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
What methods of obturation exist?
Cold lateral compaction
- Master cone as same size as your master apical file and then use a finger spreader to create space for accessory cones to fill the voids.
What is a cone fit radiograph?
After doing final rinse with EDTA and sodium hypochlorite
- Place master apical cone into canal, while it is still wet.
Take radiograph and see if the MAC is at the CWL.
Also can check clinically if you mark the CWL on the cone with the tweezers and check it goes to WL.
What is the final rinse?
10 mins sodium hypochlorite- 30ml.
1 min EDTA 17%
1 min sodium hypochlorite
Then do cone fit
Then dry with paper points
Describe the process of apical gauging.
First stage of obturation.
Take the equivalent K file to the reciprocal file that you used at CWL.
Put it to CWL and then place apex locator on it.
- gentle apical pressure and it should not reach 0.
This tells us we have apical control- can now obturate with the equivalent master apical cone.
Describe, in simple terms, the procedure for reciproc.
Coronal flare with R25 at 2/3 EWL.
Determine CWL
Create glide path with size 15 file
Then take R25 to CWL.
Apical gauging with equivalent K file
Final rinse with sodium hypochlorite and EDTA
Master cone fit
Dry the canal
Obturate
If someone is pregnant, is it okay for them to have endo treatment?
In the first trimester, it should be emergency intervention only.
How long should you wait after to do endo treatment after someone has had an MI?
6 months.
Emergency treatment should be provided in consultation with patient’s cardiologist.
How would you get consent for a procedure?
Explain the diagnoses and clinical findings to the patient.
Treatment options available for those diagnoses
Why you think a particular treatment is necessary
Consequences, risks and benefits of treatment
Likely prognosis after treatment
Your recommended treatment
Cost of proposed treatment
What might happen if the proposed treatment is not carried out
Whether the treatment is guaranteed, how long it is guaranteed for and any exclusions that apply.
Ask if the patient has any questions.
Record all of this in the patient’s notes.
What are the potential risks of endo treatment?
Failure
Perforation
Instrument separation
Post-op pain
Hypochlorite accident
Damage to exiting restorations
Caries
Why is sodium hypochlorite a good irritant?
Antimicrobial
Dissolves pulp remnants and collagen
Only root canal irrigation that dissolves necrotic and vital tissue
Helps disrupt sear layer
What factors are important for sodium hypochlorite function?
Volume
Concentration
Contact
Mechanical agitation
Exchange
What concentration is used for sodium hypochlorite?
Between 0.5 and 6%.
We use Parcan in GDH- 3%.
What is manual dynamic irrigation?
Using sodium hypochlorite within the canal plus using your MAC to manually disrupt the biofilm as well.
What is used to remove the smear layer?
17% EDTA for 1 minute.
Why is it important to dry the canal in between the terminal rinses with EDTA and NAOH?
Reduces the therapeutic benefits of sodium hypochlorite.
What are some of the complications of sodium hypochlorite?
Discolouration of fabrics
Ophthalmic injuries due to eye contact
Apical extrusion lidding to tissue encores
Allergic reaction
What are the common symptoms of sodium hypochlorite extrusion?
Ecchymosis along the superficial vasculature on the same side
Pain
Swelling
Haemorrhage
Neurological complications
Airway obstruction
What are the guidelines for use of sodium hypochlorite?
Give patient PPE
Dam placement
Ensure all syringes labelled accordingly
Side vented needle for irrigation
27G luer lock syringe
Never fill the syringe more than 2/3 full
Never bind the needle into the root canal at any time
Depress the plunger with the index finger and never the thumb.
What is the purpose of an intra-canal medicament?
Placed in between appointments in an attempt to destroy the micro-organisms and prevent reinfection.
Control of root resorption
Reduce inflammation and exudate
What is the gold standard intra-canal medicament?
Non-setting calcium hydroxide for 7 days
- Ultracal or Optident.
Must come into direct contact with bacterial cell wall to be effective.
What is Ledermix and when would you use it?
Anti-microbial and anti-inflammatory paste.
- Contains corticosteroid and tetracycline.
Used in cases of hot pulp.
What is the goal of obturation?
Prevent passage of micro-organisms and fluid along the root canal
Fill the whole root canal system
Block apical foramina and dentinal tubules and accessory canals.
What techniques are available for obturation?
Cold lateral compaction
Warm compaction- vertical or lateral
Continuous wave obturation
Carrier based obturation
If the tooth had an open apex, what would you need to do?
Create an apical plug- use either MTA or biodentine.
How does MTA act as an apical plug?
Biocompatible but is also osseo-inductibe- we see bone and cementum growing alongside it.
What is the function of a root canal sealer?
Seals space between dentinal wall and core
Fills voids and irregularities in canal, lateral canals and between GP points
Lubricates during obturation
After obturation, what must you do?
Obtain adequate coronal seal to prevent bacterial recontamination of the root canal system or fracture of the tooth.
We want both a good coronal seal and a good apical seal.
What is the 5 and 10 year survival rate for Endodontically treated teeth?
Lots of varying factors- indirect vs direct restorations, ferrule present, quality of endo tx, type of tooth.
5 year- 85-90%
10 years- 75-80%
What is the survival rate of endodontically treated teeth with indirect and direct restorations post-endo treatment?
Indirect at 3 years- 92%
Direct with amalgam or composite at 3 years- 83%
But Indirects have much better long term prognosis- 5-10 years, 6 times more likely to fail without an indirect restoration.
- indirect- 81%, direct- 62%
Study showing teeth that had to be extracted following endo treatment- 85% did not have an indirect restoration.
