Endodontics
Course Review
Enoch Ng, DDS 2014
Cleaning and Shaping the Root Canal System
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Debridement – removal of irritants (bacteria, tissue, etc) from canal system
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Chemomechanical – instrumentation and irrigation
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Cleaning – ideally instruments contact and plane walls to loosen debris
o
NaOCl – dissolved organic matter, destroys bacteria
o
Irrigants – flush loosened/suspended debris/sludge from canal space
Irrigation
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Lubrication, flush debris from canal, disinfection, tissue dissolution, removes smear layer
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NaOCl – oxidative action on sulfhydryl groups of bacterial by HOCl
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Bactericidal - inhibits enzymes, disrupts metabolism, causes cell death
NaOCl + H
2
O
NaOH + HOCl
HOCl = active biocide, dissolves organic tissue
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5.0% highly toxic compared to 0.5%
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Technique – syringe with irrigating needle
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Requires safety glasses – can damage tissue, ruin clothing
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Rubber dam isolation with seal (oraseal)
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Passive and slow injection of solution into canal
Never force needle into canal, closer to apex = greater risk of injury
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Files can carry irrigating solution further into canals
Capillary action of smaller diameter canals causes solution retention
Excess solution aspirated away with needle
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Frequent irrigation = less debris and less apical blockage
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Ideal Irrigant
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Provides lubrication during instrumentation
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Flushes debris from canal, removes smear layer
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Dissolves organics in fins and isthmi, bactericidal
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Low cytotoxicity
Dry vs Wet Instrumentation
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Dry instrumentation
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Apical extrusion of material negligible
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More difficult to instrument canals – easier to plug apex with debris
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Instruments more likely to jam and separate
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Wet instrumentation
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Apical extrusion dependent on canal length and file size
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Less difficult to instrument canals
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No instrument separation
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Tissue Dissolution
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Solvent action limited by surface contact, volume, and exchange of solution
Amount of organic matter
Frequency and intensity of mechanical agitation (fluid flow)
Available surface area of free or enclosed tissue (larger surface area = faster dissolution)