Lectures # 8-9 Oral Ecology & Biofilm Flashcards
What are biofilms?
Matrix-enclosed bacterial populations adherent to each other and/or or to surface or interfaces, bacteria products, and salivary proteins.
As long as these ________________, bacterial ________________ are fed well and maintained properly they generally cause little problem
- normal flora
- biofilms
Note: If not fed properly (too many sweets, poor hygiene) disease can follow.
What is the new thinking of microbial colonization of living host?
Microbes do not live as separate individual colonies but rather as complex communities called biofilms.
What are the basic biofilm properties?
1) cooperating communities of different microorganisms
2) Microorganisms are arranged in microcolonies
3) Microcolonies are surrounded and attached together by protective matrix
4) Within and between, the micro colonies are differing environments
5) Microorganisms have primitive communication system
6) Microorganisms in biofilms are more resistant to antibiotics, antimicrobial and host responses
As the plaque in the mouth frows thicker it becomes less _________ to _______ and ______________
- permeable
- oxygen
- saliva
Thicker plaque builds up what?
- HIGHER concentrations of TOXIC products, acids, and inflammatory bacterial components.
- These changes with increased thickness and density result in growth of different species and changes the character of the dominant plaque organisms.
Which species are the dominant species of the biofilms?
Step and Actinomyces
What changes can be observed with build up of plaque and poor hygiene?
- Increased inflammatory materials (e.g, FMLP, cell wall products, and probably most importantly LPS) around the gingival crevice causes, gingivitis and eventually a pseudopocket and then real pockets and increased growth of gram - (best suited for anaerobic ,CO2 rich, asaccharolytic enthronements of deeper pockets.
- Eventually this can lead to the loss of attachment we call periodontal disease, and are available to infect the tooth pulp if the hydroxyapatite shell is breached.
What benefits can the normal flora provide?
-Bacteria that exist in “equilibrium” w/ the host and generally do not cause disease.
(inhibit the colonization of pathogenic organisms)
(Inhibits colonization of pathogenic microorganisms, produce vitamins that are required by the host.)
What is supplemental flora?
Found in a minority of the population where they generally act like normal flora
Example: Women that carry S. aureus in their vaginal flora where it doesn’t cause disease
What does transient flora consist of?
- Microorganisms that are brought to the area from somewhere else (via contamination?)
- They almost always have a difficult time colonizing and competing in the area, generally cleared within hours or days.
Microbial flora falls into what 3 major groups?
1) Normal flora
2) Supplemental flora
3) Transient flora
What are the roles of normal flora?
1) Competition
2) Vitamin K synthesis
3) Immune stimuli: LPS–> GUT INCREASE DTH, etc
4) Source of opportunists
5) Etiologic agents of caries & chronic inflammation periodontal disease
What is oral ecology?
Colonization of the oral cavity and formation of plaque biofilm
During birth a child’s oral cavity is colonized by what?
Vaginal microorganisms that can survive in the mouth (e.g., Candida, Lactobacillus, etc )
-Baby continues to be colonized by other microbes from “kissing” etc.
When the teeth erupt into the mouth, what are the 4 niches that develop?
1) Fissures
2) Approximal surfaces
3) smooth surface
4) gingival-tooth surfaces
Note: This allows dental plaque biofilm to first form
Plaque bacteria must be able to _______ very well to the __________.
- adhere
- tooth surface
(they must not be washed away by saliva, or food & drink)
Some bacteria like _______ finally find a place wehre they can colonize and compete well with the appearance of the deep pits & fissures of the 2nd molars.
-Strep mutans
With the eruption of the 2nd molars, the dental plaque ecology becomes relatively _______
-stable
What is the window of step. mutans infectivity for 2nd molars?
19-33 months
What are some life changes the “stable” plaque biofilm does evolve with ?
1) Puberty
2) Major diseases
3) Oral care
4) home environment
Where in the mouth do most bacteria call home?
Tongue papilla and crypts (large surface area that is protected from the flushing of saliva) Also non-keratinized
After teeth erupt any bacteria that can adhere strongly to the pellicle (dental pellicle, or acquired pellicle) ________ ?
Examples?
-Find a place to live
Examples: S. sanguinis and S. mitis
Pioneer species provide further binding sites for secondary colonizers in the _________?
- Growing plaque biofilm
- More bacteria will colonize when plaque thickens and it becomes hard for saliva washing.
Which bacteria can’t hold to saliva pellicle?
-Salivarius
not dependent on the enamel surface for colonization like mutans is
Most of the early oral colonization of babies likely comes from _______
-Their mother (or primary care-giver)
Note: This is why there is a direct link w/ mom’s S. mutans and baby’s
Many bacteria require the hard surface of teeth to effectively ________________________________?
-Colonize and remain in the mouth
______________ is a pioneer species in tooth plaque development? When do they appear?
Strep. sanguinis, which DO NOT appear until after the teeth erupt
___________, which also require teeth hard surfaces to effectively colonize, typically first appear in LARGE numbers when the pits & fissures of the 2nd molar emerge.
-When do they emerge?
- Step. mutans
- about 19 months
Oral bacterial species are not evenly _________ , but rather find their own ___________
- Distrubuted
- ecological niche
Which microorganism (s) is present in high proportions in the saliva and tongue?
Srep. salivarius
Which microorganism (s) is present in high proportions in the supraginigival plaque?
Mostly Gram +:
- S. sangius** (highest)
- S. milleri
- S. mutans
- Actinomyces
Note: Very few gram (-)
Which microorganism (s) is present in highest proportions in the subginigival plaque?
Gram (-) species:
1) Treponema sp.
2) Fusobacterium
Note: Very few gram (+)
Why do species that do well are supragingivally are different from the subgingival flora?
Because they can adhere to the surface and not be rinsed off.
What makes subgingival flora different?
Being able to live on protein substrate, and in the absence of oxygen.
What is the pH difference between Supragingivally and subgingival flora?
Supragingival = Slightly ACIDIC b/c it eats carbs(FERMENTED) and makes it more acidic
Subgingival= Slightly BASIC b/c it eats proteins and has NH4+ as a waste product
What are some characteristic differnces between Supragingivally and subgingival flora?
- Morphology
- Oxygen relationship
- Motility
- Diseases
Supragingivally:
- Morphology = Coccii, Branched RODS
- Oxygen relationship = Facultative & Some Anaerobes
- Motility = FIRMLY ADHERENT to plaque
- Diseases = Caries & Gingivitis
Subgingival:
- Morphology = Mostly Rods & Spirochetes
- Oxygen relationship = MOSTLY Anaerobes & Facultative
- Motility = Adherence LESS pronounced with many motile forms
- Diseases = Gingivitis, Periodontitis + ENDO
What happens when the plaque on the biofilm matures?
It begins to exclude the saliva, oxygen, and some food sources CAUSING bacterial growth to SLOW and pathologies to INCREASE.
Note; Even with careful plaque removal plaque regenerates rapidly in a coordinated manner reforming the biofilm
Dr. Harold Loe developed a model to study the effects of what?
Of poor oral hygiene (“not mowing the lawn) and found that an INCREASE in anaerobic forms & rods, as well as an increased total bacterial mass, which correlated w/ the appearance of gingivitis.
Note: This was REVERSIBLE after 21 days of non-brushing (the experimental subject stopped brushing for 21 days)
What was the summary of Dr. Harold Loe model?
- As time went on the % of gram-negative Anaerobic bacteria INCREASED, while the number of “Aerobic bacteria” DECREASED
- At the SAME time the gram (- )’s were INCREASING so was GINGIVITIS.
**Once the oral hygiene resumed numbers revered to normal & gingivitis reversed.
As plaque INCREASED in complexity and density what develops?
A FOOD CHAIN, where some bacteria end products provide the substrate or conditions beneficial for other bacteria.
__________ bacteria can live off the lactic acid produced by _________ and ______________.
- Veillonella
- Strep and Actinomyces
***NOTE: This may be beneficial by removing excess cariogenic acids
In supragingival plaque the food chain starts with the bacteria that can metabolize the ________________
Food we eat (SUGARS are the MOST important here)
_______________ are the primary feeders at this stage
Step. species
Note: Numerous bacteria utilize the secreted end products of the “primary feeders”
In Subgingival plaque the primary food source is ?
PLASMA PROTEINS in the gingival fluid
Who are the “primary feeders” subgingivally?
Various ASACCHAROLYTIC, GRAM (-) RODS
In Supragingival, who are the “vigilante flora”?
They displace primary colonizers
- Bactericins
- NH4
- H2S
How does the Plaque food chain look Supragingival?
1) Begins with the Pioneer species (STREP)—> pelical (biofilm) proteins
- Take in O2, Carbs, and Saliva
2) “Hangers on” (Actinomyces)
3) “Secondary feeders” (Veillonella, Nisseria)
- Use Lactate end product
- Remove lactic acids.
- Make Acetate & Formate
4) “Vigilante flora”
How does the Plaque food chain look in the Subgingival?
-Begins with the “CLIMAX community” (Gram (-) Rods & spirochetes)
- End product Acetate: Used by
- Fusobacteria
- Bacteroides
- peptococcus
- -End product Formate: Used by
- Camptlobacter
- Wozinella
What is MENADIONE?
“Vitamin K precursor”
-Acts as a fertilizer (vitamins) for carries bugs
Normal host resistance blocks progression at most sites, even without “advanced oral hygiene” Most advanced perio-pockets are filled with_________?
Microorganisms (bugs) WITHOUT ACTIVE DISEASE
