Lecture: Micro of Caries Flashcards
(38 cards)
What three components form the multi factorial nature of Caries?
Key Oral Microorganisms
Susceptible Host
Environmental Trigger (poor diet./oh)
What are the three groups of evidence for Caries as an infectious disease?
1) Gnotobiotic Animal Studies:
- Specificity -Diet -Transmission -Antimicrobial agents
2) Human Epidemiology Studies
- Cross sectional -Longitudnal
3) Vaccinations in Rodents and Primates
Why are Vaccinations restricted to experiments?
Vaccines left for life threatening conditions
What are the 4 implicated microbes in Caries?
Mutans Streptococci (MS)
Actinomyces
Lactobacilli
Bifidobacteria
What are the species and serotypes of Mutans Streptococci?
Srep. mutans ( c,e,f)
Strep, sobrinus (d,g)
What species and serotypes of MS are also found but not in humans?
Strep. cricetus (a)
Strep. rattus (b)
What are the species of Actinomyces?
A. naeslundii
A. odontolyticus
(A. israeli/ A.gerencseriae)
What is the species name for Lactobacilli and Bifidobacterium?
Lactobacillus spp.
Bifidobacterium spp.
Describe Mutans Streptococci
- 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)
Describe Actinomyces
-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
Describe Lactobacilli
- 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
Describe Bifidobacterium
- Gram positive rod
- Branched cells
- Recently implicated in Caries
What are key differences in study deisgn to investigate microflora
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
What are the challenges in understanding the microbial aetiology of dental caries?
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
What do cross sectional human studies show?
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
What do cross sectional studies show about fissure caries?
71% of Caries Fissures had >10% MS (percentage of total cultivable microflora)
70% of caries free fissures had no detectable MS
What do longitudnal human studies show?
-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)
What role do other bacteria?
Some are acidogenic and low pH isolaes, eg Strep. mitis and Srep oralis. (Maybe also Actinomyces and Bifidobacterium)
Others are Lactate using species
What species uses Lactate?
Veillonella spp. Converts Lactate into Propionate and Acetate
Veillonella is a gram negative coccus, anaerobic and utilizes acid in plaque
-Produces weaker acids
What can be said about the variations in species and strain acid production?
Strep. sobrinus - very fast
Strep. mutans - very fast
Some overlap
What three bacteria produce base and what specifically do they produce?
S. salivarius - urea
S. sanguinis -arginine
A. naeslundii - urea
Briefly describe the Arginine deminase system
Arginine-> Citruline + AMMONIA
Citruline + Carbamyl -P -> ATP + CO2 + AMMONIA
What is the role of Bacteria in Other forms of Caires?
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
What Culture Bacteria are found in Infected Dentine?
CULTURE: MS, Lactobacilli, Actinomyces spp., Gram negative Anaerobic rods (eg Prevotella spp.)