Management of root canal treatment failure

Question 1

List four signs of root canal treatment failure

Answer 1

-Presence of clinical signs / symptoms of Endodontic origin e.g swelling
-enlargement of existing PARL
-New PARL
-persistence of PARL after 4 years

Question 2

What are the indications for non surgical RE RCT?

Answer 2

-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

Question 3

In what three ways is Re RCT different to de novo RCT?

Answer 3

-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

Question 4

List the 6 principles of re rct?

Answer 4

1. remove all restorative material atraumatically as poss
2. assess restorability
3. remove all root filling material without removal of dentine
4. gauge canal and assess for missed anatomy/canals
5. refine/modfy shape of the canals
6. complete RCT

Question 5

What are the three types of canal sclerosis seen?

Answer 5

1. irregular tertiary dentine making the canal narrower and irregular surface but the canal pathway is retained
2. dentine tubule sclerosis -harder to instrument but canal patent
3. dystrophic pulp calcification-narrowing of canal and more prone to blockage

Question 6

What are the reasons for Endodontic surgery?

Answer 6

1. Emergency: Incision and drainage or trephination
2. Biopsy
3. Peri-radicualar surgery
4. Corrective surgery: root resection/hemisection
5. Replanatation
   6.Regnerative procdures
6. Decompression

Question 7

What is trephination?

Answer 7

-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

Question 8

When would biopsies be indicated?

Answer 8

Routinely taken during Endodontic surgery and usually excisional in nature

Question 9

What are the stages to periradicualr surgery?

Answer 9

Access through mucosal flaps
Curettage of lesion
Root end resection
Root end cavity preparation
Root end filling

Question 10

What are the principles to flap design?

Answer 10

Good access
minimising trauma
good blood supply to the flap
avoid damage to surrounding structures

Question 11

What factors may affect where the flap relieving incisions are placed?

Answer 11

Avoid:
mental nerve
boney prominences
large boney defects
muscle attachments

Question 12

Where should you elevate the flap from?

Answer 12

The attached mucosa to avoid excess damage

Question 13

What should you periodically do to the flap once retracted?

Answer 13

Irrigate with saline to prevent dehydration

Question 14

Once the flap is elevated what is the next stage?

Answer 14

Osteotomy: identify the root end from the pre op radiographs and working lengths if the cortical plate is intact

Question 15

What type of bur is used?

Answer 15

Round tungsten carbide bur
copious saline

Question 16

Once the osteotomy has been performed what is the next stage?

Answer 16

Curettage of the surgical site to allow full view of the root end. MUST SEND FOR HISTO

Question 17

Following curretage what is the next stage?

Answer 17

Root end resection

Question 18

How much of the root should normally be resected and why?

Answer 18

usually around 3mm as most of the canal complexities lie in this region but remove in sections and visualise the root end

Question 19

What angle should the root be resected at?

Answer 19

Perpendicular to the long axis of the tooth

Question 20

Why is a 90% resection angle advised?

Answer 20

Exposes minimal dentinal tubules

Question 21

What angle was previously advised to resect at?

Answer 21

45 degrees to aid visualisation but with micro surgery kits this is less of an issue now

Question 22

Following resection what should be placed on the root end?

Answer 22

Methylene blue 1% to assess for canal complexities/cracks and extend as required

Question 23

Once resected and stained what is the next stage of periradicualr surgery?

Answer 23

Root end cavity prep

Question 24

What are the features of an ideal root end cavity prep?

Answer 24

Walls are parallel and at least 3mm deep

Question 25

What instrument is helpful in root end cavity prep?

Answer 25

Ultrasonics

Question 26

What materials can be used for root end fillings?

Answer 26

Amalgam historically
MTA, GIC and IRM most commonly used

Question 27

When placing the root end filling what should be put in the surgical crypt?

Answer 27

Cotton pellets soaked in LA

Question 28

What is the benefit of Pro Root MTA?

Answer 28

10-15mins setting time vs 4 hours for MTA
Portland cement and bismuth oxide (no CaPhos)

Question 29

Prior to closing the flaps what should be taken?

Answer 29

LCPA

Question 30

When is through and through surgery indicated?

Answer 30

When cannot control exudate through orthograde CMD

Question 31

How is through and through surgery carried out?

Answer 31

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

Question 32

How should the flap be closed?

Answer 32

-Flap repositioned and then compressed with a damp gauze

Question 33

What sutures should be used?

Answer 33

mono filamentous suture e.g nylon type
used to use black silk but stopped as this was braided

Question 34

Once the sutures are placed what should be done to the wound?

Answer 34

Decompressed for 10-15minutes to allow only a thin clot to form

Question 35

What should be avoided once the flap is sutured?

Answer 35

Ensure the flap is not under tension