Plaque Flashcards
what are the properties of a biofilm?
spatially organized in a 3D structure
bacterial cells enclosed in an extra cellular matrix
increases habitat range of individual bateria
what is the organic matrix of plaque?
30%
host and bacterial products
gingival area proteins from exudate
what does the composition and behavior of organisms in the matrix depend on?
site
time
individuals
what is the acquired pellicle?
layer of material acquired by a clean tooth
mucins/salivary glycoproteins/minerals/immunoglobulins
occurs in seconds
reaches a peak - composition/form can still change
removed by positive friction
where do bacteria attach to?
attach to pellicle not enamel
composition of pellicle?
mucins PRP's statherin amylase lysozyme albumin immunoglobulins GTF's glucans
what is initial attachment?
reversible/non specific interaction
long range - van der waals
short range - hydrogen bonding
how does bacteria adhere to the pellicle?
ordered accumulation - pioneer to climax community
what are glucans?
glucose polysaccharides with glucose molecules linked by 1-3 a or 1-6a bonds
what are dextrans?
water sol glucans with 1-6a links
what are mutans?
water insol glucans with 1-3 and 1-6 a links
what are fructans?
fructose polysaccharides of fructose molecules joined by 2,6 B or 2,1 B links
what are levans?
fructans with many 2-6 links
what are adhesins?
specific molecules on bacterial surface
recognize specific ligands or receptors on tooth surface
often associated with fimbrae
what are lectins?
sugar binding proteins
recognize carbohydrate groups and bind them
often associated with fimbrae
what are fimbrae?
hair like proteinaceous appendages
adhesion to enamel/pellicle
adhesion to other bacteria
stages of plaque development?
clean enamel surface 2 seconds - pellicle formation 1 min - pioneer bacteria 2 hours - micro colonies and extra cellular polysachh. 2 hours on - biofilm development 48 hours - mature plaque
what bacteria appear in 24 hours?
gram positive and negative cocci
negative - oralis group
positive - neisseria
after 24 hours what bacteria predominate?
strep - 95%
S.sanguinis most common
what is stage 1 of succession?
strep attach to acquired pellicle
what changes are seen in the biofilm in the first week?
increased diversity of gram positive bacteria
pioneer species reduce
actinomyces and anaerobes increase/strep decrease
what is the second stage of succession?
strep is joined or replaced by actinomyces
what is stage 3 of succession?
gram negative species fusobacterium joins
what are the three types of adhesion seen in plaque?
cell substratum adhesion
homotypic
heterotypic
