Week 8 Rodrigo- Endodontic Microbiology

Question 1

What can lead to endo infections?

Answer 1

• Caries
• Trauma
• Perio disease
• Invasive operative procedures

Question 2

Where are the dentinal tubules the largest vs smallest diameter?

Answer 2

• Largest diameter near the pulp (2.5um)
• Smallest diameter near enamel/cementum (0.9um)

Question 3

What is the major cause of pathogenesis of endodontic infection?

Answer 3

Bacteria

Question 4

How can periodontal pathogens reach pulp?

Answer 4

• Dentinal tubules
• Apical and lateral ramifications

Question 5

What are the microbiological goals of endo treatment?

Answer 5

Eradicate bacterial colonisation or reduce bacterial load to levels that permit periradicular tissue healing

Question 6

How much of a root canal remains untouched after root canal treatment? + consequence of this?

Answer 6

60-80%. Instruments usually fail to touch all the walls causing unprepared areas to harbour microorganisms

Question 7

What is required for disease and signs/symptoms to come about?

Answer 7

• Bacteria have to reach quorum of cells (threshold) to cause disease (apical periodontitis) and clinical signs and symptoms.
• Disease will persist if canals aren’t cleaned/shaped adequately as bacterial levels are above threshold

Question 8

What factors contribute to pathogenesis? What can we influence as denstist?

Answer 8

• Numbers of bacteria
• Virulence
• Interaction
• Resistance

P=NVI/R

We can reduce number of bacteria as dentists

Question 9

What bacteria are associated with failed RCT?

Answer 9

• Gram +ve are more resistant to root canal treatment e.g. E- faecalis
• Gram -ve are easier to kill

Question 10

What causes pulpal inflammation before pulp is exposed?

Answer 10

Diffusion of bacterial products through dentinal tubules

Question 11

Where are bacteria in apical periodontitis vs abscess?

Answer 11

• Bacteria are in the canal in apical periodontitis and barrier prevents spread of infection to alveolar bone (intraradicular infection)
• Bacteria extrude through apex in abscess (extraradicular infection)

Question 12

What are biofilms composed of?

Answer 12

• Bacteria (15%)
• EPS matrix- polysaccharides, proteins, nucleic acids (85%)

Question 13

What is intra-radicular infection + 3 types?

Answer 13

Caused by microorganisms colonizing the root canal system and can be subdivided into 3 categories according to the time microorganisms entered the root canal system:

• Primary infection
• Secondary infection
• Persistent infection

Question 14

What is secondary infection caused by?

Answer 14

Caused by microorganisms not present in primary infection but introduced in root canals at some time after intervention e.g. touching GP cones or files

Question 15

What is primary infection caused by?

Answer 15

Caused by microorganisms that initially invade and colonise necrotic pulp tissue

Question 16

What is persistent infection caused by?

Answer 16

It is caused by microorganisms that were members of primary or secondary infection and in some way resisted intracanal antimicrobial procedures and were able to endure periods of nutrient deprivation in treated canals e.g.

Question 17

What bacteria are present in primary intraradiucalr infection?

Answer 17

Mixed (multispecies ) community dominated by anaerobic bacteria belonging to diverse genera of gram negative and gram positive bacteria. Larger lesions → high bacterial diversity and density in canal

Question 18

What are major causes of post tx apical periodontitis?

Answer 18

Persistent or secondary intraradicular infections

Question 20

What disease are dependent on intraradicular infection?

Answer 20

• Acute apical abscess
• Chronic abscess
• Wet canals (persistent exudation)

Question 21

What does it mean to be independent of intraradicular infection?

Answer 21

No longer fostered by intraradicular infection

Can persist even after successful eradication of intradicular infection