ENDO Retreatment procedures Flashcards
According to the European Society of Endodontology’s Quality Guidelines, when should RCT’s be followed up?
clinical and radiographic follow-up at least 1 year after tx
When following up RCTs what are we looking for?
complete bony healing
if this does not happen, follow up for 4 years
When is root canal retreatment indicated?
- persistent PA pathology following RCT
- new PA pathology associated with a root-filled tooth
- a new restoration is planned for tooth and radiographic assessment shows an inadequate root canal filling and/or PA radiolucency
What is a radiographic sign of persistent PA pathology?
no radiographic signs of bony healing after 4 years
what is a sign of new PA pathology associated with root-filled tooth?
initial healing but a new radiolucency develops some time later
root canal system has become infected subsequent to previous treatment
does periradicular periodontitis affect endodontic tx?
yes
what are the prognostic factors for the success rate of root canal retreatment?
- pre-op PA lesion
- apical extent of root canal filling
- quality of coronal restoration
what are the terms to describe the outcome of root canal retreatment?
healed
healing
asymptomatic function
persistent/ recurrent/ emerged disease
described a ‘healing’ retreated root canal?
clinical - no signs or symptoms
radiological - reduced radiolucency in follow up <4 years
described a ‘healed’ retreated root canal?
clinically - no signs/ symptoms
radiological - no residual radiolucency, or scarring after surgery
describe a ‘asymptomatic function’ retreated root canal?
clinical - no signs or symptoms combined with no or persistent radiolucency, reduced in size or unchanged.
describe a ‘persistent/ recurrent/ emerged disease’ retreated root canal?
clinical - with or without symptoms
radiological - new, increased, unchanged or reduced after > 4 years
what are the guidelines for prevention of post treatment disease?
- rubber dam isolation
- proximity of preparation to apical constriction
- sufficient taper of preparation
- adequate irrigation and placement of interappointment medicament
- correct extension of root canal obturation without extrusion
- adequate coronal seal to prevent re-infection
what are indications for root canal retreatment?
- previous treatment has failed (signs of inflammation or infection)
- persistent symptoms, sinus tract, swelling, pain
- failure of previous treatment because of technical reasons
- existing pathology and new restoration planned for tooth
what is a sinus tract a sign of?
chronic abscess
list the causes of post-treatment disease?
- intraradicular microbes
- extraradicular infection
- foreign body reaction
- true cyst
where do you find intraradicular microbes and why?
apical parts of root canal often where inaccessible by instrumentation (difficult to disinfect)
explain extraradicular infection?
microbes have evaded host defense mechanisms and have established themselves in the PA tissues
what is a foreign body reaction?
reaction to extrusion of RCT filling material
specifically, what are the microbial causes of post-treatment disease?
- intraradicular microbes
- extraradicular microbes
- radicular cyst
- cracked teeth, vertical root fracture
- coronal leakage
what is the major cause of endodontic treatment failure?
intraradicular infection, persistent or secondary
what is the difference between persistent infection and secondary infection?
persistent - microbes not removed in initial treatment, they remain in the root canal system after disinfection and interappointment dressing
secondary - microbes enter root canal system by a coronal leakage
specifically, what are the non-microbial causes of post treatment disease?
- cholesterol crystals
- foreign body reactions in periapical tissues
what bacteria have been found to be persistent?
gram positive
how may you still find bacteria in well treated canals?
they do not always maintain an infectious process
they may be located in areas where they have no access to periapical tissues
what are common microbes found in retreatment cases?
E faecalis
strep
lactobacillus
actinomyces propionibacterium
candida albicans
where are the possible origins of microbes found in retreatment cases?
contamination during initial treatment
leaving a tooth on open drainage
coronal leakage post-treatment
in most cases, what prevents microorganisms from invading the periapical tissues?
apical periodontitis
when microbes overcome the defense barrier of apical periodontitis what happens?
they establish an extraradicular infection e.g., acute apical abscess
what is the most common odontogenic cyst of inflammatory origin?
radicular cyst
where do radicular cysts arise from?
epithelial cell rests in periodontal ligament
what is the difference between a true cyst and a pocket cyst?
a pocket cyst will heal following endodontic treatment whereas a true cyst wont
what is a true cyst?
lesion enclosed by epithelial lining
what is a pocket cyst?
epithelial sac communicates with root canal system
what are the non-microbial causes of post-treatment disease?
cholesterol crystals
foreign body reaction
what are cholesterol crystals?
from dying cells during chronic inflammation
what materials can cause a foreign body reaction?
gutta percha
sealers
paper points
cotton pellets
why may people gave a foreign body reaction to paper points/ cotton pellets?
they contain cellulose in which the body cannot breakdown
what are the treatment options you would give to a pt for root canal retreatment?
do nothing
xLA
retreatment
surgical retreatment
during retreatment, what do you remove the pulp chamber with?
ultrasonic
what is the risk of access through existing crowns?
higher risk of perforation due to reduced visibility and tooth alignment may be altered by the crown
explain sectioning crowns?
section imp taken
crown sectioned into 2 halves
removed with excavator
when removing crowns what burs are used?
diamond for porcelain crowns
tungsten carbide for metal crowns
in what situations can you not use a wamkey to remove a crown?
if an adhesive cement has been used
name types of crown removers?
crown tapper
KaVo Coronaflex
when would you use a crown remover?
crown margins not intact
what is a risk when removing a post?
root fracture
what are the 2 main techniques for post removal?
ultrasonic energy
post pulling devices
describe the ultrasonics for post removal?
peizoelectric ultrasonics
vibrations 30-40kHz
tips have a blunt end
what must the nurse do when you are using a piezoelectric ultrasonic to remove a post?
blow air/ water coolent at the tip
if not, the heat can cause bony necrosis
what are the types of post pulling devices?
egglers post pulling device
ivory minatiure post puller
ruddle post pulling kit
massarann kit
when removing a post, what technique must be tried first?
ultrasonic then use post pullers if you need
what material, used for posts, does not always show up on a radiograph?
quartz fibre
how may quartz fibre posts fail?
fibres become contaminated by moisture and then frey
what does the RTD fibre post removal kit contain?
pin drill: creates a pilot hole through post
channel hole
piezo size 2: removes remaining fibres
why are thermafil obturators not used any more?
they have a central plastic sprue covered in GP which is very hard to remove
what has thermafil been replaced with?
guttacore - the sprue is made from cross linking GP so it is easier to remove
what is resorcinol?
an endodontic paste used in eastern european countries containing formaldehyde
what are the techniques used to remove gutta percha?
rotary endo files
ultrasonics
heat
solvents
what rotary endodontic files are used for retreatment?
dentsply protaper D files
PTG endo instruments
what rpm and torque are rotary protaper retreatment files used at?
600rpm
4Ncm
why are rotary protaper retreatment files not flexible?
made from NiTi
what are the sizes of protaper retreatment files?
D1 - 16mm 30
D2 - 18mm 25
D3 - 22mm 20
why may D1 Protaper retreatment file cause ledges and perforations
it has a partially cutting tip
what files are used when using PTG to remove GP (PTG sequence)?
F2 or F3, length 21 depending on canal diameter
set to 600rpm
work from 3-1
work in 1mm increments checking EAL until WL and patency have been achieved
when using PTG to remove GP, what would you do if the apical part of the canal is underprepared/ not obturated?
negotiate with size 10 file
establish WL/ patency
complete prep using PTG sequence at 300rpm
what technique may you use to remove GP if a single cone obturation or it is poorly compacted?
hedstrom files and solvent
why is the hedstrom file and solvent technique not suitable when removing GP from narrow, curved canals?
files made from stainless steel so less flexible
what are types of solvents for GP?
chloroform
turpentine
DMS IV (eugenol)
Endosolv R (resin)
Endosolv E (eugenol)
when should you never use solvents?
when preparing a post space - it can compromise seal
what technique would you use to remove carrier-based GP?
hedstrom file and solvent
protaper D files
how do you remove silver points?
do not cut coronal end
remove with stieglitz forceps or gently trough around with fine ultrasonic tip
why are endodontic pastes no longer recommended in most countries?
shrinkage and poor seal
made from toxic materials: often contain paraformaldehyde
what happens if endo pastes are over extended?
nerve paraesthesia
