life cycle of biofilm
acquired pellicle immediately forming over the clean tooth’s surface and it’s composed of _______ & ________, thus protecting the enamel from acidic activity. Planktonic microbes attach via fimbriae, travel by using flagellas & can happen within hours. This stage is considered REVERSIBLE, hydrodynamic forces may make the bacteria detach and move somewhere else. What stage am I?
salivary glycoproteins & antibodies; what is the initial attachment stage 1
gram positive species that colonize the mouth? Gram negative bacteria that colonizes the mouth.
Streptococcus, peptostreptococcus, actinomyces, rothia, eubacterium, mycoplasm;
Neisseria, veillonella, campylobacter, aggregatibacter, prevotella, spirochetes of NUG
quorum sensing bacteria and proportionate host response, high microbial biomass, chronic resolution of inflammation
incipient dysbiosis
plaque accumulation → gingival inflammation → tissue destruction. Limitations:
Too simple
Doesnt explain…
Why most gingivitis doesnt become periodontitis
Why some periodontitis comes with little biofilm
Why a person might have a significant destruction at some sites but not others
nonspecific plaque hypothesis - historical
who are the early, secondary and late colonizers?
gram positive cocci - streptococcus sp. ; gram positive rods - actinomyces, rothia, eubacterium and gram negative rods ; gram negative rods and are motile!
escaping from the matrix and is an essential part of the life cycle of biofilm because it also allows for biofilm to spread and colonize to new surfaces. What stage am I?
stage 5 - dispersion
tooth associated bacteria? They can invade what? And are what kinds of bacteria?
S.mitis, S.sanguis, A.viscous; invade dentinal tubules; filamentous microbes, cocci, and rods
frank dysbiosis (pathogenic biofilm), disproportionate host response thus damage to CT and bone, high microbial biomass, failed resolution of inflammation, chronic nonresolving inflammation, & genetic behavioral and environmental risk factors are present
establish dysbiosis
increase in certain pathogens in plaque biofilm → periodontitis. The shift is from beneficial microbiota → pathogenic microbiota and gram pos (aerobic) to gram neg (anaerobic). Certain species appeared interdependent and different groups/complexes were assigned a color. What are these colors as well to the what hypothesis is this, and what do the colors mean?
specific plaque hypothesis; orange/red - periodontitis & yellow/green/blue/purple - gingival health
describe the sequence of bacterial colonization
microbial succession (dominant microbes) : early → secondary → late. Environmental modification: aerobic → anaerobic. Nutritional supply → saliva → GCF
microbes overpower the hydrodynamic forces that stick to the tooth and produce substances that attract other free-floating or ________ microbes. Composition of early colonizers affect what? What stage am I?
planktonic; affects who can attach later and the eventual development of biofilm. Stage 2 - permanent, irreversible attachment
tissue associated bacteria? Where do they adhere? And what kinds of bacteria are found here?
S.oralis, S. intermedius, P.ginigvalis, P. intermedia, T. forsythia, F. nuceleatum; epithelium; spirochetes and flagellated bacteria that can invade gingival tissue
genetically distinct bacteria attach to one another & composition of early colonizers affects who can attach later and thus the eventual development of biofilm
coaggregation
nonspecific bacteria accumulation → inflammatory response → changes to local environment → pathogenic bacteria able to grow more easily → damage to periodontal tissues. This hypothesis combines key features of specific plaque hypothesis and nonspecific plaque hypothesis. What is this hypothesis and what does it support?
ecological plaque hypothesis - current; sites with BOP, deep PD associated with high GCF flow → changes in environment favorable for pathogens
what are the 3 features that enable inhibiting microbes to tolerate stressors
blocking, mutual protection, hibernation, quiescence
bacteria that is firmly attached produces an extracellular protective matrix which is also called? This protects against host immune defenses and consists of glycolipids and bacterial DNA. What stage am I?
extracellular polymeric substance; stage 3 - maturation phase I matrix formation
what’s the benefit of bacteria residing in biofilm?
ECM secreted by microbes in biofilm made of proteins and sugars. Allows for microbes to be more tolerant to harsh conditions & more resistant to:
Host immune system
Antimicrobial treatment
Environmental stressors
release of small proteins (signaling molecules) to communicate. Used to signal new bacteria to join biofilm, and signal formation of new matrix. Sharing of information between bacteria which is critical for growth and survival. This allows for interspecies communication and allows for them to adapt rapidly to a changing environment
quorum sensing
pathogenic microbes in biofilm → uncontrolled host inflammatory response → damage to periodontal tissues. Pathogens are not the direct cause of destruction and it recognizes contribution of host factors on periodontitis initiation, severity, and progression. What is this hypothesis and what does it support?
microbial homeostasis-host response hypothesis - current; microbe population associated with health remains stable over time, equilibrium. Host immune response → tissue destruction
complex, multilayered with gram staining effects peptidoglycan layer in the cell envelope - classifying bacteria in gram negative and positive. What colors resonate with each kind of staining? What is different about about gram negative bacteria?
what is the bacterial cell envelope? Purple gram positive and pink for gram negative. Gram negative has a thicker outer membrane because it is composed of lipopolysaccharides (an endotoxin and major virulence factor)
what happens during the microcolony formation? And how is mature biofilm internally organized?? ALSO WHAT STAGE AM I!!
cell division and recruitment, microbial blooms which are periods of specific species grow rapidly and away from the tooth. mushroom shaped colonies (pedunculated) form and are very diverse communities. Exchange genetic material and nutrients; multilayered, fluid channels, cell-cell communication (direct & chemical), bacterial signaling via quorum sensing - release of small proteins! Stage 4 - maturation phase II - mushroom shaped microocolonies
Socransky’s specific plaque hypothesis says that these certain species of bacteria appear interdependent?
T.forsythia, P.gingivalis, T.denticola
a portion of the population may lay dormant until environmental conditions are favorable! Some antibiotics are effective against metabolically active bacteria, thus ineffective against hibernating bacteria.
hibernation, quiescence
specific bacterial species → shift from symbiosis to dysbiosis → triggers uncontrolled host response → damage to periodontal tissues. Builds on the microbial homeostasis-host immune response hypothesis. What bacteria is the possible starter of the shift from beneficial to pathogenic? What is this hypothesis and what does it support?
P. gingivalis; keystone pathogen-host response hypothesis - current; no evidence that specific pathogens directly cause tissue damage and no evidence to show that the host inflammatory and immune response can cause tissue damage
who's the most precious
hazel