plaque and periodontal microbiology Flashcards
what are the classifications of plaque?
supragingival and subgingival
composition of plaque as a biofilm.
microcolonies of bacteria and matrix or glycocalyx
matrix is mostly what?
water and aqueous solutes
the organic part of matrix is generally what?
mixture of exopolysacharides, proteins, salts, and cell materials
the inorganic component of matrix is what?
mostly calcium and phosphorus
what do the exopolysacharides do?
maintain integrity of biofilm
whats roles does the matrix play?
protects microbes, prevents them from desicating, acts as a buffer
what allows cells to aggregate?
fimbria, pilli, bacterial capsule
whats quorum sensing?
involves regulation of expression of specific genes through the accumulation of signaling compounds that mediate intercellular communication
3 phases of plaque formation
pellicle formation, initial adhesion, colonization
aquired pellicle
has peptides, proteins and glycoproteins and attaches to all the hard and soft tissues( formation starts within a few minutes of oral hygiene)
what are the 2 layers of the pellicle
thin basal layer, thick globular layer
which color are the primary colonizers?
yellow, green, purple, blue
can periodontal pathogens fulfill kochs postulates?
no!
what are socranskys postulates?
association-pathogens are found in higher number in diseased people
elimination- elimination of pathogen makes disease go away
host response- there should be evidence of a host response to a specific pathogen that is causing tissue damage
virulence factors- pathogen may function to damage the host tissues
animal studies- pathogen affects animals as well
indigenous theory of periodontal bacteria origin
resident flora overgrow and become opportunistic pathogens causing periodontal diseases
exogenous theory or periodontal bacterial origin
plaque accumulations dont doesnt itself cause problems. The patient must also become infected with specific periodontal pathogens that are transmitted from another source
Therapy for indigenous therapy
complete elimintation is impossible. You just have to suppress them so the normal host immune function can spark into action
therapy for exogenous therapy
complete elimination from oral cavity via antibiotics
non-specific plaque hypothesis
the quantitiy of the bacteria is what causes the problem.
whats wrong with the non-specific plaque hypothesis?
it describes gingivitis but not periodontitis. ( not all gingivitis progresses to periodontitis)
specific plaque hypothesis
specific bateria produce noxious products which mediate periodontal destruciton
what about the microbial shift hypothesis?
falls within the specific plaque hypothesis. A shift in beneficial commensal species to an increase of specific pathogens which are associated with periodontitis
Ecological plaque hypothesis
environmental changes favor the growth of gram negative and proteolytic species of bacteria which cause inflammation and tissue changes. This cause greater degree of tissue damage and periodontitis
A. actinomycetemcomitans
5 serotypes, associted with LJP, important in refractory periodontitis, invades gingival connective tissue. produces leukotoxin
p. gingivalis
virulence factors are fibrial adhesins, LPSs capsule, collagenase and trypsin like enzymes
P intermedia
p nigrescens is a subgroup which is more virulent.
