Management of endodontic failures

Question 1

Endodontic outcome aim (3)

Answer 1

 The aim of endodontic treatment is to prevent or cure
periapical periodontitis
 When assessing outcomes of endodontic treatment we
are assessing whether we have met this aim
 Ideally, the outcome should be the absence, or in cases
where there were signs of preoperative periapical
periodontitis, the resolution of periapical periodontitis
after endodontic treatment

Question 2

Outcome criteria - strict vs loose (4)

Answer 2

Strict criteria:
 This requires no symptoms , no clinical signs of disease, and no periapical radiolucencies for endodontic treatment to be deemed a success.
 This is ideal, but may be unrealistic.
Loose criteria:
 This requires no symptoms, no clinical signs of disease and a decrease (or at least no increase) in the size of the preoperative periapical radiolucency for endodontic treatment to be deemed a success.
 This is a more realistic approach

Question 3

Outcome criteria - survival (3)

Answer 3

 A more pragmatic approach may be to use ‘survival’ as
the outcome criteria
 This is defined as the tooth being present in the arch,
asymptomatic and functional (ie there may still be
clinical and radiographic signs of pathology, which
may even be worsening)
 This is useful for comparing to the survival rate of
implants (to ‘level the playing field’)

Question 4

Better terms to describe outcome criteria than success and failure (4)

Answer 4

 Favourable
 Uncertain
 Unfavourable
This complies with the current European Society of
Endodontology guidelines

Question 5

What do the studies say about the outcome of endodontic treatment? (4)

Answer 5

 These generally have different study designs and outcome criteria, and
include systematic reviews and prospective studies
 Some of the most recent and well recognised are the studies undertaken at the Eastman Dental Hospital by Paula Ng
 Depending on the outcome criteria and type of study success rates of
around 85% were reported
 Depending on the case outcomes of up to 95% can be achieved

Question 6

Which factors affect endodontic treatment outcome? (4)

Answer 6

Despite the heterogeneity in study outcomes, there is
good evidence to support three main factors affecting
endodontic outcome:
 Preoperative status of the periapical tissues
 Quality of the root canal filling
 Quality of the coronal restoration

Question 7

Preoperative status of the periapical tissues (4)

Answer 7

 The outcome is likely to be more favourable when the pulp is vital, has pulpitis or is necrotic but uninfected
 Probability of success can be in the region of 95% in these cases
 In teeth with signs of periapical periodontitis (i.e. a PA radiolucency on a radiograph) success reduces to around 85%, probably because the root canal is more heavily infected
 The likelihood of a successful outcome appears to be reduced further when the PA radiolucency is larger than 5mm in diameter

Question 8

Quality of the root canal filling (5)

Answer 8

Endodontic treatment is more likely to be successful
when the root canal filling is satisfactory
This is defined as extending to within 2mm of the
radiographic apex, and well compacted
The likelihood of a successful outcome is lower when :
 The root filling is overextended/long
 The root filling is underextended/short
 The root filling contains voids

Question 9

Quality of the coronal restoration (4)

Answer 9

 Endodontic treatment is more likely to be successful when the quality of the coronal restoration is satisfactory
 The restoration should have no marginal deficiencies, defects or
recurrent caries which can act as routes for bacteria to re-infect the root canal
 Some studies have indicated an increased success rate when a fullcoverage coronal restoration is placed (e.g. a crown) following
endodontic treatment
 Whilst placing a crown is often desirable following completion of
endodontic treatment to improve coronal seal and structural durability,
each tooth should be assessed on its own merits regarding whether to
place a crown or a direct restoration

Question 10

Assessing endodontic outcome (3)

Answer 10

 Patient should be assessed 9-12 months following completion of endodontic treatment for a clinical and radiographic assessment
 Patient may be reviewed earlier if they are
experiencing continued symptoms, but a radiograph
should not usually be taken unless further developments are suspected (eg root fracture etc)
 Depending on the outcome at review, patients may need to be reviewed for up to four years

Question 11

The review apt should include (3)

Answer 11

 Assessment of the patient’s symptoms
 Clinical examination
 Radiographic examination

Question 12

Patient symptoms (3)

Answer 12

Patients should be asked regarding pain, swelling and/or loss of
function
However, a lack of symptoms does not always prove a favourable outcome – a clinical and radiographic examination are also required
Continued discomfort/pain may be due to persistent periapical infection, but also due to other reasons:
 Occlusal interferences
 Food trapping in the area
 Tooth fracture
 Neurogenic pain
 Non-odontogenic pain e.g. sinusitis, TMD, atypical facial pain

Question 13

Neurogenic pain (5)

Answer 13

Nerves around tooth become sensitised even after infection has cleared
Low grade
On and off
Nothing specific brings it on
Root treatment will not help
They need to go to a pain clinic
Medication could help

Question 14

Clinical examination (7)

Answer 14

 Presence/absence of a sinus tract or swelling
 Tenderness to palpation in the sulcus and soft tissues
 Tenderness to percussion of the tooth
 Presence of tooth fractures
 Presence of dental caries
 Periodontal status: probing depths and mobility
 Quality of the coronal restoration

Question 15

Radiographic examination (6)

Answer 15

 Quality of the root filling
 Presence/absence of a periapical radioluncency
 Size of the PA radiolucency (if present) and comparison to the preoperative PA lesion (increase, decrease, no change in size)
 Quality of the coronal retoration
 Presence of caries
 Periodontal condition
CBCT has been shown to have superior accuracy in detecting periapical pathology, however, this would only be indicated in
specific situations e.g. persistent pain with no signs on a conventional radiograph

Question 16

Criteria for a favourable outcome (4)

Answer 16

For the outcome of endodontic treatment to be
deemed favourable, the following criteria should be
observed:
 The patient is symptom-free
 The tooth is functional
 Clinically, the associated tissues are healthy
 Radiographically, the associated periapical tissues
appear healthy

Question 17

Criteria for an uncertain outcome (3)

Answer 17

In certain cases the clinician may not be able to clearly
classify the outcome of treatment as favourable or
unfavourable:
 There are no signs or symptoms, however:
 Radiographically, the periapical radiolucency has
persisted (remained the same size or only reduced in size) within the four-year assessment period

Question 18

Criteria for an unfavourable outcome (4)

Answer 18

The patient is complaining of symptoms, e.g. pain, swelling
The endodontically treated tooth is not functional, e.g. the patient avoids eating on it
Clinically, there are signs of infection, e.g. sinus tract, swelling
Radiographically:
 A new periapical radiolucency has developed
 The periapical radiolucency has increased in size
 Radiographically, the periapical radiolucency has persisted (remained
the same size or only reduced in size) at or after the four-year assessment
period

Question 19

When to place a definitive restoration (3)

Answer 19

 Placing a definitive restoration soon after completion of endodontic treatment will improve coronal seal and
structural durability
 Studies have shown that placing an indirect
restoration increases the prognosis for the tooth,
however, each tooth should be assessed on its own
merits
 Wait until clinical signs and symptoms have resolved
before placing an indirect restoration but do not feel
obliged to wait until there is radiographic resolution of
the lesion

Question 20

Why does endodontic treatment fail? (4)

Answer 20

Intraradicular infection
 Persistent infection: residual microbes left within the root canal
following the endodontic treatment
 Secondary infection: Microbes which have re-entered the canal
following endodontic treatment (coronal leakage, fractures etc)
Extraradicular infection
 Periapical actinomycosis, displacement of infected dentine etc
True cysts
 Apical true cysts are self-sustaining and do not heal following satisfactory root canal treatment
Foreign body reaction
 Foreign bodies (e.g. gutta percha) can compromise healing

Question 21

Recognising post-treatment disease (2)

Answer 21

As with assessing outcome of your own endodontics, a
thorough assessment of the patient’s symptoms, clinical
signs and radiographic assessment is essential
If you did not undertake the endodontic treatment
yourself, you also need to ascertain a history of the previous
endodontic treatment:
 Where was it performed?
 When was it done?
 What was the original diagnosis?
 Did the original treatment remove the symptoms initially?
 What techniques were used and how long did it take?

Question 22

Management of endodontic failures (3)

Answer 22

 Once it has been decided that a root treatment has failed,
options regarding future management need to be
considered
Management of endodontic failures can be complex from
both a treatment planning perspective and treatment
perspective
If endodontic treatment has failed there are four main
options:
 No treatment (monitoring)
 Extraction
 Endodontic retreatment
 Apical surgery

Question 23

No treatment (monitoring) (4)

Answer 23

When the outcome is not favourable according to strict
criteria but the tooth is stable enough to warrant review,
rather than intervention
For example, the tooth may be symptom-free but have a
non-healing periapical radiolucency
Monitoring will avoid the risks associated with reintervention
The patient should be advised:
 The tooth will require regular review
 To return if signs/symptoms develop
 That an acute flair up may occur at any time

Question 24

Extraction (5)

Answer 24

Extraction is the quickest way to deal with endodontic
disease
Consider extraction when:
 The patient does not wish to have further treatment and
monitoring is not an option
 Teeth where the restorability is doubtful
 Non-functional teeth/teeth with no strategic value
 Teeth with untreatable disease e.g. root fracture,
advanced periodontal bone loss etc

Question 25

Endodontic retreatment (5)

Answer 25

 The treatment of choice when post-treatment disease is
present and the patient is keen to save the tooth
 Only consider if the tooth is restorable
 Even if the previous obturation looks adequate, you do not
know how well the tooth was disinfected, whether rubber
dam was used etc etc
 The goal of endodontic retreatment is the same as initial
treatment: eradicate microbes and provide a good apical
and coronal seal
 When undertaken properly, success rates can be nearly as
high as primary treatment (83% vs 80%)

Question 26

Endodontic retreatment (3)

Answer 26

Prior to initiating retreatment, a patient should be
advised that:
 During treatment the tooth may be deemed
unrestorable e.g. discovery of a catastrophic fracture,
gross caries etc
 Root canal retreatment is complex and there are risks
e.g. perforation, which may render the tooth
unrestorable or at least reduce the prognosis
 It may not be possible to fully instrument canals if they
are blocked etc and this will affect the prognosis

Question 27

Surgical endodontics (7)

Answer 27

Surgical endodontics should only be carried out when it is not possible (or pragmatic) to carry out root canal retreatment
Indications for surgical endodontics:
 Where root canal retreatment would have an unfavourable outcome
 Obstructions within the canal which cannot be removed/negotiated
with orthograde treatment
 Teeth with long/wide posts which risk root fracture if removal is attempted
 Perforations which require surgical repair
 Investigative procedures (e.g. biopsies, confirmation of root fractures etc)
 Extraradicular infection and true cysts

Question 28

The canal contents which require removal can include (5)

Answer 28

 Gutta percha
 Endodontic posts
 Thermafil carriers
 Silver points
 Fractured instruments etc
-in addition, repair of iatrogenic perfrations may be required

Question 29

Removal of gutta percha (5)

Answer 29

There are a variety of techniques for removing gutta
percha:
 Gates glidden burs followed by hand files (K-files and H-files)
 Retreatment rotary NiTi files
 Solvent technique
 Combinations of the above

Question 30

Gates glidden burs and hand files (7)

Answer 30

 Gates glidden burs can be used to remove the coronal GP
 Hand files can then be used to remove the apical GP
 Hedstrom files are useful for gripping GP by engaging it in its cutting flutes
 Proceed cautiously!
 Check files regularly for distortion
 Ideally GP should always be visible to ensure you remain centred within the canal
 Tactile sensation of GP feels more ‘rubbery’ (obviously!) compared to dentine

Question 31

Retreatment rotary files to remove GP (3)

Answer 31

 Some systems (e.g. Protaper) produce files which are specially designed to remove GP
 They are more resistant to fracture and designed to
move dislodged GP in a coronal direction
 Never use Protaper SX, S1 or S2 files to remove GP –
they are too fragile at the tip

Question 32

Solvent technique to remove GP (4)

Answer 32

 Certain solvents can be used to soften GP aiding its
removal
 Examples include chloroform, xylol, eucalyptus oil and orange oil
 We use chloroform in the hospital but there are some
COSHH limitations
 Should be used sparingly, ideally following bulk
removal with other instruments due to the tendency for it to become smeared everywhere!

Question 33

Combination of techniques to remove GP (3)

Answer 33

Most of the time a combination of techniques is used:
 Gates glidden or rotary NiTi to remove coronal GP
 Rotary NiTi or hand files to remove apical GP
 Using solvents as required, particularly to help remove the final GP in the apical portion

Question 34

Removal of endodontic posts (5)

Answer 34

Metal endodontic posts can be
removed using a number of
techniques
 ‘Trephining’ around the post using an
ultrasonic tip or specialised kit (Masserann)
 Using ultrasonic to break the cement lute
 Grabbing the post with fine forceps
 Specialised endodontic post removal kits
(e.g.Ruddle, Egler etc)
 Combinations of the above

Question 35

Removal of endodontic posts (6)

Answer 35

 The first stage is to remove the crown on the tooth and
then remove the core material, leaving only the post sticking out from the canal
 Cast cores need to be reduced carefully, so the core is reduced to the post width extending out of the canal to give
something to grip to
 The appropriate technique or combination of techniques
can then be used to loosen the post
 Threaded posts can often simply be unscrewed
 Fibre posts are usually bonded in and are
difficult to loosen
 The most effective way to remove them is to
use a diamond bur or ultrasonic to remove the
post by drilling down through the middle of
the post

Question 36

Removal of Thermafil carriers (6)

Answer 36

 Plastic Thermafil carriers can be challenging to
remove
 They have a groove down them which is meant to
be engaged by a file prior to removal, however this
is often ineffective
 Use hand files/rotary files to remove coronal GP
(maybe using a solvent) then try to ‘grab’ the
carrier
 The ‘braiding’ technique can be very effective –
braid 2 hand files around the carrier and exert a
pull in the coronal direction
 Once the carrier is removed the remaining GP can be removed using the previously described
methods
 Thermafil have recently released new carriers made
from GP which are easier to remove

Question 37

Removal of silver points (4)

Answer 37

 Silver points are not commonly found
nowadays
 It is however important to recognise them
on a radiograph
 Silver points were discovered to corrode over
time and they can therefore disintegrate
during removal
 Techniques to remove them include troughing around them with ultrasonics, trephining with a Masserann kit, grabbing them with fine forceps and using the
braiding technique

Question 38

Removal of fractured instruments (3)

Answer 38

 Fractured instruments can be very
challenging to remove
 If an instrument cannot be removed
you can attempt to bypass it
 Removal is attempted by first achieving
good access and vision (microscope
essential!)
 Ultrasonics or a modified gates glidden bur
can be used to create a ‘staging platform’
 A combination of techniques (ultrasonics,
hand files, Masseran kit etc) can be used to
attempt to loosed and remove the fragment
 If successfully removed the remainder of the
endodontic treatment can be completed
conventionally

Question 39

Success in removal of fractured instruments depends on (4)

Answer 39

 Where the instruments has fractured
 What type of instrument it is
 How long the fragment is
 How accessible it is

Question 40

Repair of perforations - prognosis depends on (4)

Answer 40

 The size of the perforation
 The location of the perforation
 The condition of the remaining tooth
 How infected it is

Question 41

Repair of perforations (3)

Answer 41

 Perforations indicate a poor prognosis for
the tooth
 Perforations can be repaired internally or
externally
 MTA or biodentine are the materials of
choice for repairing perforations

Question 42

Options for managing patients when you’re in practice (3)

Answer 42

 Don’t automatically assume that because it is endodontic
retreatment it is ‘specialist’ and therefore beyond your
capabilities
 However, consider your own experience and limitations before
embarking on treatment
 Assess the case – a ‘thready’ obturation or single cone may be
relatively easy to remove

Question 43

If you decide to refer a patient, you may have the following options (3)

Answer 43

 Refer to a local dentist who is either a specialist or has a
‘special interest’ in endodontics, however, this is likely to be private
 Refer to a local hospital with an endodontic service,
however, not all hospitals with a restorative service
accept patients for endodontics
 Remember, CCDH does not accept referrals for molar
endo (even for retreatment)