This document discusses irrigation techniques and medicaments used during root canal treatment. It provides an overview of the objectives of irrigation including flushing, lubricating, dissolving tissues, and removing the smear layer. Common irrigants like sodium hypochlorite, chlorhexidine, hydrogen peroxide, and EDTA are described in detail regarding their antimicrobial properties, tissue dissolving ability, and impact on smear layer removal. Manual dynamic irrigation techniques and sonic/ultrasonic activation are presented as methods to improve irrigant agitation and penetration beyond the lumen. Complications of irrigant extrusion are also reviewed.

1. Irrigation and Medicaments

2. Rationale for irrigation
Classic In vivo studies have shown reductions in bacterial counts after mechanical preparation with hand
filing and saline irrigation. However culturable bacteria were still present afterward.
(Siquera et al., Bystrom and Sundqvist, Orstavik and Dalton)
Mechanical preparation alone cannot predictably eliminate/reduce the bacterial load within the canals
Why?
• Insignificant antibacterial activity of saline
• Bacterial penetration of dentinal tubules (Love 1996)
• Biofilm
• Accessory canals, lateral canals, canal ramifications (De Deus 1975)

3. Every root canal system has spaces that can not be
cleaned mechanically .
The only way to clean webs, fins and anastomoses is
through effective use of irrigation solution.
“of all the phases of anatomic study in the human
system, one of the most complete is that of the pulp
cavity morphology” - Barret 1925
MAIN AIM OF MECHANICAL PREPARATION IS TO FACILITATE
IRRIGANT PENTETRATION TO THE FULL EXTENT OF THE CANAL
SYSTEM

4. Objectives of irrigation:
Mechanical Biologic
Flushing Antimicrobial activity
Lubricating
Dissolution of organic materials
Smear Layer Removal

5. • Flushing action and debris removal
• Dissolve inorganic tissue (dentin)
• Low surface tension (penetration of dentinal
tubules)
• Dissolve organic matter (dentin collagen, pulp
tissue, biofilm)
• Effective antimicrobial – bacteria, virus, yeast,
fungi
•No irritation or damage periapical
tissues
•Does not weaken tooth structure
•Stable in solution
•Prolonged antibacterial action
•Inexpensive/Easy to use
Ideal properties of irrigants

6. Sodium Hypochlorite (NaOCl)
Effective antimicrobial
Excellent organic tissue solvent
Lubricant
Fast acting
Why do we like it?
Caustic agent – very toxic to periapical tissues
Not substantive
Labile
Taste/smell
No effect on inorganic components (eg smear
layer)
Why do we not like it?

7. NaOCl + H2O ↔ NaOH + HOCl ↔ Na+ + OH- + H+ + Ocl-
Three modes of action:
1. Chloramination
Hypoclorous acid (OCL-) causes Irreversible oxidation of cellular enymes and components of cell membrane
2. Saponification
Dissolution of Organic Material
Phospholipid degradation – breakdown of fatty acids and lipids within organic materials
NaOCL + fatty acids  soap + glycerol
3. High pH (>11)
cell membrane integrity, inhibits enzymatic activity and disrupts cell metabolism

8. Used in varying concentrations ranging 0.5% - 5%
E.g. Dakins Solution – 0.5% Miltons 1% Parcan 3%
Domestic Bleach is usually sold as 3-5%
Does it matter what concentration of bleach we use?
Any concentration above 0.5% eliminated bacterial suspensions within 30secs - 30minutes (Bystrom et al. 1970)
Higher concentrations:
+ improved and quicker tissue dissolving capacity (Berber et al.)
+ quicker elimination of bacteria - 30sec for 5.25% versus 30mins for 0.5% (Vianna et al.)
- greater cytotoxic and caustic effect on periapical tisses with 5.25% versus 1.0% (Pashley et al.)
- thicker solution with higher surface tension and therefore lower wettability of the canal wall.

9. NaOCl effect on dentin
Degradation of the organic component of dentine – reduced elasticity and strength (Grigoratus et al.)
Concentration dependant effect on mechanical properties – erosion of dentinal tubules etc
Allergic Reaction to NaOCl
Unlikely
Contact dermatitis reported with skin contact (minimised with rubber dam usage)
Greater cytotoxic and caustic effect on periapial tisses with 5.25% versus 1.0% (Pashley et al.)
NaOCl effect on dentine bonding
NaOCl compromises bond strength
1. Effecting the organic components of enamel/dentine necessary for hybrid layer formation
2. Residual free radicals from oxidation reaction inhibits composite polymerisation reaction
10% sodium ascorbate (antioxidant/reducing agent) scrub prior to bonding

10. Improving Efficacy of NaOCl
1. Increase temperature of NaOCl
Bactericidal rates doubled for each 5°C rise in the range of 5 to 60°C
1% NaOCl at 45°C similar dissolution capacity to 5.25% solution at 20°C
(Sirtes et al 2005)
2. Replenish NaOCl as often a possible (after every file)
NaOCl is a very labile compound - free chlorine is readily depleted
Important to continually refresh the irrigant - especially apically (Moorer and Wesselink)
3. Inter appointment medication with CaOH
Synergistic tissue dissolution properties (Hassellgren 1984)
4. Ultrasonic Activation
Acoustic streaming (agitation) results in greater penetration of the irrigant
US energy also increases the temperature of the irrigant (see above)

11. Why are in vitro findings not reflected in in vivo studies/our day to day practice?
1. Higher volume of solution in vitro
2. Anatomical considerations- fins/lateral canals/anastamoses etc
3. Planktonic bacteria/dentine blocks are very different to biofilm
4. Presence of obstructions/other materials such as GP, necrotic tissue, inflammatory
exudate etc
5. Buffering capacity of dentine (resulting in lowering the pH)
In vitro studies demonstrate killing of practically all microorganisms in a few seconds/minutes - when
concentrated solutions are used.
Whereas the in vivo effectiveness of NaOCl in the root canal against the infecting microflora is somewhat
disappointing.

12. Chlorhexidine Gluconate (CHX)
Mode of Action:
Permeates the cell wall or outer membrane and breaks down the bacterial cytoplasmic membrane
Bacteriostatic at low concentrations (0.2%) Bacteriocidal at higher concentrations (2%)

13. Chlorhexidine (CHX)
Less effective than NaOCl on biofilm
Organic matter reduces its
antibacterial efficacy
No tissue dissolving capacity
Why do we like it? Why do we not like it?
Low toxicity to healthy periapical
tissues
Substantive for up to 4 weeks
Wide antimicrobial spectrum
Improves dentine bonding

14. Cytotoxicity of CHX:
Normally used at concentrations 0.12% - 2.0%
Low level of cytotoxicity both locally and systemically
CHX effect on dentine bonding:
Inhibition of matrix metallo proteinase (MMPs) which degrade the hybrid layer in dentine bonding
Application of CHX improves dentine bond stability
Effect on biofilm:
CHX is ineffective in disrupting or removing the protective
Interaction with NaOCl + CHX :
Insoluble brown precipitate (parachloroanaline) forms when used in conjunction with NaOCl – carcinogenic and
occludes tubules
Important to carry out a saline rinse as an intermediary flush

15. Substantivity:
CHX is adsorbed onto the dentine – positive charged CHX binds electrostatically to hydroxyapatite
Inhibiting recolonization of the dentine walls
Continual antibacterial effect for up to 30 days (Rosenthal et al. 2004)
When would you use CHX:
1. Retreatment cases:
Adjunct/addition to the “usual” irrigating regime
2. Resistant bacteria – E.feacalis
E. faecalis contains a proton pump which enables it to survive in high pH environments
3. Suspected perforation – iatrogenic/resorption

16. Iodine
Mode of action:
Potent broad spectrum antibacterial solution
10% iodine potassium iodide
Advantages
Rapid action even at low concentrations
Broad spectrum
Disadvantages
No tissue dissolving capacity
Allergic reaction common (shellfish)
Discolouration of dentine
Indications:
5-10min iodine soak (Kvist et al. 2004)
Persistent disease cases that are not responding to NaOCl/CaOH treatment

17. Hydrogen Peroxide (H202)
Mode of action:
H202  H20 + O2
Effervescence (bubbling) of O2 has a flushing/physically agitation effect
Release free radicals (OH-) which oxidises bacterial cell walls and
proteins
Advantages
Low tissue toxicity
Bleaching effect - breaks down ferrous
haemolytic pupal breakdown products
Oxygen is toxic to anaerobic bacteria
Debris removal due to flushing activity
Disadvantages
Weak antibacterial effect
Weak tissue dissolving capacity
Possible pain/emphysema due
to O2 release

19. Smear Layer
Chemo-mechanical preparation leaves a layer of debris on the root canal wall which occludes dentinal tubules
Comprised of dentin particles, remnants of vital or necrotic pulp tissue, bacterial components and retained irrigants
Surface thickness:
Extension in tubules:
1 to 5 μm
40 μm to 100um

20. Smear Layer - Should it stay or should it go…..??
Advantages
1. Occludes dentinal tubules – creating
“plugs” which limit bacterial, nutrient and
toxin penetration
2. Entombing any surviving bacteria from
surrounding canal system
(Safavi et al. 1990, Pashley et al. 1985)
Disadvantages
1. Harbour bacteria and bacterial toxins which can act
as a source of reinfection
(Meryon & Brook 1990)
2. Act as a substrate nutrients for surviving bacteria
(George et al. 2005)
3. Prevents penetration of irrigants and medicaments
into tubules
(Haapasalo & Ørstavik 1987)
4. Prevents penetration of sealer into tubules and
therefore affecting obturation seal.
(Saunders and Saunders 1992)

21. Evidence is unequivocal…….
+ increased irrigant penetration and enhanced disinfection following smear layer removal
- contradictory evidence for obturation seal and effect on bacterial proliferation
Only one study looked at the effect of smear layer removal on outcome/healing which found no significant difference
between smear and no smear layer (Byström and Sundqvist 1985)
Evidence for smear layer removal…..?
How do we get rid of it?

22. 17% Ethylene Diamine Tetra Acetic Acid (EDTA)
Mode of action:
Chelating agent - binds to calcium ions (from smear layer or dentine) to form soluble calcium chelates
Demineralises and softens root canal wall dentine to depths of 20–50 μm in approximately 5 mins.
Mild antibacterial properties – weakens bacterial cell membranes

23. Interactions with NaOCl:
EDTA neutralises the tissue dissolving capacity of NaOCl
(Grawehr et al.)
Saline rinse important between irrigants
Interactions with CHX:
White foggy precipitate caused by the degradation of CHX
(Rasimck et al.)
Effect on dentine:
Reduction in flexural strength and modulus of elasticity
(proportional to length of exposure)
Prolonged exposure can result in erosion of peritubular
and intertubular dentine

24. Alternatives to EDTA
Organic Acids
Citric Acid, Tannic Acid and Polyacrylic Acid used in 10-40% concentrations
Similar demineralising capacity as EDTA in removing smear layer (Yamada et al. 1983)
HEBP – Etidronic Acid
No effect on proteolytic capacity of NaOCl
Weaker than EDTA/Organic acids – needs to be used in conjuction with NaOCL to effectively
remove smear layer

25. Combination Irrigants
QMix
Ingredients:
17% EDTA CHX Detergent
Detergent reduces surface tension and improve wettability (Grossman)
No tissue dissolving and weak antimicrobial properties
Premixed solution does not from the white precipitate that occurs with using them individually
Qmix removes smear layer as effectively as EDTA (Stojicic et al)

26. Combination Irrigants
MTAD
3 % Doxycycline
4.25% Citric Acid
Tween 80 (detergent)
Tetraclean
Doxycycline
Citric Acid
Propylene glycol
Tetracyclines:
Wide spectrum antibiotics – inhibiting protein synthesis
Substantive - binds to dentine therefore bacteriostatic
No tissue dissolution and relatively weak antimicrobial properties

27. Why use the fancy combo irrigants?
Safer - Low cytotoxicity compared to NaOCl (Zhang et al.)
Lower surface tension due to wetting agents
Better smear removal compared to EDTA – especially in apical third (Torabinajad et al.)
NaOCl causes cell lysis - releasing antigenic molecules (eg endotoxins)
Why not?
Cost
Weak antibacterial effect
No tissue dissolution
RECOMMENDATION: MUST BE USED IN CONJUNCTION WITH NaOCl

29. Application of Irrigants

30. Syringe Irrigation
Side venting:
- minimises apical extrusion
- flushes debris “upwards” out of canal
Use smallest gauge possible and place as close to apex as possible
Finger pressure only
Passive fit in canal
Luer lock design
a) Bevelled
b) Open ended
c) Safe ended

31. Prebend irrigation neede to 90 degrees to a predetermined length from pre op radiographs

32. Finger pressure only to minimise risk of extrusion

33. Considerations:
1. Irrigant stays mainly in canal lumen
2. Irrigant delivered only 1mm deeper than tip
3. Increasing volume of irrigant does not improve flushing action or debris removal
4. Vapour lock – important to recapitulate with a small file after every irrigant application

34. Irrigation Complications - Hypochlorite Extrusion
Symptoms:
Immediate severe pain
Immediate oedema of the soft tissue
Oedema spreads to neighbouring structures –
orbits, lip or cheeks
Profuse interstitial bleeding result in profuse
ecchymosis

35. 24 hrs post op - ulceration and
sloughing of mucosa
3 weeks post op -
osteonecrosis
Pooling of bleach during
treatment – chemical burn of soft
palate

36. Management:
1. Critical to recognise what is happening
2. Calm the patient – can be difficult as they may be writhing in the chair
3. Immediate irrigation with saline or local anaesthetic solution
4. Leave the access cavity open to encourage drainage and escape for inflammatory exudate/blood
Optional but probably necessary - 5. Change your underpants……
Evidence on prescribing antibiotics and steroids is unequivocal
ANY RISK TO AIRWAYS NEEDS EMERGENCY TRANSFER TO A+E
24 hrs post op: ice pack and NSAIDS/painkillers
24 - 48hrs post op: heat pack and NSAIDS/painkillers
Daily review of the patient – assess healing and reassurance

37. Avoiding extrusion of irrigant:
1. Rubber Dam Isolation and relevant PPI
2. Side venting irrigation needle
3. Place irrigant 2mm short of working length (even shorter in open
apex cases)
4. Avoid excessive pressure when applying irrigant – finger rather
than thumb pressure
5. Avoid locking need in the canal

38. Manual Dynamic Agitation
Well fitting GP cone pumped up and down in 2-3mm strokes
GP cone displaces irrigant into anatomy away from the main canal lumen.
Facilitating exchange of the apical irrigant with fresh coronal solutions.
Eliminates Vapour Lock
*CARE TO NOT PUMP THE CONE TO APEX ESPECIALLY IN
CASES DUE TO RISK OF ETRUDINT IRIGANT INTO THE APEX *

39. Brushes
Adjunct for debridement of the canals and to agitate the irrigants
Physical disruption of biofilms on wall of main canal lumen
Manual brushes: Navitips, Endo brush
Rotary brushes:
Canal Brush – 600 rpm flexible polypropylene bristles

40. Brushes - Any Good ?
- ? Ability to reach apex without excess enlargement
- ? Bristles left in canal irregularities
- ? Amount of penetration into tubules and irregularities
- ? Compaction of debris at apex
Reports of improved coronal cleanliness but NO difference in middle and apical third cleanliness (AL
Hadlaq SM et al. 2006)
*Paeds: use of small interdental brushes in immature necrotic incisors*

41. Sonic Agitation – Endo Activator
Tip oscillates at 1 – 6 KHz
High amplitude movement (back-forth action) compared to ultrasonic
Strong and flexible polymer tips
Smooth and non cutting
Minimal apical extrusion (Townsend et al. 2009)

43. Sonic Agitation – Vibringe
Traditional syringe delivery of irrigant
Battery driven vibrations to stir up/agitate the irrigant as it is delivered
9000 oscillations per mins
Similar issues to syringe agitation:
1. Vapour lock
2. Placing needle tip close to apex
3. Risk of extrusion

44. Sonic Agitation – Ripisonic
Aggressive sonic file
Stainless steel with barbed edges – may damage the prepared canal walls
Attaches to slow handpiece airline

45. Ultrasonic Agitation
Passive movement of a file within the canal system which transmits energy
to the irrigant solution.
Frequency: 20-30,000 Khz
Two modes of action:
Acoustic streaming and Cavitation
Acoustic Streaming -
Vortex like fluid movement around the vibrating file
Agitated irrigant - shear forces on biofilm and bacteria walls
- penetration into ramifications
Dampening effect of contact with canal walls
- precurved files to match canal curvatures
- apply tip to start of curvature

46. Cavitation -
Rapid movement of file creates air bubbles which expand/contract
Implosion/expansion releases energy as shockwaves and heat
Requires unimpeded movement of the file - ? possible within confines of a canal or curved canals
(many researchers concluded that cavitation does not occur in vivo)

47. Clinical Advantages of PUI:
More effective then syringe irrigation in removing organic debris (Gutarts et al. 2005)
Improves tissue dissolving capacity of NaOCl – increasing temperature (Cunningham 1980)
Effective in removing smear layer (Turkun and Cengez 1997)
Improved cleaning and disinfection isthmi and ramifications (Gutarts et al. 2005)
Does it make a difference to outcome?!

48. Negative Pressure Pressure Irrigation – Endo Vac

49. Negative Pressure Irrigation – Endo Vac
Advantages:
Promising canal cleanliness and SEM studies
Safely carries irrigant to within 1mm of apex
Minimal risk of apical extrusion (lower post op pain etc) and eliminates vapour lock
Continuous replenishment of irrigant
Endo activator resulted in the cleanest canals when compared to manual agitation, PUI, EndoActivator and
Syringe Irrigation. EA achieved 99% disinfection of canal isthmi and ramifications. (Klyn et al. 2010)
Disadvantages:
Cost - £70 / case

50. Positive + Negative Pressure Irrigation – Rinse Endo
Disadvantages:
Risk of apical extrusion
Technical difficulties attaining suction seal above tooth
Advantages:
Frequent irrigant replenishment

51. Lasers in Disinfection
Laser emitting diode  flexible optical fibre  heat and energy into canal system
Pros:
Potential microbial efficacy
Effective at smear layer removal
Cons:
Excess energy can melt/burn dentinal tubules
Energy channelled through tip off fibre – risk of frying
periapex through large foramen
Currently developing a spiral optical fibre to enable
lateral irradiation of tubules

52. Photo Activated Disinfection
Photosensitive solution placed in canals - Methylene blue and toluidine blue
Activated with light of a specific wavelength
Releasing antimicrobial oxygen free radicals

54. Inter appointment Medications
When?
1. Unable to complete treatment in on visit – time/complications
2. Suppuration or exudate within the canal that cannot be stopped
3. Presence of a swelling/sinus
4. Retreatment/Persistent disease cases
5. Immature Apicies – apexification/apexogenesis
Definition:
antimicrobial agent that is placed inside the root canal between treatment appointments in an
attempt to destroy remaining microorganisms and prevent reinfection

55. Ideal properties of medicament:
Antimicrobial Effect
Non toxic to periradicular tissues
Ease of removal and application
Low surface tension and easily diffuse into canal system
Physical barrier to reinfection
Substantive antimicrobial effect

56. Calcium Hydroxide (CaOH2)
Disassociation of CAOH2–> CA2+ + OH- Strong alkali with pH of 11.5
Two Modes of Action:
Antibacterial:
1. Damage to bacterial cytoplasmic membrane
- lipid peroxidation of the phospholipids in the membrane
- highly reactive free radicals (Coltran et al 1999)
2. Protein denaturation
- Increase pH results in breakdown of ionic bonds in protein tertiary structures
- disrupting enzyme activity and cell metabolism (Voet and Voet 1995)
3. Damage to bacterial DNA
- hydroxyl ions disrupts DNA structure and induces mutation
Tissue Dissolving:
Similar to that of NaOCl but to a lesser degree – saponification reaction – (negated by extended application time)

57. pH gradient over time in monkey teeth after application of CaOH - Nerwich et al. 1993
<- Canal lumen - coronal
<- Canal lumen – apical
<- Root outer wall – coronal
<- Root outer wall – apical

58. Calcium hydroxide is effective as long as a high pH is maintained
Canal lumen pH 11  root surface ph 9
Buffering action of root dentine (proton doors within the hydroxyapatite)
(Tronstad et al. 1981)
10 -14 days for pH to rise in periphery of root (Nerwich et al. 1993)
What is the optimal length of application?
Unequivocal evidence….
Sjogren (1991) reported 100% disinfection after one week
Orstavik (1991) and Barbosa et al. (1997) reported approx 75% disinfection at 1 week
Cvek (1976) and Bystrom et al. (1985) reported over 90% disinfection after 4 weeks of application
Prolonged application of CaOH is probably necessary….longer the better…… gradual diffusion of hydroxyl ions though dentine

59. Considerations with CaOH
Resistant Bacteria – E.Faecalis
E.Faecalis is a bacteria commonly cultured in persistent disease/retreatment cases.
1. Bacterial coagulation/adherence to collagen within dentine (Love et al.)
2. Deep penetration into tubules (Haapasolo et al.)
3. Intracellular proton pump (Evans et al.)
Strategies - Alternative medicaments such as CHX or Iodine
Bacterial Lipopolysaccaride (LPS)
Potent antigens released during bacterial cell lysis
LPS  release potent inflammatory mediators and prostaglandins  periapical bone resorption
CaOH disrupts protein structure of LPS  reduce periapical bone loss and encourage healing
(Safavi and Nicholls 1993)

60. Modes of Delivery:
Water soluble:
Saline, methylcellulose solution
Highest disassociation of hydroxyl ions
Readily washed away by periradicular fluids
Viscous vehicles :
Glycerine, polyethylene glycol (PEG)
Oily vehicles:
Eugenol, Camphoricated parachlorophenol
(CMCP)
Thicker consistency
Useful in suppurating/exudative canals
Lowest disassociation of hydroxyl ions
Difficult to remove - leaves residue

61. Effect on Dentine:
Degradation of organic component of dentine leads to reduction in strength and flexural modulus (Grigoratus et al.)
30-50% reduction in fracture strength and modulus of elasticity with long term application - greater than 6 months
e.g. apexification of immature teeth. (Andreasson et al.)
CaOH Toxicity:
Well tolerated by bone and pulp tissues. Resorbed if extruded into periapex
Interaction with NaOCl:
CaOH makes necrotic tissue more susceptible to the solubilising action of NaOCl (Hasselgren et al. 1984)
Method of Removal:
Instrumentation with 17% EDTA followed by NaOCl
Patency filing + circumferential filling of master apical file and ultrasonic activation
CaOH remnants may occludes dentinal tubules and affect obturation seal (similar to smear layer) (Kim and Kim)

62. Corticosteroid – Antibiotic Combination
Mode of action:
Corticosteroid - Triamcinolone
Bacteriostatic Antibiotic - Tetracycline
Poor inter appointment medication - weak antimicrobial properties
30% corticosteroid released within 24hours
Indications:
Inflamed/Hyperaemic pulps
Traumatised teeth – prevent/arrest/inhibit external inflammatory resorption arising on the root surface
? Efficacy in minimising post op discomfort when canals over instrumented

63. Questions?
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