Lecture 3 - Microbiology of Dental Caries

Question 1

This is the most common site for caries; patients have otherwise low caries rates

Answer 1

pits & fissures

Question 2

Caries are found here less often and are usually diet-related; found in patients with moderate to high caries rates

Answer 2

smooth surface and proximal caries

Question 3

Caries found here in patients with exposed root surfaces (sequelae of periodontitis)

Answer 3

root surface caries

Question 4

Caries found at restoration margins or under restorations

Answer 4

secondary caries

Question 5

Lactic acid produced by bacteria dissolves mineral from enamel

Answer 5

demineralization

Question 6

Salivary minerals are deposited in enamel

Answer 6

remineralization

Question 7

Bacteria in biofilms on surface of tooth produce ______ _____ from glycolysis of sugars.

Answer 7

lactic acid

Question 8

Lactic acid ________ pH and mineral matrix of tooth dissolves

Answer 8

decreases (becomes more acidic)

Question 9

Tooth surface is stabilized by _________ proteins so initial demineralization is subsurface (thin shell of enamel left overlying body of lesion)

Answer 9

pellicle

Question 10

________ occurs when subsurface demineralization becomes too severe or extraordinary force is applied to surface.

Answer 10

Cavitation

Question 11

As long as surface is retained, ____________ and “healing” of lesion are possible.

Answer 11

remineralization

Question 12

Remineralized tooth structure is (stronger or weaker) than virgin enamel.

Answer 12

stronger

due to the incorporation of fluoride into HA crystal structure

Question 13

What are the 5 properties of caries-causing bacteria?

Answer 13

1. attach and form biofilm
2. produce acid (acidogenic)
3. survive acid (aciduric)
   * **4. continue to produce acid at low pH
4. survive “famine” between meals

Question 14

What are the most common supragingival organisms (difficult to distinguish)?

Answer 14

Streptococci

Question 15

Which bacteria is involved in both caries initiation and progression?

Answer 15

S. mutans

Question 16

This bacteria is the primary caries pathogen, is a gram + cocci, facultative, and ferments carbohydrates as only nutrient source.

Answer 16

S. mutans

Question 17

Which bacteria does S. mutans attach to in forming a biofilm?

Answer 17

S. sanguinis

Question 18

S. mutans is well-adapted for ______ or _______ (it can thrive during good times and bad)

Answer 18

feast (active transport)

famine (good scavenger)

Question 19

T/F

S. mutans has an advantage to host due to low levels of lactate which is protective.

Answer 19

True

Question 20

What interferes with transport and intracellular processes of S. mutans?

Answer 20

Fluoride

Question 21

This bacteria is closely related to S. mutans and is strongly associated with caries, but is usually found in lower numbers than S. mutans.

Answer 21

S. sobrinus

Question 22

This bacteria is ubiquitous, is the earliest acquired oral bacteria, is bound by salivary amylase, and is not typically cariogenic.

Answer 22

S. mitis

Question 23

This bacteria is found in healthy (non-cariogenic) plaque, adheres well via adhesins, can survive without sugar, and is often causative agent of infective endocarditis.

Answer 23

S. sanguinis

Question 24

This bacteria is detected in saliva, but grows on tongue and teeth; some strains make bacteriocins that prevent S. progenies colonization (probiotic).

Answer 24

S. salivarius

Question 25

This bacteria may contribute to root caries and early stages of enamel caries.

Answer 25

Actinomyces

Question 26

This bacteria ferments lactate and protects against acid; anaerobic gram negative cocci

Answer 26

Veillonella

Question 27

This group of bacteria includes casei, rhamnosus, gasseri, fermentum and is important in established or deep lesions; anaerobic gram + rod

Answer 27

Lactobacilli

Question 28

These bacteria may be important in deep caries and are anaerobic gram + pleomorphic rods.

Answer 28

Bifidobacterium and scardovia

Question 29

S. sanguinis binds to ________ via specific adhesins.

Answer 29

pellicle

Question 30

S. mutans binds to _ ________ via specific adhesins.

Answer 30

S. sanguinis

Question 31

S. mutans uses _____________ to make extracellular matrix from sucrose.

Answer 31

glucosyltransferase (Gtf)

Question 32

Extracellular matrix is composed of ______, a cross-linked insoluble polysaccharide.

Answer 32

glucan

Question 33

S. mutans attaches to glucan via _______-________ proteins.

Answer 33

glucan-binding

Question 34

Can survive low pH

Answer 34

aciduric (acid tolerant)

Question 35

Can drive pH down

Answer 35

acidogenic (acid producing)

Question 36

S. mutans can ferment sugars at ___ pH.

Answer 36

low

Question 37

______ bacteria grow and make acid at high pH and stop at low pH.

Answer 37

Healthy

Question 38

_____ bacteria grow and make acid best at low pH.

Answer 38

Caries

Question 39

A short term effect of sugar consumption is…?

Answer 39

decreased pH

Question 40

T/F

Long term effects of sugar consumption may be more important and results in a vicious cycle.

Answer 40

True

Question 41

Studies have shown that the pH of plaques significantly decrease after a 2-minute 10% _______ rinse.

Answer 41

glucose

Question 42

It is hypothesized that the “window of infectivity” for S. mutans is around __ months based on cultivation, but can be acquired earlier.

Answer 42

26

Question 43

Caries vaccines would target what two things?

Answer 43

glucosyltransferase (Gtf)

glucan-binding proteins

Question 44

Mucosal vaccination would provide _____ immunity (nasal & ingested).

Answer 44

active

Question 45

Antibodies raised in tobacco plants and in immunized cow’s milk would provide ________ immunity and show effects when repeated doses are combines with removal of biofilm.

Answer 45

passive

Question 46

Pheromone or antibody guided antimicrobials kill only target species.

Answer 46

Specifically targeted antimicrobial peptides (STAMPs)