacterial enzymes into two classes of polymer (glucans and fructans) which can be used to consolidate attachment or act as extra cellular nutrient storage compounds, respectively. Dairy products (milk, cheese) have some influence on the ecology of the mouth.
  60. 60. The ingestion of milk or milk products can protect the teeth of animals against caries This may be due to the buffering capacity of milk proteins or due to decarboxylation of amino acids after proteolysis since several bacterial species can metabolize casein.
  61. 61. Sugar substitutes are sweet-tasting compounds that cannot be metabolized to acid by oral bacteria. Xylitol, for example, is inhibitory to Xylitol the growth of S. mutans, and lower levels of this species are found in plaque and saliva of those that frequently consume alternative sweetener. products containing this
  62. 62. ADHERENCE AND AGGLUTINATION Chewing and the natural flow of saliva (mean rate = 19 ml/h) will detach microorganisms not firmly attached to an oral surface. Although saliva contains between 108 and 109 viable micro-organisms per ml, these organisms are all derived from the teeth and mucosa, with plaque and the tongue being the main contributors.
  63. 63. Salivary components can aggregate certain bacteria which facilitates their removal from the mouth by swallowing. Bacteria are unable to maintain themselves in saliva by cell division because they are lost at an even faster rate by swallowing.
  64. 64. The molecules responsible for agglutination are mucins. Mucins are high molecular weight glycoprotein's. These Mucins not only agglutinate oral bacteria, but can also interact with exogenous pathogens such as Staphylococcus aureus and Pseudomonas aeruginosa, as well as viruses (e.g. aeruginosa influenza virus)
  65. 65. Dental plaque formation involves an ordered colonization by a range of bacteria. The early colonizers interact with, and adhere to, saliva coated enamel, while later colonizers bind to already attached species (co-aggregation).
  66. 66. ANTIMICROBIAL AGENTS AND INHIBITORS Anti-plaque agents are distinguished from antimicrobials on the basis of their mode of action. Anti-plaque agents remove already attached cells, or prevent adhesion of new cells to the tooth surface. Unlike antimicrobials which are designed to kill (bactericidal) or inhibit the growth (bacteriostatic) of the bacteria.
  67. 67. Both types of agent can be delivered from toothpastes (dentifrices) and mouthwashes. Antibiotics given systemically or orally for problems at other sites in the body will enter the mouth via saliva or GCF and affect the stability of the oral microflora
  68. 68. Within a few hours of taking prophylactic high doses of penicillin's, the salivary microflora can be suppressed permitting the emergence of antibioticresistant bacteria.
  69. 69. Host defences The health of the mouth is dependent on the integrity of the mucosa (and enamel) which acts as a physical barrier to prevent penetration by micro-organisms or antigens . The host has a number of additional defence mechanisms which play an important role in maintaining the integrity of these oral surfaces.
  70. 70. HOST GENETICS Gender and race can influence disease susceptibility, and possibly also affect the microflora. In an adult periodontitis group, P. gingivalis and Peptostreptococcus anaerobius were associated more with black subjects whereas, Fusobacterium nucleatum was found more commonly in white individuals.
  71. 71. The reasons for this are unknown, but may reflect some variation in the local immune response. The microflora of twin children living together was more similar than that of unrelated children of the same age. Further analysis showed that the micro flora of identical twins was more similar than that of fraternal twins, suggesting some genetic control.
  72. 72. ACQUISITION
  73. 73. ACQUISITION OF THE RESIDENT ORAL MICROFLORA
  74. 74. The foetus in the womb is normally sterile. During delivery the baby comes into contact with the normal microflora of the mother's uterus and vagina, and at birth with the micro-organisms of the atmosphere and of the people in attendance.
  75. 75. Despite the widespread possibility of contamination, the mouth of the new born baby is usually sterile. From the first feeding onwards, however, the mouth is regularly inoculated with micro-organisms and the process of acquisition of the resident oral microflora begins.
  76. 76. Acquisition depends on the successive transmission of micro-organisms to the site of potential colonization. Initially, in the mouth, this is by passive contamination from the mother, from food, milk and water, and from the saliva of individuals in close proximity to the baby. S. salivarius, mutans salivarius streptococci and some other species transmitted from mother to child via saliva. are
  77. 77. Mutans streptococci found in children appeared identical to those of their mothers in 71 % of 34 infant-mother father to pairs examined. No evidence of infant transmission of mutans streptococci was observed, although transmission between spouses may occur with some periodontal pathogens, such as P. gingivalis. gingivalis
  78. 78. The first micro-organisms to colonize are termed pioneer species, and collectively they make up the pioneer microbial community. These pioneer species continue to grow and colonize until environmental resistance is encountered. This can be due to several limiting forces (including physical and chemical factors) which act as barriers to further development.
  79. 79. In the oral cavity, physical factors include the shedding of epithelial cells (desquamation), and the shear forces from chewing and saliva flow. Nutrient requirements, redox potential, pH, and the antibacterial properties of saliva can act as chemical barriers limiting growth. One genus or species is usually predominant during the development of the pioneer community.
  80. 80. The pioneer micro-organisms are S. salivarius, S. mitis and S. oralis. With time, the metabolic activity of the pioneer community modifies the environment providing conditions suitable for colonization by a succession of other populations, by: Changing the local Eh or pH. Modifying or exposing new receptors for attachment. Generating novel nutrients.
  81. 81. Eventually a stable situation is reached with a high species diversity; this is termed the climax community. A climax community reflects a highly dynamic situation and must not be regarded as a static state. The diversity of the pioneer oral community increases during the first few months of life, and several Gram-negative anaerobic species appear .
  82. 82. When the infants were followed longitudinally during the eruption of the primary dentition, gram-negative anaerobic bacteria were isolated more commonly, and a greater diversity of species were recovered from around the gingival margin of the newly erupted teeth (infant mean age = 32 months).
  83. 83. These findings confirmed that the eruption of teeth has a significant ecological impact on the oral environment, and its resident microflora. The acquisition of some bacteria may occur optimally only at certain ages.
  84. 84. Studies of the transmission of mutans streptococci to children have identified a specific 'window of infectivity' between 19 and 31 months (median age = 26 months). This opens up the possibility of targeting preventive strategies over this critical period to reduce the likelihood of subsequent colonization in the infant.
  85. 85. ALLOGENIC AND AUTOGENIC SUCCESSION The development of a climax community at an oral site can involve examples of both allogenic and autogenic succession. In allogenic succession, factors of non microbial origin are responsible for an altered pattern of community development.
  86. 86. For example, species such as mutans streptococci and S. sanguis only appear in the mouth once teeth have erupted .The increase in number and diversity of obligate anaerobes once teeth are present is an example of autogenic succession in which community development is influenced by microbial factors
  87. 87. AGEING AND THE ORAL MICROFLORA Birth Infancy and early childhood Adolescence Adulthood
  88. 88. DECIDUOUS DENTITION PERMANENT DENTITION
  89. 89. HUMAN ORAL FLORA Gram-positive facultative cocci Gram-negative facultative rods Staphylococcus epidermidis Staph. aureus Streptococcus mutans Strep. sanguis Strep. Mitis Strep. Salivarius Strep. Faecalis Beta-hemolytic streptococci Enterobacteriaceae Hemophilus influenzae Eikenella corrodens Actinobacillus Actinomycetemcomitans
  90. 90. Gram-positive anaerobic cocci Gram-positive anaerobic rods Peptostreptococcus sp Actinomyces israelii A. odonotolyticus A. Viscosus Lactobacillus Gram- negitive anaerobic cocci Gram-negative aerobic or facultative cocci Diphtheroids Corynebacterium Eubacterium Neisseria sicca N. Flavescens
  91. 91. Gram-negative anaerobic cocci Gram-negative anerobic rods Veillonella alcaescens Bacteroides asaccharolyticus V. parvula B. Gingivalis B. Fragilis Fusobacterium periodonticum F.nucleatum
  92. 92. Spirochetes Yeasts Treponema denticola T. Microdentium Candida albicans Geotrichum sp. Protozoa Mycoplasma Entamoeba gingivalis Tirchomonas tenax Mycoplasma orale M. pneumoniae
  93. 93. DISTRIBUTION OF THE RESIDENT ORAL MICROFLORA
  94. 94. FACTORS AFFECTING THE DISTRIBUTION OF ORAL MICRO-ORGANISMS Host receptors Bacterial adhesins
  95. 95. CELL WALL OF STREPTOCOCCUS
  96. 96. METABOLISM OF ORAL BACTERIA
  97. 97. PLAQUE
  98. 98. DEFENITION Dental plaque can be defined as the soft deposits that form the biofilm adhering to the tooth surfaces or other hard surfaces in the oral cavity, including removable and fixed prosthesis. The term Biofilm is used to describe communities of micro-organisms attached to a surface.
  99. 99. Steps in formation of plaque
  100. 100. Bacteria attached to Enamel Pellicle
  101. 101. Initial colonization
  102. 102. Biofilm Formation
  103. 103. Colonies of Rods and Filamentous Bacteria
  104. 104. Mature plaque (Corncob Formation)
  105. 105. PLAQUE AS SEEN WITH NAKED EYES AFTER STAINING WITH ERYTHROCINE
  106. 106. MICRO-ORGANISMS FOUND IN PLAQUE
  107. 107. Predominant microflora of the dental plaque
  108. 108. CLASSIFICATION OF PLAQUE BASED ON THE SITE Supra gingival (Smooth surface) plaque. Sub gingival plaque. Approximal plaque Fissure plaque Denture plaque
  109. 109. Gradients in dental Plaque
  110. 110. Microbial homeostasis in dental plaque
  111. 111. Factors involved in break down of microbial homostasis
  112. 112. Factors involved in microbial interaction in dental plaque
  113. 113. MICROFLORA IN DISEASE INFECTIONS OF THE MOUTH Infection Dental caries Periodontal diseases Surgical infection a) Dry socket b) Dental abscess c) Osteomyelitis d) Ludwig’s angina e) Pericoronitis Organism Streptococcus mutans Bacteroides, Actinomyces Actinomyces Oral streptococci Staphylococcus aureus β -haemolytic streptococci Bacteroides
  114. 114. INFECTIONS OF THE MOUTH Infection Organism Soft tissue infections a) Diphtheria C. Diphtheriae b) ANUG Fuso-spirochaetes c) Cancrum oris Fuso-spirochaetes d) Tuberculosis M. Tuberculosis e) Leprosy M. Leprae Viral infections a) Herpetic stomatitis b) Herpes Zoster c) Mumps d) Measles Herpes simplex Varicella-zoster Mumps virus Measles virus
  115. 115. INFECTIONS OF THE MOUTH Infection Organism Fungal infections a) Candidosis Candida albicans b) Histoplasmosis H. Capsulatum c) Sporotrichosis Sporotrichum schenkii Miscellaneous a) Erythema multiforme b) StevensJohnson syndrome
  116. 116. MICROFLORA IN DISEASE Interrelationship that leads to dental disease
  117. 117. Dental caries Property
  118. 118. Acids produced in caries
  119. 119. Bacteria in caries
  120. 120. PLAQUE HYPOTHESIS
  121. 121. PERIODONTAL DISEASE
  122. 122. Hypothesis in periodontal disease
  123. 123. Mechanism of tissue distruction in periodintal disease
  124. 124. BACTERIA IN GINGIVITIS
  125. 125. GINGIVITIS
  126. 126. BACTERIA IN CHRONIC PERIODONTITIS
  127. 127. PERIODONTITIS
  128. 128. Bacterial invasion
  129. 129. OPPORTUNISTIC INFECTIONS
  130. 130. Virulance factor of candida albicans
  131. 131. Predisposing factors of oral candidosis
  132. 132. Classification of primary oral candidiasis
  133. 133. Principal fungi affecting the oral cavity
  134. 134. REVIEW OF LITTERATURE
  135. 135. Budtz-Jorgensen E, Theilade. E, Theilade J: Quantitative relationship between yeasts and bacteria in denture induced stomatitis. (1983) They conducted an electron microscope study on denture plaque. A smear was prepared from denture scraping and examined by light microscope. Most organisms were gram negative cocci or rods, Some filaments were also seen. In one subject only yeast were seen. The acquired deposits was not seen to invaginate the denture base.
  136. 136. Further he concluded that denture plaque may be present without clinically demonstrable signs of stomatitis. He also stated that the presence of denture plaque constitutes the principal cause leading to the inflammation of the palatal mucosa.
  137. 137. Thomas E Rams, Thomas W, Roberts, Helt tatun & Paul H.Keyer(1984) conducted a study on the subgingival microbial flora associated with human dental implants. They concluded that the microorganisms around protruding dental implants are similar to the bacterial population around natural teeth.
  138. 138. FRANK R. M. et. aI, Transmission electron microscopy of plaque accumulations in denture stomatitis(1985) They found that in general the ultrastructure of denture plaque in patients with denture stomatitis, was quite different from that of dental plaque with respect to the pellicle and plaque matrix, as well as the distribution and nature of the organisms present.
  139. 139. R.Holt,M.G.Newman,F.Kratochvil,S.Jeswani, M.Bugler,S.Khorsandi and M.Sanz,1986 Implants are subjected to many of the same bacterial etiologic factors as natural teeth and their placement and maintenance should be subject to same standard treatment as natural teeth. of periodontal
  140. 140. Michael G, Newman ThomasF, Flemig 1988 The microbiota associated with stable and failing implants is similar to the microbiota of periodontally respectively healthy and diseased teeth
  141. 141. Quirynen M, Listgarten MA, 1990 No significant changes in the distribution of bacterial morphotypes could be found between implants and natural teeth. Srinivas Koka, Michael E.Razzog,Thomas J.Blocess, Salam Syed (1993) Conducted a study on the microbial colonization of dental implants in partially edentulous subjects. They concluded that Branemark dental implants placed in partially edentulous patients may be colonized by disease associated bacteria within 14 days of second stage surgery.
  142. 142. Hajishengallis G, Michalek SM.( 1999) Current status of a mucosal vaccine against dental caries Research efforts towards developing an effective and safe caries vaccine have been facilitated by progress in molecular biology, with the cloning and functional characterization of virulence factors from mutans streptococci, the principal causative agent of dental caries, and advancements in mucosal immunology, including the development of sophisticated antigen delivery systems and adjuvants that stimulate the induction of salivary immunoglobulin A antibody responses. 151
  143. 143. Cell-surface fibrillar proteins, which mediate adherence to the salivary pellicle, and, glycosyltransferase enzymes, which synthesize adhesive glucans accumulation, are and virulence allow microbial components of mutans streptococci, and primary canidates for a human caries vaccine 152
  144. 144. Ueta E, Tanida T, Yoneda K, Yamamoto T, Osaki T (2001) Increase of Candida cell virulence by anticancer drugs and irradiation. The influence of anticancer drugs and irradiation on Candida cell proliferation, adherence to HeLa cells and susceptibility to antifungal drugs (amphotericin B IIld miconazole) and neutrophils were examined using two Candida albicans. 153
  145. 145. Correspondingly, surviving Candida cells after these treatments were resistant to nentrophils, with a reduction to half of the killing. These results indicate that anti-cancer drugs and irradiation potentiate the virulence of Candida cells, or eliminate Candida cells with low virulence, thereby enhancing the risk of oral and systemic candidiasis. 154
  146. 146. Ling L-J, Hung S-L, Tseng S-C, Chen Y-T, Chi LY, Wu K-M, Lai Y-L. (2001) Association between betel quid chewing, periodontal status and periodontal pathogens. This investigation examined whether an association exists between betel quid chewing and signs of periodontal disease and determined the prevalence of Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis by polymerase chain reaction . 155
  147. 147. This investigation examined whether an association exists between betel quid chewing and signs of periodontal disease and determined the prevalence of actinomycetemcomitans Actinobacillus and Porphyromonas gingivalis by polymerase chain reaction . The periodontal status of 34 betel quid chewers and 32 non-betel quid chewers were compared. 156
  148. 148. A significantly higher prevalence of bleeding on probing was found in betel quid chewers than non-chewers among the subjects with higher plaque level, greater gingival inflammation, deeper probing depth or greater attachment loss. Also, the results suggested that betel quid chewers may harbor higher levels of infection with A. actinomycetemcomitans and P.gingivalis than non-betel quid chewers. 157
  149. 149. Vitkov L, Krautgartner WD, Hannig M, Weitgasser R, Stoiber W (2002) Candida attachment to oral epithelium. Inflamed oral mucosa biopsies from patients with thrush and high candidal density were observed in a transmission electron microscope (TEM) using ultrahistochemical staining with ruthenium red for glycocalyx visualization. Candida adhesion itself is assumed to induce mucosal inflammation 158
  150. 150. Ersin NK, Kocabas EH, Alpoz AR, Uzel A.(2004 ) Transmission of Streptococcus mutans in a group of Turkish families . Eight mothers who had high S. mutans levels in unstimulated saliva and 8 children aged between 2 and 3 years participated in the study. Plaque samples from each child were collected with the tips of sterile toothpicks for S. mutans counts. Although not part of the original study design, S. mutans samples were also obtained from the unstimulated saliva of the three fathers who shared the same households. .The mothers or the fathers could be the source for the transmission of S. mutans to their children. 159
  151. 151. CONCLUSION
  152. 152. The mouth has a resident microflora with a characteristic composition that exists, for the most part, in harmony with the host. This microflora is of benefit to the host and contributes to the normal development of the physiology and host defences. Components of this microflora can act as opportunistic pathogens when the habitat is disturbed or when micro-organisms are found at sites not normally accessible to them. Dental diseases, caused by imbalances in the resident microflora, are highly prevalent and extremely costly to treat.
  153. 153. Emphasis has to be given for maintenance of good oral hygiene “PREVENTION IS BETTER THAN CURE”
  154. 154. References – 1.Oral Microbiology 4 th edition Philip Marsh, Michael V Martin. 2. Oral Microbiology and Immunology Newman and Nisengard . 3. Microbiology for Dental students 3 rd edition T H Melville and C Russell. 4. Basic Medical Microbiology Robert F Boyd and Brian G . 5. Oral Microbiology and Infectious disease.3 rd ed Schuster
  155. 155. 6. Kees Mcyoledjh, Menny J.A Merija, Wila A.Vas der rcijcles Gerry M.Raghobar, Arjan Vissis, Boundwijn stegesga “Microbiota around root-forms endosseous implants’ a review of the literature Int. J.Oral Maxillofacial implants 2002; 17:829-838 . 7. Mombelli A, Buser, D Lang N.P ”Colonization of osseointgrated titanium implants in edentulous patients early results” Oral Microbiology & Immunology 1988; 3-113-120 8. Quirjnen M listgarters M.A” the distribution of bacterial morphotoypes around natural teeth and titanium implants ad modum branemark”. Clinical oral Implants Research 1990; 1:8-12.
  156. 156. 9. Sreenivas Koka, Michael Razziig, Thomas J.Bolem, Salam Syed , “ Microbial colonization of dental implants in partially edentulous subjects” J.Prosthet Dent 1993; 70;141-4 10.Thomas E, Rams, Thomas W.Roberts, Helt Tatum & Paul H.Keys “The Gingival microbial flora associated with human dental implants”. J.Prosthet Dent 1984 11.Budtz-Jorgensen E , Theilade E, Theilade J “ Quantative relationship between yeast and bacteria in denture induced stomatitis. J Dent Research 1983; 91; 134 – 142.
  157. 157. 12. Frank RM et al Transmission electron microscopy of plaque accumulation in denture stomatitis. JPD 1985 ; 53: 115-124
  158. 158. THANK YOU

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