What is the objective of RCT?
To provide an environment that allows the healing of peri-radiculat tissues so that the tooth is retained as a functional unit in the dental arch
Why is obturation important?
Some studies show that up to 58% of endodontic failures are due to incomplete obturation
What is the difference between biological and technical success/failure in RCT’s?
- There may be a technical failure (such as not to the apex, voids etc) but might still get healing and be biologically sucessful
- May look like you have technical success but still biological failure occurs (doesnt heal)
Achieving what specific part of obturation has been highlighted as being important in gaining biological success with RCT’s?
Achieving a good apical seal
What factors of obturation are important in gaining success? (as well as apical seal)
- Apical/lateral seal
- Sealer/core materials
- Timing of obturation
- Length
- Assessment
- Coronal seal
What is the purpose of filling the root canal system?
To prevent the passage of microorganisms and fluid along the root canal system
How is the completion of root canal preparation (chemo-mechanical disinfection) verified?
by taking a radiograph with the root canal instrument(s) (or filling cones) inserted to the full working length
Where should root canal preparation/the working length end?
The preparation should end at the junction of the pulpal tissue and periodontal tissue.
The working length should be as close as possible to the cemento-dentinal junction as this is usually where the apical constriction (narrowest part of the canal) is.
What are the different ways that the working length can be determined?
- using an apex locator
- Radiographically determined
How can yous use an apex locator to work out working length?
You want to get a reading of 0 on the apex locator then take 0.5mm off of this length to get your working length.
If you get a red reading, this means that you are in the PDL.
How do you radiographically determine the workign length?
You take a radiograph with an instrument etc in at the estimated working length then if it is at the apex subtract 1mm
Is radiographically determined WL or using an apex locator more accurate?
apex locator
What factors can make determining the working length from a radiograph difficult?
The curvature of the root canals can change the working length as well as root resorption. Root resorption can make determining the working length complicated. It can be hard to distinguish the apex on the radiograph and if there is a wide apex, you may have to create a new working length further up the canal.
How does the length of obturation affect success rates?
Both fillings that are too long and too short decrease the success rates
When obturating, it is important to block what and why?
- important to block both the apical foramina and the dentinal tubules and accessory canals
- because the biofilm can infiltrate into the dentine in the accessory canals
If we have filled canals, have we removed all the bacteria?
no - just because we have filled canals, does not mean that there are no bacteria left. It is impossible for us to remove all of the biofilm present.
However, through obturating we can prevent the bacteria from getting a supply of nutrients.
When should canals be obturated (timing)?
Filling should be undertaken after the completion of root canal preparation and when the infection is considered to have been eliminated and the canal can be dried
What factors should be considered when timing obturation?
- Signs and symptoms
- Want the patient to be free of disease signs and symptoms
- Don’t want to obturate when there is a draining sinus or the patient is in pain
- Pulp status
- If pulp is vital want to try to obturate in a single visit as it isn’t infected so don’t want to delay obturation and allow more colonisation
- Periapical status
- If there is a large radiolucency then the infection is probably related to a chronic problem so might want to dress then obturate later
- Difficulty
- Might not be able to obturate in one visit
- Patient management
- Sedation
- P might not be able to come for long visits or handle them
