Management of root canal treatment failure Flashcards
List four signs of root canal treatment failure
-Presence of clinical signs / symptoms of Endodontic origin e.g swelling
-enlargement of existing PARL
-New PARL
-persistence of PARL after 4 years
What are the indications for non surgical RE RCT?
-when residual infection is due to intraradicular infection and can be treated through conventional access without excessive damage to tooth structure
-technical re-treatment prior to replacing coronal restoration
-where there was a risk of contamination due to leakage
In what three ways is Re RCT different to de novo RCT?
-infection may have been altered to favour more gram positive bacteria or bacteria more difficult to eradicate
-access to the infection inhabited by iatrogenic errors/blockages
-tactile feedback of natural canal has been inhibited
List the 6 principles of re rct?
- remove all restorative material atraumatically as poss
- assess restorability
- remove all root filling material without removal of dentine
- gauge canal and assess for missed anatomy/canals
- refine/modfy shape of the canals
- complete RCT
What are the three types of canal sclerosis seen?
- irregular tertiary dentine making the canal narrower and irregular surface but the canal pathway is retained
- dentine tubule sclerosis -harder to instrument but canal patent
- dystrophic pulp calcification-narrowing of canal and more prone to blockage
What are the reasons for Endodontic surgery?
- Emergency: Incision and drainage or trephination
- Biopsy
- Peri-radicualar surgery
- Corrective surgery: root resection/hemisection
- Replanatation
6.Regnerative procdures - Decompression
What is trephination?
-Surgical perforation of the alveolar cortical plate to release the accumulated periradicular exudate
-Can use trephine burs or s sterile spreader
-Used when cannot establish draininage through the tooth
When would biopsies be indicated?
Routinely taken during Endodontic surgery and usually excisional in nature
What are the stages to periradicualr surgery?
Access through mucosal flaps
Curettage of lesion
Root end resection
Root end cavity preparation
Root end filling
What are the principles to flap design?
Good access
minimising trauma
good blood supply to the flap
avoid damage to surrounding structures
What factors may affect where the flap relieving incisions are placed?
Avoid:
mental nerve
boney prominences
large boney defects
muscle attachments
Where should you elevate the flap from?
The attached mucosa to avoid excess damage
What should you periodically do to the flap once retracted?
Irrigate with saline to prevent dehydration
Once the flap is elevated what is the next stage?
Osteotomy: identify the root end from the pre op radiographs and working lengths if the cortical plate is intact
What type of bur is used?
Round tungsten carbide bur
copious saline
Once the osteotomy has been performed what is the next stage?
Curettage of the surgical site to allow full view of the root end. MUST SEND FOR HISTO
Following curretage what is the next stage?
Root end resection
How much of the root should normally be resected and why?
usually around 3mm as most of the canal complexities lie in this region but remove in sections and visualise the root end
What angle should the root be resected at?
Perpendicular to the long axis of the tooth
Why is a 90% resection angle advised?
Exposes minimal dentinal tubules
What angle was previously advised to resect at?
45 degrees to aid visualisation but with micro surgery kits this is less of an issue now
Following resection what should be placed on the root end?
Methylene blue 1% to assess for canal complexities/cracks and extend as required
Once resected and stained what is the next stage of periradicualr surgery?
Root end cavity prep
What are the features of an ideal root end cavity prep?
Walls are parallel and at least 3mm deep
What instrument is helpful in root end cavity prep?
Ultrasonics
What materials can be used for root end fillings?
Amalgam historically
MTA, GIC and IRM most commonly used
When placing the root end filling what should be put in the surgical crypt?
Cotton pellets soaked in LA
What is the benefit of Pro Root MTA?
10-15mins setting time vs 4 hours for MTA
Portland cement and bismuth oxide (no CaPhos)
Prior to closing the flaps what should be taken?
LCPA
When is through and through surgery indicated?
When cannot control exudate through orthograde CMD
How is through and through surgery carried out?
tooth is accessed
then flap raised, osteotomy etc then flat plastic placed at root end then sealer injected and warm GP placed into canal. Root end cavity filled with MTA
-IRm placed coronally but avoid too much force
How should the flap be closed?
-Flap repositioned and then compressed with a damp gauze
What sutures should be used?
mono filamentous suture e.g nylon type
used to use black silk but stopped as this was braided
Once the sutures are placed what should be done to the wound?
Decompressed for 10-15minutes to allow only a thin clot to form
What should be avoided once the flap is sutured?
Ensure the flap is not under tension
