Starting December 1, 2018, the Self-Instruction program will be exclusively available online. We will still publish Self-Instruction (S-I) exercises at the end of every corresponding General Dentistry article, but now you can pay online, test online, and receive your continuing education (CE) verification online. Earning CE has never been easier. 

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If you have any questions, or if you are unsure of your enrollment status, please call the Manager, Examinations and Self-Instruction, toll-free at 888.243.3368, ext. 4336.

Participants must answer at least 12 of 15 questions correctly (80%) to earn CE credit.

AGD - Self-Instruction Exercise No. 417 - Basic Science
Mouthwashes: an in vitro study of their action on microbial biofilms and cytotoxicity to gingival fibroblasts

Self-Instruction Exercise No. 417
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Exercise No. 417
Subject Code: 010
Basic Science

The 15 questions for this exercise are based on the article Mouthwashes: an in vitro study of their action on microbial biofilms and cytotoxicity to gingival fibroblasts on pages 28-34. This exercise was developed by Kim Capehart, DDS, PhD, MBA, in association with the General Dentistry Self-Instruction committee.

Reading the article and successfully completing this exercise will enable you to:

  • learn the effects of commercial mouthwashes on microorganisms;
  • describe the characteristics of biofilms; and
  • recognize which bacteria are affected by mouthwashes.

Answers for this exercise must be received by February 28, 2019.

  1. Which Pseudomonas species was evaluated in this in vitro study?

    A. P argentinensis
    B. P anguilliseptica
    C. P alcaligenes
    D. P aeruginosa

  2. Biofilms are structured communities of microbial cells that adhere to a surface and exhibit ______________ heterogeneity.

    A. homogenous
    B. genetic
    C. phenotypic
    D. tumor

  3. ___________ easily adheres to the tooth surface because of its synthesis of extracellular proteins.

    A. Staphylococcus aureus
    B. Enterococcus faecalis
    C. Streptococcus mutans
    D. Escherichia coli

  4. Isolates of ___________ have been obtained from supragingival and subgingival biofilms of patients with periodontitis and hospitalized patients with respiratory infections.

    A. Candida albicans
    B. E coli
    C. P aeruginosa
    D. S aureus

  5. _________ colonizes deep in dentin and may have the ability to invade tubules, providing an escape from endodontic treatment effects.

    A. S aureus
    B. E faecalis
    C. S mutans
    D. P aeruginosa

  6. E coli is a gram-negative bacterium that has lipopolysaccharides present in the _________ membrane.

    A. inner
    B. middle
    C. outer
    D. basement

  7. When systemically disseminated from the oral cavity, ________ can cause primary respiratory infections in hospitalized and immunocompromised patients.

    A. C albicans
    B. S mutans
    C. E coli
    D. P aeruginosa

  8. In this study, what agar culture plates were used for C albicans?

    A. potato dextrose agar
    B. brain-heart infusion agar
    C. dermatophyte test agar
    D. Sabouraud-dextrose agar

  9. The surviving cells in biofilms after exposure to antiseptics were verified by analysis of the metabolism of _______.

    A. MTT
    B. XTT
    C. MTS
    D. WTS

  10. Which statistical analysis was used to compare the mean values of the groups treated with antiseptic for each biofilm and culture?

    A. Newman-Keul
    B. post hoc analysis
    C. Spearman rho
    D. Tukey

  11. Evaluated mouthwashes had a significant antibiofilm effect on the viability of all of the following except one. Which is the exception?

    A. C albicans
    B. S aureus
    C. S mutans
    D. P gingivalis

  12. All of the following biocompound formulations have a plant origin except one. Which is the exception?

    A. Listerine
    B. Cepacol
    C. Peridex
    D. Scope

  13. The biocompound _________________ has antimicrobial activity against S aureus, methicillin-resistant S aureus, P aeruginosa, E coli, and C albicans.

    A. eucalyptol
    B. carvacrol
    C. menthol
    D. thymol

  14. The action of ________ was observed in E faecalis and S aureus biofilms as well as in E coli in planktonic form.

    A. eucalyptol
    B. carvacrol
    C. menthol
    D. thymol

  15. Which bacteria prevalent in the subgingival biofilm of HIV patients increase the chances of developing aggressive periodontitis?

    A. P aeruginosa
    B. E faecalis
    C. S aureus
    D. E coli


Please respond to the statements below, using the following scale:
1 Poor; 2 Below average; 3 Average; 4 Above average; 5 Excellent

Practicality of the content 1 2 3 4 5
Benefit to your clinical practice 1 2 3 4 5
Quality of illustrations 1 2 3 4 5
Clarity of objectives 1 2 3 4 5
Clarity of exercise questions 1 2 3 4 5
Relevance of exercise questions 1 2 3 4 5
Did this exercise achieve its objectives? Yes No
Did this article present new information? Yes No
How much time did it take you to complete this exercise? mins