Endo Failure

Question 1

How is success defined

Answer 1

• ESE guidelines define a successful outcome
  
  • Success means different things to researchers, clinicians and patients
  • Technical vs biological outcome

Question 2

What is a successful outcome according to ESE

Answer 2

○ Absence of pain, swelling and other symptoms
○ No sinus tract
○ No loss of function
○ Radiological evidence of a normal PDL

Question 3

What is a uncertain outcome according to ESE

Answer 3

○ Radiographic changes remaining the same size or only diminished in size
○ 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 RCT is usually considered to be associated with post-treatment disease

Question 4

What is an unfavorable outcome according to ESE

Answer 4

○ The tooth is associated with signs and symptoms of infection
○ A radiologically visible lesion has appeared subsequent to treatment or a pre-existing lesion has increased in size
○ A lesion has remained the same size or has only diminished in size during the 4 year assessment period
○ Signs of continuing root resorption are present
○ In these situations retreatment is advised

Question 5

When should RCT be checked

Answer 5

should be assessed at least after 1 year and subsequently as required

Question 6

What are exceptions to unfavorable outcome

Answer 6

• An extensive radiological lesion may heal but leave a locally visible, irregularly mineralized area
• This defect may be a scar tissue formation rather than a sign of persisting apical periodontitis
The tooth should continue to be assessed

Question 7

What is the issue with determining success

Answer 7

• Means different things to different people
A greater success rate is seen in those with a looser criteria e.g for some simply retention alone was considered successful in which the success rate was 95%

Question 8

What leads to failure

Answer 8

Most failures occur when tx procedures mostly of a technical nature, have not reached a standard satisfactory for the control and elimination of infection

Question 9

What are the 4 factors that are leading to failure

Answer 9

pre-op
operative factors
technical complication leading to biological failure
additional factors

Question 10

What are pre op factors

Answer 10

§ Presence or absence of lesion
□ Vital has best outcome
□ Non-vital without periapical lesion has better prognosis than one with a periapical lesion

Question 11

What are the operative factors contributing to success

Answer 11

□ Filling extending to within 2mm of radiographic apex
® If short may indicate that disinfection is not adequate and a good apical seal is not created so the outcome is diminished
□ Filling not extruded
® Extrusion = bad outcome
® Apical constriction may be destroyed
□ Well condensed root filling with no voids
Good quality coronal restoration

Question 12

What is a technical complication leading to biological failure

Answer 12

Coronal leakage due to failure of coronal seal

Question 13

What are the additional factors that contribute to success

Answer 13

□ Presence of sinus
□ Increased lesion size
□ No perforation
□ Getting patency
□ Penultimate rinse with EDTA (especially with retreatment)
□ Avoiding mixing chlorhexidine and sodium hypochlorite
Absence of flare up

Question 14

What are the factors that contribute to success

Answer 14

finding all canals
achieving and maintaining latency
avoiding creation of ledges (iatrogenic)
avoid separation of instruments (iatrogenic0

Question 15

What leads to creation of ledges

Answer 15

§ Poor planning
			§ Poor access
			§ Poor length control
			§ Forcing instruments
			§ Failure to observe sequence
Failure to maintain patency

Question 16

What are the laws for pulp chamber floor anatomy

Answer 16

law of centrality
law of symmetry
law of color change
law of orifice location

Question 17

What is law of centrality

Answer 17

○ Pulp chamber lies central within the tooth at the level of the ACJ and lies concentric to the surface of the tooth at the level of the ACJ
Undulations of the root canal match that of the root surface at the level of the ACJ

Question 18

What is the law of symmetry I

Answer 18

§ 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

Question 19

What is the law of symmetry II

Answer 19

§ Except for the 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

Question 20

What is the law of color change

Answer 20

The colour of the pulp-chamber floor is always darker than the walls

Question 21

What is the law of orifice location I

Answer 21

§ The orifices of the root canals are always located at the junction of the walls and the floor

Question 22

What is the law of orifice location II

Answer 22

§ The orifices of the root canals are located at the angles in the floor-wall junction

Question 23

What is the law of orifice location II

Answer 23

§ The orifices of the root canals are located at the terminus of the root developmental fusion lines
§ These dark lines lead us to the orifice at each of the corners

Question 24

What are biological reasons for failure

Answer 24

persistant intra-radicular infection 
extraradicular bacteria
non microbial agents
cholesterol crystals
foreign body reactions which delay healing 
scar tissue healing

Question 25

What are the persistent intra radicular infection due to

Answer 25

○ Canal complexities
○ Biofilm
○ Resistant bacteria
Enterococcus faecalis has been identified but role is controversial

Question 26

What are non microbial agents

Answer 26

○ Cyst formation - epithelial lines cavities

Developed from mature granuloma, inflammatory mediators acting on epithelial cell rests

Question 27

What is the periapical cysts

Answer 27

• Split in the literature into true and pocket cysts
○ True = separate from root canal
○ Pocket = continuous with it
• Prevalence varies in the literature but best evidence is approx. 15%

Question 28

Is therapy required for cysts

Answer 28

• Granulomas, abscesses or cysts are primarily caused by root canal infection, we should use a treatment protocol that will eliminate their aetiology in the root canal system rather than their product
A granuloma or pocket cyst will resolve but a true cyst will not so may require surgical intervention

Question 29

How do we decide on retx

Answer 29

• Decision making process depends on an accurate diagnosis

• Establish the cause of failure
○ Technical e.g perforation/separated instrument
○ Root fracture
○ Other odontogenic pain
Non odontogenic pain e.g atypical facial pain

Question 30

How do we decide on assessing restorative prognosis

Answer 30

• Check for presence of fractures - need good magnification and illumination
• Assess remaining amount of tooth structure
Can you get a good seal and will the restoration last

Question 31

What are options for pretreatment planning

Answer 31

○ Keep under observation
§ Need to have conversation with patient to figure out the cause
§ If a non odontogenic cause e.g malignant change in periradicular tissues then may want to move to other tx
○ Orthograde retreatment
○ Surgical treatment
§ Removing periradicular tissues, root tip and creating a seal from the apical region up
○ Extraction

Question 32

What is the best outcome for failure

Answer 32

• Already seen that most failures due to inadequate disinfection of the root canal system initially, leaving residual bacteria
  
  • In most causes therefore, non-surgical retreatment will offer best outcome

Question 33

How do we determine complexity of re tx

Answer 33

• If the original anatomy has not been damaged, the complexity of the treatment is not high
  
  • If there are fractured instruments, blockages, ledges, severe curvatures, it is more complex and so consider referral
  • Apical surgery is complex and considered a specialist treatment - consider referral