Endodontics Flashcards
Topics covered: endodontic retreatment, endodontic surgery, diagnosis and management of complex cases, pathological root resorption
1
Q
What are the follow-up periods following root canal treatment?
A
Follow-up at least 1 year after treatment
And then follow-up for up to 4 years
2
Q
What are the indications for endodontic re-treatment?
A
- 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.
3
Q
What prognostic factors determine the success rate of retreatment?
A
- Pre-operative PA lesion
- Apical extent of root canal filling
- Quality of coronal restoration
4
Q
Which 4 terms are used to describe endodontic treatment outcomes?
Give clinical and radiographic findings for each outcome.
A
- 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
5
Q
List 6 factors that can help to prevent post-treatment disease:
A
- 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
6
Q
What might be the cause of post-treatment disease?
A
- 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
7
Q
Why are intra-radicular microbes difficult to disinfect?
A
As they are situated in the apical part of the root canal system.
8
Q
Which extra-radicular microbes are frequently found in post treatment disease?
A
Actinomyces and Propionibacterium propionicum.
9
Q
Which cyst is the most common odontogenic cyst of inflammatory origin?
A
Radicular cyst
10
Q
Where do radicular cysts arise from?
A
The epithelial cell rests in the PDL
11
Q
Radicular cysts can be either true cysts or pocket cysts.
What is the difference between a true cyst and a pocket cyst?
A
True cyst - lesion enclosed by epithelial lining
Pocket cyst - epithelial sac communicates with the root canal system
12
Q
Which type of radicular cyst (true or pocket) usually resolves after endo treatment?
A
Pocket cysts
13
Q
Which type of radicular cyst (true or pocket) may require remedial surgical intervention?
A
True radicular cyst
14
Q
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?
A
Gram positive bacteria
15
Q
Are bacteria that remain in the root canal system after root canal disinfection and interappointment dressing, always infectious?
A
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.
16
Q
How many bacterial species remain in the canals following good root canal treatment?
How does this compare to inadequately treated canals?
A
Good RCT - 1-5 remaining species
Inadequate RCT - 1-20 remaining species
17
Q
In retreatment cases, how many more times is E faecalis likely to harbour in the root canal system vs. initial treatment cases?
A
Retreatment cases are 10X more likely to harbour E faecalis.
18
Q
Which 6 microbes are commonly found in retreatment cases?
A
- E. faecalis
- Streptococcus
- Lactobacillus
- Actinomyces
- Propionibacterium
- Candida albicans
19
Q
How do cholesterol crystals form in periapical tissues?
A
They form as a result of cells dying during chronic inflammation.
20
Q
List 4 foreign bodies may cause a reaction in the PA tissues following root-treatment:
A
- Gutta percha
- Sealers
- Paperpoints
- Cotton pellets
21
Q
Why might paperpoints and cotton pellets cause a foreign body reaction?
A
They contain cellulose which is non-biodegradable (body cannot break it down) - therefore acts as a constant irritant to the tissues.
22
Q
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?
A
That the technical difficulties will make the treatment more complex.
Attempting to treat the tooth may result in treatment failure.
23
Q
When accessing through sound fixed pros work for retreatment cases what must you be cautious about when doing this?
A
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.
24
Q
How do you remove a crown?
A
- 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)
25
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.
26
What can make post removal difficult, potentially leading to the need for PA surgery or extraction of the tooth on retrieval?
Adhesive resin cements
27
What must you use when removing root canal filling material?
Magnification
28
What instruments are best for removing gutta percha?
ProTaper Gold files
29
How would you remove GP using ProTaper Gold files?
1. Measure estimated WL on pre-treatment x-ray
2. Depending on canal diameter select either F2 or F3 finishing file
3. Set rpm to 600
4. 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
5. 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
30
Other than ProTaper gold files, what other methods can be used for the removal of GP?
1. Ultrasonics
2. Heat
3. Solvents - Chloroform, Turpentine, DMS IV (Eugenol), Endosolv R (Resin) and Endosolv E (Eugenol)
4. Hedstroem files and solvent
31
What can be used to remove Silver points?
Stieglitz forceps or fine ultrasonic tip
32
What can be used to remove a the carrier based system Thermafil?
Hedstroem files and solvent
OR
ProTaper D files
33
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.
34
When is heat useful in removing GP?
Useful when removing coronal GP for post placement
35
When should you never use solvents for removal of GP?
When removing GP for post space prep - as can compromise coronal seal.
36
When are solvents useful for removing GP?
If GP looks dried up
37
When are Hedstroem files NOT effective?
In narrow curved canals.
- this is because they are made of SS so are less flexible
38
When are Hedstroem files useful for removing GP?
Removal of a single cone obturation
OR
Poorly compacted GP
39
What must you NOT do with Hedstroem files?
Engage in the canal wall
40
What are the 4 aims of endodontic surgery?
1. Access, clean, and disinfect the root canal system
2. Reduce the number of microorganisms
3. Remove necrotic tissue
4. Seal the system to prevent reinfection
41
What are the 5 causes of persistent PA radiolucency's in endo-treated teeth?
1. Intra-radicular infection
2. Extra-radicular infection
3. Foreign body reaction
4. True cyst
5. Fibrous scar tissue
42
What pre-operative medications are advised prior to endodontic surgery?
1. Anti-inflammatory agents - ibuprofen 600mg immediately before surgery (inhibits cyclo-oxygenate, preventing the formation of inflammatory mediators).
2. Anti-bacterial rinses - 0.2% chlorhexidine night before, morning of, and 30 mins before appointment.
3. Pre-medication - 5mg diazepam if very nervous.
43
List 4 indications for PA surgery:
1. Failure of previous endo treatment - if re-treatment is not possible or will not correct the problem
2. Anatomical deviations - torturous, curved roots, canal calcifications preventing complete cleaning and obturation
3. Procedural errors - ledges, blocks, perforations, file breakages, overfills
4. Exploratory surgery - identification of root fractures
44
List 5 contraindications to periapical surgery:
1. Anatomical factors:
- proximity to neurovascular bundle
- thick cortical bone
- difficult access - e.g. palatal root of upper molars
2. Inadequate periodontal support
3. Non-restorable tooth
4. Medical history:
- bleeding disorders
- recent MI
- cancer treatment
- medication that puts the pt. at risk of MRONJ
5. Inadequate skill and ability of surgeon
45
What 3 things do you need to carry out endodontic microsurgery?
1. Magnification
2. Instruments
3. Illumination
46
What are the different magnification ranges?
Low magnification: (x3 - x8) - wider field and high focal depth
Medium magnification: (x10 - x16) - moderate focal depth
High magnification: (x20 - x30) - shallow focal depth, inspection of fine detail
47
What lens system do loupes follow?
The convergent lens system (Greenough system)
48
What is the disadvantage of the convergent lens system (Greenough system) seen in loupes?
Users eyes must converge - ocular muscles can tire causing eye strain and fatigue
49
What is the benefit of using a microscope system over loupes?
Because the microscope is already focused to infinity - less tiredness
50
Outline the 13 step procedure of endodontic surgery:
1. Anaesthesia
2. Flap design
3. Flap elevation
4. Flap retraction
5. Osteotomy
6. Curettage of granulation tissue
7. Haemostasis
8. Root End Resection
9. Inspection of resected root surface
10. Ultrasonic retrocavity preparation
11. Root-end filling
12. Suturing
13. Repositioning and suturing of flap
51
Which receptors does lidocaine activate?
Alpha receptors in arteriolar muscles, submucosa, and periodontium.
52
What is unique about articaine?
It is the ONLY amide LA that contains a thiophene ring and an additional ester ring.
53
What are the 7 rules of flap design in endodontic surgery?
1. The flap must never cross a bony defect (site of pathology).
2. The releasing incisions should be over concave bone surfaces and not convex bone eminences.
3. The end of the vertical incision at the gingival crest should finish at the mesial or distal line angles and curve so that the incision meets the free gingival margin at 90* to the gingival contour - allows for better healing.
4. The other end should NOT enter the mucolabial fold.
5. The base must be as wide as its free edge and vertical releasing incision should follow the direction of the vascularisation network.
6. The periosteum must be raised with the flap.
7. The retractor must rest on bone and NOT soft tissue.
54
Name 2 commonly used flap designs for endodontic surgery?
1. Full thickness mucoperiosteal flap
2. Split thickness flap - papilla-based incision
55
What are the advantages and disadvantages of a split thickness flap (papilla-based incision) ?
Advantages - prevents gingival recession, heals well/quickly
Disadvantages - requires very small 6-0 sutures (2 sutures per papilla), can be time consuming to suture back together.
56
What size of blade is normally used for relieving incisons?
size 15 or 15c
57
Which elevator is used to raise a periosteal flap for endodontic microsurgery?
Prichard periosteum elevator 4.5mm or 5.5mm
58
Which retractor is used in endodontic microsurgery?
What feature of these retractors makes them useful in endodontic microsurgery?
Kim Pechora retractors.
They have serrated tips at the working ends to give better anchorage.
59
What does an osteotomy involve?
Removal of the cortical plate to expose the root end
60
What intra-operative topical haemostatic agents can be used?
Epinephrine pellets - Racellets, most effective/economic.
Ferric sulphate - forms a plug
Calcium sulphate - blocks open vessels and aids bone regeneration
Others - surgical wax, thrombin gel/foam, surgicel, collagen (not as effective and more expensive)
61
What does root resection in endodontic microsurgery involve?
1. Under magnification 3mm of the root end is resected using an Impact Air surgical hand-piece 45* and Lindermann bur.
2. Once the apex has been resected remove it using an excavator.
3. Examine at medium magnification for the presence of the PDL (use methylene blue dye to stain the PDL to ensure resection is complete).
62
What instrument is used to carry out ultrasonic retrocavity preparation?
Ultrasonic microtips (Piezo ultrasonic units and KiS tips) - diamond or zirconium nitride coated
63
Name 2 common root-end filling materials that can be used in endodontic surgery:
1. Zinc oxide eugenol cements
- Immediate restorative material (IRM)
- Super ethoxybenzoic acid
2. Mineral Trioxide Aggregate (MTA) - best available
64
Which suture material/size would be most appropriate for a papilla-based incision following endo microsurgery?
Prolene 6-0 or 7-0
65
Which suture material/size would be most appropriate for a flap with sulcular incisions and free gingiva following endo microsurgery?
Prolene 5-0
66
List 7 complications that can occur with endodontic surgery:
1. Post-op pain
2. Swelling
3. Bruising
4. Paraesthesia
5. Serious infection
6. Lacerations
7. Maxillary sinus perforation
67
Which guidelines should you follow for endodontic surgery?
Royal College of Surgeons (RCS) - Guidelines for Surgical Endodontics
- Guidelines for Periradicular Surgery 2020
68
What can cause rotary file fracture?
1. Torsional stress - tip binds in canal, elastic limit exceeded
2. Cyclical fatigue - repeated tension and compression
69
Relating to file size and taper, which files are more likely to fracture due to torsional stress?
Fine, more flexible files
70
Relating to file size and taper, which files are more likely to fracture due to cyclical fatigue?
Thicker, less flexible files
71
How would you manage a fractured file case in a patient that has irreversible pulpitis (minimally infected canals) and no existing periapical pathology?
How will this influence the prognosis?
If possible remove the fragment or bypass it.
If not possible the retained fragment should NOT influence the prognosis.
72
How would you manage a fractured file case in a patient that has infected canals?
If fracture occurs towards the end of instrumentation - assume the canals are disinfected and embed the fragment in filling material if it cannot be removed.
If fracture occurs early in treatment, the canal beyond the instrument cannot be cleaned and this may be directly responsible for failure - attempt removal or bypass if possible
73
List a few examples of techniques/instruments that can be used to remove fractured files:
Hedstroem files
Gripping devices - fine haemostat or Stieglitz forceps
Excavators
Ultrasonics
Tube systems
BTR pen
74
If a file has fractured in the canal, what must you inform the patient?
1. Warn them of the incident.
2. It is not always the direct cause of treatment failure.
3. It can influence the success rate of treatment.
4. Further complications can occur.
5. Further treatment may be needed.
75
What is a ledge in endodontic treatment?
An iatrogenically created irregularity (platform - firm stop) in the canal, that impedes access of the instruments to the apex
76
What might be the cause of ledge formation?
Inadequate access cavity
Incorrect assessment of canal curvature
Failure to pre-bend ss files
Using larger, stiffer ss instruments
Failure to use instruments in a sequential manner
Cutting on inward rather than outward stroke
Bypassing a fractured instrument
Negotiation of a calcified canal
77
What might cause a canal blockage?
1. Apical patency not confirmed or secured when working length is measured using the EAL.
2. During instrumentation pulpal tissue is packed and solidified in the apical constriction by the use of instruments.
3. Instrumentation is not accompanied by copious irrigation and recapitulation.
4. Instruments are not cleaned before their insertion in the canal.
78
What are the signs of a canal blockage?
1. Instruments or GP cones are no longer able to reach full WL.
2. Tactically feels almost solid but penetrable
3. Short obturation on radiograph
79
How might a blockage affect the prognosis of RCT?
If a blockage is recognised and corrected, there is no effect on the prognosis.
When it cannot be corrected it may have a negative effect on the treatment outcome - particularly in infected cases.
80
Never keep a rotary file in the same position for more than ......... second.
1
81
What is resorption?
Transitory or progressive loss of cementum or cementum/dentine by action of activated clast cells.
82
What causes resorption?
1. Injury - mechanical, chemical, infections of root canal or PDL
2. Stimulation - infection, pressure
3. Systemic/endocrine diseases
4. Idiopathic
83
What happens to cementoblasts during resorption?
They are destroyed directly or become necrotic as a result of compromised blood supply to the PDL or pulp.
84
Which systemic/endocrine diseases can result in resorption?
- Hypo and hyperthyroidism
- Calcinosis
- Gaucherie syndrome
- Turner syndrome
- Paget's disease
- Herpes Zoster
85
Which mechanical injuries may result in resorption?
Trauma
Surgical procedures
Excessive pressure (impacted teeth, cysts, tumours, orthodontic treatment)
86
Where are the clastic cells (odontoclasts and osteoclasts - cells responsible for resorption) located?
Howships lacunae
87
How does multinucleated osteoclast cells form?
By the binding of RANKL to RANK - this causes fusion of osteoclast precursor cells forming multinucleated osteoclast cells
88
What is the most common cause of resorption?
Pulp infection
89
What most commonly causes external root resorption?
Trauma - intrusion, lateral luxation, avulsion
90
What part of the cementum is affected in external inflammatory root resorption?
Non-mineralised pre-cementum
91
How does external inflammatory root resorption progress?
It progresses due to microbial stimulation from the infected necrotic pulp.
92
How do you treat external inflammatory root resorption?
1. Remove necrotic pulp as soon as you see signs of EIR.
2. Use CaOH as an interappointment dressing
Note - in many cases the resorption is too advanced to treat.
93
What is invasive cervical resorption?
A type of external inflammatory root resorption that develops immediately apical to the epithelial attachment in the cervical region.
Can be mistaken for internal resorption.
94
What causes invasive cervical resorption?
Developmental, physical/chemical trauma
- for example orthodontics, general trauma, surgery, intra-coronal bleeding.
This results in loss of protective non-mineralised layer at the CEJ.
95
What clinical features can be seen in invasive cervical resorption?
Asymptomatic
Tooth may appear pink
Positive sensibility test
Vital or non-vital tooth - +/- infection
96
Why might the tooth still be vital in invasive cervical resorption?
Tooth will be vital in earlier stages as pulp is protected by a layer or dentine and pre-dentine - eventually the lesion will perforate the canal wall resulting in canal infection and necrosis.
97
How is invasive cervical resorption classified?
Class I - small with shallow preparation
Class II - close to the coronal pulp (no radicular extension)
Class III - Deeper but not beyond coronal third
98
What is the one difference between internal resorption and invasive cervical resorption radiographically?
In invasive cervical resorption you would observe the pulpal canal running through the radiolucency.
(this would NOT be observed in internal resorption)
99
How would you treat invasive cervical resorption?
1. Remove granulation tissue from defect using 90% trichloroacetic acid
- difficult procedure
- soft tissues must be protected with glycerol gel
2. Restore with GI, composite or biodentine
3. RCT if communication with pulp canal
100
What causes internal root resorption?
Results from damage to odontoblastic layer and pre-dentine.
Aetiology unknown - but mostly as a result of trauma.
101
What can extensive internal resorption result in?
Pink discolouration of the crown (this may be confused for invasive cervical resorption however internal root resorption is very rare.
102
Which radiographs/radiographic techniques are useful for confirming diagnosis of internal resorption?
CBCT and Parallax
103
How would you treat internal cervical resorption?
RCT if tooth can be saved - lesion difficult to clean and obturate
Thermoplastic heated techniques
If left untreated will cause perforation and clast cells can obtain nutrients from the surrounding tissues
104
Which teeth are affected by impacted tooth/tumour pressure resorption?
Maxillary canines and mandibular 3rd molars
105
Which tumours most frequently result in resorption?
Slow growing tumour:
- Cysts
- Ameloblasts
- Giant cell tumours
- Fibreosessous lesions
106
In which cases might teeth be non-vital as a result of impacted tooth/tumour pressure resorption?
if impacted tooth/tumour is located near the apical foramen disrupting the blood supply.
107
How do you treat impacted tooth/pressure resorption?
Surgery to remove the stimulation factor
108
What might result in ankylosis root resorption?
Severe traumatic injuries (intrusive luxation, avulsion with delayed implantation)
109
How might ankylosis root resorption appear clinically?
Teeth lack physiological mobility and sound metallic to percussion, sometimes in infraocclusion.
110
How do you treat ankylosis root resorption?
Functional splint placement for 7-10 days and RCT to prevent pulpal infection root resorption.
111
What is the difference between ankylosis and replacement resorption?
In ankylosis there is no loss of root dentine and cementum merely fusion or close proximity of root and bone
Whereas in replacement resorption dentine and cementum are lost and replaced with bone.
112
