Managing root canal failure Flashcards
what are the different definitions of successful endodontic treatment ?
- strict criteria 1956 = after RCT the PA architecture should return back to normal - difficult as it take a while to return eg. 4yr period
- loose criteria 1993 = tooth functional and asymptomatic, no sinus present and legion radiographically is resolving
- survival 2004 = is tooth still there, easy to measure = binary choice - doesn’t take into account if tooth is functional
- failure = persistence of disease
how do we diagnose failure ?
- Periapical lesions not always visible radiographically until cortical plate penetrated (Seltzer and Bender)
- Large lesion may be present without overt radiographic signs esp in lower molar region where theres thick cortical bone
- Symptoms can be mixed, if present = we can’t just use symptoms to diagnose
how can we overcome the weaknesses of conventional radiography ?
CBCT
Need to consider dose – if conventional film gives you the answer do you need a CBCT
Likely to become a normal part of endodontic diagnosis in the future
why do RC’s fail?
- presents of bacteria in canals
- intraradicullar can still be present = have to look at surgery in these cases
- case reports of more esoteric causes
- Siqueira (2014) states that most common cause for failure is treatment that does not conform to accepted standards
- Persistent versus Emergent disease
- presistance = RCT not good enough to decontaminate canal and persistent biofilm flares up
- emergent = RCT leaked due to poor seal biofilm now gone into RC and disease has emerged
failure summary ?
Generally the RCT hasn’t been done properly
Might look pretty, doesn’t mean it’s been done right
Missed canals are very common
how do we tx plan
- arrive at accurate diagnosis ie. is it a cyst, fracture, PA disease
- Consider options – non-surgical retreatment (redo), retreatment (remove the cyst or granuloma etc) , extraction with or without prosthodontic replacement or monitor
- And write in your notes that you have discussed this
what do we need to look at for non surgical retreatment ?
- restorability assessment
ie. how restorable is it?
how do we do a restorability assessment ?
- First part of endodontic procedure should always be a restorability assessment
- how much tooth structure left
- Cause of much endodontic ‘failure’ is restorative ie tooth fractures or not enough seal
- need to be honest with pt of we can’t do RCT
- Cracks, insufficient dentine, not enough ferrule
- All about vision and illumination
- Literature shows that in order to assess restorability you need to remove existing restorations (Abbott, 2004)
- Not always practical
- If you leave the restoration in, must have consent
- If you are taking the restoration out, must have consent
- Need to visualise final restoration at the start of the treatment plan
what can we use as a guide to assess restorability ?
- restorability index
- Method of assessing remaining dentine and its strategic value
- Splits tooth into segments and gives a score based on tooth structure remaining
- need to take study casts of tooth and give scores to dentine heights = very complex
what are some other refactors we see in restorability ?
- vertical root fracture = contraindication
how do we spot vertical root fractures ?
-Deep but narrow probing defect
-Sinus more coronally (gingival margin) placed than usual – sinus trace radiograph helpful
-‘Halo’ or ‘J-shaped’ bone loss pattern on radiograph
what else do we consider in tx plan?
- cuspal coverage necessary in most posterior teeth
- After reduction for cuspal coverage restoration is there enough dentine left?
- implant vs RCT, what is the most predictable outcome for this patient
when we have made the decision that tooth is restorable what do we need to consider ?
Has it been well treated or not? (bioloigcally and technically)
What is it filled with?
Original anatomy versus damaged anatomy (have we got ledges, perforations etc)
what is apical surgery ?
Direct to surgery not generally the best option unless you know the case
Surgical success rates improve with improved non-surgical root canal treatment
summary for pretreatment planning cases ?
Why did it fail?
Nice white stripes are just that
Restorative failures arguably more common than endodontic failures – can you fix it?
If symptoms persist during retreatment, consider your original diagnosis
what are some retreatment techniques ?
Need to find all the canals – know the anatomy
Ensure the roof of the pulp chamber is entirely removed so you can see all of the pulpal floor
Follow Krasner and Rankow rules
Removal of GP
Best if possible en masse
Braiding technique = passing few small files around big GP and then twisting then pull out
Use of reciprocation / rotary then pull out = can damage wall if you apply too much pressure
Hand files and solvent
how do hedstrom files work to remove gP?
having cutting edge which engages with GP
Do not screw into dentine
If can’t engage the GP then soften with solvent (endosolve)
Important to know what you are trying to remove
what can mechanised techniques can we use to remove GP?
Can use both rotary files or reciprocating files
Specific retreatment files also exist (ProTaper D1, D2, D3)
Tend to be quite stiff and end cutting – be wary
how do we finish off prep once GP removed ?
Solvent useful at the end to remove sealer and persistent bits of GP
Once GP removed, undertake chemo-mechanical preparation as with a primary RCT case
how do we obturate re-tx cases ?
If there has been an issue with obturation previously consider options?
Beware the damaged apex – cold lateral compaction will often give you control
- heat compaction may not be suitable esp if I caused issues previously
Re-tx summary?
Quite often GP so poorly condensed very easy to remove
Always try and remove en masse as this is neater
Do not force Retreatment Files or GG drills, easy to create ledges or perforations
Solvent is useful, but can get messy
Heat can be useful to help engagement of files in the GP
Practice makes perfect
summary
Good prognosis for retreatment
Often not really a retreatment, just doing the primary properly
Well treated (both chemically and biologically) teeth more difficult to get a result
Restorability is critical
Fractures increasingly prevalent - eg due to bruxism
Consider what was wrong before and correct it
