rct irrigation Flashcards
What is responsible for endo infection?
Obligate anaerobic bacteria (polymicrobial)
What are the aims of irrigation?
Kill and remove microorganisms
Remove necrotic/inflamed tissue, dentine debris and smear layer
Provides lubrication and reduces friction for instrumentation
What are the obstacles in disinfection?
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
How are there anatomical complexities?
Webs
Loops
Cul de sac
Fins
Lateral canals
Apical delta
Types I-V
What does the smear layer consist of?
In/organic substances
Fragments of odontoblastic processes
Microorganisms
Necrotic debris
Created during cleaning and shaping
What are fluid dynamics?
Irrigant only penetrates 1-2mm around needle
Absence of fluid motion- stagnation plane and no flushing of debris in apical region
What are fluid dynamic rules for irrigation?
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
How far should the needle be from the apex?
2mm
3-4mm if open apex
What is dynamic pumping?
Introduce gutta percha point matched to master cone in a flooded canal to working length
Gentle in and out motion to stir up irrigant
What is a biofilm?
Any group of microorganisms in which cells stick to each other on a surface
Frequently embedded in EPS (extracellular polymeric substance)
What is EPS?
Polymeric conglomeration of extracellular DNA, proteins and polysaccharides
What are planktonic cells?
Single cells that may float in a liquid medium
- easily flushed out
What is MIC?
Minimum inhibitory concentration
Can be 100-1000x higher in biofilm than suspension culture
What is an example of a resistant bacteria?
E. faecalis
Can survive as monoculture in canals
Most freq species in root tx teeth w prevalence value of 90%
High resistance to NaOCl
What are ideal characteristics of an endo irrigant?
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
What are current irrigant solutions?
1. NaOCl
2. EDTA
3. CHX
4. IPI
5. MTAD
6. Hydrogen peroxide
7. PAD
8. Electronically activated water
What is NaOCl?
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
What happens if you increase the temp of NaOCl?
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)
Why do you need to continuously replenish NaOCl?
Chloride ion responsible is rapidly consumed (2min) esp. in first phase
What are disadvantages of NaOCl?
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
What is EDTA?
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
What is a chelating agent?
Scavenges up and forms ring shaped internal complexes w metallic ions, inc. Calcium
Is citric acid used?
Not as effective chelating agent than EDTA
What is chlorhexidine?
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
What are disadvantages of CHX?
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
What is IPI?
Iodine (2%) potassium iodide (4%)
Acts as oxidising agent attacking key group proteins, nucleotides and FAs
Broad spectrum inc. E faecalis
Substantive
Low toxicity
What are disadvantages of IPI?
1. Allergic reaction to iodine
2. Stains dentine
3. Not stable w organic
4. Doesn’t dissolve tissue/remove smear layer
What is hydrogen peroxide?
Hydroxy free radicals destroy proteins and DNA
Conc- 3-5%
Active against bacteria, virus, yeast
Not used routinely anymore
What are disadvantages of hydrogen peroxide?
1. Poor antimicrobial efficacy
2. Low tissue dissolving
3. Can release O2 gas (seepage in tissue may lead to air emphysema)
What is MTAD?
Mixture of-
3% doxycycline (broad spectrum)
4.25% citric acid (removes smear layer)
Surface active detergent
No adverse effect on physical properties
What are disadvantages of MTAD?
1. Less efficient on biofilm
2. Toxic
3. Expensive
4. Issues w bacterial resistance
5. Risk of tetracycline staining
What is PAD?
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
What are disadvantages of PAD?
1. Depends on power, length of exposure, absorption of light and distance
2. No benefit over others
3. Expensive
What is electronically activated water?
Electrolyses saline solution
Creates hypochlorous acid and free radicals to remove biofilm and destroy bacteria
Lack studies showing efficacy/safety
What is ultrasonic agitation of irrigants?
Acoustic micro steaming
Enhances antibacterial effect of irrigants
Disrupts biofilm
Eliminates more bacteria
Can use specific tips/standard files
