Endodontic failure Flashcards
What are the success rates of root canal treatment?
- Range from 31% to 100%
- Clearly not always as well as we would hope
- No significant change in outcomes in recent times
Which guidelines determine a successful outcome?
- ESE guidelines
- BUT ‘success’ means different things to - researchers, clinicians and patient
- Technical versus biological outcome
When should root canal treatments be assessed?
- At least after 1 year and subsequently as required
What should be looked for when assessing the outcome of root canal treatment? (4)
- Absence of pain, swelling and other symptoms
- No sinus tract
- No loss of function
- Radiological evidence of a normal PDL
What determines an ‘uncertain’ outcome of root canal treatment?
- If radiographic changes remain the same size or has only diminished in size. In this situation it is advised to assess the lesion further until it has resolved or for a minimum period of 4 years. If a lesion persists after 4 years the root canal treatment is usually considered to be associated with post-treatment disease
Root canal treatment has an ‘unfavourable’ outcome when…? (4)
- The tooth is associated with signs and symptoms of infection
- A radiographically visible lesion has appeared subsequent to treatment or a pre-existing lesion has increased in size
- A lesion has remained the same or has only diminished in size during the 4 year assessment period
- Signs of continuing root resorption are present
- In these situations it is advised that the tooth required further treatment
What is the exception we may see radiographically that does not show an unfavourable outcome?
- An extensive radiological lesion may heal but leave a locally visible, irregularly mineralised area
- This defect may be scar tissue formation rather than a sign of persisting apical periodontitis
- The tooth should continue to be assessed
What is the basis of the ESE guidelines based on?
- Based on strict radiographic criteria for success
What is loose criteria on definitions of outcomes?
- Where we don’t need to see a complete absence of a lucency
- Can see a lucency that is getting smaller
Why do root canal treatments fail?
- Most failures occur when treatment procedures, mostly of a technical nature, have not reached a satisfactory standard for the control and elimination of infection
What is a pre-op factor that affects the success of root canal treatment?
- Presence or absence of a lesion
(if the tooth is vital vs non-vital has a little effect on outcome BUT non-vital with periapical lesion has a big effect)
What are operative factors that contribute to the success of root canal treatment? (4)
- Filling extending to within 2mm of the radiographic apex (if its short may indicate that we haven’t disinfected adequately or might indicate that we haven’t created a good apical seal and the chances of success are diminished)
- Make sure filling doesn’t extrude out the apex (this has a negative impact on outcome)
- Well condensed root filling with no voids
- Good quality coronal restoration
What is a technical complication that can lead to biological failure?
- Coronal leakage
- Difficult to establish causality
- Currently - good coronal restoration coupled with good quality root canal treatment
Give a list of factors that may influence the outcome of root canal treatment? (7)
- Presence of a sinus
- Increased lesion size
- No perforation
- Getting patency
- Penultimate rinse with EDTA
- Avoiding mixing CHX and NaOCl
- Absence of a flare up
What is a failed biological objective that can cause failure of root canal treatment?
- Missed canals
- Means we fail to disinfect the root canal completely
For upper 6’s if there is no … canal, you have probably just not found it yet?
- MB 2
- Be careful to look for this anatomy
READ paper ‘anatomy of the pulp chamber floor’
- Essential reading
Explain centrality in relation to the RCS?
- The pulp chamber lies central in the tooth at the level of the CEJ
Explain concentricity in relation to the RCS?
- The pulp chamber lies concentric to the surface of the tooth at the level of the CEJ
Learn the laws in the anatomy of the pulp chamber floor paper
Add the laws to the flashcards
What is the Law of Symmetry I?
- Except for maxillary molars, the orifices of the canals are equidistant from a line drawn in a mesial-distal direction through the pulp-chamber floor
What is the Law of Symmetry II?
- Except for maxillary molars, the orifices of the canals lie on a line perpendicular to a line drawn in a mesial-distal direction across the centre of the floor of the pulp chamber
What is the Law of Colour Change?
- The colour of the pulp-chamber floor is always darker than the walls
What is the Law of Orifice Location I?
- The orifices of the root canals are always located at the junction of the walls and the floor
What is the Law of Orifice Location II?
- The orifices of the root canals are located at the angles in the floor-wall junction
What is the Law of Orifice Location III?
- The orifices of the root canals are located at the terminus of the root developmental fusion lines (dark lines that run across the floor)
One factor that contributes to success is achieving and maintaining patency. What can blockages be due to?
- Can be due to severe curvature
What are factors that contribute to failure of RCT? (7)
- Iatrogenic - avoid the creation of ledges, avoid separation of instruments
- Poor planning
- Poor access
- Poor length control
- Forcing Instruments
- Failure to observe sequence of instruments
- Failure to maintain patency
What factors can cause persistent intra-radicular infection, which is a biological reason for failure of RCT? (4)
- Canal complexities
- Biofilm (disease - exceptionally difficult to manage)
- Resistant bacteria
- Enterococcus faecalis has been identified, but role is controversial
What are 2 examples of extra-radicular bacteria that can be a biological reason of failure of RCT?
- Actinomycosis
- Extruded biofilm
Cyst formation (epithelial lined cavity) can be a non-microbial, biological reason for failure of RCT. How do these develop?
- Develop from mature granuloma, inflammatory mediators acting on epithelial cell rests (in the peri-radicular tissues)
What are the 2 types of periapical cysts?
- True cysts and pocket cysts
What is the difference between a true cyst and a pocket cyst?
- A true cyst is separate from the root canal whereas a pocket cyst is continuous through the root canal
How do we manage granulomas, abscesses or cysts?
- They are primarily caused by root canal infection, we should use a treatment protocol that will eliminate their etiology in the root canal system rather than their product
What are 3 biological reasons for failure of RCT not already stated?
- Cholesterol crystals
- Foreign body reactions - delayed healing
- Scar tissue ‘healing’
For retreatment decision making the decision making process depends on an accurate diagnosis. We need to establish the cause of failure. What are the possible causes? (4)
- Technical e.g. perforation, separated instrument
- Root fracture
- Other odontogenic pain
- Non-odontogenic pain e.g. atypical facial pain
When assessing the restorative prognosis of RCT what are we looking for? (3)
- Check for the presence of fractures - need good magnification and illumination
- Assess remaining amount of tooth structure
- Have you got a good seal and will the restoration last?
When retreatment planning what are the options for management? (4)
- Keeping under observation (KUO)
- Orthograde treatment (going from the top down)
- Surgical treatment (this is removing the peri-radicular tissues, the root tip and creating a seal from the apical region up)
- Extraction
What is orthograde treatment in relation to root canals?
- Going from the top down
What is surgical treatment in relation to root canals?
- This is removing the peri-radicular tissues, the root tip and creating a seal from the apical region up
What are most failures of RCT due to?
- Most failures due to inadequate disinfection of the root canal system initially, leaving residual bacteria
- In most cases therefore, non-surgical retreatment will offer the best outcome
How complex is retreatment in the original root anatomy has not been damaged?
- Complexity of treatment is not high
How complex is retreatment is there are fractured instruments, blockages, ledges or severe curvatures?
- IT is more complex and so consider referral
- Apical surgery is complex and considered a specialist treatment - consider referral
What would the strategy for retreatment be if the canal is filled with insoluble resins?
- Ultrasonic
What would the strategy for retreatment be if the canal is filled with Gutta-Percha?
- Handfiles +/- solvent
- Protaper D/Reciproc
What would the strategy for retreatment be if the canal is filled with soluble pastes?
- Handfiles +/- solvent
- Protaper D/Reciproc
How difficult is it to remove poorly condensed GP?
- Generally easier
What kind of files would we use to remove poorly condensed GP from the root canal system ?
- Hedstroem files (to withdraw the GP point)
How difficult is it to remove well condensed GP from a root canal?
- Generally harder
- Need to create a space (so may need to use solvents)
What solvent may we use when trying to remove GP from a root canal?
- Might use eucalyptus oil
What handfiles/approach would you use to remove GP from a root canal?
- Stratified approach with simple approach initially then more complex approach
- 1st file is a headstrong file - used to try to withdraw GP
- But may need to use other files to make your way through the GP
- C files are fairly rigid which would allow you to penetrate the GP mass
Protaper D1 has an active tip. What does this allow?
- Allows better initial penetration into material
Why do we need to be careful when we use Protaper D1 files?
- With a curved canal we can readily lead to perforation
- Use these files with great caution
What is the retreatment sequence process when using Protaper D files?
- Protaper D1 - for coronal filling removal
- Protaper D2 - for middle filling removal
- Protaper D3 - for apical filling removal
What is the Protaper D1 file used for?
- For coronal filling removal
What is the Protaper D2 file used for?
- For middle filling removal
What is the Protaper D3 file used for?
- For apical filling removal
What is the process for Protaper retreatment? (5)
- Select lowest speed that effectively engages obturation material 500-700rpm
- Gently press D1 into GP and remove frequently to clean flutes
- Continue with D1 until obturation material removed from coronal one-third of canal
- Auger obturation material from middle one-third of canal with D2
- Remove material from apical third with D3, stopping 2-3mm short of apex
What is the RECIPROC system?
- Single file system that is very effective in removing the GP
What colour of RECIPROC system file would you use to remove GP in narrow canals?
- Red (called R25)
What colour of RECIPROC system file would you use to remove GP in medium canals?
- Black (called R40)
What colour of RECIPROC system file would you use to remove GP in large canals?
- Yellow (called R50)
Is the RECIPROC system for retreatment efficient?
- Very efficient
- Remove bulk of GP (US, heat carrier)
What are the 2 solvents we may use when using the RECIPROC system for retreatment of a root canal?
- Chloroform
- Eucalyptus oil
Which RECIPROC file would we use to remove the bulk of the GP in the root canal?
- R25 (red file)
Which files do we use to increase apical enlargement in the RECIPROC retreatment system? (2)
- R40 + R50
If possible we want to use the RECIPROC retreatment system with no solvent. Why is this?
- The problem is that solvents leave a smear of GP on the surface which can obstruct the dentinal tubules
- If having difficult then use eucalyptus oil to soften because if fail to do this risk is you create a ledge or perforation
