Caries

Question 1

quorum sensed by

Answer 1

autoinducers

Question 2

quorum and biofilms

Answer 2

activate genes that support survival or are beneficial in community/biofilm
EPS secretion, metabolic changes, drug-resistance genes
different between Gram= and Gram-
coordination of population

Question 3

quorum sensing in Gr. negative bacteria

Answer 3

low cell density: low AHL concentration, no gene expression
high cell density: high AHL concentration, transcription activated

Question 4

function of polysaccharides

Answer 4

structure
buffer for pH
binds to nutrients - concentrate near bacteria
retain water
prevent or impede phagocytosis
bind to antibiotics
promotes lateral gene transfer
increase antibiotic resistance

Question 5

how do polysaccharides increase antibiotic resistance

Answer 5

pH changes
decrease in active growth
physical separation of compound from bacteria
other bacteria available to die first

Question 6

acquiring antibiotic resistance genes

Answer 6

vertically and horizontally
transformation, transduction, conjugation

Question 7

core genomes of bacteria acquire mutations over time which can limit susceptibility to

Answer 7

antibiotics

Question 8

biofilms limit what and promote what

Answer 8

limit penetrations of antibiotics and promote the spread of antibiotic resistance genes

Question 9

furanones

Answer 9

inhibit bacterial colonization and biofilm development
inhibit normal signaling through AHL quorum-sensing

Question 10

dental caries

Answer 10

a multifactorial, biofilm-associated disease characterized by dissolution of tooth hard tissue due to the attack of acids produced by bacteria in dental plaque

Question 11

dental caries etiology

Answer 11

host factors: saliva, immune status, tooth strength
diet: fermentable carbohydrates
plaque microorganisms: cariogenic bacteria - S. Mutans
time: both longitudinal and frequency of eating and cleaning

Question 12

cariogenicity

Answer 12

the ability to initiate tooth decay or caries

Question 13

cariogenic pathogens have these features

Answer 13

involved biofilm formation (biofilm former)
compete for resources and ecological niches (competitive)
produce acids from carbohydrates (acidogenicity)
survive and continue to produce acids at low pH (aciduricity)

Question 14

streptococcus mutans

Answer 14

Gram +, cocci in chain, most important

Question 15

lactobacillus

Answer 15

gram +, rods, grow well at pH 5, progression, deep lesions

Question 16

actinomyces

Answer 16

gram +, branching filament, root caries

Question 17

characteristics of S. Mutans

Answer 17

initiates biofilm formation
generates lots of EPS
highly competitive
effective and rapid use of many sugars
grow at low pH

Question 18

_____ allows S. mutans to outcompete other bacteria

Answer 18

sucrose

Question 19

S. mutans - sucrose-dependent biofilm formation

Answer 19

glucan and fructan are examples of EPS
-form part of the plaque matrix
-facilitate S. mutans adherence to surface
-serve as carbohydrate storage/reserve
-as targets for other bacteria to bind to
Adhesin Ag I/II protein and receptor Gp-340

Question 20

functions of glucan and fructan

Answer 20

provides receptors for other bacteria
can act as a carbon source

Question 21

fermentation

Answer 21

a pathway in which the reducing power generated by oxidative reactions is re-oxidized by metabolites produced by the pathway

Question 22

organic acids

Answer 22

bacteria produce organic acids from fermentable carbohydrates

Question 23

heterofermentative bacteria

Answer 23

produce acetic, propionic, succinic, formic

Question 24

homofermentative

Answer 24

produces S. mutans > 90% lactic acid

Question 25

pKa of lactic acid

Answer 25

3.85

Question 26

S. mutans ferments sucrose to

Answer 26

lactic acid

Question 27

the stephan curve

Answer 27

describes the effect of fermentable sugars in ingested foods on plaque pH

Question 28

demineralisation of enamel and dentin occurs when pH

Answer 28

enamel: < or = 5.5
dentin: < or = 6.2

Question 29

S. mutans intracellular polysaccharide

Answer 29

storage form of carbohydrate, produced during excess sucrose
IPS serves as a source for energy and acid production, contributes to acidogenicity

Question 30

how does IPS contribute to aciduricity

Answer 30

IPS provides energy for ATPase
ATPase drives protons out of cells
helps maintain neutral pH in the cytoplasm

Question 31

inhibiting S. mutans

Answer 31

fluoride treatment
inhibiting enolase
antibiotics

Question 32

fluoride treatment

Answer 32

forms fluorapatite instead of hydroxyapatite during remineralisation
less soluble than regular hydroxyapatite
converts 2-PG to PEP
inhibits glucose utilization and lactic acid production

Question 33

antibiotic treatment in inhibiting S. mutans

Answer 33

systemic antibiotics - Penicillin
topical - chlorhexidine rinse - prevents plaque formation