Periodontal microbiology

Question 1

What are the mucosal infections?

Answer 1

• Thrush
• Angular cheilitis
• Denture stomatitis

Question 2

What are the periodontal infections?

Answer 2

• Gingivitis
• Periodontitis

Question 3

What are the influences on the oral microflora?

Answer 3

• Host factors
• Diet
• Saliva
• Gingival crevicular fluid
• Microbial interactions
• Gaseous environment

Question 4

What is meant by host factor influence on oral microflora?

Answer 4

• Systemic disease
• Antibiotic use
• Oral hygiene methods

Question 5

What is included in diet influence on oral microflora?

Answer 5

• Chemical composition
• Physical consistency
• Frequency of intake

Question 6

What is included in saliva influence on oral microflora?

Answer 6

• Flow rate
• pH balance
• Antimicrobial factors

Question 7

What is included in gingival crevicular fluid influence on oral microflora?

Answer 7

• Antimicrobial components
• Humoral immunity

Question 8

What is included in microbial interactions influence on oral microflora?

Answer 8

• Competition
• Co-operation

Question 9

What is included in gaseous environment influence on oral microflora?

Answer 9

• Oxygen conc

Question 10

What are the periodontal classifications?

Answer 10

• Gingivitis
• Chronic perio
• Aggressive perio
• Necrotising periodontal disease
• Peri-implantitis

Question 11

What is included within active disease microbiologically and immunologically?

Answer 11

• Cytotoxins
• Proteinases
• LPS
• H2S
• Pathogenic bacteria
• Non-protective immune responses
• Disruption of tissue homestasis

Question 12

What are host factors for development of periodontal disease?

Answer 12

• Smoking/tobacco use
• Genetics
• Pregnancy/puberty
• Systemic disease
• Nutrition

Question 13

In a healthy tooth what bacteria is present within tooth pocket?

Answer 13

• Colonisation of normal oral flora
• Healthy gums (gingiva)

Question 14

In tooth with gingivitis what is present within pocket?

Answer 14

• Proportion of periodontopathogenic bacteria increases
• Mild inflammation at edge of gum

Question 15

In tooth with periodontitis what is present within pocket?

Answer 15

• High conc of periodontopathogenic bacteria
• Severe inflammation and pocket formation
• Degradation of soft and bone tissue

Question 16

What are the development phases of bacteria?

Answer 16

• Naked surface with no bacteria
• Conditioning film with host salivary glycoproteins
• Linking film e.g. streptococcus
• Coaggregation, re-conditioning film e.g. Actinomyces and Streptococcus
• Accumulation, Shedding e.g. Actinomyces, Streptococcus and Fusobacterium

Question 17

What type of bacteria is present in health, gingivitis and periodontitis?

Answer 17

Health = gram-positive aerobic
Gingivitis = on its way to gram-negative anaerobic
Periodontitis = Gram-negative anaerobic

Question 18

How does the biofilm develop?

Answer 18

• Adhesion of bacteria
• Colonisation of bacteria
• Accumulation of different bacteria
• Creates a complex community
• Then dispersal of bacteria occurs

Question 19

What bacteria is present in health?

Answer 19

• Oral streptococci,
• Actinomyces
• Fusobacterium

Question 20

What bacteria is present in gingivitis?

Answer 20

• Actinomyces
• Prevotella intermedia
• Bacteroides
• Fusobacterium nucleatum

Question 21

What bacteria is present in periodontitis?

Answer 21

• Porphyromonas gingivalis
• Prevotella intermedia

Question 22

What is a commensal community compared to disease community?

Answer 22

Commensal has constraint and exclusion of pathogens
Disease has overgrowth of pathogens

Question 23

How is a multi-species biofilm formed?

Answer 23

• Colonisations occurs through adhesion molecules
• Early colonisers of various streptococcal species bind to acquired pellicle
• Actinomyces and Veillonella species associate closely with Streptococcal species
• Form primary layer of bioflilm
• Intermediate colonisers like F. nucleatum adhere to primary complex members
• Pathogenic bacteria like P.gingivalis and A.actinomycetemcomitans bind to intermediate colonisers
• Forms multi-species biofilm

Question 24

What is Porphyromonas gingivalis?

Answer 24

• Oral pathogen
• Gram-neg non-motile rod, strict anaerobe
• Black pigmented from iron accumulation from hemin

Question 25

What are virulence factors ?

Answer 25

• Refer to the components or structure of microorganism that helps in establishment of disease of infection

Question 26

What are some examples of virulence factors?

Answer 26

• Fimbriae adhesins
• Different proteases (Collagenase, fibrinolysin, phospholipase A, Phosophatases)
• Endotoxin (LPS)
• Capsular polysaccharides
• Tissue toxic metabolic by-products (hydrogen sulphide, ammonia, fatty acids)

Question 27

What are gingipains for?

Answer 27

• Provide peptides from heme from nutrition
• Possess haemaglutanin (HagA) domains for attachment
• Activate matrix metalloproteases (MMP’s)
• RgpA (arginine specific)
• Kpg (lysine specific)

Question 28

How do gingipains manipulate host defences?

Answer 28

• Degradation of innate receptors
• Degradation of cytokines IL-8 and ICAM-1

Question 29

How does P.gingivalis cause bone resorption?

Answer 29

• Encounters saliva and salivary molecules
• Leads to subgingival colonisation and adaptation
• Production of proteases, toxins and toxic by-products in pocket
• Leads to disruption of innate immunity and tissue and bone homeostasis