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 aerobicGingivitis = on its way to gram-negative anaerobicPeriodontitis = 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 pathogensDisease 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