Endodontics Flashcards
Topics covered: endodontic retreatment, endodontic surgery, diagnosis and management of complex cases, pathological root resorption
What are the follow-up periods following root canal treatment?
Follow-up at least 1 year after treatment
And then follow-up for up to 4 years
What are the indications for endodontic re-treatment?
- Signs of persistent PA pathology following RCT
- no radiographic signs of bony healing after 4 years. - New PA pathology associated with root-filled tooth
- initial healing but a newly developed radiolucency appears some time later
- root canal system has become infected subsequent to previous treatment - New restoration planned for tooth and radiographic assessment shows inadequate root canal filling and/or a PA radiolucency.
What prognostic factors determine the success rate of retreatment?
- Pre-operative PA lesion
- Apical extent of root canal filling
- Quality of coronal restoration
Which 4 terms are used to describe endodontic treatment outcomes?
Give clinical and radiographic findings for each outcome.
- Healed:
- no clinical signs/symptoms
- no residual radiolucency seen radiographically
- no scarring after surgery - Healing:
- no clinical signs/symptoms
- reduced radiolucency in follow-up period <4 years - Asymptomatic function:
- no clinical signs/symptoms
- persistent radiolucency (reduced in size or unchanged) - Persistent/recurrent/emerged disease:
- with of without clinical signs and symptoms
- new, increased, unchanged or reduced radiolucency after >4 years
List 6 factors that can help to prevent 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 reinfection - place a good quality definitive restoration as soon as possible following RCT
What might be the cause of post-treatment disease?
- Microbial causes:
- Intra-radicular microbes
- Extra-radicular microbes
- Radicular cyst (true cyst or pocket cyst)
- Cracked teeth/vertical root fracture
- Coronal leakage - Non-microbial causes:
- Cholesterol crystals in PA tissue
- Foreign body reaction in PA tissues
Why are intra-radicular microbes difficult to disinfect?
As they are situated in the apical part of the root canal system.
Which extra-radicular microbes are frequently found in post treatment disease?
Actinomyces and Propionibacterium propionicum.
Which cyst is the most common odontogenic cyst of inflammatory origin?
Radicular cyst
Where do radicular cysts arise from?
The epithelial cell rests in the PDL
Radicular cysts can be either true cysts or pocket cysts.
What is the difference between a true cyst and a pocket cyst?
True cyst - lesion enclosed by epithelial lining
Pocket cyst - epithelial sac communicates with the root canal system
Which type of radicular cyst (true or pocket) usually resolves after endo treatment?
Pocket cysts
Which type of radicular cyst (true or pocket) may require remedial surgical intervention?
True radicular cyst
Which type of bacteria are more resistant to antimicrobial treatment and have the ability to adapt to harsh environmental conditions in instrumented and medicated root canals?
Gram positive bacteria
Are bacteria that remain in the root canal system after root canal disinfection and interappointment dressing, always infectious?
No:
- residual bacteria may die after obturation
- they may also be present in insufficient numbers and virulence
- or they may be located in areas where they have no access to PA tissues.
How many bacterial species remain in the canals following good root canal treatment?
How does this compare to inadequately treated canals?
Good RCT - 1-5 remaining species
Inadequate RCT - 1-20 remaining species
In retreatment cases, how many more times is E faecalis likely to harbour in the root canal system vs. initial treatment cases?
Retreatment cases are 10X more likely to harbour E faecalis.
Which 6 microbes are commonly found in retreatment cases?
- E. faecalis
- Streptococcus
- Lactobacillus
- Actinomyces
- Propionibacterium
- Candida albicans
How do cholesterol crystals form in periapical tissues?
They form as a result of cells dying during chronic inflammation.
List 4 foreign bodies may cause a reaction in the PA tissues following root-treatment:
- Gutta percha
- Sealers
- Paperpoints
- Cotton pellets
Why might paperpoints and cotton pellets cause a foreign body reaction?
They contain cellulose which is non-biodegradable (body cannot break it down) - therefore acts as a constant irritant to the tissues.
You are planning a re-treatment case.
If following radiographic assessment you find that the previous RCT resulted in a fractured instrument or perforation, what additional points must you discuss with the patient as part of the consent process?
That the technical difficulties will make the treatment more complex.
Attempting to treat the tooth may result in treatment failure.
When accessing through sound fixed pros work for retreatment cases what must you be cautious about when doing this?
There is an increased risk of perforation as visibility is reduced and tooth alignment may be altered by the crown.
MUST assess the pre-treatment radiograph prior to access - if there are any potential difficulties REMOVE THE CROWN.
How do you remove a crown?
- Take a sectional impression first in putty
- Section the crown into 2 halves
- Use a diamond bur for porcelain, tungsten carbide bur for metal
- Be careful not to cut the core!
- Remove halves using an excavator
Other methods:
- WAMKEY (can only use in the absence of adhesive cement)
- Crown removers (crown tapper, KaVo Coronaflex)
What must you always warn patients when attempting to remove a post?
There is a risk of root fracture - may make the tooth unrestorable and require extraction.
What can make post removal difficult, potentially leading to the need for PA surgery or extraction of the tooth on retrieval?
Adhesive resin cements
What must you use when removing root canal filling material?
Magnification
What instruments are best for removing gutta percha?
ProTaper Gold files
How would you remove GP using ProTaper Gold files?
- Measure estimated WL on pre-treatment x-ray
- Depending on canal diameter select either F2 or F3 finishing file
- Set rpm to 600
- Use in coronal 2/3 of canal
- work from F3 > F2 > F1 if req
- only go as far to the GP then go down in 1mm increments checking with the EAL until WL and patency have been achieved - If the apical part of the canal is underprepared/not obturated
- negotiate with size 10 file
- establish WL/patency
- complete preparation using normal PTG sequence at 300rpm
Other than ProTaper gold files, what other methods can be used for the removal of GP?
- Ultrasonics
- Heat
- Solvents - Chloroform, Turpentine, DMS IV (Eugenol), Endosolv R (Resin) and Endosolv E (Eugenol)
- Hedstroem files and solvent
What can be used to remove Silver points?
Stieglitz forceps or fine ultrasonic tip
What can be used to remove a the carrier based system Thermafil?
Hedstroem files and solvent
OR
ProTaper D files
When are Ultrasonics useful in removing GP?
Useful for removing GP from pulp chamber and entrance to canals.
Fine tips are good at removing remaining tags of GP - must carry out carefully with magnification.
When is heat useful in removing GP?
Useful when removing coronal GP for post placement
When should you never use solvents for removal of GP?
When removing GP for post space prep - as can compromise coronal seal.
When are solvents useful for removing GP?
If GP looks dried up
When are Hedstroem files NOT effective?
In narrow curved canals.
- this is because they are made of SS so are less flexible
When are Hedstroem files useful for removing GP?
Removal of a single cone obturation
OR
Poorly compacted GP
What must you NOT do with Hedstroem files?
Engage in the canal wall
What are the 4 aims of endodontic surgery?
- Access, clean, and disinfect the root canal system
- Reduce the number of microorganisms
- Remove necrotic tissue
- Seal the system to prevent reinfection
What are the 5 causes of persistent PA radiolucency’s in endo-treated teeth?
- Intra-radicular infection
- Extra-radicular infection
- Foreign body reaction
- True cyst
- Fibrous scar tissue
What pre-operative medications are advised prior to endodontic surgery?
- Anti-inflammatory agents - ibuprofen 600mg immediately before surgery (inhibits cyclo-oxygenate, preventing the formation of inflammatory mediators).
- Anti-bacterial rinses - 0.2% chlorhexidine night before, morning of, and 30 mins before appointment.
- Pre-medication - 5mg diazepam if very nervous.
List 4 indications for PA surgery:
- Failure of previous endo treatment - if re-treatment is not possible or will not correct the problem
- Anatomical deviations - torturous, curved roots, canal calcifications preventing complete cleaning and obturation
- Procedural errors - ledges, blocks, perforations, file breakages, overfills
- Exploratory surgery - identification of root fractures
List 5 contraindications to periapical surgery:
- Anatomical factors:
- proximity to neurovascular bundle
- thick cortical bone
- difficult access - e.g. palatal root of upper molars - Inadequate periodontal support
- Non-restorable tooth
- Medical history:
- bleeding disorders
- recent MI
- cancer treatment
- medication that puts the pt. at risk of MRONJ - Inadequate skill and ability of surgeon