Endodontic Failure Flashcards
What should be assessed after a year of RCT?
- Absence of pain, swelling and other symptoms
- No sinus tract
- No loss of function
- Radiological evidence of a normal PDL
What is an uncertain outcome?
if radiographic changes remain the same size or has only diminished in size.
if lesion persists after 4 years, the RCT is usually considered to be associated with post treatment disease
When does RCT have an unfavourable outcome?
- 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
What can be left after treatment that is not a sign of persisting apical periodontitis?
a locally visible irregularly mineralised area due to scar tissue formation
What is a pre-op factor that affects success?
presence or absence of lesion
What are operative factors contributing to success?
- Filling extending to within 2mm of radiographic apex (subtract one) but not extruded
- Well condensed root filling with no voids
- Good quality coronal restoration
What are technical complications leading to biological failure?
- Coronal leakage
- Difficult to establish causality
- Good coronal restoration coupled with good quality RCT
What additional factors contribute to success?
- presence of sinus
- lesion size
- no perforation
- getting patency
- penultimate rinse with EDTA (reRCT)
- avoiding mixing CHX and NaOCL
- absence of a flare up
What is a failed biological objective that contribute to success?
- missed canals
Law of Symmetry I
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
Law of Symmetry II
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
Law of colour change
the colour of the pulp chamber floor is always darker than the walls
Law of Orifice location 1
the orifices of the root canals are always located at the junction of the walls and the floor
Law of Orifice location 2
the orifices of the root canals are always located at the angles in the floor-wall junction
Law of Orifice location 3
the orifices of the root canals are located at the terminus of the root developmental fusion lines
What can blockages be due to?
severe curvature
Why do iatrogenic problems occur? (ledges)
- poor planning
- poor access
- poor length control
- forcing instruments
- failure to observe sequence
- failure to maintain patency
What are iatrogenic problems that can occur?
avoid separation of instrument
avoid creation of ledge
What are biological reasons for failure?
persistent intra-radicular infection
extra-radicular bacteria
non-microbial agents
cholesterol crystals
foreign body reactions (delayed healing)
scar tissue healing
Why can persistent intra-radicular infection occur?
- canal complexities
- biofilm
- resistant bacteria
- enterococcus faecalis
What is extra-radicular bacteria due to?
actinomycosis
extruded biofilm
What is the non-microbial agent that can cause failure?
cyst formation
epithelial lined cavity
developed from mature granuloma, inflammatory mediators acting on epithelial cell rests
What two types of periapical cysts are there?
true cysts and pocket cysts
What does the decision to retreat involve?
establish cause of failure
- technical e.g. perforation, seperated instrument
root fracture
other odontogenic pain
non odontogenic pain
What should be checked restoratively?
check for presence of fractures
assess remaining amount of tooth structure
good seal
What are the options for management?
- keep under observation
- orthograde retreatment
- surgical treatment
- extraction
Solution for insoluble resins?
ultrasonics
Solutions for gutta percha?
handfiles with/out solvent >
protaper D/ reciproc
Solutions for soluble pastes?
handfiles with/out solvent >
protaper D/ reciproc
What files are used for removing poorly condensed gutta percha?
hedstroem files
Why is the protaper D1 used?
active tip - allows better initial penetration into material
After D1 is used, what is next?
D2 - for middle filling removal
then
D3 - for apical filling removal
What speed should be used for protaper?
500-700rpm
Where should you should the protaper removal?
2-3mm
How can you by-pass ledges?
with pre-curved C files
How can you used reciproc for retreatment? (very efficient)?
remove bulk of gutta-percha (US, heat carrier)
use solvent (chloroform, eucalyptus oil)
use R25 as described
increased apical enlargement (R40, R50)
brushing with reciproc
