Caries Microbiology Flashcards
What is colonisation?
- When microbes find a new host and start to multiply
What is normal flora?
- A balance can develop between colonised microbes and humans - will lead to ‘so called’ normal flora
If microbes cause disease what is this called?
- An infection
What is an endogenous infection?
- If source of microbe is patients own flora
What is an exogenous infection?
- IF the source of microbe is flora from outside the patients body
What is dental plaque?
- A diverse microbial community (predominantly bacteria) found on the tooth surface, embedded in a matrix of polymers of bacterial and salivary origin
What is the main aetiological agent associated with caries?
- Plaque
The oral microbiome is predominantly found on hard tissues. Where else can it be found? (2)
- Also found on dorsum of tongue
- Can be found on soft tissues (shedding)
We are sterile at birth, so where so we get bacterial species from? (4)
- Food
- Milk
- Water
- Mothers Saliva
What are the 4 stages of plaque development?
- Colonisation by pioneer bacteria
- Outcrowth
- Secondary colonisation
- Climax community
What are the basic concepts of oral microbiology? (5)
- A wide variety of microbes regularly enter the oral cavity
- Saliva, pH, temperature, immune system prevent many species from surviving
- Brushing and flossing teeth clears some built up biofilm
- Oral antibiotics inhibit growth
- Symbiosis of the oral microbes that are able to survive these conditions form an elaborate scaffold that lived on the tooth enamel and at the interface with the gums. It forms a barrier for incoming bacteria
What is caries?
- Loss of mineralised surfaces of the tooth
- Surface are permanently damaged by the microbial plaque
- Underlying dentine is at risk, or damaged
Caries is a multi-factorial disease. What are 2 main factors?
- Microbial biofilms
- Acidity: sugar metabolism
What are the characteristic for a low caries risk person? (4)
- Alkalia producing bacteria such as S. sanguinis
- Unstimulated saliva flow of >1ml/min
- Infrequent sucrose consumption
- Fluoride intake to levels allowing production of fluorapatite
What are the characteristics for a high caries risk person? (4)
- Acid prodcing bacteria such as mutans streptococci and lactobacilli
- Unstimulated saliva flow of <0.7ml/min
- Frequent consumption of high levels of sucrose and other fermentable carbohydrates
- Little or no fluoride intake
What is involved in the process of caries progression? (6)
- Adhesion
- Survival & growth
- Biofilm formation
- Complex plaque
- Acid
- Caries
What are the key cariogenic pathogens? (5)
- Streptococcus mutans
- Lactobacillus acidophilus
- Actinomyces Viscous
- Candida albicans
- Nocardia spp.
What is the factor that drives demineralisation?
- Microbial metabolism
What is the role of Pili on a bacterial cell?
- Help attach
What is the role of the capsule on a bacterial cell?
- Sticky and helps to evade the immune system
What is the role of Flagella on a bacterial cell?
- To help swim through saliva
What are caries associations with S. mutans? (long answer - learn it)
FACTORS RELATED TO CARIOGENICITY OF STREPTOCOCCUS MUTANS
• Significant correlations in humans between S mutans counts in saliva and
plaque with the prevalence and incidence of caries
• S. mutans can be isolated from precise sites on the tooth surface before the
development of caries
- Correlation between the progression of carious lesions and S mutans counts
- Produces water-soluble and insoluble extracellular polysaccharides from sucrose
which help in the colonization of tooth surfaces by consolidating microbial
attachment
• Most effective streptococcus in experimental caries in animals (rodents and
non-human primates)
• Ability to initiate and maintain microbial growth and to continue acid production
in sites with a low pH
- Rapid metabolism of sugars to lactic and other organic acids
- Can attain the critical pH for enamel demineralization more rapidly than other
common plaque bacteria
• Produces intracellular polysaccharide which can act as a food store for use when
dietary carbohydrate is low
• Immunisation of animals with S mutans significantly reduces the incidence of
caries
What is included in Koch’s Postulates: The Germ Theory Of Disease? (4)
- The microbe must be present in ever care of the disease
- The microbe must be isolated from the diseased host and grown in pure culture
- The disease must be reproduces when a pure culture is introduces into a susceptible host
- The microbe must be recovered from an experimentally infected host
What kind of micro-organism is streptococcus mutans?
- Gram positive coccus
