M13 plaque

Question 1

define plaque

Answer 1

microbial community found on the tooth surface

biofilm and not planktonic growth

Question 2

what is a biofilm?

Answer 2

name given to microbial communtites attached to a surface

Question 3

what are the properties of a typical biofilm?

Answer 3

spatially organized in a 3d structure
bacterial cells enclosed in extracellular matrix
increases habitat range of individual bacteria

Question 4

what is organic matrix made up of?

Answer 4

glycocalyx or extracellular polymeric substances

30% total volume

Question 5

define acquired pellicle and list its contents

Answer 5

The layer of material acquired by a cleaned tooth

• mucins
• salivary glycoproteins
• minerals and immunoglobulins

Question 6

where does bacteria attach to?

Answer 6

do not attach/adhere directly to the enamel, they attach to the pellicle

Question 7

what forces are used for long range weak interactions?

Answer 7

van der waals - 100 nm

Question 8

what forces are used for short range interactions?

Answer 8

less than 2nm

hydrogen bonding

Question 9

what is the calcium bridge in a salivary glycprotein attached to?

Answer 9

bacterial cell wall which is negatively charged

enamel has a weak positive charge so it doesnt go to it

Question 10

features of lipoteichoic acid/?

Answer 10

amphipathic material
gram +ve cell wall
- binds blood group substances found in pellicle

Question 11

what allows initial attachement to become adhesion?

Answer 11

extracellular polysaccahride - strong system

• irreversible attachement
• glucans or fructans

Question 12

what is special about the sucrose bond?

Answer 12

sucrose - supports polysaccharide synthesis

Question 13

which enzymes is used to produce glucans?

Answer 13

glucosyltransferase (GTF)

Question 14

what enzyme is used to produce fructans?

Answer 14

fructosyltransferase (FTF)

Question 15

extracellular DNA (eDNA)

Answer 15

can be major components of EPS

Question 16

what does DNAse do?

Answer 16

releases bacteria and inhibits biofilm formation

Question 17

what are adhesins?

Answer 17

specific molecule on bacterial surfaces which recognise specific ligands or receptors on tooth surface - fimbrae

Question 18

what are lectins?

Answer 18

sugar binding protein which recognise carbohydrate groups and bind them –> fimbrae

Question 19

how does fimbrae attache to pellicle?

Answer 19

'’hair like’’ proteinacous appendages

Question 20

what bacteria posses fibrils and allow coadhesion?

Answer 20

streptococcus crista

Question 21

describe colonisation and biofilm formation

Answer 21

• short range adhesion
• growth and metabolic activity
• microcolony formation
• co-aggregation/ co-adhesion

climax community

Question 22

which gram +ve plaque is first to develop within 2 hours?

Answer 22

oralis mits and sanguinis

Question 23

which gram -ve bacteria is first to develop within 2 hours?

Answer 23

neisseria and haemophilus

Question 24

which streptococci dominate for 24 hours?

Answer 24

S.sanguinis

Question 25

what happens in stages of succession?

Answer 25

1. streptococcus spp. attach to acquired pellicle
2. streps replaced by actinomyces
3. gram -ve specis eg fusobacterium

Question 26

what are the changes seen during 1st week?

Answer 26

increased diversity of gram + bacteria

Question 27

describe the different types of adhesions seen in dental plaque

Answer 27

1. cell-substratum adhesion - cell to enamel
2. homtypic cell - cell adhesion : E - A - A
3. heterotypic ; E-A-B

Question 28

which bacteria is involved in corn cob complexes?

Answer 28

strep sanguinis or crista

Corynebacterium