test 2, caries microbiology part 1

Question 1

bacteria associated with caries were originally thought to be what 2?

Answer 1

streptococcus mutans and lactobacillus

Question 2

current biofilms models point to what?

Answer 2

multiple pathogens

Question 3

the ecological plaque hypothesis is the most accepted model to describe the caries process. This model invovles….

Answer 3

1. a pH specific disease
2. selection process is driven by pH not carb availability
3. when acid producing bacteria dominate the biofilm demineralization occurs

Question 4

how many different bacteria have been identified in the human oral microbiome?

Answer 4

700-800

Question 5

what is the exteded ecological plaque hypothesis?

Answer 5

commensal bacteria have shown to adapt and live in acidic environments, but they also develop the ability to produce acids themselves contributing to the disease!!!

Question 6

demineralization always ____ bacteria

Answer 6

preceeds

Question 7

what are the first colonizers?

Answer 7

gram+ aerobic orgs called non-ms bacteria ( @ this point 95% of bacteria are non MS strep strains)

Question 8

as the plaque matures, what bacteria join the party?

Answer 8

actinomyces( at htis point only 2 % of the bacteria are MS)

Question 9

in what zone do the bacteria start to mix and become MS strains?

Answer 9

zone of destruction

Question 10

As pH starts to drop, who joins the party?

Answer 10

Mutans streptococci

Question 11

what are themajor bacterial groups in white spot lesions?

Answer 11

actinomyces and non-MS bacteria

Question 12

what are the major bacterial groups in cavitated dentin lesions?

Answer 12

MS ( ~30%),

Question 13

what bacteria stick to the pellicle?

Answer 13

the non-MS strains

Question 14

what do the non-MS strains produce?

Answer 14

extracellular polysacharides (glucans and fructans). These fill in gaps between bacteria and accelerate plaque formation

Question 15

what do the MS strains stick to?

Answer 15

to the base of plaque the non-MS and actinomyces produce

Question 16

what do the MS strains use to stick to the plaque?

Answer 16

adhesions- antigen I/II, water insoluable glucatn ( now they can do work!)

Question 17

After MS join the party what do they produce to start destroying teeth?

Answer 17

acids!

Question 18

do both non-MS and MS metabolize sugars into acids?

Answer 18

yes

Question 19

what happens when sugars are in abundance in the mouth?

Answer 19

non-MS & MS store the sugars and intracellular polysacharides for later use( this allows them to work between meals)

Question 20

non-MS strains produce wha pH after sugar metabolization?

Answer 20

4-5.2

Question 21

MS strains produce what pH after sugar metabolization?

Answer 21

4

Question 22

whats the critical value for demineralizaion?

Answer 22

5.5, so both can cause demineralization

Question 23

do all non-MS strains have the same affect on pH?

Answer 23

no, theyre all over the place ( mosaics)

Question 24

aciduric bacteria were able to grow on root surface caries at what pH?

Answer 24

4.8

Question 25

actinomyces are uureolitic which means?

Answer 25

can utilize lactate as a carbon source for growth

Question 26

a breakthrough on non-Ms strains showed they can change their physiologic charecteristics accoriding the the pH their in. What does this mean?

Answer 26

they actually increased acid production when placed in acidic conditions
Ex: When grown at pH7 and then placed in pH 5.5, their acidogenicity was increased to 3.93-4.12!

Question 27

even though the non-Ms produce acid, are they more competative than the Ms?

Answer 27

no, competition becomes more apparent at about 4 pH. This is where the non MS lose their ability to grown and produce their glycans. So Ms becomes more aciduric and acidogenic at low pH

Question 28

as pH starts to drop, which bacteria are prevelant?

Answer 28

MS and lactobacillus

Question 29

so what do intermittent drops in PH do? ( to threshold of 5.5)

Answer 29

result in increase in “low pH” non-MS and actinomyces spp.

Question 30

what does prolonged acidic conditions result in? ( below the 5.5 threshold)

Answer 30

causes MS to become prevelant

Question 31

what happens when pH levels approach 4?

Answer 31

non-Ms become excluded and replaced by MS and lactobacillus

Question 32

which bacteria can grow in anaerobic conditions?

Answer 32

MS strains , the non MS die out