M13 plaque Flashcards
define plaque
microbial community found on the tooth surface
biofilm and not planktonic growth
what is a biofilm?
name given to microbial communtites attached to a surface
what are the properties of a typical biofilm?
spatially organized in a 3d structure
bacterial cells enclosed in extracellular matrix
increases habitat range of individual bacteria
what is organic matrix made up of?
glycocalyx or extracellular polymeric substances
30% total volume
define acquired pellicle and list its contents
The layer of material acquired by a cleaned tooth
- mucins
- salivary glycoproteins
- minerals and immunoglobulins
where does bacteria attach to?
do not attach/adhere directly to the enamel, they attach to the pellicle
what forces are used for long range weak interactions?
van der waals - 100 nm
what forces are used for short range interactions?
less than 2nm
hydrogen bonding
what is the calcium bridge in a salivary glycprotein attached to?
bacterial cell wall which is negatively charged
enamel has a weak positive charge so it doesnt go to it
features of lipoteichoic acid/?
amphipathic material
gram +ve cell wall
- binds blood group substances found in pellicle
what allows initial attachement to become adhesion?
extracellular polysaccahride - strong system
- irreversible attachement
- glucans or fructans
what is special about the sucrose bond?
sucrose - supports polysaccharide synthesis
which enzymes is used to produce glucans?
glucosyltransferase (GTF)
what enzyme is used to produce fructans?
fructosyltransferase (FTF)
extracellular DNA (eDNA)
can be major components of EPS
what does DNAse do?
releases bacteria and inhibits biofilm formation
what are adhesins?
specific molecule on bacterial surfaces which recognise specific ligands or receptors on tooth surface - fimbrae
what are lectins?
sugar binding protein which recognise carbohydrate groups and bind them –> fimbrae
how does fimbrae attache to pellicle?
'’hair like’’ proteinacous appendages
what bacteria posses fibrils and allow coadhesion?
streptococcus crista
describe colonisation and biofilm formation
- short range adhesion
- growth and metabolic activity
- microcolony formation
- co-aggregation/ co-adhesion
climax community
which gram +ve plaque is first to develop within 2 hours?
oralis mits and sanguinis
which gram -ve bacteria is first to develop within 2 hours?
neisseria and haemophilus
which streptococci dominate for 24 hours?
S.sanguinis
what happens in stages of succession?
- streptococcus spp. attach to acquired pellicle
- streps replaced by actinomyces
- gram -ve specis eg fusobacterium
what are the changes seen during 1st week?
increased diversity of gram + bacteria
describe the different types of adhesions seen in dental plaque
- cell-substratum adhesion - cell to enamel
- homtypic cell - cell adhesion : E - A - A
- heterotypic ; E-A-B
which bacteria is involved in corn cob complexes?
strep sanguinis or crista
Corynebacterium
