Irrigation in Endodontics Flashcards
Mark Barber
Endodontic infection
Primary RCTs are
Periapical and pulpal infections do not develop without the presence of bacteria
Polymicrobial
Aims of irrigation
Killing and removal of microorganisms
Removal of necrotic/inflamed tissue
Removal of dentine debris and smear layer
Provides lubrication and reduces friction for
instrumentation
Obstacles in RCT disinfection
Anatomical complexities
Smear layer
Fluid dynamics
Biofilm and Resistant Microbiota
Anatomical complexities - purpose and examples
Only 61% of walls are instrumented
therefore 40% of canals remain infected after instrumentation
Webs Loops Cul de sac Fins Lateral canals Apical delta
What does mechanical instrumentation do
Irrigation is..
Creates funnel shape as pathway for chemical instrumentation
Only way to disinfect majority of root canal system
Smear layer
Consists of??
Created during cleaning and shaping
Covers instrumented canal walls
Inorganic substances Organic substances Fragments of odontoblastic processes Microorganisms Necrotic debris
Problems associated with smear layer
Protection for bacteria
Inhibits/delays penetration of irrigant into dentinal tubules
Fluid dynamics
Fluid motion
As close to apex as possible
- 1-2mm penetration further than needle end
- Needle tip needs to be close to apical region
Stagnation plane is created - debris accumulates
No flushing of debris/penetration of irrigant into apical region
Rules for irrigation
Side-venting needle
Use a luer-lok syringe
Keep the needle tip moving to prevent it wedging and forcing irrigant through the apex
Use gentle pressure
If the needle bends - stop
Constant agitation to improve fluid flow
Size 27/30 gauge needle
GP role
Use GP point to improve irrigant exchange in the apical region
Biofilm
Exists within canals
Adhere to dentinal walls
Distinct from planktonic cells and are 100x more resistant than coronal bacteria
Stages of biofilm formation
Attachment
Colonisation
Growth
Biofilm stats
What must reach this layer?
Where are bacteria less susceptible to antimicrobial killing?
Biofilm is a bacterial layer on internal wall of dentine -
Irrigants must reach this layer In biofilm, bacteria are far less susceptible to antimicrobial killing
Resistant Microbiota
Which bacteria exhibit high level of resistance? - most frequent species in reinfection of RT teeth
Where can they survive?
Why are they responsible?
E. faecalis
Can survive as monoculture in root canals
E. faecalis is the most frequent species in root-canal
treated teeth, with prevalence values reaching up to
90% of the cases
E. Faecalis association with failure of endodontic treatment is at least partially, from high resistance of this species to NaOCl’
Ideal characteristics of an endodontic irrigant
Effective action Non irritant Stable Prolonged effect Active in presence of bodily tissues Low surface tension Not stain tooth structure Does not induce cell mediated response Able to remove smear layer non-toxic, non antigenic, non carcinogenic No adverse effects on physical properties of exposed dentine No adverse effect on sealing ability Easy Expensive
Basic principles of preparation
Mechanical prep must allow?
A combination of mechanical preparation
and irrigation with appropriate chemicals
is a fundamental principle of endodontics
– hence the term ‘chemo-mechanical
preparation’
Mechanical preparation must be sufficient
to allow penetration of the irrigant to the
apical region of the canal
Current irrigation solutions
NaOCl
CHX
H2O2
Advantages of NaOCl
Dissolves organic matter including BIOFILM and dentine debris
Antimicrobial effect against ALL endodontic bacteria
Affordable
To maintain desired effect when diluted - use
Larger volumes
Increased time of action
How to increase efficiency of NaOCl
Optimal effect?
Increase temp = increased tissue dissolution
60 degrees dissolves tissue but can also destory osteoblasts
x2 effect for every 5 degree rise
Continous replenishment of irrigant to get optimal effect of NaOCl
Disadvantages of use of NaOCl
Minimal smear layer removal Affects mechanical dentine properties
Rare cases of allergic reactions
Toxic to vital tissues
Causes metallic corrosion
EDTA - what is it
Avoid overuse because
Use - instructions
Synthetic amino acid
Removes smear layer as it is a chelating agent (same as citric acid)
Not bactericidal but eventually kills bacteria
Non toxic
Results in excessive removal of dentine
Penultimate rinse for 1-2 mins
Chlorhexidine is
Disadvantages
Broad spectrum Bactericidal at low and static at high concs Persistent activity following removal Less toxic No harmful effects
Forms brown precipitate
Use intermediate eg saline if using with bleach
Cannot remove smear layer
Potential for allergic reaction
Iodine/potassium iodide - what is it
Mechanism
2% iodine in 4% potassium iodide
Oxidising agent which attacks key group proteins, nucleotides and fatty acids –> cell death
Iodine/potassium iodide -
Works against -
Advantages
Disadvantages
Favoured in?
Broad spectrum including against Efaecalis, P. Aeruginosa and yeast species
Substantive effects
Low toxicity relative to NaOCl
Allergic reaction to iodine • Can stain dentine • Not stable in presence of organic material • No tissue dissolving property • Unable to remove smear layer
Re-treatment
H2O2 - what is it - mechanism
Advantages
Disadvantages
Is it used?
Hydroxy-free radicals (•OH) destroy proteins and DNA
- Concentrations varying from 3% and 5%
- Active against bacteria, viruses and yeasts.
- Antimicrobial efficacy is poorer than NaOCl
- Less tissue dissolving capacity than NaOCl
- Can release O2 gas (bubbles)
- Potential danger: seepage into the tissues may lead to air
emphysema. - No longer used as routine irrigant
Mixture of tetracycline, acid and detergent
Roles of each component
Mechanism
Advantages
Disadvantages
Doxycycline is antimicrobial
Citric acid takes smear layer away
Detergent disinfects
Doxycycline provides broad-spectrum antibacterial effect
- Citric acid removes the smear layer
No adverse effect on physical property of tooth.
Less efficient on biofilm
- More toxic than NaOCl
- Expensive
- Risk of bacterial resistance (Tetracycline)
- Risk for tetracycline staining
Ideal protocol
NaOCl and EDTA
Current protocol
NaOCI alone produces a superficially clean canal but fails
to remove the smear layer.
EDTA left superficial dentine behind
The current protocol in the hospital is to use NaOCl
throughout the endodontic procedure followed by a
penultimate flush of EDTA
Ultrasonic agitation - mechanism
Activates irrigant ultrasonically to improve efficacy
Causes acoustic micro streaming
Enhances antimicrobial efficiency
Disrupts biofilm
Can eliminate more bacteria from the root canal
Can be performed with a standard file attached to ultrasonic tip
PAD
Photo-activated disinfection
- A dye (often toluidine blue) is introduced
to the root canal - A low power laser is then used to activate
the dye - The photosensitiser molecules attach to
bacteria and following the introduction
of the laser irradiation, oxygen is
produced which ruptures the cell wall
PAD
advantages
disadvantages
Broad-spectrum of activity with little risk of
resistance
May destroy some bacteria left by some other
irrigants
No risk of toxicity
Efficacy depends on power, length of exposure,
absorption of light into tissues and distance from
tip-to-target
No evidence to suggest any benefit over other
irrigants
Expensive
