The Microbiology of Dental Caries

Question 1

what type of caries is most common and found in patients with otherwise low caries rates

Answer 1

pit and fissure caries

Question 2

what type of caries is diet related and less common, usually patient is at higher risk for caries

Answer 2

proximal or smooth surface caries

Question 3

where do root caries usually form

Answer 3

on exposed root surfaces

Question 4

where do we find secondary caries

Answer 4

around dental restorations

Question 5

explain demineralization vs remineralization process of enamel

Answer 5

constant tug-of-war

lactic acid demineralized tooth structure but salivary minerals remineralize tooth structure

at equilibrium=no caries

Question 6

when initial caries start to form what is the integrity of the tooth structure like

Answer 6

hard outer shell but becomes soft underneath

feels rough with assessment instrument

Question 7

physiologically what is happening when caries begin to form

Answer 7

tug-of-war no longer in equilibrium

remineralization process cannot keep up with the demineralization process (too much lactic acid)

Question 8

when does cavitation form

Answer 8

when the soft tooth structure gets so soft it cannot support the overlying hard shell of enamel and it collapses

Question 9

what is the first sign of cavity formation

Answer 9

white spot lesion

chalky white

Question 10

T/F: extraordinary force on a subsurface demineralized tooth with a hard outer shell of enamel can cause cavitation

Answer 10

TRUE

Question 11

how do bacteria lower the pH of environment for teeth

Answer 11

bacteria produce lactic acid from glycolysis of sugars

Question 12

when is remineralization of the tooth possible and when is biological repair no longer an option

Answer 12

remineralization with fluoride and saliva can occur as long as the outer shell of enamel stays intact

once cavitation, biological repair is not possible

Question 13

T/F: remineralized tooth structure is weaker than virgin enamel

Answer 13

False

remineralized tooth structure is stronger than virgin enamel because F ion is incorporated into the hydroxyapatite

Question 14

which type of caries is very hard to diagnose at early stages

Answer 14

pit and fissure caries

Question 15

why do patients with good oral hygiene still get pit and fissure caries

Answer 15

anatomical problem

toothbrush bristles cannot reach the depth of the grooves

Question 16

what is the preventative treatment for pit and fissure caries?

Answer 16

sealants

Question 17

which dental arch is more affected in baby bottle caries and why

Answer 17

upper arch

because babies tend to place their tongue over lower arch protecting the teeth when drink from bottle

Question 18

Is it possible to guarantee that class I restoration will last a lifetime?
What about class II?

Answer 18

Yes for class I

For class II no
will get recurrent decay at some point

Question 19

what is the key property that caries causing bacteria needs to have

Answer 19

need to be able to continue to produce acid at low pH

Question 20

Aa role in caries

Answer 20

we are not sure if Aa causes caries or not

Question 21

as caries progress which pathogen becomes more prevalent

Answer 21

lactobacillus

Question 22

Veionella and S. mutans have partnership in caries causing situations

Answer 22

veionella increases lactic acid metabolism

Question 23

what is a primary caries pathogen

Answer 23

s. mutans

Question 24

what category of bacteria is s. mutans

Answer 24

facultative anaerobe

Question 25

can s. mutans attach directly to a tooth

Answer 25

no, it attaches to s. sanguis which attaches to a tooth

Question 26

what are two reasons s. mutans is a primary cariogenic pathogen

Answer 26

1. very good at developing biofilms

2. can survive during times of famine (between meals) ; can extract sugar out of very dilute solutions

Question 27

what strain is most commonly found in supragingival areas

Answer 27

streptococcus

Question 28

how does fluoride ion combat S. mutans

Answer 28

fluoride ion actually more readily (passively) gets through cell membrane as pH drops

interferes with transport mechanisms and intracellular processes

also gets into tooth structure and makes the mineral less simple to dissolve

Question 29

s. sobrinus

Answer 29

strongly associated with caries

found in lower number than s. mutans

Question 30

s. mitis

Answer 30

first thing babies acquire

salivary a-amylase binds s. mitis

not cariogenic

Question 31

where is s. sanguis found

how does it attach

how does it work

what systemic disease can it cause

Answer 31

found in healthy plaque (good bacteria)

attaches to tooth pellicle via adhesins

works well at high pH; produces ammonia so helps increase the pH

causative agent of IE

Question 32

where is s. salivarious found

is it associated with caries?

Answer 32

found on the tongue and teeth

associated with caries

Question 33

what type of caries is actinomyces associated with

what is their shape

Answer 33

associated with root caries

filamentous in shape

Question 34

what does veillonella do

classify as gram + or -

Answer 34

ferments lactate–>proprionate and increase pH

gram -

Question 35

characteristics of lactobacilli

Answer 35

gram +

rod shaped

important in progression of caries not initiation

Question 36

when are bifidobacterium and scardovia important

Answer 36

deep caries

Question 37

when do s. sanguis and s mutans produce the most lactic acid? at what level of pH?

Answer 37

s. sanguis produces lactic acid until the pH drops below 6.5, than s. mutans takes over and finally lacobacillus takes over when pH is very low

Question 38

effect on frequent sugar consumption

• short term
• long term

Answer 38

short term causes drop in pH

long term may be more important
-resting pH becomes lower initially so when sugar is consumed pH drops even lower

Question 39

does eating at meals vs snacking all day affect the plaque accumulation on teeth

Answer 39

yes, studies show that kids that snacked all day long had more plaque then kids that just ate at meals

both kids were using the same oral hygiene home care regimen

Question 40

when do we start to get s. mutans during development as a child

Answer 40

around 2 years old

when primary molars erupt–have more surface area to harbor bacteria

Question 41

everybody has s. mutans but what can we do to prevent the bad effects of the bacteria

Answer 41

don’t give it sugar

will not function if no sugar

Question 42

T/F: kissing babies can cause transfer of s. mutans from caregiver to child

Answer 42

false; not much evidence that shows this

Question 43

what are some investigations going on to acquire a way to prevent caries as whole disease

Answer 43

immunization against s. mutans

passive immunity

• tobacco plants
• cows milk
• repeated dose in combination of mechanical removal

replacement therapy: replace wild type strain with genetically engineered strain of s. mutans

STAMP (specifically targeted antimicrobial peptidases)