Biofilms and periodontal disease : risk factors

Question 1

What does lack of oral hygiene lead to?

Answer 1

initial plaque formation

Question 2

Where does the initial plaque formation take place?

Answer 2

along the gingival margin & from interdental space, which further extends in cervical direction along the root surfaces

Question 3

What is the ecological shift of the biofilm?

Answer 3

there is a transition from the early aerobic environment characterized by Gram+ve facultative species to a highly oxygen- deprived environment in which Gram-ve anaerobic microorganism predominate, leads to progression of periodontal disease

Question 4

What are examples of examples of gram-negative anaerobic bacteria which predominate in biofilms?

Answer 4

fusobacteria, filaments, spiral forms and
spirochetes

Question 5

What type of surface provides an opportunity for microorganisms to attach?

Answer 5

Rough intraoral surfaces (crowns, implant abutments, denture bases) accumulate & retain more plaque & calculus in terms of thickness, area & colony forming unit.

Question 6

What can decrease rate of plaque formation?

Answer 6

Smoothing intraoral surfaces decreases rate of plaque formation

Question 7

What is the threshold for surface roughness which bacteria can adhere to surfaces?

Answer 7

{Ra 0.2 micrometers}, above which bacterial adhesion is facilitated

Question 8

Where does early plaque formation occur faster?

Answer 8

• In lower jaw, compared to upper jaw
• In molars areas
• On buccal tooth surfaces, compared to oral sites.
  (Especially upper jaw)
• In inter-dental regions compared to buccal or oral surface

Question 9

What is virulence?

Answer 9

degree of pathogenicity of a microorganism
Microbial invasion

Question 10

What are 3 factors which influence bacterial virulence?

Answer 10

microbial invasion
enzymes
endotoxins

Question 11

What are 2 ways which microbial invasion can influence virulence of bacteria?

Answer 11

• True invasion (i.e. microbial colonization and proliferation within the tissues)
• Displacement or translocation of bacteria from the biofilm into the soft tissues.

Question 12

What are examples of enzymes which create virulent bacteria?

Answer 12

proteases
leukotoxin

Question 13

What is the role of proteases and virulence?

Answer 13

degrade collagen leads to the tissue destruction

Question 14

What is an example of a protease which breaks down collagen?

Answer 14

Arg1

Question 15

What bacteria produces Arg1?

Answer 15

P. gingivitis

gram negative

Question 16

What is the role of endotoxin and virulence?

Answer 16

a PAMP of a lipopolysaccharide on the outside of gram-negative bacteria and induce an immune inflammatory response

Question 17

What is an example of an endotoxin?

Answer 17

LPS of gram-negative bacteria

Question 18

What strain are periodontal bacteria?

Answer 18

negative

Question 19

What are examples of virulence factors of P. gingivalis?

Answer 19

Question 20

What are examples of virulence factors of Aggregatinbacter actinomycetemcomitans?

Answer 20

Gram-negative, facultative anaerobe, nonmotile bacterium