Biofilms

Question 1

Below which pH leads to demineralisation

Answer 1

PH 5.5

Question 2

List the 6 microbial stages of caries

Answer 2

Adhesion
Survival and growth
Biofilm formation
Complex plaque
Acid
Caries

Question 3

What are some of the key carcinogenic foods

Answer 3

Fermentable carbohydrates
Along with cooked startches (retentivity bin the mouth- slowly leach out and become fermentable carbs).

Question 4

4 elements of remineralisation

Answer 4

Saliva
Fluoride
Plaque control
Dietary modification

Question 5

Which type of bacteria are endo infections derived from?

Answer 5

Endogenous microflora

Opportunistic

Question 6

Which bacteria are involved in endodontic infections?

Answer 6

Primary endo infection- dominated by gram -ve anaerobic rods (poly microbial)

Secondary endo infection- gram +ve (enterocuccus faecalis)

Bacteroides, prevotella (gram -ve)
Strep

Etc.. other microorganisms

Question 7

List 5 virulence factors of enterocuccus faecalis

Answer 7

Endotoxins
Adhesions
Collagenases
Hyaluronidase
Immune evasion

Question 8

Which 2 organisms can support each other in endo infection and can be treated with NaOCl and EDTA

Answer 8

C. albicans and E. faecalis

Question 9

What is the keystone pathogen of perio and list some virulence factors

Answer 9

Porphyromonas gingivalis (gram -ve anaerobe)

Virulence factors- endotoxin, fimbriae, collagenases, gingipains (activate MMPs, degrades cytokines and innate receptors) etc…

Question 10

What are some influence on the oral microflora

Answer 10

Host factors- medication, systemic disease, OH
Diet
Saliva
Gingival crevicular fluid (anti microbial components)
Microbial interactions (competition and co-operation)
Gaseous environment (oxygen concentration)

Question 11

Describe the development of periodontitis

Answer 11

Proportion of periodontopathogenic bacteria increases causing mild inflammation at the edge of the gum (gingivitis)

This progresses to high concentration of bacteria causing severe inflammation and pocket formation, resulting in degradation of soft tissue and bone.

Conditioning film- linking film (strep)- co aggregation/ re-conditioning film (actinomyces)- accumulation of biofilm.

Question 12

Which type of bacteria are associated with periodontitis?

Answer 12

Gram -ve anaerobe

P gingivalis
T forsythia
T denticola

Question 13

What are the stages of biofilm development?

Answer 13

Adhesion
Colonisation
Accumulation
Complex community
Dispersal

Question 14

What are some bacteria found in health?

Answer 14

Oral streptococci- actinomyces, veillonella

Question 15

What bacteria are associated with gingivitis?

Answer 15

Actinomyces, prevotella intermedia, Bacteroides

Question 16

What is the local and systemic effect of a dysbiotic biofilm?

Answer 16

Local- destructive inflammation of tissues
Systemic- host immune response including pro inflammatory cytokines and antibodies to host cross reactive antigens (can target organs)

Question 17

What is the effect of prebiotics

Answer 17

Can change the micro biome by providing with correct, healthy microorganisms.

Question 18

What are the 4 main types of candida in the oral cavity

Answer 18

Psuedomembranous (thrush)
Erythematous (atrophic, denture related)
Hyperplastic (Candida leukoplakia- associated with pre malignancy)
Angular cheilitis

Question 19

What are the 2 most opportunistic pathogenic yeasts and what are the differences?

Answer 19

Candida albicans, candida glabrata

Albicans is sensitive to fluconazole and myconozol whereas glabrata is not

Question 20

What is the function of hyphe (on Candida albicans)

Answer 20

Grows in reaction to stress
Allows it to adhere and invade tissue (reaching bloodstream).

Question 21

Give 3 examples of hydrolytic enzymes present in biofilm

Answer 21

Phospholipases
Haemolysin
Proteinase

Question 22

How is a candida infection diagnosed and treated

Answer 22

Oral rinse/ swab taken from site (or biopsy is candida leukoplakia)
Grown on chromogenic agar
- differentiate between albicans and glabrata (treat with an -azol or nystatin)

Question 23

What is the mode of action of antifungals

Answer 23

Fungistatic (eg fluconazole) - Inhibit the ability of ergosterol synthesis (molecule on cell membrane)

Fungicidal (nystatin) - bind with ergosterol directly, causing pores which lead to leakage of cytoplasmic contents and cell death. (Can be toxic)

Echinocandins- act on enzyme producing beta glucans, which de stabilises the cell wall causing cell death - not yet used in dentistry

Question 24

What is the role of cholorhexidine in a fungal infection

Answer 24

Antiseptic and anti-candidal

Question 25

Give an example of a novel antifungal compound

Answer 25

Diluted tea tree oil

Question 26

Why is it difficult to establish causality for a specific bacteria in endo infection?

Answer 26

It is dificultades to obtain a sample without contamination