Endodontic Failure: Post Treatment Disease

Question 1

What two diagnosis is required when diagnosing a primary root canal disease?

Answer 1

A pulpal dx

Periradicular dx

Question 2

What should be included in diagnostic description of post-treatment disease?

Answer 2

Partially treated pulp canals
Missed canals
Procedural mishaps

Question 3

How do you diagnose post treatment disease? I.e. what would you ask pt, what would you examine for e/o and i/o

Answer 3

Take a thorough pain history
Ask when root canal treatment was done and where there any problems?

O/E examine for: 
Swellings/sinus 
TTP 
Mobility 
Periodontal probing depths >3mm 
Tenderness on buccal palpation

Question 4

Why may upper canines have ongoing tenderness to buccal pressure after RCT?

Answer 4

Upper canines can have a buccal fenestration that gives ongoing tenderness to buccal pressure after RCT

Question 5

How would you distinguish which root is lingual and which is buccal in multi-rooted teeth?

Answer 5

SLOB rule:-
Same lingual (furthest)
Opposite buccal (moves the opposite way)
I.e. if you move the x-ray head mesially, the two roots will move distally but the buccal one will be the opposite direction of the movement and the lingual will be the one in the same direction

Question 6

In post-treatment disease, what are the 3 diagnostic categories?

Answer 6

Previously treated and asymptomatic PRP
Previously treated and chronic apical abscess
Previously treated and acute apical abscess

Question 7

In image 1, the causes of post treatment disease is labelled 1-4.
Name all of them.

Answer 7

1. Intraradicular microorganisms
2. Extraradicular infection
3. Foreign body reaction
4. True cysts

Question 8

What are some causes of intra-radicular infections?

Answer 8

• poor access cavity design
• untreated major and minor canals
• poorly prepared canals…poorly obturated canals
• ledges
• perforations
• separated instruments
• newly introduced micro-organisms
• coronal leakage during or after endodontics

Question 9

What is extraradicular infection and how can it occur?

Answer 9

Microbial invasion and proliferation in the periradicular tissues.
Can occur in perio-endo lesion where pocketing extends to the apical foramina, extrusion of infected dentine chips during instrumentation, overextended instrumentation/drying.filling materials (through apex), biofilms which grow through the apical constriction and form an external apical biofilm.

Question 10

What is a foreign body reaction?

Answer 10

Foreign materials in the periradicular tissues that are associated with chronic inflammatory response. Can be caused by obturation materials, sealer, small particles of GP.

Question 11

How does a true radicular cyst occur?

Answer 11

Form when retained embryonic epithelium begins to proliferate due to presence of chronic inflammation

Question 12

What are the 2 types of radicular cyst described by simon 1980?

Answer 12

True radicular cysts

Periapical pocket cysts

Question 13

What are the features of true radicular cysts?

Answer 13

An enclosed cavity totally lined with epithelium
Has no communication with the RCS
Does not heal after a RCT

Question 14

What are the features of periapical pocket cysts?

Answer 14

The epithelium is attached to the margins of the apical foramen.
The cyst lumen is open to the infected canal and hence can communicate directly with it
Pocket cysts heal after RCT.

Question 15

What are some red flags before going into post-treatment disease endodontics?

Answer 15

History of parafunction/bruxing 
History of frequent post decementing 
Occlusal wear facets 
Large/wide RCT/posts 
Long narrow perio pockets (can also indicate perio-endo lesion)
Vertical root fracture

Question 16

What reasons are most common for a failed root canal?

Answer 16

Is often due to persistent or secondary infection of the RCS.
Secondary intraradicular infections.
Microbes are not present in the primary infection but have been introduced at some time later i.e. sometimes no mictobes are left after the primary RCT, but can come in by leaking seal or fracture.

Question 17

How many species is expected in canals when well obturated and in inadequate obturation?

Answer 17

Well-obturated: 1-5 species

Inadequate obturation: up to 30 species

Question 18

In secondary intraradicular infections, what species of microbes can be found?

Answer 18

Propionibacterium, actinomyces, prevotella, E faecalis, streptococcus, caninda albicans, fusobacterium nucleatum.

E faecalis frequently found.

Question 19

Having diagnosed post-treatment disease, what are the four options for treatment?

Answer 19

Do nothing
Non-surgical retreatment
Extract tooth
Surgical retreatment

Question 20

When is surgical treatment considered when treatment planning for post-treatment disease?

Answer 20

Surgery is chosen when non-surgical retreatment is not possible or when the risk to benefit ratio of non-surgical retreatment is outweighed by that of surgery

Question 21

Why is image 1 not suitable for surgery?

Answer 21

Due to its location and proximity of the neurovascular bundle, however, root canal re-treating it is extremely challenging because of access and particularly the curvature of the mesial root.