Endodontic Materials
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why are metal files used
remove soft and hard tissues remove microorganisms create space for disinfectants create shape for obturation
what is stress concentration point on a file
abrupt changes in geometric shape of a file that leads to higher stress at that point
what is work hardening
strengthening of a metal by plastic deformation crystal structure dislocation
what is nitinol
alloy of nickel and titanium
what does irrigation do
facilitate removal of debris lubrication dissolution of matter penetrate to canal periphery kill bacteria/yeasts/viruses biofilm disruption biological compatibility
what is responsible for antibacterial activity
hypochlorous acid made from sodium hypochlorite
what factors are important for sodium hypochlorite function
concentration volume contact mechanical agitation exchange
what is the smear layer made of
organic pulpal material and inorganic dentinal debris
what is the effect of the smear layer
bacterial contamination, substrate and interferes with disinfection prevents sealer penetration
how do you remove the smear layer
17% EDTA 10% citric acid
what is the volume of sodium hypochlorite used per canal and for how long
30ml at least 10 minutes after canal preparation
what is the concentration of sodium hypochlorite used
3%
what does EDTA do
remove smear layer
what is the volume of EDTA used for canal
3ml
what is the concentration of EDTA used
17%
what are the properties of an ideal obturation material
easily manipulated dimensionally stable seals canal laterally and apically non-irritant impervious to moisture unaffected by tissue fluids inhibits bacterial growth radiopaque doesnt discolour tooth sterile
what obturator do we use
gutta percha
what do sealers do
seal space between dentinal wall and core fills voids in canal lubricates during obturation
what are the properties of an ideal sealer
exhibits tackiness to provide good adhesion establishes hermetic seal radiopacity easily mixed no shrinkage on setting non-staining bacteriostatic slow set insoluble in tissue fluids tissue tolerant soluble on retreatment
what sealer is used
zinc oxide and eugenol glass ionomer resin sealers
what are the advantages of epoxy resin sealers
paste-paste mixing slow setting good sealing ability good flow initial toxicity declines after 24hrs
why are sealers containing paraformaldehyde not acceptable
they have severe and permanent toxic effects on periradicular tissues