Irrigation in endodontics

Question 1

Endodontic infection

Answer 1

Periapical and pulpal infections do not develop without the presence of bacteria
Primary root canal infections are polymicrobial
-dominated by obligate anaerobic bacteria

Question 2

Aims of irrigation

Answer 2

Killing and removal of microorganisms
Removal of necrotic/ inflamed tissue
Removal of dentine debris and smear layer
Provides lubrication and reduces friction for instrumentation

Question 3

Obstacles in root canal disinfection

Answer 3

Anatomical complexities
Smear layer
Fluid dynamics
Biofilm and resistant microbiota

Question 4

Anatomical complexities

Answer 4

Only 61% of canal walls are instrumented
40% of canal walls remain infected
Irregular and complex systems
Irrigation is the only way of disinfecting majority of root canal system

Question 5

Irregular and complex systems

Answer 5

Webs
Loops
Cul de sac
Fins
Lateral canals
Apical delta

Question 6

Smear layer

Answer 6

Created during cleaning and shaping

Covers instrumented canal walls

Question 7

Smear layer consists of

Answer 7

Inorganic substances
Organic substances
Fragments of odontoblastic processes
Microorganisms
Necrotic debris

Question 8

Problems associated with the smear layer

Answer 8

Provides protection for bacteria

Inhibits/ delays penetration of irrigant into dentinal tubules

Question 9

Fluid dynamics: fluid motion

Answer 9

-irrigant only penetrates 1-2mm further than end of needle
-needle tip therefore needs to apical region
Absence of fluid motion
-stagnation plane
-no flushing of debris/ penetration of irrigant into apical region

Question 10

Fluid dynamics: rules for irrigation

Answer 10

Use side-venting needle
Use Leur-lok syringe
Keep needle tip moving to prevent it wedging and forcing irrigant through apex
Use gentle pressure
If needle binds - stop
Constant agitation to improve fluid flow
Size 27/30 gauge needle

Question 11

How to improve irrigant exchange in apical region

Answer 11

Consider using gutta percha point

Question 12

Biofilm and resistant microbiota - EPS

Answer 12

A biofilm is any group of microorganisms in which cells stick to each other on a surface
These adherent cells are frequently embedded within a selfproduced matrix of extracellular polymeric substance (EPS)
Biofilm EPS (also referred to as slime) is a polymeric conglomeration generally composed of
extracellular DNA, proteins, and polysaccharides.
The microbial cells growing in a biofilm are physiologically distinct from planktonic cells of the same organism, which, by
contrast, are single-cells that may float or swim in a liquid
medium

Question 13

Steps of biofilm formation

Answer 13

Attachment
Colonisation
Growth

Question 14

Parts of a biofilm

Answer 14

Bulk fluid
Cell cluster
Void
Channel
Streamer

Question 15

Biofilm is a bacterial layer on internal wall of dentine

Answer 15

Irrigants must reach this layer
In biofilm, bacteria are far less susceptible to antimicrobial killing than in planktonic phase
MIC for bacteria in a biofilm are difficult to determine
Biofilm models have demonstrated survival of bacterial biofilms after treatment with antibiotics at concentrations
of 100 to 1000 times the MIC of the same bacteria measured in suspension culture

Question 16

Resistant microbiota: E. faecalis

Answer 16

E.Faecalis exhibits high level of resistance to wide range of antimicrobial agents
Can survive as monoculture in root canals
Cultures of root canals irrigated with NaOCl always yielded +ve cultures with E.Faecalis
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’

Question 17

Ideal characteristics of an endodontic irrigant

Answer 17

1. Effective antimicrobial action
2. Non irritating to the periapical tissue
3. Stable in solution
4. Have a prolonged antimicrobial effect
5. Active in the presence of blood, serum, and protein derivatives of
   tissue
6. Low surface tension
7. Not interfere with repair of periapical tissue
8. Not stain tooth structure
9. Does not induce cell mediated immune response
10. Able to completely remove smear layer
11. Non toxic, non antigenic, non carcinogenic
12. Has no adverse effects on the physical properties of exposed dentine
13. Has no adverse effects on the sealing ability of filling materials
14. Easy to use/apply
15. Inexpensive

Question 18

Basic principles of irrigation and mechanical prep

Answer 18

A combination of mechanical preparation
and irrigation with appropriate chemicals
is a fundamental principle of endodo – hence the term ‘chemo-mechanical prep’
Mechanical preparation must be sufficient
to allow penetration of the irrigant to the apical region of the canal

Question 19

Rubber dam

Answer 19

Mandatory for every endo procedure

Question 20

Current irrigation solutions in endo

Answer 20

1. Sodium hypochlorite (NaOCl)
2. Ethylinediaminetetraacetic acid (EDTA)
3. Chlorhexidine (CHX)
4. Iodine potassium iodide (IPI)
5. MTAD (Mixture of Tetracycline, acid and
   detergent)
6. Hydrogen peroxide
7. Photo-activated disinfection (PAD)
8. Electronically activated water

Question 21

Advantages of sodium hypochlorite

Answer 21

1. It is the only endodontic irrigant which
   dissolves organic matter – including biofilm
2. Antimicrobial – effective against all endodontic bacteria
3. Affordable

Question 22

Sodium hypochlorite - to maintain desired antimicrobial effect when diluted:

Answer 22

Larger volumes of irrigant are required
Increasing time for action required
-0.5% NaOCl: 30min contact time
-2.5% NaOCl: 10min
4% NaOCl: 5 min
5.25% NaOCl: <30sec

Question 23

Increasing the temp - sodium hypochlorite

Answer 23

Improve tissue dissolution (0.5% at 45°c equivalence with 5.25%)
60°C completely dissolve tissue but can destroy osteoblast
and cause corrosion of metal instrument.
> antimicrobial effect (double for each 5°c rise)

Question 24

To get optimal effect of NaOCl

Answer 24

Continuous replenishment of irrigant
Chlorine ion responsible for tissue dissolving and
antibacterial capacity is rapidly consumed (2 min) especially during the first phase of tissue dissolution

Question 25

Canal wall after prep with rotary nickel-titanium instruments

Answer 25

a) using saline as an irrigant b) using NaOCl for irrigation Notice that when using NaOCl nearly no remnants of pulpal tissue or debris were found on the canal wall

Question 26

Disadvantages of sodium hypochlorite

Answer 26

1. Minimally removes dentin debris or smear layers 2. Affect mechanical dentin properties (reduce flexural strength). 3. Rare cases of allergic-like reaction causing dermatitis 4. Toxic to vital tissue (hemolysis, epithelial ulceration, and necrosis) 5. Causes corrosion to metal object

Question 27

EDTA

Answer 27

Synthetic amino acid Removes the smear layer as it is a ‘chelating agent’ -a substance with the ability to scavenge up and form ring-shaped internal complexes with metallic ions, including calcium Not bactericidal/static -but eventually kills bacteria by starvation as metallic ions needed for growth are chelated Relatively non-toxic

Question 28

Avoid over-use of EDTA

Answer 28

Results in excessive removal of dentine

Question 29

Using EDTA

Answer 29

``` Available as a solution of 15- 17% Should be used as a penultimate rinse for approx 1-2 mins Also available as a gel to aid in canal lubrication ```

Question 30

Citric acid

Answer 30

Citric acid is also an effective chelating agent, but less so than EDTA

Question 31

Chlorhexidine

Answer 31

Cationic bibiguanide antiseptic Broad spectrum, attacking multiple sites at a cellular level making resistance less likely Bactericidal at high concentrations and static at low concs Demonstrates substantivity – has a persistant activity following removal Used in concentrations of 0.2-2% Less toxic than NaOCl No harmful effects to dentine or corrosion of instruments

Question 32

Chlorhexidine with NaOCl

Answer 32

Forms a precipitate when used with NaOCl – para chloroanaline -brown precipitate -potentially carcinogenic -if used with NaOCl use a intermediate such as saline No tissue dissolving effects Cannot remove the smear layer Potential for severe allergic reaction (very rare)

Question 33

Iodine potassium iodide

Answer 33

2% iodine in 4% potassium iodide Act as an oxidizing agent that attacks key group proteins, nucleotides and fatty acids, leading to cell death Increasingly favoured in re-treatment and heavily infected cases – but not used in isolation

Question 34

Advantages of iodine potassium iodide

Answer 34

Broad antimicrobial spectrum, including against Efaecalis, P. Aeruginosa and yeast species Substantive effects Low toxicity relative to NaOCl

Question 35

Disadvantages of iodine potassium iodide

Answer 35

``` Allergic reaction to iodine Can stain dentine Not stable in presence of organic material No tissue dissolving property Unable to remove smear layer ```

Question 36

Hydrogen peroxide

Answer 36

Hydroxy-free radicals (•OH) destroy proteins and DNA Concentrations varying from 3% and 5% No longer used as routine irrigant

Question 37

Advantages of hydrogen peroxide

Answer 37

Active against bacteria, viruses and yeasts

Question 38

Disadvantages of hydrogen peroxide

Answer 38

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

Question 39

Mixture of tetracycline, acid, detergent (MTAD) constituents

Answer 39

3% doxycycline 4.25% citric acid A surface active detergent

Question 40

Advantages of MTAD

Answer 40

Doxycycline provides broad-spectrum antibacterial effect Citric acid removes the smear layer No adverse effect on physical property of tooth

Question 41

Disadvantages of MTAD

Answer 41

``` Less efficient on biofilm More toxic than NaOCl Expensive Risk of bacterial resistance (Tetracycline) Risk for tetracycline staining ```

Question 42

Photo-activated disinfection (PAD)

Answer 42

A dye (often toluidine blue) is introduced to the root canal A low power laser is then used to activate the dye The photosensitizer molecules attach to bacteria and following the introduction of the laser irradiation, singlet oxygen is produced which ruptures the cell wall

Question 43

Advantages of Photo-activated disinfection (PAD)

Answer 43

Broad-spectrum of activity with little risk of resistance May destroy some bacteria left by some other irrigants No risk of toxicity

Question 44

Disadvantages of Photo-activated disinfection (PAD)

Answer 44

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

Question 45

Electronically activated water

Answer 45

Electronically Activated Water is also known as Oxidative Potential Water Essentially involves electrolysing saline solution Used commonly to disinfect dental piping and tubing Creates hypochlorous acid and free radicals which can remove biofilm and destroy bacteria Lack studies showing the efficacy and safety Not as effective as 3% NaOCl

Question 46

Which irrigants should we use

Answer 46

NaOCI alone produces a superficially clean canal but fails to remove the smear layer The chelating solutions (eg EDTA) alone effectively removed the smear layer but left varying amounts of superficial debris The current protocol in the hospital is to use NaOCl throughout the endodontic procedure followed by a penultimate flush of EDTA There is no universally accepted protocol for endodontic irrigation, largely due to the large number of often conflicting research studies Iodine may be useful to use as an additional irrigant in retreatment cases where bacteria may be more resistant There is increasing support for some of the newer irrigants, however, in addition to effectiveness other factors such as cost:benefit ratio also need to be considered

Question 47

Ultrasonic agitation of irrigants

Answer 47

Irrigant can be activated ultrasonically to improve the efficacy Causes ‘acoustic micro-streaming’ Enhances the antibacterial efficiency of the irrigants Disrupts the biofilm Can eliminate more bacteria from the root canal than hand instrumentation alone Can be performed with a standard file connected to an ultrasonic device or with specific endodontic tips