L33,34 Dental caries and dental plaque

Question 1

what is the initial step to infection and invasion of tissue ?

Answer 1

adherence of a microbe to an oral surface

Question 2

what are the steps to biofilm/ plaque formation ?

Answer 2

1.) formation of pellicle : glycoprotein covers all surfaces ( comes from saliva and bacterial products / debris)

2.) transport of microorganisms through saliva + generation of weak physiochemical forces

3.) pioneering microbial colonization and irreversible attachment ( weak interactions become irreversible due to adhesion between microbe and pellicle )

4.) coaggregation / coadhesion and microbial succession : cell-cell recognition of genetically different organisms : results in corncob structures

5.)mature biofilm formation ( matrix )

6.) detachment

Question 3

whats the function of the pellicle ?

Answer 3

protective barrier that prevents tissue desiccation (dryness) + provides substrate to which bacteria attach too

Question 4

what are the species responsible for INITIAL microbial colonization ?

Answer 4

mainly streptococci , especially mitis group ( S. sanguinis , S. oralis , S.mitis )

also actinomyces , haemophilius , and neisseria

Question 5

when oral health decline , there’s a transition in the type of bacteria in the oral cavity . from what to what?

Answer 5

from gram positive faculatative anaerobic species to gram negative obligate anaerobes ( fusobacterium , cocci , rods, filamentus , spirils , spirochets )

Question 6

which combitnation of microorganisms result in corn cob apperance ?

Answer 6

coeynebacterium + streptococci

eubacterium + veillonella

Question 7

which bacteria acts as an important bridge between early and late colonizing bacteria ?

Answer 7

fusobacterium

Question 8

which species have the ability to detach in order to colonize other regions ?

Answer 8

S. oralis
streptococcus mutans

Question 9

what are the mechanisims linking oral infections to secondary systemic infections ?

Answer 9

1.) metastatic infection : microbes enetering circulation through breach in oral cavity ( infective endocarditis )

2.) metastatic injury : products of bacteria endering cardiovascular system in individuals suffering from periodontitis

3.) metastatic inflammation : immunological injury due to oral organisms entering blood stream , reacting with circulating specific antibody( forming complex) and leading to immune mediated disease

Question 10

dental carries require SUPRAgingival plaque formation to occur

Answer 10

SUPRA

Question 11

What is the major group of organisms causing dental carries ?

Answer 11

S. mutans

Question 12

which organisms is responsible for progression of carries especially in dentine ?

Answer 12

lactobacillus

Question 13

what organisms is associated with root surface caries ?

Answer 13

actinomyces

Question 14

which organism requires lactate to grow ?

Answer 14

veillonella

Question 15

which organism does not metabolize normal dietary carbohydrates ?

Answer 15

veillonella

Question 16

veillonella uses lactate produced by other microorganisms and converts it into:

Answer 16

range of weaker organic acids : propronic acids

Question 17

selective media for :
- S. mitis
-lactobacillus

Answer 17

S. mutans : mitis salivarius bacterium agar / broth

s.lactobacillus : ragosa SL agar