Caries

Question 1

What is one of the main groups responsible for caries?

Answer 1

Streptococci. Mutans- these are facultative and obligate anaerobes- usually good at the tooth surface- survive changes in osmotic pressure, charge the colonisation surface.

Question 2

What are strep mutans really good at?

Answer 2

Acidogenic- Produce acid at a high rate from sugar and tolerate high concentrations of acid- aciduric

They bind to and colonise plaque on tooth surface.They produce EPS and are facultative anaerobes-

Strep uses lactase dehydrogenase to convert pyruvate to lactic acid- this allows the generation of ATP and NADH that drives the metabolic process-

Question 3

What advantage does strep mutans have?

Answer 3

S. mutans has largest number of genes associated with sugar transport and utilisation - In the oral cavity- organisms are dependent upon utilising carbohydrates- therefore the one that can access to the most amount of carbohydrate- would be at the most advantage.

Question 4

What are EPS?

Answer 4

EPS help with the build up of communities of strep mutans- act as binding sites and food storage resources- - extracellular therefore can produce lactic acid even when the consumption of carbohydrates isn’t occurring.

Establishes the functional integrity and structural integrity of biofilms.

Question 5

What are the surface protein of S mutans

Answer 5

1) glucan binding protein- they can carry out the chemical process preparing the environment for strep mutans
2) glucosyl tranferase- enable the transfer of the carbohydrate
3) protein antigen C- key for attachment to the biofilm

Important in allowing colonisation and binding

Question 6

What are the key proteins involved in attachment?

Answer 6

1) protein antigen 1/11- attach to the pellicle glycoprotein that is on the tooth surface
2) glucosyl transferase
3) glucan binding proteins

Question 7

There are other groups that metabolise carbohydrates to produce lactic acid, which are they?

Answer 7

1) lactobacilli
2) rothia denticariosa
3) actinomyces

Question 8

Lactobacillia

Answer 8

These are gram positive bacteria usually associated with diary products like cheese, milk etc. They can cope with changes in pressure, can change to allow them to adhere and attach.

Facultative anaerobe and are acidnogenic and acidic- they respond well to carbohydrate intake.

There are 3 main groups of lactobacilli based on the fermentation end points- homolactic fermenters (only produce lactic acid) that cause the most damage to hard tissue, heterolactic fermenters and facultative heterolactic fermenters.

Lactobacilli increase as streptococci fall- there are high numbers in carious dentine- limited role in causing demineralisation but important in causing progression of it once a low pH has been established

Question 9

Actinomyces

Answer 9

These are gram positive bacteria that have a role in root surface caries- plaque is more difficult to remove- it accumulates in the proximal site- more actinomyces- produce a more sticky site.

Found in sub and supra gingival plaque and has different species e.g. A. Naesludii which have a host compatible biofilm so may be less likely to cause caries.

Question 10

Rothia dentocariosa

Answer 10

Existence is linked with mature plaque populations- these are opportunistic pathogens that cause a variety of infection including endocarditis