A biofilm is _______________.
A. a loose collection of free-floating bacteria
B. a calcified collection of bacteria that cannot be easily removed
C. an acellular translucent, homogeneous film covering moist surfaces
D. a well-organized, cooperating community of microorganisms
A positive use of biofilm is _______________.
A. detoxification of human waste products
B. lining on indwelling catheters
C. coating in fish tanks
D. layer in dental unit water lines
The specific plaque hypothesis would support the following belief:
A. "Where there is more plaque, there is more disease."
B. "All bacteria in plaque contribute to gingivitis and periodontitis."
C. "Calculus plays a major role in causing periodontitis."
D. "The presence of bacterial plaque is necessary to develop periodontal disease, but not sufficient to guarantee disease."
Researchers currently believe that all of the following bacteria play a role as periodontal pathogens EXCEPT:
A. T. pallidum
B. P. gingivalis
C. A. actinomycetemcomitans
D. B. forsythus
Scientists have had difficulty in identifying specific periodontal pathogens because _______________.
A. periodontal pockets contain both pathogens and non-pathogens
B. the different bacteria in periodontal pockets require different culture media
C. periodontal disease goes through active and quiescent periods
D. All of the above.
To study biofilms, scientists have used newer microscopy techniques such as _______________.
A. wet mount microscopy
B. scanning electron microscopy
C. confocal scanning laser microscopy
D. smear microscopy
Which of the following characteristics is typical of a bacteria in a biofilm?
A. Bacteria communicate with each other by sending out chemical signals.
B. Bacteria are dispersed more or less evenly through the plaque.
C. The environment surrounding bacteria consists of the same or similar pHs.
D. Bacteria exist in isolation from each other.
Given the nature of bacteria in biofilm, which techniques may be helpful in controlling oral biofilms?
A. Keep bacteria from communicating with each other.
B. Prevent fluid flow between microcolonies of bacteria in a biofilm.
C. Change the oxygen concentration with the biofilm microenvironments.
D. All of the above.
How can a subgingival biofilm formation protect periodontal pathogens from locally delivered antimicrobial agents?
A. The biofilm prevents the antimicrobial agent from entering the periodontal pocket.
B. The biofilm matrix serves as a protective barrier.
C. The biofilm fluid channels direct the antimicrobial agent out of the pocket.
D. The biofilm changes the pH of the antimicrobial agent and inactivates the agent.
Possible new strategies to control oral biofilms include all of the following EXCEPT:
A. Control of biofilm nutrient sources.
B. Alteration of pH within biofilm microcolonies.
C. Varying the oxygen concentration within biofilm.
D. Addition of systemic antibiotics.