Canal Disinfection Flashcards
Key for successful endo bc the files can’t reach all the walls of the canal.
Thorough irrigation
Ideal irrigant has high or low surface tension?
LOW- so it can spread to all the surfaces of the canal.
Types of Irrigants
NaOCl
EDTA
CHX
NaOCl alkaline or acidic?
Alkaline
The gold standard irrigant that:
- dissolves both vital and necrotic tissue,
- removes the organic component of the smear layer,
- kills bacteria,
- eliminates biofilm
- Lubricating action
- Cytotoxic
NaOCl
NaOCl mechanism of action
- Saponification
- Amino acid neutralization
- Chloramination
- Alkaline pH (>11)
- Hydrolysis
A fatty acid is heated with an alkali to make soap and alcohol.
Saponification
A chemical species that donates an electron pair to an electrophile to form a chemical bond; it’s electron rich.
Nucleophile
Nucleophiles work during this step of NaOCl’s MOA.
Saponification
An acid-base reaction, which yields a salt and water.
Amino acid neutralization
A rxn where chloramines are made from Chlorine and Ammonia
Chloramination
This pH (specifically, these IONS) alters the cell membrane by loss of phospholipids and fatty acids.
Disrupts cellular processes and enzymatic activity.
Alkaline ; OH- ions
Substance that dissolves tissue into soap and glycerol via saponification.
NaOCl
This product of NaOCl MOA interferes with cellular metabolism.
Chloramines
This disinfectant irreversibly inactivates essential bacterial enzymes via oxidation of sulfhydryl groups by Chlorine.
NaOCl
This is used as a chelating agent (underlined) in root canals to remove calcium, demineralize and soften dentin, and remove the smear layer.
EDTA
Used to negotiate calcified canals.
EDTA
Removing this increases Ca(OH)2 diffusion through the tubules, and increases tubule penetration by the sealer.
Smear layer
This irrigant is followed by a final rinse of NaOCl so the bleach can kill the bacteria in the tubules.
EDTA
A bis-biguanide antiseptic used to prevent colonization of microbes and to kill microorganisms on surfaces;
known for its substantivity.
Chlorhexidine
Definition: The binding of disinfectant to dentin and soft tissue with prolonged release.
Gives residual antimicrobial activity for a long time.
Substantivity
This substance:
- Kills bacteria
- Does NOT dissolve pulp tissue.
- Does NOT eliminate biofilm
- Does NOT remove the smear layer
CHX
Do not mix these two irrigants together.
NaOCl and CHX
CHX MOA.
Positively charged CHX binds to Negatively charged phosphates in the bacterial cell wall, creating pores that disrupt the cell’s osmotic equilibrium, and the cell lyses.
A gas bubble of NH3 and CO2 forms at the apical canal by hydrolysis of organic tissue, making it impossible to irrigate the most apical part of the canal.
Vapor lock
Which canals get vapor lock?
Closed
T/F: higher concentrations of NaOCl will dissolve tissue faster and increase antimicrobial effectiveness.
True
When is the only time the canal should be dry?
When ready to place the sealer.
T/F: increasing NaOCl temperature before irrigating will increase its effectiveness.
True
What’s this process called: agitating the bleach into uninstrumentable portions of the canal.
Activation
Cannot do this to the irrigant around root curvatures bc the metal tip will create procedural errors.
Activation
Definition: Activation of fluid and hydrodynamic shear forces near a small vibrating object.
Acoustic streaming
Definition: Use the alternating high frequency movement of an instrument tip to form submicroscopic voids. These voids implode and make shock waves that spread through the medium.
Cavitation.
This SONIC device is used for activation of the irrigant.
Uses polymer tips, which are safe to use around curvatures.
Not as strong as ultrasonics.
Does NOT create cavitation.
EndoActivator
Has low frequency (1500-6000 Hz) and high amplitude
Sonic
Has High frequency ( >20,000) and low amplitude.
Ultrasonic
Forms when you mix CHX and NaOCl.
PCA (para-chloroaniline)
PCA is _____.
carcinogenic.
This irrigant inhibits NaOCl by reducing the amount of free Chlorine.
EDTA
Reduces the amt of free Chlorine bc it’s a chelating agent.
This doesn’t lose its chelating ability when mixed with NaOCl.
EDTA
Mixing these two irrigants makes a salt, which is harmless.
CHX and EDTA
Which intracanal medicament is this:
- Alkaline pH
- Bactericidal
- Dissolves pulp tissue
- Stimulates hard tissue formation
- Resorbable
- Eliminates biofilm?
Ca(OH)2
Ca(OH)2 MOA:
1) Damages the cytoplasmic membrane
2) Protein denaturation
3) Damage to DNA
How long does it take for Ca(OH)2 to get rid of most of the bacteria in the canal?
1 week; is NOT effective short-term.
This material does reduce the bacterial load, but has not been shwon to increase outcomes.
Ca(OH)2
