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CSA > Lecture: Micro of Caries > Flashcards

Lecture: Micro of Caries Flashcards

1
Q

What three components form the multi factorial nature of Caries?

A

Key Oral Microorganisms
Susceptible Host
Environmental Trigger (poor diet./oh)

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2
Q

What are the three groups of evidence for Caries as an infectious disease?

A

1) Gnotobiotic Animal Studies:
- Specificity -Diet -Transmission -Antimicrobial agents
2) Human Epidemiology Studies
- Cross sectional -Longitudnal
3) Vaccinations in Rodents and Primates

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3
Q

Why are Vaccinations restricted to experiments?

A

Vaccines left for life threatening conditions

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4
Q

What are the 4 implicated microbes in Caries?

A

Mutans Streptococci (MS)
Actinomyces
Lactobacilli
Bifidobacteria

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5
Q

What are the species and serotypes of Mutans Streptococci?

A

Srep. mutans ( c,e,f)

Strep, sobrinus (d,g)

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6
Q

What species and serotypes of MS are also found but not in humans?

A

Strep. cricetus (a)

Strep. rattus (b)

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7
Q

What are the species of Actinomyces?

A

A. naeslundii
A. odontolyticus
(A. israeli/ A.gerencseriae)

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8
Q

What is the species name for Lactobacilli and Bifidobacterium?

A

Lactobacillus spp.

Bifidobacterium spp.

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9
Q

Describe Mutans Streptococci

A
  • Gram Positive Cocci/short rods cocci bacilli
  • Generally found on hard non shedding surfaces (not soft)
  • Implicated in initiation of Caries
  • Lot of acid production- pH 3.9-4.2
  • Very Rapid Sugar transport
  • High Acid Tolerence
  • Produces Soluble and Insoluble EPS
  • Produces IPS (Strep. sobrinus is low IPS)
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10
Q

Describe Actinomyces

A

-Gram Positive branched rods
-Common in dental plaque
Spome species implicated in root caries
-Opportunistic Pathogen
-Medium sugar transport, little known about systems
-pH 4.4 to 4.8.
-Medium Acid Tolerence
-Medium EPS production
Produces IPS

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11
Q

Describe Lactobacilli

A
  • Gram Positive rod implicated in adcanced dental caries
  • Later stages of disease
  • Rapid Sugar Production little known about systems
  • pH 3.8 to 4.1
  • Very high growth at pH 5
  • Low production of EPS
  • Produces IPS
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12
Q

Describe Bifidobacterium

A
  • Gram positive rod
  • Branched cells
  • Recently implicated in Caries
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13
Q

What are key differences in study deisgn to investigate microflora

A

Cross Sectional: Single time point samples compare areas of health to areas of disease
Longitudnal design:- Multiple samples over time and compare areas where disease occurred to areas of health

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14
Q

What are the challenges in understanding the microbial aetiology of dental caries?

A

Challenges:

  • Disease occurs at sites with natural, diverse microflora
  • Pathogens found at health sites (often component of dental plaque))
  • Lesions can remineralise
  • Pathogenic traits are relatively non specific
  • Multi-factorial nature of Caries
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15
Q

What do cross sectional human studies show?

A

Increased MS at caries sites
(Proportions and isolfation frequency)
There is an INVERSE relationship between MS and Strep. sanguinis
Some sites with Caries have no MS, some sites have MS but not caries

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16
Q

What do cross sectional studies show about fissure caries?

A

71% of Caries Fissures had >10% MS (percentage of total cultivable microflora)
70% of caries free fissures had no detectable MS

17
Q

What do longitudnal human studies show?

A

-Confirm increased MS at caries sites
MS can occur after first signs of demineralisation
Caries cna occur without MS
Role of other species in progression (Lactobacilli in advanced lesions)

18
Q

What role do other bacteria?

A

Some are acidogenic and low pH isolaes, eg Strep. mitis and Srep oralis. (Maybe also Actinomyces and Bifidobacterium)
Others are Lactate using species

19
Q

What species uses Lactate?

A

Veillonella spp. Converts Lactate into Propionate and Acetate
Veillonella is a gram negative coccus, anaerobic and utilizes acid in plaque
-Produces weaker acids

20
Q

What can be said about the variations in species and strain acid production?

A

Strep. sobrinus - very fast
Strep. mutans - very fast
Some overlap

21
Q

What three bacteria produce base and what specifically do they produce?

A

S. salivarius - urea
S. sanguinis -arginine
A. naeslundii - urea

22
Q

Briefly describe the Arginine deminase system

A

Arginine-> Citruline + AMMONIA

Citruline + Carbamyl -P -> ATP + CO2 + AMMONIA

23
Q

What is the role of Bacteria in Other forms of Caires?

A

Nursing Bottle Caries: MS and Lactobacilli
Root surface Caries:
Early studies: Actinomyces spp
Later studies: Mutans streptococci/ lactobacilli
Recent studies: DIverse microflora
Actinomyces spp. MS and gram negative rods

24
Q

What Culture Bacteria are found in Infected Dentine?

A

CULTURE: MS, Lactobacilli, Actinomyces spp., Gram negative Anaerobic rods (eg Prevotella spp.)

25
Q

What Molecular Bacteria have been found in Infected Dentine?

A

31 New Taxa
Strep Mutans
Eubacterium saburreum
Diverse array of Lactobacillus spp (50% of species)
Diverse array of Prevotella spp (50% of species)

26
Q

What does Data suggest about the make up of infected dentine bacteria?

A

Data suggest combinations of acidogenic bacteria combined with proteolytic and collagenolytic anaerobes

27
Q

What are the Bacterial Metabolism essential steps in Health and in Caries?

A

HEALTH: Host Glycoproteins-> Dental Plaque -> Slow acid production and neutral pH-> Little or no demineralisation
In CARIES: Fermentable sugars-> Dental Plaque-> Rapid Acid Production -> Demineralisation

28
Q

What are the charecteristics of Cariogenic Bacteria?

A
  • Rapid Sugar Transport and acid Productions (eg PEP-PTS Sugar Transport system)
  • Acidurity
  • Extracellular Polysaccharide (EPS)
  • Intracellular Polysaccharide (IPS)
29
Q

What are the characteristics of Strep. sanguinis?

A 
Medium sugar transport
pH 4.4- 4.8
Poor Acid Tolerance
Soluble and Insoluble EPS produced
Does produce IPS
30
Q

What are the three hypothesise for Plaque?

A

Specific P. H. (Target on certain types)
Non specific P.H. (outcome related, net effect)
Ecoological P.H.

31
Q

What characterises the Ecological Plaque Hypothesis?

A

Certain Bacteria Important
Extended Ecological to show bacteria can adapt to new conditions
AETIOLOGY MAY NOT BE MONO SPECIFIC many species contribute
CARRIAGE OF PATHOGENS Clinically insignificant leves
environmental regulation of gene expression
DISEASE PREVENTABLE AND CONTROLLABLE BY direct inhibition of causative organisms- maintenance of natural balance- interference with factors driving deletrious shifts in microflora

32
Q

What are the four key elements in controlling dental caries? What three other approaches also exist?

A 
PLAQUE CONTROL
FLUORIDE
SUGAR SUBSTITUTES
ANTIMICROBIAL & ANTI PLAQUE AGENTS
Replacement therapy, Vaccination, Passive immunisation
33
Q

What does the Fluoride approach to Controlling Dental Caries involve?

A
  • Fluorapatite
  • Remineralisation (targeted)
  • Acidify cell interior (H+F-)
  • Inhibit IPS synthesis
  • Remove competitve opportunity for MS (low pH environment)
34
Q

What does the Sugar Substitute approach to Dental Carie involve?

A

-Bulking agents (Sorbitol , Xylitol)
-Intense Sweetners (Saccharin , Aspartame)
-Not, or weakly metabolised to Acid
-Stimulate Saliva Flow
-Weal antimicrobial activity (Xyltol to s. Mutans)
-

35
Q

What is the Antimicrobial and Antiplaque approach in controlling caries?

A
  • Toothpastes and mouthwashes
  • Chlorhexidine gold standard anti plaque
  • Triclosan, metal salts, plant extracts
  • MIC v sub MIC effects (eg inhibit glycolysis , sugar transport)
  • Antimicrobial and antiplaque activity
36
Q

What is replacement therapy?

A

Probiotics in oral cavity to reduce of effect of carious bacteria
Dairy Strains: Exclude cariogenic bacteria ?
Strep. salivarius is a bacteriocin producing strain

37
Q

Describe Caries Vaccination

A

Mouth has full immune response
Streptococci are targetable pathogens
Vaccines based on whole cells, glucosyltransferases, cell wall associated proteins
Vaccines worked in rodents and primates, no approval for humans

38
Q

What is Passive Immunisaiton?

A
  • Coat surface with ANTIBODIES or SYNTHETIC ANTIBODY FRAGMENTS
  • Reduces MS colonisation
  • Safe, acceptabel and non invasive

CSA (1 decks)

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