Y3 L5 Root canal cleaning Flashcards
What does root canal cleaning refer to?
Using a variety of techniques, medicaments and irrigants to ideally remove all inorganic debris, organic substrate and micro-organisms.
What are the aims of cleaning?
- To prevent the tooth from being a source of micro-organisms i.e. eliminating infection.
- Vital cases = asepsis. Preventing infection usually in the treatment of irreversible pulpitis.
- Non vital cases = antisepsis. Treating infection i.e. apical periodontitis.
Describe the principle of asepsis in vital pulp therapy.
- Sterile working environment
- Rubber dam
- Coronal disinfection
- Sterile instruments
- Stable, well-sealed, temporary restoration
- High quality permanent coronal restoration
NB: these apply to non-vital cases as well.
Describe the principle of antisepsis in non-vital endodontics.
- Removal of the inner portion of the canal wall where dentinal tubules are most heavily infected- mechanical means
- Removal of as many micro-organisms as possible from the canal system, including isthmuses, crevices and lateral areas of oval canals- chemical irrigants required
- Remove sources of substrate for bacterial growth, internal sources- necrotic pulp tissues, external sources- quality of restorative seal
What are the methods of bacterial reduction?
- Instrumentation
- Irrigation
- Antimicrobial medication
- Sealers
- Other e.g. lasers, photo-activated disinfection, high frequency electrical pulses, ozone
What are the 2 components of root canal cleaning?
- Removal of bacteria
- Management of the smear layer
What cleaning materials are used in the UDH?
- Sodium hypochlorite 2% (NaOCl)
- EDTA 17%
- Chelating agents (e.g. Glyde)
- Saline
- Endodontic chlorhexidine
What are the features of an ideal irrigant?
- Has a broad antibacterial spectrum
- Efficacious against anaerobic and facultative microorganisms
- Dissolves and digests necrotic tissue
- Prevents formation of smear layer or dissolves it
- Inactivates endotoxins
- Non-toxic systemically
- Non-caustic to local tissues
Describe sodium hypochlorite 2%.
- Gold standard for disinfecting
- Has a broad antibacterial spectrum
- Dissolves and digests endodontic micro-organisms and necrotic tissue
- Removes organic components from the smear layer
- Inactivates endotoxins
- At low concentrations it is minimally irritating
- Must replenish regularly constantly dripping into canal as it will become inactivated if just left there. Reduced effectiveness.
How long should NaOCl be used for?
Between 20 minutes and 2 hours
Does temperature affect NaOCl efficacy?
No.
Agitation has a greater effect than increasing temperature.
Does increasing concentration affect NaOCl efficacy?
- Antibacterial efficacy of sodium hypochlorite remains unchanged regardless of its concentration
- Higher concentration increases risk of tissue damage to the patient if apical extrusion occurs
How do you prevent a hypochlorite accident?
- Must keep irrigant needle 3-4mm from the apex
- Use side vented needle
- Must set rubber stopper on needle
- Keep syringe moving
- Gentrle drips
- Maximum 2% NaOCl
What should you do if a hypochlorite accident occurs?
What is the smear layer?
A powdery, loose adherent layer, typically 1-2um thick on the surface of the canal wall.
- After mechanical instrumentation, this smear layer is left behind.
- It is composed of bacteria, necrotic debris, particulate dentine debris, pulpal remnants.
- Occludes dentinal tubules.
Outline the standard irrigation regimen in RCT.
Describe the technique for placing a temporary CaOH2 dressing.
- CaOH mixed with water or available as a pre-mixed aqueous solution (e.g. Hypocal)
- Syringe in or use paper points to place into canals
- Cotton pledget to seperate CaOH2 from temporary dressing
- GIC or PolyF used for temp dressing (good seal)
