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BDS3 Endodontics > Endodontic failure > Flashcards

Endodontic failure Flashcards

1
Q

What are the success rates of root canal treatment?

A
  • Range from 31% to 100%
  • Clearly not always as well as we would hope
  • No significant change in outcomes in recent times
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2
Q

Which guidelines determine a successful outcome?

A
  • ESE guidelines
  • BUT ‘success’ means different things to - researchers, clinicians and patient
  • Technical versus biological outcome
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3
Q

When should root canal treatments be assessed?

A
  • At least after 1 year and subsequently as required
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4
Q

What should be looked for when assessing the outcome of root canal treatment? (4)

A
  • Absence of pain, swelling and other symptoms
  • No sinus tract
  • No loss of function
  • Radiological evidence of a normal PDL
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5
Q

What determines an ‘uncertain’ outcome of root canal treatment?

A
  • 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
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6
Q

Root canal treatment has an ‘unfavourable’ outcome when…? (4)

A
  • 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
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7
Q

What is the exception we may see radiographically that does not show an unfavourable outcome?

A
  • 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
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8
Q

What is the basis of the ESE guidelines based on?

A
  • Based on strict radiographic criteria for success
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9
Q

What is loose criteria on definitions of outcomes?

A
  • Where we don’t need to see a complete absence of a lucency

- Can see a lucency that is getting smaller

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10
Q

Why do root canal treatments fail?

A
  • Most failures occur when treatment procedures, mostly of a technical nature, have not reached a satisfactory standard for the control and elimination of infection
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11
Q

What is a pre-op factor that affects the success of root canal treatment?

A
  • 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)

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12
Q

What are operative factors that contribute to the success of root canal treatment? (4)

A
  • 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
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13
Q

What is a technical complication that can lead to biological failure?

A
  • Coronal leakage
  • Difficult to establish causality
  • Currently - good coronal restoration coupled with good quality root canal treatment
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14
Q

Give a list of factors that may influence the outcome of root canal treatment? (7)

A
  • 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
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15
Q

What is a failed biological objective that can cause failure of root canal treatment?

A
  • Missed canals

- Means we fail to disinfect the root canal completely

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16
Q

For upper 6’s if there is no … canal, you have probably just not found it yet?

A
  • MB 2

- Be careful to look for this anatomy

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17
Q

READ paper ‘anatomy of the pulp chamber floor’

A
  • Essential reading
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18
Q

Explain centrality in relation to the RCS?

A
  • The pulp chamber lies central in the tooth at the level of the CEJ
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19
Q

Explain concentricity in relation to the RCS?

A
  • The pulp chamber lies concentric to the surface of the tooth at the level of the CEJ
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20
Q

Learn the laws in the anatomy of the pulp chamber floor paper

A

Add the laws to the flashcards

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21
Q

What is the Law of Symmetry I?

A
  • 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
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22
Q

What is the Law of Symmetry II?

A
  • 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
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23
Q

What is the Law of Colour Change?

A
  • The colour of the pulp-chamber floor is always darker than the walls
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24
Q

What is the Law of Orifice Location I?

A
  • The orifices of the root canals are always located at the junction of the walls and the floor
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25
Q

What is the Law of Orifice Location II?

A
  • The orifices of the root canals are located at the angles in the floor-wall junction
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26
Q

What is the Law of Orifice Location III?

A
  • The orifices of the root canals are located at the terminus of the root developmental fusion lines (dark lines that run across the floor)
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27
Q

One factor that contributes to success is achieving and maintaining patency. What can blockages be due to?

A
  • Can be due to severe curvature
28
Q

What are factors that contribute to failure of RCT? (7)

A
  • 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
29
Q

What factors can cause persistent intra-radicular infection, which is a biological reason for failure of RCT? (4)

A
  • Canal complexities
  • Biofilm (disease - exceptionally difficult to manage)
  • Resistant bacteria
  • Enterococcus faecalis has been identified, but role is controversial
30
Q

What are 2 examples of extra-radicular bacteria that can be a biological reason of failure of RCT?

A
  • Actinomycosis

- Extruded biofilm

31
Q

Cyst formation (epithelial lined cavity) can be a non-microbial, biological reason for failure of RCT. How do these develop?

A
  • Develop from mature granuloma, inflammatory mediators acting on epithelial cell rests (in the peri-radicular tissues)
32
Q

What are the 2 types of periapical cysts?

A
  • True cysts and pocket cysts
33
Q

What is the difference between a true cyst and a pocket cyst?

A
  • A true cyst is separate from the root canal whereas a pocket cyst is continuous through the root canal
34
Q

How do we manage granulomas, abscesses or cysts?

A
  • 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
35
Q

What are 3 biological reasons for failure of RCT not already stated?

A
  • Cholesterol crystals
  • Foreign body reactions - delayed healing
  • Scar tissue ‘healing’
36
Q

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)

A
  • Technical e.g. perforation, separated instrument
  • Root fracture
  • Other odontogenic pain
  • Non-odontogenic pain e.g. atypical facial pain
37
Q

When assessing the restorative prognosis of RCT what are we looking for? (3)

A
  • 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?
38
Q

When retreatment planning what are the options for management? (4)

A
  • 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
39
Q

What is orthograde treatment in relation to root canals?

A
  • Going from the top down
40
Q

What is surgical treatment in relation to root canals?

A
  • This is removing the peri-radicular tissues, the root tip and creating a seal from the apical region up
41
Q

What are most failures of RCT due to?

A
  • 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
42
Q

How complex is retreatment in the original root anatomy has not been damaged?

A
  • Complexity of treatment is not high
43
Q

How complex is retreatment is there are fractured instruments, blockages, ledges or severe curvatures?

A
  • IT is more complex and so consider referral

- Apical surgery is complex and considered a specialist treatment - consider referral

44
Q

What would the strategy for retreatment be if the canal is filled with insoluble resins?

A
  • Ultrasonic
45
Q

What would the strategy for retreatment be if the canal is filled with Gutta-Percha?

A
  • Handfiles +/- solvent

- Protaper D/Reciproc

46
Q

What would the strategy for retreatment be if the canal is filled with soluble pastes?

A
  • Handfiles +/- solvent

- Protaper D/Reciproc

47
Q

How difficult is it to remove poorly condensed GP?

A
  • Generally easier
48
Q

What kind of files would we use to remove poorly condensed GP from the root canal system ?

A
  • Hedstroem files (to withdraw the GP point)
49
Q

How difficult is it to remove well condensed GP from a root canal?

A
  • Generally harder

- Need to create a space (so may need to use solvents)

50
Q

What solvent may we use when trying to remove GP from a root canal?

A
  • Might use eucalyptus oil
51
Q

What handfiles/approach would you use to remove GP from a root canal?

A
  • 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
52
Q

Protaper D1 has an active tip. What does this allow?

A
  • Allows better initial penetration into material
53
Q

Why do we need to be careful when we use Protaper D1 files?

A
  • With a curved canal we can readily lead to perforation

- Use these files with great caution

54
Q

What is the retreatment sequence process when using Protaper D files?

A
  • Protaper D1 - for coronal filling removal
  • Protaper D2 - for middle filling removal
  • Protaper D3 - for apical filling removal
55
Q

What is the Protaper D1 file used for?

A
  • For coronal filling removal
56
Q

What is the Protaper D2 file used for?

A
  • For middle filling removal
57
Q

What is the Protaper D3 file used for?

A
  • For apical filling removal
58
Q

What is the process for Protaper retreatment? (5)

A
  • 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
59
Q

What is the RECIPROC system?

A
  • Single file system that is very effective in removing the GP
60
Q

What colour of RECIPROC system file would you use to remove GP in narrow canals?

A
  • Red (called R25)
61
Q

What colour of RECIPROC system file would you use to remove GP in medium canals?

A
  • Black (called R40)
62
Q

What colour of RECIPROC system file would you use to remove GP in large canals?

A
  • Yellow (called R50)
63
Q

Is the RECIPROC system for retreatment efficient?

A
  • Very efficient

- Remove bulk of GP (US, heat carrier)

64
Q

What are the 2 solvents we may use when using the RECIPROC system for retreatment of a root canal?

A
  • Chloroform

- Eucalyptus oil

65
Q

Which RECIPROC file would we use to remove the bulk of the GP in the root canal?

A
  • R25 (red file)
66
Q

Which files do we use to increase apical enlargement in the RECIPROC retreatment system? (2)

A
  • R40 + R50
67
Q

If possible we want to use the RECIPROC retreatment system with no solvent. Why is this?

A
  • 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

BDS3 Endodontics (8 decks)

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