rct irrigation

Question 1

What is responsible for endo infection?

Answer 1

Obligate anaerobic bacteria (polymicrobial)

Question 2

What are the aims of irrigation?

Answer 2

Kill and remove microorganisms
Remove necrotic/inflamed tissue, dentine debris and smear layer
Provides lubrication and reduces friction for instrumentation

Question 3

What are the obstacles in disinfection?

Answer 3

1. Anatomical complexities- only 61% instrumented, rest remain infected
2. Smear layer- protection for bacteria, inhibits/delays irrigant into tubules
3. Fluid dynamics
4. Biofilm and resistant microbiota

Question 4

How are there anatomical complexities?

Answer 4

Webs
Loops
Cul de sac
Fins
Lateral canals
Apical delta

Types I-V

Question 5

What does the smear layer consist of?

Answer 5

In/organic substances
Fragments of odontoblastic processes
Microorganisms
Necrotic debris

Created during cleaning and shaping

Question 6

What are fluid dynamics?

Answer 6

Irrigant only penetrates 1-2mm around needle
Absence of fluid motion- stagnation plane and no flushing of debris in apical region

Question 7

What are fluid dynamic rules for irrigation?

Answer 7

1. Side venting needle
2. Luer-lok syringe
3. Keep needle tip moving
4. Gentle pressure
5. If needle binds- stop
6. Constant agitation to improve flow
7. Size 27/30 gauge needle

Question 8

How far should the needle be from the apex?

Answer 8

2mm

3-4mm if open apex

Question 9

What is dynamic pumping?

Answer 9

Introduce gutta percha point matched to master cone in a flooded canal to working length

Gentle in and out motion to stir up irrigant

Question 10

What is a biofilm?

Answer 10

Any group of microorganisms in which cells stick to each other on a surface
Frequently embedded in EPS (extracellular polymeric substance)

Question 11

What is EPS?

Answer 11

Polymeric conglomeration of extracellular DNA, proteins and polysaccharides

Question 12

What are planktonic cells?

Answer 12

Single cells that may float in a liquid medium
- easily flushed out

Question 13

What is MIC?

Answer 13

Minimum inhibitory concentration
Can be 100-1000x higher in biofilm than suspension culture

Question 14

What is an example of a resistant bacteria?

Answer 14

E. faecalis
Can survive as monoculture in canals
Most freq species in root tx teeth w prevalence value of 90%
High resistance to NaOCl

Question 15

What are ideal characteristics of an endo irrigant?

Answer 15

1. Effective antimicrobial
2. Non-irritating
3. Stable in solution
4. Prolonged effect
5. Active in blood, serum and protein derivatives of tissue
6. Low surface tension
7. Not interfere w repair
8. Non staining
9. Doesn’t induce cell mediate I. response
10. Completely remove smear layer
11. Non toxic/antigenic/carcinogenic
12. No adverse effects on physical properties of exposed dentine
13. No adverse effects on sealing ability of materials
14. Easy to use
15. Inexpensive

Question 16

What are current irrigant solutions?

Answer 16

1. NaOCl
2. EDTA
3. CHX
4. IPI
5. MTAD
6. Hydrogen peroxide
7. PAD
8. Electronically activated water

Question 17

What is NaOCl?

Answer 17

Sodium hypochlorite- essentially supermarket bleach w/o thickener

1. Only irrigant that dissolves organic inc. biofilm
2. Effective against all endo bacteria
3. Affordable

0.5%- 30 min
2.5%- 10 min
4%- 5 min
5.25%- <30s

Question 18

What happens if you increase the temp of NaOCl?

Answer 18

1. Improve tissue dissolution (0.5% at 45C=5.25%)
2. 60C completely dissolve tissue but destroy osteoblasts and cause metal corrosion
3. Increase antimicrobial effect (2x each 5C rise)

Question 19

Why do you need to continuously replenish NaOCl?

Answer 19

Chloride ion responsible is rapidly consumed (2min) esp. in first phase

Question 20

What are disadvantages of NaOCl?

Answer 20

1. Minimal removal of dentine debris/smear layer
2. Reduces flexural strength
3. Rare allergy
4. Toxic to vital tissue (haemolysis, epithelial ulceration, necrosis)
5. Corrosion to metal

Question 21

What is EDTA?

Answer 21

Ethylenediamine tetra-acetic acid
Solution- 15-17% (penultimate rinse for 1-2mins)
Gel form- glyde- usually for sclerosed, aids lubrication
Synthetic AA
Removes smear layer as it’s a ‘chelating agent’
Not bactericidal/static (eventually kills by starvation due to chelation)
Relatively non toxic
Shouldn’t over use- excessive removal of dentine

Question 22

What is a chelating agent?

Answer 22

Scavenges up and forms ring shaped internal complexes w metallic ions, inc. Calcium

Question 23

Is citric acid used?

Answer 23

Not as effective chelating agent than EDTA

Question 24

What is chlorhexidine?

Answer 24

Cationic bisbiguanide antiseptic
Broad spectrum
Bacteriacidal at high conc
Static at low conc
Substantivity
Conc- 0.2-2%
Less toxic than NaOCl
No harmful effects to dentine

Question 25

What are disadvantages of CHX?

Answer 25

1. Forms precipitate w NaOCl- para chloroanaline (brown, potentially carcinogenic)- use intermediate as saline before using 2. No tissue dissolving effects 3. Can’t remove smear layer 4. Severe allergic reaction rare

Question 26

What is IPI?

Answer 26

Iodine (2%) potassium iodide (4%) Acts as oxidising agent attacking key group proteins, nucleotides and FAs Broad spectrum inc. E faecalis Substantive Low toxicity

Question 27

What are disadvantages of IPI?

Answer 27

1. Allergic reaction to iodine 2. Stains dentine 3. Not stable w organic 4. Doesn’t dissolve tissue/remove smear layer

Question 28

What is hydrogen peroxide?

Answer 28

Hydroxy free radicals destroy proteins and DNA Conc- 3-5% Active against bacteria, virus, yeast Not used routinely anymore

Question 29

What are disadvantages of hydrogen peroxide?

Answer 29

1. Poor antimicrobial efficacy 2. Low tissue dissolving 3. Can release O2 gas (seepage in tissue may lead to air emphysema)

Question 30

What is MTAD?

Answer 30

Mixture of- 3% doxycycline (broad spectrum) 4.25% citric acid (removes smear layer) Surface active detergent No adverse effect on physical properties

Question 31

What are disadvantages of MTAD?

Answer 31

1. Less efficient on biofilm 2. Toxic 3. Expensive 4. Issues w bacterial resistance 5. Risk of tetracycline staining

Question 32

What is PAD?

Answer 32

Photo activated disinfection Toluidine blue dye Low power laser activated Photosensitiser molecules attach to bacteria and singlet oxygen produced to rupture cell wall Broad spectrum No toxicity

Question 33

What are disadvantages of PAD?

Answer 33

1. Depends on power, length of exposure, absorption of light and distance 2. No benefit over others 3. Expensive

Question 34

What is electronically activated water?

Answer 34

Electrolyses saline solution Creates hypochlorous acid and free radicals to remove biofilm and destroy bacteria Lack studies showing efficacy/safety

Question 35

What is ultrasonic agitation of irrigants?

Answer 35

Acoustic micro steaming Enhances antibacterial effect of irrigants Disrupts biofilm Eliminates more bacteria Can use specific tips/standard files