W8 - Microbiology of Endo Infections - Rodrigo

Question 1

Does dentine exposure always cause potential pulp exposure?

Answer 1

Only when thickness is considerably reduced and permeability is increased

Question 2

How does dentinal tubule size change in the tooth

Answer 2

Conical conformation

largest widest diameter near pulp, smallest near the enamel

Question 3

Microbiological goal of endo tx (2)

Answer 3

Eradicate bacterial colonization or

Reduce bacterial load to levels that permit perradicular tissue healing

Question 4

What percentage of root surface area remains untouched even after instrumentation

Answer 4

59. 6% to 79.9% untouched
    * this is why irrigants are important

Question 5

Pathogenesis equation

What is the only thing you can change?

Answer 5

P = pathogenesis

N = number of bacteria

V = virulence

I = interaction

R = resistance

You can only change the number of bacteria. Not virulence, interaction, etc

Question 6

Which type of bacteria are associated with more failures of endo (not species)

Why? (3)

Answer 6

Gram positive

• Bc they are more resistant to antimicrobials
• Can adapt to harsh environmental conditions in medicated canals
• gram neg are easy to kill

Question 7

Does pulp only become inflamed once there is exposure from caries?

Answer 7

No - bacterial products can move through tubules and cause pulpal inflammation before exposure

Question 8

Answer 8

Irrev pulp

Question 9

Are bacteria IN the canal or OUT of the canal in apical periodontitis?

Answer 9

Inside the canal → the LEO is the consequence of bac in the canal

When bac are OUT of the canal → Abscess

Question 10

What is in biofilm? Percentage? (2)

Answer 10

15% bacterial colony

85% EPS - Extracellular Polymeric Substance

Question 11

2 types of endodontic infections classified by anatomic location

Answer 11

Intraradicular infection (3 types)

Extraradicular infection

Question 12

3 types of intraradicular infection

Answer 12

Primary infection

Secondary infection

Persistent infection

Question 13

What causes primary infection?

Answer 13

Caused by microorganisms that
initially invade and colonize the
necrotic pulp tissue

type of primary intraradicular infection

Question 14

What causes secondary infection?

Answer 14

Caused by microorganisms not present in the primary

• *infection** but introduced in the root canal at some time after
• *intervention**
• type of intraradicular infection*
• Couldve been introduced by microleakage or touching the file with gloves before treatment

Question 15

What causes persistent infection

Answer 15

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

type of intraradicular infection

leftover bacteria in canal

Question 16

Synonym of persistent infection

Answer 16

Late failure

“can even happen 12 years later”

Question 17

12 years later

Answer 17

Late failure / persisting infection

Question 18

How does the size of the lesion affect bacteria colony?

Answer 18

Larger the lesion = higher bacterial diversity and density

Question 19

What type of bacterial species occupy primary interradicular infection?

Answer 19

Mixed species but mostly anaerobic bacteria of gram negative and positive type

Question 20

What is the major cause of post treatment apical periodontitis

Answer 20

Intraradicular infection - either persistent or secondary

• Usually of gram-positive bacteria

Question 21

Examples of Intraradicular vs Extraradicular infection

Answer 21

Intraradicular - apical periodontitis → constitutes effective barrier against spread of infection to bone and other sites

Extraradicular - abscess → bacteria have overcome the barrier and are spreading

Question 22

Where is the bacteria / infection in extraradicular infection?

Answer 22

Have pushed through apex

Question 23

What is Rodrigo’s only solution for extraradicular infection?

Answer 23

Apical surgery

51:45

Ex. apical periodontitis with development of external biofilm

Question 24

3 Examples of extraradicular infections that are dependent on intraradicular infections

Answer 24

Acute / chronic apical abscess

“wet canals” - persistent exudation

Question 25

2 examples of scenarios where extraradicular infection is independent of intraradicular infection

Answer 25

• No longer fostered by the intraradicular infection
• Persistence of extraradicular infection even after successful eradication of intraradicular infection