Card Set Information
Endo lecture 8
What are teh 4 steps in RCT?
What is the goal of obturation?
Create complete seal along the length of the root canal
From coronal opening to the apical termination
Includes Apical seal, Coronal seal, Lateral seal
How does obturation create apical seal of the root canal?
movement of fluid through small spaces, like a leakage
Percolation leads to endodontic failure
Bacteria lose viability after obturation
How does obturation create a coronal seal?
Permanent restoration needs to be placed within reasonable time frame
Coronal leakage can communicate oral cavity and periradicular tissues
A main reason for RCT failure
How do we achieve a lateral seal?
A void in mid root can sometimes be acceptable
Lateral canals communicate periodontium and RC space
What are the requirements for obturation
Asymptomatic (not on sore tooth)
Cleaned and shaped canal to optimal size
How do we do lateral condensation?
Select and place master gutta percha cone
Achieve correct length and tug-back
Place RC sealer in the canal
Laterally place, then condense accessory gutta percha cone
What is the master cone?
Standardized gutta percha point that is the same size as the
final apical file
Fits to full working length with tug back
What is tug back?
Tightness or resistance to withdrawal
of the master cone
Created by fit of master cone to flare of apical 1-2mm of the cavity preparation
What is the function of the apex locator?
Apex locator can establish where the constriction is
Should be slightly short of the
How short of the apical foramen do we want to be?
From .5-1.5mm of the anatomical length
How do we use the accessory files?
We use multiple tips to take the full canal to length
Push them with the plugger to the CEJ and then establish coronal seal
Why do we need to reduce the gutta percha past the CEJ?
The sealer can stain the tooth, turning it gray
What are the two types of filling materials?
Gutta Percha- Sap of Malaysian sapodilla
What is Gutta percha?
Beta dental form from the tree
Expands on heating, shrinks on cooling
What are silver points?
A filling material
corrosion leads to failure and staining
: limited use today
What are the components of gutta percha?
Zinc oxide (primary ingredient)
Gutta percha (plasticity)
Metal sulfates (radiopacity)
What are the two types of gutta percha points
: master cone
: accessory cones
What are standardized gutta percha points?
in size and taper #25-100
Match master cone to master apical file
Fits snugly with tugback into apical preparation
Sanitize master cone in NaOCl for
What are non-standardized gutta percha points
Greater flare and feather tips than standardized
Fills flared portion of canal around the master cone
5 types of taper (M, FM, MF, FF, etc)
The ideal master cone
Goes to the working length (WL)
Gives you tug-back
Most important and difficult portion of root canal obturation
What are the 4 ways master cone can go wrong?
1. Debris at apex
: short working length
2. Cone too big
: short working length, tug-back
3. Cone too small
: full working length
4. Good cone
: full WL, tug-back,
What are the 5 root canal sealers
1. Zinc-oxide Eugenol (Roth)
2. Epoxy resin (plastics)
3. N2; RC2B (formaldehyde)
4. CaOH Sealers (w/ ZOE)
5. Glass ionomer(bonds dentin)
Zinc-oxide-eugenol root canal sealers
Good seal, easy to handle
Can decompose in water
Epoxy Resin root canal sealer
Antimicrobial, long working time, good seal
Toxicity and insolubility possible
N2; RC2B root canal sealer
Formaldehyde is active ingredient
No longer used
Calcium hydroxide sealers
CaOH2 incorporated into ZOE sealer
Potential osteogenic effect at the apex
Questional long-term stability and toxicity
Glass Ionomer Root canal sealers
Adequate apical and coronal seal
Insoluble, retreatement difficult
Worry about post-operative discomfort?
No. It's usual and doesn't indicate obturation success
How do we use radiographs to evaluate obturation?
Lateral canals leading to radiographic lesion
What will happen to extruded sealer?
It will be gone in 6 months, along with any lucencies
Places to lose seal and fail RCT
Over/underextended and over/underfilled canal
Multiple portals of exit
undetected major canals (like MB2)