Lecture 3: The microbiology of dental caries

Question 1

most common place where caries occur

Answer 1

pits and fissures

Question 2

what type of caries are associated with patients with moderate to high caries increment, also diet related?

Answer 2

proximal and smooth surface caries

Question 3

caries found at restoration margin

Answer 3

secondary caries

Question 4

how do caries occur?

Answer 4

body’s salivary reminerlization can’t keep up with bacterial acid production

Question 5

what initially stabilizes the enamel surface during demineralization?

Answer 5

pellicle protein

Question 6

T/F initial demineralization is subsurface

Answer 6

true

Question 7

T/F healing of a lesion is possible as long as the cavitation isn’t into dentin

Answer 7

false, as long as the surface is retained

Question 8

remineralized tooth structure is stronger than virgin enamel because of incorporation of _____ into the ______

Answer 8

fluoride, hydroxyappetite crystal structure

Question 9

bacteria that produce acid are ______

Answer 9

acidogenic

Question 10

bacteria that survive acid are _____

Answer 10

aciduric

Question 11

how do bacteria survive famine?

Answer 11

• use multiple fermentable sugars at low concentrations

- accumulate storage polysaccharides

Question 12

bacteria of initiation

Answer 12

• streptococcus mutans
• other strep, S. sobrinus, S. salvarius
• veilonella
• actinomyces

Question 13

which acid metabolizes lactic acid, raising the pH?

Answer 13

veilonella

Question 14

bacteria of progression

Answer 14

• s. mutans
• lactobacillus casei, rhamnosus, gasseri, fermentum
• bifidobacterium and scardovia

Question 15

what are the most common supragingival organisms?

Answer 15

• step

Question 16

types of mutans strep

Answer 16

s. mutans and s. sobrinus

Question 17

types of mitis strep

Answer 17

• s. sanguinis
• s. parasanguinis
• s. mitis
• s. pneumoniae
• s. gordonii
• s. salivarius

Question 18

what is the primary caries pathogen?

Answer 18

s. mutans

Question 19

what bacteria does s. mutans attach to?

Answer 19

s. sanguinis

Question 20

important characteristics of s. mutans

Answer 20

• gram positive, cocci, facultative
• ferments carbs
• elaborate ECM

Question 21

what interferes with the transport and intracellular processes in s. mutans at low pH?

Answer 21

fluoride, diffuses into cell at low pH

Question 22

characteristics of S. sobrinus

Answer 22

• associated with s. mutants (mutans)
• strongly associated with caries
• found in lower #’s than mutans

Question 23

what enzymes are affected by F-?

Answer 23

• glucosyl-tranferase (bringing glucose into cell)

- enolase (formation of lactic acid)

Question 24

what is the earliest acquired oral bacteria?

Answer 24

• s. mitis

Question 25

characteristics of s. mitis?

Answer 25

- ubiquitous (found everywhere) - bond to salivary amylase - not cariogenic

Question 26

T/F s. mitis is cariogenic

Answer 26

false

Question 27

what bacteria is responsible for infective endocarditis?

Answer 27

s. sanguinis

Question 28

characteristics of s. sanguinis

Answer 28

- in healthy (noncariogenic) plaque - gram positive, cocci, facultative - colonizes on pellicle - produces lactic acid at high pH - can survive without sugar (arginine hydrolase pathway)

Question 29

what is the product of the arginine hydrolase pathway?

Answer 29

NH3

Question 30

what are some niches of s. salvarius?

Answer 30

tongue and tooth

Question 31

characteristics of s. salvarius

Answer 31

- associated with caries - detected in saliva, doesn't grow there - excludes s. pyogenes (bacteriocin)

Question 32

what type of caries is actinomyces associated with?

Answer 32

root caries

Question 33

what is the structure of actinomyces?

Answer 33

filamentous

Question 34

T/F actinomyces is gram negative

Answer 34

false

Question 35

T/F veillonella ferments carbohydrates

Answer 35

false

Question 36

how does veillonella raise the pH?

Answer 36

ferments lactate to propionate

Question 37

T/F veilonella is a gram negative cocci

Answer 37

true

Question 38

characteristics of lactobacilli

Answer 38

- important in deeplesions - gram positive rods - anaerobic (deep) - extremely acid tolerant

Question 39

T/F bifidobacterium and scardovia may be important in deep caries and are gram positive rods like lactobacilli

Answer 39

true

Question 40

T/F s. mutans binds to the pellicle via adhesins and s. sanginis binds to s. mutans via adhesins

Answer 40

false, other way around

Question 41

how does s. mutants attach to glucan?

Answer 41

via glucan binding protein

Question 42

T/F s. sanguinis beats s. mutans at high pH, but s. mutans does better at low pH fermenting sugars

Answer 42

true

Question 43

what two species of bacteria can grow at low pH?

Answer 43

- s. mutans | - L. casei

Question 44

long term consequence of sugar consumption is more _____ in plaque

Answer 44

s. mutans

Question 45

what is an alkali-generating organism?

Answer 45

s. sanginis (NH3)

Question 46

T/F a person who constantly snacks normally has a resting pH 3 units below someone who doesn't snack

Answer 46

false, 1 pH unit

Question 47

T/F all children have s. mutans

Answer 47

true

Question 48

what are the two targets of s. mutans vaccines?

Answer 48

- glucosyl transferase | - binding proteins