Irrigation and Disinfection Flashcards
How do root canal infections start?
Don’t develop w/o bacteria
Primary infections are polymicrobial - dominated by obligate anaerobic bacteria
What does irrigation achieve?
Kill and removal of microorganism, necrotic and inflamed tissue, dentine debris and smear layer
Provide lubrication
Why does canal anatomy cause problem with disinfection?
Only 61% canals instrumented - 40% remain infection
Irregular and complex system
Why does smear layer affect disinfection?
Provides protection for bacteria, inhibit and delay penetration or irrigant into dentine tubules
What is smear layer?
Created during cleaning and shaping - cover instrumented canal wall
Inorganic and organic substance, fragment odontoblastic process, microorganism, necrotic debris
How does fluid dynamic affect disinfection?
Irrigant penetrate 1-2mm further end of needle - needle needs to be apical region
Absence fluid motion = stagnation plane - no flushing of debris
What are the rules of irrigation?
Use side venting needle Luer-lok syringe Size 27/30 gauge Keep needle tip moving - prevent wedging Constant agitation
What is biofilm?
Group of microorganism in which cells stick to each other
Adherent cells embedded in self-produced matrix of extracellular polymeric substance
What is EPS?
Polymeric conglomeration generally composed of extracellular DNA, proteins and polysaccharides
When are bacteria less susceptible to antimicrobials?
In planktonic phase
What is the most resistant microbiota?
E. faecalis - prevalence 90%
Can survive as monoculture
Associated failure endo tx
Highly resistant to species of NaOCl
Ideal characteristics of irrigant?
Effective antimicrobial, not irritation periapical tissue, stable in solution, low surface tension, not stain, no cell immediate immune response, remove smear layer, non toxic, non carcinogenic, no adverse effect exposed dentine, no adverse affect sealing, easy use, inexpensive
Sodium hypochlorite as irrigant?
Dissolves organic matter including biofilm
Antimicrobial, affordable
Disadvantage NaOCl?
Diluted therefore need large bol Minimal removal dentine debris/ smear layer Reduce flexural strength dentine Rare case allergic reaction Toxic vital tissue Corrosion metal object
What is EDTA?
Synthetic amino acid Chelating agent - remove smear layer Relatively non-toxic Different solution % Use penultimate rinse for 1-2min
Disadvantage EDTA?
Not bacteriostatic/cidal - eventually kill via starvation
Over use = removal of dentine
What is chlorhexidine?
Cationic bibiguanide antiseptic Broad spec - resistance less likely Bactericidal at high conc and static low conc Less toxic NaOCl No corrosion
Disadvantage chlorhexidine?
No tissue disolving affect
Potential severe allergic reaction
Form parachloroanaline when used NaOCl = brown precipitate - potentially carcinogenic
What is iodine potassium iodide?
Oxidising agent - attack key group proteins, nucleotides and fatty acid = cell death
Favoured in re-tx cases
Broad spec inc. against e.faecalis, p. aeruginosa and yeast species
Disadvantages iodine potassium iodide?
Allergic reaction to iodine
Can stain dentine
Not stable in presence of organic material
No tissue dissolving properties
What is hydrogen peroxide?
Hydroxyl-free radicals destroy proteins and DNA
Active against bacteria, virus and yeast
Disadvantages of hydrogen peroxide?
Antimicrobial efficacy is poor and less tissue dissolving than NaOCl
Can release 02 gas - lead air emphysema
What is MTAD?
Mixture tetracylcine, acid and detergent
Doxycycline provides broad-spec antibacterial effect
Citric acid removes smear layer
Disadvantages MTAD?
Less efficient on biofilm More toxic than NaOCl Expensive Risk of bacterial resistance Risk tetracycline staining