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Flashcards in History and Science Biofilms Deck (29)
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1

Dental Plaque as a Biofilm

 

  • ¡Dental plaque is an oral biofilm composed of ____bacteria per ____
  • ¡Teeth form a unique surface in the human body
    • ____
    • ___
    • ____
  • ____ is key for plaque initiation
    • ___________ remove ____ bacteria
       


¡Dental plaque is an oral biofilm composed of 108 bacteria per milligram
¡Teeth form a unique surface in the human body
§Non-shedding
§Fluid
§Non-sterile environment
¡Adherence is key for plaque initiation
§Saliva flow/shear forces remove planktonic bacteria
 

2

General Plaque Concepts

 

  • ¡Supragingival plaque-forms_______
  • ¡Subgingival plaque-forms_______
  • ¡Calculus- plaque that becomes ____
    • ___%_______________
    • ____% ____________
  • ¡Formation of plaque associated with_______
    • ____ associated with ____
    • _______associated____
       


¡Supragingival plaque-forms above gumline
¡Subgingival plaque-forms below gumline
¡Calculus- plaque that becomes calcified
§80% mineralized material
§20% organic material
¡Formation of plaque associated with oral diseases
§Caries associated with supra-gingival
§Gum diseases associated subgingival
 

3

Early studies of plaque composition
1683

 

Dental Plaque: 

 

Healthy plaque: 

white matter thick as if it were batter

 

Many animicules moving

Biggest sort: strong swif motion

2nd sort spun round like a top (much more in number)

4

Healthy Plaque

5

Antique plaque continued

 

 

He repeated observations on 2 old men who had never cleaned their teeth

Great company of animalcules

Biggest sort: bent body into curves on going fwd

Such enormous number that all water seemed to be alive

6

Gross

7

Germ Theories of Disease
1800’s

 

Microorganisms, which are too small to be seen without the aid of a microscope, can ____ ____ ___ and cause____ ____

•___ ____ ____


___ ____ ___

  • •Bacteria are associated with ___ ___
  • _____of wounds improves ____
  • Washing ___ and ____ before surgery is a   good idea
  • ___ and___ ______


___ _ ____ 
_____ _____ ____ of _____
___ ___ of ____
•“Micro-organisms of the human mouth: the __ and ___ diseases which are caused by then ” published ___

Microorganisms, which are too small to be seen without the aid of a microscope, can invade the body and cause certain diseases

•Joseph Jackson Lister
•Inventor of compound microscope

•Baron Joseph Lister
•Bacteria are associated with wound infections
•Disinfection of wounds improves healing
•     Washing hands and instruments before surgery is a   good idea
•    Listerine and Listeria monocytogenes

•Willoughby D. Miller, DDS.
•Chemo-parasitic theory of caries
•Focal Theory of Infection
•“Micro-organisms of the human mouth: the local and general diseases which are caused by then ” published 1890


 

8

What changes occur in dental plaque to produce gingivitis?
 

People started to believe that plaque

But they thought that

___ matters ___ doesnt 

People started to believe that plaque causes oral disease.

But they thought all microbes were bad and caused disease

They thought it type of bacteria didn't batter, only number

9

Experimental Gingivitis Model

 

Start with

No __ ___ until ____ ____

Measure ___ and ___ of bacteria at ___ ___ using ___ ___

Once gingivitis develops, ___________

Continue to observe bacteria until 


§
§
§Start with healthy individuals with no gingivitis
§
§No oral hygiene until gingivitis develops
§
§Measure number and type of bacteria at gingival margin,   using Gram Stain
§
§Once gingivitis develops, return to standard oral hygiene   measures
§
§Continue to observe bacteria until gingival health returns
 

10

Results from Experimental Gingivitis Study

  • Gingivitis develops in ____ days
  • Bacterial flora goes through ___ stages after cleaning stops
    • ____ days :
      • §Bacteria are mainly _________
      • ___ ____
    • ___ days:
      •  
      •  
      •  
    • ___  days :
      •  
      •  
      •  
      •  
      •  
      •  
  • •After cleaning resumes
    • §Health returns within _ days
    • §Flora returns to mainly___
    • §No ___, ____ bacteria§
    • §

Gingivitis develops in 6-15 days

•Bacterial flora goes through 3 stages after cleaning stops
§1-2 days :
§Bacteria are mainly Gram-positive cocci
§few leukocytes
§2-6 days:
§Gram-positive cocci
§Long filamentous rods
§some leukocytes (WBC)
§6-15 days :
§Gram-positive cocci
§Long filamentous rods
§Spirochetes/vibrios (long and short motile, curved rods)
§Gram-negative rods
§gingival bleeding
§heavy leukocyte infiltration
§
•After cleaning resumes
§Health returns within 7 days
§Flora returns to mainly cocci
§No spirochetes, Gram-negative bacteria§
§

11

Modern Plaque Studies

 

  • ¡The EGM study showed:
    • §Early colonizers are mostly _________
    • §Intermediate stage of _________
    • §Late stage of mostly ________
  • ¡Modern studies were done to determine ___ ___, ____ ____ 
  • ¡Modern Molecular Microbiology
    • ____ ____ ____ _____
    • ____ ____


¡The EGM study showed:
§Early colonizers are mostly Gram positives, cocci
§Intermediate stage of long filamentous bacteria
§Late stage of mostly Gram  negative bacteria
¡Modern studies were done to determine species involved, biofilm appearance 

¡Modern Molecular Microbiology
§16S rDNA Direct sequencing
§Confocal Microscopy
 

12

16s rDNA analysis of DNA

 

  • ¡Many oral bacteria can not be __________
    • §Instead we detect them through ___
  • ¡16s is a ribosomal sub-unit ___
  • ¡Highly ___ at the ___ level
  • ¡Surrounded by ___ ___ ___, allowing ___  of ___ ___ 16s genes in same sample
  • ¡Used to identify over ____ species of bacteria in plaque
  • ¡Most___ __ __ ____ ___
     


¡Many oral bacteria can not be cultured in the laboratory
§Instead we detect them through DNA
¡16s is a ribosomal sub-unit gene
¡Highly unique at the species level
¡Surrounded by highly conserved DNA, allowing PCR of many different 16s genes in same sample
¡Used to identify over 900 species of bacteria in plaque
¡Most accurate method to identify species
 

13

Species specific 16S region

14

Bacterial 16s DNA

15

How many species of bacteria are in the oral cavity?

1179

24% named

8% cultured but not named

68% cant be cultured

16

Caries vs No caries?

Diff community of bacteria in healthy teeth and in disease

Its a whole community shift not just 1 or 2 species

17

Graph

Healthy Implant, Healthy Tooth , Periodontitis and Peri-implantitis all have different communities of bacteria

Peri-implantitis in bw Healthy implant and Periodontitis

18

19

Confocal Microscopy

 

  • ___ images of biofilms
  • ¡Allow biofilm to form on___ ___
  • ___ bacteria with___ ____
  • ¡Use confocal microscope to image
    • §The confocal takes images in ____
    • §For a thick sample, it may take _____ images
    • §Computer software assembles the ____ into a ______
  • ¡Can study ___ ____at once, to study bacterial _____, ___ _____
     


¡3D images of biofilms
¡Allow biofilm to form on enamel chip
¡Stain bacteria with fluorescent probes,
¡Use confocal microscope to image
§The confocal takes images in “slices”
§For a thick sample, it may take 10-100 images
§Computer software assembles the slices into a 3D stack
¡Can study several species at once, to study bacterial interactions, structural features
 

20

16S rDNA: What species are in plaque in health, gingivitis

 

21

22

16s Results

23

24

Microscopy Results


¡Bacterial complexes biofilm on the tooth in _____ ____ _____
____
____ by ___ colonizers
_____ by ___/____ colonizers
§Composition of ___ plaque _____ health
§Host factors may act to ____ _____of mature biofilms 
 


¡Bacterial complexes biofilm on the tooth in an orderly fashion
§Pellicle
§Adherence by early colonizers
§Co-aggregation by bridging/late colonizers
§Composition of mature plaque influences health
§Host factors may act to limit composition of mature biofilms 
 

25

Adhesion and Co-aggregation Basics


¡All oral bacteria that biofilm have ___ _____ that they recognize
§Will adhere to ____ ____
§Will ____ ____ with ____ ____

§Provides ____ nature to plaque formation
¡Use__-_______ ____to test for specific pairs of bacteria that co-aggregate 
 


¡All oral bacteria that biofilm have specific receptors that they recognize
§Will adhere to certain molecules
§Will co-aggregate with specific bacteria
§Provides temporal nature to plaque formation
¡Use co-aggregation assay to test for specific pairs of bacteria that co-aggregate 
 

26

Pellicle adhesions

  • ¡Pellicle forms within ____ on a clean tooth
  • _____ from saliva
  • §Provides specific___  for ____  ___ers
  • __________
    • §S. gordonii
    • §A. naeslundii
  • ______
    • §F. nucleatum
  • ________
    • §S. gordonii
    • §S. oralis
    • §S. mitis
  • §S. sanguinis
     


¡Pellicle forms within seconds on a clean tooth
§Proteins from saliva
§Provides specific receptors for early colonizers
¡Proline-rich proteins
§S. gordonii
§A. naeslundii
¡Statherin
§F. nucleatum
¡Mucins
§S. gordonii
§S. oralis
§S. mitis
§S. sanguinis
 

27

Co-aggregation

 

  • _____-_____ interactions between bacteria allow the plaque biofilm to _____
    • _______
    • _____ ______
      • ▪Can ____________
      • ____ bacteria
         


¡Adhesin-receptor interactions between bacteria allow the plaque biofilm to mature
§Streptococci
§Fusobacterium nucleatum
▪Can coaggregate with almost all other oral bacteria
▪Bridge bacteria
 

28

Metabolism also plays a role

  • •Early colonizers/ bridge bacteria ____ the ___ ____
    • §Reduce ____
    • §Begin ____ ___ ____
    • §Provide___ ___ for later colonizers
  • •Late colonizers
    • ____/_____complex
    • §Gram-____
    • Shapes ___ and ___
    • O2 status
    • §Use ____ as nutrient
    • ____-gingival plaque

  •  


•Early colonizers/ bridge bacteria change the oral environment
§Reduce Oxygen
§Begin breaking down food
§Provide binding sites for later colonizers
•Late colonizers
§Orange/red complex
§Gram-negative
§Rods and Spirochetes
§Strict Anaerobes
§Use proteins as nutrient
§Sub-gingival plaque
¡
 

29

Summary

  • ¡The ____-____ ____ link has been investigated over centuries
    • _____
    • ___ ____
  • ¡Bacterial communities are important for _____ and ____ in the oral cavity
  • ¡Bacterial ____ and the ___ ____ determine health status
    • §Gingivitis (orange complex)
    • §Periodontitis (red complex)
  • ¡Plaque forms in an _____ ____
    • _____/_____
    • §Driven by ____/_____
    • ____ relationships
  • ¡Pioneer bacteria ___ the environment for the middle and late colonizers


¡The plaque-oral health link has been investigated over centuries
§Microscopy
§Molecular techniques
§
¡Bacterial communities are important for colonization and survival in the oral cavity
§
¡Bacterial communities and the host response determine health status
§Gingivitis (orange complex)
§Periodontitis (red complex)
 


¡Plaque forms in an orderly fashion
§Structurally/temporally
§Driven by adhesion/coaggregation relationships
§Metabolic relationships
§
¡Pioneer bacteria prepare the environment for the middle and late colonizers
¡
§
¡