Instrumentation of Root Canal System Flashcards
What is the aim of instrumentation of the root canal system?
Remove canal contents- infected soft and hard tissues
Give disinfecting irritants apace to gain access to the canal space
Create space for delivery of intra-canal medicaments
Retain integrity of radicular structures
What is recapitulation and patency filing?
Recapitulation- using a small file to ensure latency and dislodge debris before introducing a larger file.
Patency filing- placing the file into the apical constriction to contact apical tissues.
What is the modified double flare technique?
Involves development of an initial coronal flare, followed by apical flare.
Then step back technique allows you to create a continuous taper.
- uses GG and stainless steel K files.
What are the different file movements that can be utilised?
Balanced force- for smaller K files
Watch winding- for larger k files
What is corrected working length?
Distance in mm from a known coronal reference point to the position of in the apical region of the tooth, where endodotnic preparation and obturation terminates.
What are the design objectives of endo treatment?
Continuously tapered funnel shaped canal
Maintain apical foramen in original position
Keep apical opening as small as possible
How can you get your corrected working length?
File into canal at EWL and take a PA
Electronic apex locator
What is estimated working length?
Estimated length at which instrumentation should be limited.
Measure distance between coronal reference point and radiographic apex and subtract 1mm- based off a pre-op radiograph.
What is a master apical file?
Largest diameter file that is taken to WL- therefore represents the final preparation size of the apical portion of the canal at WL.
What type of file can be used to extirpate the pulp?
Barbed broach
Must not engage the canal- only to remove th pulp contents.
What are the advantages of NiTi vs SS?
More flexible
Less lateral pressure required
Increased cutting efficiency
Good safety
What are the disadvantages of NiTi preparation?
Prone to fracture
Expensive
Access can be difficult in posterior teeth
Unsuitable for complex canal anatomy
What is chemomechanical disinfection?
Chemo- using chemicals to disrupt biofilm and smear layer
Mechanical- shaping the root canal space and debriding canal.
When analysing a tooth on a radiograph for root treatment, what are we looking for?
Number of roots
Number of canals
Anatomy of roots- curved, splayed.
Length of roots
Angulation of roots
Proximity to vital structures
Canal calcifications- pulp space narrow or wide?
How far does the PA pathology extend?
Any posts or large coronal restorations already in situ
Separated instruments
Ledges or perforations
What methods can be used to determine corrected working length?
Electronic Apex locator
WL radiograph using paralleling technique
Paper points
Describe, in simple terms, the stages of modified double flare technique.
Access
Coronal preparation at 2/3 of EWL
Work out CWL
Apical preparation
Apical gauging
Apical flare
What sealer is used to obturate?
AH plus- epoxy resin sealer
Slow setting- 8 hours
Good selling ability
Initial toxicity declining after 24 hours
What are the components of GP?
20% gutta percha
65% zinc oxide
10% radio pacifiers
5% plasticisers