endodontic failure Flashcards
what is success
- the accomplishment of an aim or a purpose
- the good or bad outcome of an undertaking
what are the success rates of root canal treatment
- range from 31% to 100%
- works most of the time but not always
- outcomes haven’t changed significantly in recent times
how is success defined
- ESE guidelines define success as a successful outcome
- success means different things to different people
- consider technical versus biological outcome
when should root canal treatment be assessed
- at least after 1 year and subsequently as required
- gives enough time for signs, symptoms to subside and radiographic evidence of healing to be present
what would endodontic success look like
- 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 of has only diminished in size
- if lesion persists after 4 years, the RCT associated with post treatment disease
what are the 4 signs that RCT has an unfavourable outcome
1 = tooth associated with signs and symptoms of infection 2 = a radiologically visible lesion has appeared subsequent to treatment or pre-existing lesion has increased in size 3 = lesion has remained the same size 4 = signs on continuing root resorption
what are the exceptions to uncertain outcomes
- scar tissue
tooth should continue to be assessed
what is loose criteria for success
- don’t need to see complete absence of radiolucency we can see one getting smaller
- important to recognise that people base success on different things
how can the strictness of criteria have an effect on success rates
- strict criteria gives lower success rates than loose criteria
- success criteria has big impact on numbers
why must you consider biological and technical failure
- can have technical failure but biological success, or could have technical success but biological failure
- important that we do follow up on treatment
why do root treatments fail
- haven’t managed infection
- infection could be in an area we can’t get to
what are some pre-op factors that affect success
- presence or absence of a lesion
- if tooth vital or non-vital
what are some operating factors that affect success
- filling extending to within 2mm of radiographic apex
- well condensed root filling with no voids
- good quality coronal restoration
- technical complication leading to biological failure
- missed canals
what does it mean if the filling is too short
- we haven’t disinfected adequately or created a good apical seal
how does extruding GP affect outcome
- have a negative effect
- indicates other problems with preparation
what technical complications can lead to biological failure
- coronal leakage
- difficult to establish causality
- presence of a sinus
- increased lesion size
- no perforation
- getting latency
- penultimate rinse with EDTA
- avoiding mixing CNX and NaOCl
- absence of a flare up
how can you avoid missing canals
- is we miss anatomy, we fail to disinfect
- have to be careful we don’t miss things on radiograph
- expect the unexpected
- careful of how we assess radiographs
what are the laws to help us with success
- law of centrality
- law of concentricity
- law of the CEJ
- law of symmetry
- law of colour change
- law of orifice location
what is the law of centrality
- the floor of the pulp chamber is always located in the centre of the tooth at the level of the CEJ
- pulp chamber lies central of the tooth at the CEJ and concentrate with level of root surface at level of CEJ
what is the law of concentricity
- the walls of the pulp chamber are always concentric to external surface of the tooth at the level of the CEJ
what is the law of the CEJ
- the CEJ is the most consistent, repeatable landmark for locating the position of the pulp chamber
what is the law of symmetry 1
- except for maxillary molars, the orifices of the canal are equidistant from a line drawn in a mesial distal direction through the pulp-chamber floor
what is the law of symmetry 2
- except for maxillary molars, the orifices of the canal lie on a line perpendicular to a line drawn in a mesial-distal direction across the centre of the floor of the pulp chamber
what is the law of colour change
- the colour of the pulp-chamber floor is always darker than the walls
- important feature
- enhanced with magnified field of view
what is the law of orifice location 1
- the orifices of the root canals are always located at the junction of the walls and the floor
- lies along junction o vertical walls and horizontal floor
what is the law of orifice location 2
- the orifices of the root canals are located at the angles in the floor-wall junction
- if looks wall junction comes to a point the orifices walls lies at the corners
what is the law of orifice location 3
- the orifices of the root canals are located at the terminus of the root developmental fusion lines
- dark lines run across the floor of pulp chamber and lead us to orifice
what are some factors that contribute to success
- achieve and maintain latency
- blockages can be due to sever curvatures - need to manage these carefully
- lots of irrigation and recapitulation
what are some factors that contribute to failure
- iatrogenic = avoid creation of ledges
- poor planing
- poor access
- poor length control
- forcing instruments
- failure to observe sequence
- failure to maintain patency
what are some biological reasons for failure
- persistent intra-radicular infection
- extra-radicular bacteria
- non-microbial agents
- cholesterol crystals
- foreign body reactions = delayed healing
- scar tissue ‘healing’
what are persistent intra-radicular infections
- canal complexities
- biofilm
- resistant bacteria
- enterococcus faecalis has been identified, but role is controversial
what are extra-radicular bacteria
- actinomyces
- extruded biofilm = made way out of root canal space so can’t decried/disinfect
what are non-microbial agents
- cyst formation = periodical cysts (true and pocket cysts)
- developed from mature granuloma, inflammatory mediators acting on epithelial cell rests
what is a true cyst
- are separate from root canal
what causes cysts
- granulomas, abscesses, or cysts are primarily caused by root canal infection
- if manage cause, then should go away but if it is a true cyst then this won’t help
what could be the cause of apical pathology
- technical = perforation, separated instrument
- root fracture = could be untreatable
- other odontogenic pain = need to discern this cause
- non-odontogenic pain
what may you need to do to assess restorability of tooth
- may need to dismantle to assess if restorable or fracture
- need good magnification and illumination
- assess remaining tooth structure
what are the options for management
- keep under observation
- orthograde pretreatment = going from top and down
- surgical treatment = remove periradicular tissues and root tip and creat a seal from apical region up
- extraction = typical treatment for endo failure
what are most failures due to
- inadequate disinfection of the root canal system, leaving residual bacteria
what re-treatment often gives best outcome
- non-surgical re-treatment
what can increase the complexity
- if the original anatomy has not been damaged the complexity of the treatment is not high
- if there are fractured instruments, blockages, ledges, sever curvatures, it is more complex and so consider referral
- apical surgery is complex and considered a specialist treatment
what does the strategy for re-treatment depend on
- the material found within the root canal space
what re-treatment do you do for insoluble resin
- ultrasonics
what re-treatment do you do for GP
- handles +/- solvent
- proper/ Reciproc
what re-treatment do you do for soluble pastes
- handfiles +/- solvent
- proper/Reciproc
how do you remove GP
- if poorly condensed then easier = use Hedstroem files
- if well condensed then harder = need to create space to get file in, use solvents
how do we use handfuls +/- solvents
- stratified approach and very simple initially then we add complexity
- use hedstroem file to engage GP and try withdraw first = use C files to allow you to penetrate the GP mass
- may use eucalyptus oil to help dissolve GP to get files deeper
how do we use ProTaper re-treatment
- D files
- D1 has active tip to allow better initial penetration into material, allows files to penetrate while rotating inGP mass
- need to be aware of curves = can lead to perforation
- start with D1 (coronal filing) then work through D2 (middle filing) and D3 (apical filing)
how do we use Reciproc system
- files correspond to ISO sizing
- has a regressive taper = allows for coronal shaping without unnecessary tooth loss
- single file reciprocating system that is very efficient
- remove bulk of GP before determining WL
- use solvent
- use R25
- brushing with file (peck motion)
- increase apical enlargement
- remove GP and thermal carrier
- once removed most GP then use Reciproc or Reciproc Blue to finish preparation
