chemomechanical disinfection Flashcards
aetiology of endodontic disease
biofilm resistance
provides protection against antimicrobials
Antimicrobials may fail to penetrate beyond the surface layers of the biofilm
Antimicrobials may be trapped and destroyed by enzymes
Antimicrobials may not be active against non-growing microorganisms
Expression of biofilm-specific resistance genes (e.g., efflux pumps)
Stress response to hostile environmental conditions (e.g., leading to an overexpression of antimicrobial agent-destroying enzymes).
clinical objectives of endo
remove canal contents
eliminate the infection
design objectives in endo
create a continuously tapering funnel shape
maintain apical foramen in orginal position - as small as possible
mechanical preparation creates space to allow
to allows irrigating solutions and medicaments to more effectively eliminate micro-organisms from the root canal system
why stages in preparation go coronal towards apices
to reduce bacterial load and not take it back
sizing of the canal determined by
Size determined by initial size of root canal apex
Passive exploration known as “gauging”
Apical preparation size controversial
Usually at least ISO size 25
Some advocate 30 and larger to allow irrigation
Canal curvature impacts upon what is achievable safely
ideal properties of disinfectant
low cost
washing action
reduces friction
killing of planktonic and biofilm microbes
detachment of biofilm
non-toxic and non-allergenic
doesn’t weaken dentine
Sodium Hypochlorite (NaOCl)
NaOCl ionises in water into Na+ and the hypochlorite ion, OCl-
Establishes equilibrium with hypochlorous acid (HOCl)
Acid/Neutral HOCl predominates
pH 9 and above OCl- predominates
HOCl is responsible for antibacterial activity
why NaOCl
potent antimicrobial activity
dissolves pulp remnants and collagen
ONLY root canal irrigant that dissolves necrotic and vital tissue
disrupts smear layer by acting on organic component
factors important for NaOCl function
concentration
volume
contact
mechanical agitation
exchange
concentration of sodium hypochlorite
presence of organic material affects antibacterial activity
used between 0.5% and 6%
we use 3% in GDH - Parcan
contact for NaOCl
coronal flaring is key to prepare the entrance
we use syringe - as recommended by fluid dynamics model
endoactivator allows vibration for smooth irrigation = mechanical agitation
manual dynamic irrigation
moving GP point in and out of canal
problems with NaOCl
has effect on dentine - edits its organic content = 3 % protects dentine
doesn’t have an ability to remove smear layer by itself
effect on organic material = not just the dentine, but discolouration of fabrics, opharlmic injuries and allergic reactions
can cause tissue necrosis
preparation of the canal for obturation
smear layer is formed during prep
organic pulpal material and inorganic dentinal debris
superficial 1-5µm with packing into tubules
bacterial contamination, substrate and interferes with disinfection
prevents sealer penetration !!
smear layer is removed
EDTA is a chelating agent that is capable, when used with NaOCl, of removing smear layer
17% solution used
1 minute contact time necessary
dry after NaOCl, aspirate and then go again
chlorhexidine digluconate
Antibacterial activity – studies show conflicting results, may have similar activity to NaOCl.
Less antifungal activity that NaOCl
Somewhat active against biofilms, but unable to disrupt biofilms
e.g. corsodyl
Adsorbtion of CHX prevents microbial colonisation for time beyond time of application
Varying times, upto 12 weeks
GDH proposed protocol cleaning and shaping
Once canal preparation is complete the canal should be finally irrigated with:
3% NaOCl throughout instrumentation and at least 30mL after instrumentation complete with MDI – at least 10 minutes prior to obturation
17% EDTA 1min penultimate rinse
3% NaOCl final rinse
Dry canal using absorbent paper points between irrigants
common symptoms of NAOCl extrusion
pain
swelling
ecchymosis - BRUISING
hemorrhage
neurological complications
airway obstruction
classic NaOCl accident
bruising along the course of superficial venous vasculature
very rare
risk factors
excessive pressure during irrigation
needle being locked within the canal
loss of control pf working length = use burr stopper !!
larger apical diameters/constriction (root resorption, immature teeth and developmental anomalies)
anatomical factors / proximity to sinus - check anatomy - UR 6,7
watch out for nigher NaOCl concencration
pressure is the problem
patent apical foramen
facilitied by ANATOMY
need POSITIVE-PRESSURE IRRIGATION
pressure at the periapex EXCEED the venous pressure in the superficial veins of the neck
flow rate is 1 mL/15 sec
management of NaOCl extrusion
all treatment should stop
keep calm
advise what happened
pain present = LA
allow bleeding until HAPOIG
give steroid paste (e.g. odontopaste) into a root canal, ensure no pressure
do not obturate, just seal
priority pain relief
review in 24h
refer if severe
