Endo Flashcards
What is the pathway of development for enamel?
Ectoderm to enamel organ, to ameloblasts to enamel
What is the pathway of development for the root?
Enamel organ to HERS to root formation
What is the pathway of development for the pulp cells?
Ectomesenchyme to dental papilla to pulp cells
Pulp cells are mostly:
Fibroblasts, but also odontoblasts
Why not just proceed immediately with root canal?
We want to maintain vitality, delay the restorative cycle, and not significantly weaken the tooth
Why is an irreversible pulpitis tooth potentially able to heal, but not a necrotic pulp?
Necrotic pulps have no capacity to heal as they have no viable cells to create a dentine seal
Describe pulp testing response of asymptomatic irreversible pulpitis
Usually respond normally to thermal testing, but may have had trauma or deep caries that would likely result in a pulp exposure
Pulp Necrosis alone does not cause apical periodontitis, unless the canal is infected with microbes. True or false
True
Why might a pulp not respond to pulp testing, aside from necrosis
Calcification, large restorations, recent history of trauma
What are the advantages of selective etch?
Preserve dentine spear plugs so less irritation and post op sens compared to total etch.
What is the key advantage of composite resin over amalgam
Micromechanical retetion and seal
What is the key ingredeitn in MTA and Endosequence
Calcium Silicate
Calcium silicate based cements such as MTA and Endosequence release what upon setting?
Calcium Hydroxide
What is the advantage of Calcium Hydroxide on the pulp
Antibacterial and promotes bony and dentine tissue formation
What are two disadvantages of Calcium Silicate based cements
Difficult handling, long setting time, stains teeth
Why are news materials like MTA and CaSi cements superior to plain Calcium Hydroxide for vital pulp therapy?
Sealing ability (don’t wash away and permit bacterial re-entry)
What pulp diagnoses allow indirect pulp capping?
Clinically healthy or Reversible pulpitis
What pulp diagnoses would permit direct pulp capping?
Clinically health, reversible pulpitis or irreversible pulpitis (severity dependent)
What is the protocol for direct pulp capping?
Establish haemostasis with NaOCl and pressure, then CaSi cement over pulp (1-2mm thick) then GIC over that (1-2mm thick) then definitive restoration.
In what situation must you do total caries removal
RCT needed, or indirect restoration needed
VPT: If you expose a pulp and can’t achieve haemostatis in under 5 minutes, what do you do?
Remove more tissue, then give it another 5 minutes, then proceed with pulpotomy followed by CaSi and CR. If you still can’t get haemostasis, RCT or Exo
What are the indications for RCT or Exo
- Apical pathology
- Necrotic pulp
- Symptomatic irreversible pulpitis
- Irreversible pulpitis unable to achieve haemostasis for VPT
Why wouldn’t VPT be successful?
- Incorrect initial diagnosis
- Inadequate seal
What is the difference between reactionary dentinogenesis and reparative dentinogenesis
- Reactionary - odontoblasts sense demineratisation of dentine (matrix proteins being released) and descends toward the pulp and lays dentine
- Reparative - primary odontoblasts are damaged and necrose. Ectomesenchymal cells differentiate into odontoblast-like cells and create a different type of dentine. Repair so no tubules.
Why is it important to prepare to within 0.5 to 1mm of apical constriction?
Generally there are lots of bacteria and biofilm in the apical third. It is important that we prepare into this region to enlarge it sufficiently for irrigants to reach.
Why are irrigation needles side vented?
To prevent apical extrusion.
Means irrigant only goes 1mm past needle tip at best!
How should you perform a watch winding motion?
180 degrees clockwise then anticlockwise with slight apical pressure.
Does watch winding cut?
No.
Use Balanced force technique to cut.
What is balanced force technique/
- Quarter turn clockwise
- Maintain apical pressure
- full turn anticlockwise
- Will cut
What size files should you use for watch winding
8,10,15
Working length should be taken from a stable reference point. What is the ideal point?
A reduced cusp
Why is recapitulation important? (4)
Passing a small file to full WL between each working file helps to:
- Smooth steps
- Prevent blockages
- Maintain length
- Keep irrigant moving - removing debris from walls and bringing into solution
What is anti-curvature filing?
Filing away from inner curve
What does Sodium Hypochlorite do? (NaOCl)
- Kills bacteria
- Lubricate canal
- Dissolve pulp tissue
What strength NaOCl should be used for antibacterial effect in the pulp?
0.5% to 5%
Has same antibacterial effect but lower strength less effective at dissolving tissue
What should you do if you cant get the irrigant to length?
Prepare and taper the canal - makes path for irrigation.
Provided it’s not going out the apex you can’t use too much.
What is in Odontopaste?
- Clindamycin
- ZnOE
- Triamcinolone (steroid)
What length do you need to get to before doing any coronal preparation?
At least 13mm
List the cells found in the pulp:
- Odontoblasts
- Undifferentiated mesenchymal cells
- Fibroblasts
- Macrophages
- Lymphocytes
- PMNs
- Immunocompetent dendritic cells
What makes a pulp ‘vital’
Blood flowing through the pulp
What are the two causes of the reduction in pulp size
- Age (secondary dentine)
- Wear
It is generally agreed that the pulp can survive if there is only …..mm of dentine remaining over it.
0.25mm
Why does trauma often result in necrosis of the pulp in adults?
Blood supply through the apex is cut off
Which tooth has the largest pulp chamber?
What rate is secondary dentine laid down
0.8 microns per day
When might you see reparative dentine as opposed to reactionary
Injurious prep or pulp exposure
On average pulp areas in sectioned clinical crowns are what % larger than radiographs suggest
23%
Do instruments in the pulp come into intimate contact with the trigeminal nerve?
No. The pulp is just an innervatted connective tissue, like the PDL.
Blood only occupies about what % of the health pulp space
5%
It is generally agreed that the pulp can survive is there is mm of dentine remaining over it.
0.25mm
Which is most important to pulp survival:
a) Dentine thickness
b) Bur speed
c) Cavity conditioning
d) Filling material used
a) dentine thickness
Why it important to replant a young tooth as soon as possible
To restore blood flow to permit rest of apex to form
The most important factor in succes when wanting pulp to survive is:
Ability to arrest haemorrhage
What are the two main bacteria involved in caries
Strep mutans
Strep Sobrinus
Pain on percussion before endodontic treatment indicates:
a) reversible pulpitis
b) irreversible pulpitis
c) pulp necrosis
d) inflamed periodontal tissues
e) exposed dentine
d) Inflammed periodontal tissues
The walking bleach technique:
a) Uses heat treatment
b) requires patients to report in 24 hours
c) can be done in poorly obturate canals
d) uses mixtures of sodium perborate and 3% hydrogen peroxide
d) tooth stain remover (hydrochloric acid)
d) Uses mixtures of sodium perborate and 3% hydrogen peroxide
The most appropriate irrigant for a permanent tooth with an open apex is:
a) LA solution
b) 1% NaOCl
c) 5.25% NaOCl
d) 2.5% NaCl
e) 0.2% CHX
b) 1% NaOCl
A 12 year old boy presents with a complicated fracture of his 21 following a rugby tackle. There is no lateral luxation but the tooth is sensitive to hot and cold. You take a history and 2 PA radiographs at different angles. Sensibility testing gives a delayed response. The most appropriate management for the 21 at this appointment is:
a) Pulpectomy immediately as the tooth will become non-vital
b) Partial pulpotomy with MTA and follow up in 6 months to a year
c) Direct pulp cap with GIC and follow up in 6 months then 1 year
d) Partial pulpotomy with MTA and follow up in 6 weeks
e) Direct pulp capping with CaOH and pulpectomy after 7 days as the tooth will become non vital
d).
Direct pulp capping is not appropriate in this case as will be dirty.
Maxillary central, lateral incisors and canines usually only have 1 canal.
True or false
True
The maxillary first premolar has a 91% chance of having how many canals?
2
The maxillary second premolar has a 59% change of having how many canals?
2.
But also a 40% chance of only 1 canal.
The maxillary first and second molars have a 90-91% change of having how many canals-
4
The mandibular central incisors has 57% chance of having how many canals?
1.
But also a 43% chance of 2 canals!
The mandibular lateral incisor has a 55% chance of having how many canals
55% chance of 1 canal
45% chance of 2 canals!
The mandibular canine has an 86% chance of having how many canals?
1
The mandibular first premolar has a 77% chance of having how many canals?
1
The mandibular second premolar has a 88% chance of having how many canals?
1
The mandibular first molar has a 67% chance of having how many canals?
- Usually two mesial and one distal canal.
33% chance of having four.
The mandibular second molar has a 79% chance of having how many canals-
3 (2 mesial, 1 distal)
What size GP to use for tracing sinus tract
30
What is the usual recall protocol for endo
6 months, then annually for 4 years
There should be some evidence of healing of periapical pathology at six months. A large % of cases are healed by:
1 year
4 ways of differentiating odontogenic periapical pathology lesions from non-odontogenic lesions -
- Loss of lamina dura
- Hanging drop
- Radiolucency remains at apex
- Cause of infection is usually evidence
What normal anatomical variation might cause this appearance?
Tori
List requirements of an access cavity
- Permit removal of all pulp chamber contents
- Permit direct vision of the pulp chamber floor and canal orifices
- Facilitate introduction of instruments into the canal opening
- Provide access as directly as possible to the apical 1/3 of canal
- Four walls
- Conserve coronal tooth structure
What are the Krasner and Rankow rules for the relationship of the pulp chamber to the clinical crown (3)
- The pulp chamber is always in the centre of the tooth at the level of the CEJ
- The walls of the pulp chamber are always concentric to the external surface of the crown at the level of the CEJ
- The distance from the external surface of the crown to the wall of the pulp chamber is the same throughout the circumference of the tooth, at the level of the CEJ
What are Krasner and Rankows 6 rules regarding relationships of the pulp chamber floor
- Except for maxillary molars, the orifices of the canals are equidistant from a line drawn in a mesial direction through the pulp chamber floor
- Except for maxillary molars, the orifices of the canals lie on a line perpendicular to a line drawing in a mesial-distal direction across the centre of the floor of the pulp chamber
- The colour of the pulp chamber floor is always darker than the walls
- The orifices are always located at the junction of the walls and floor
- The orifices are located at angles in the floor/wall junction
- The orifices are located at the terminus of the root developmental lines
Checking the path of the root canal with a small file for patency is called:
Pathfinding
3 sgns you would look for to say canal is ready to be obturated
- Improved sinus tract
- Reduced swelling
- No longer TTP
What is GP made from
1,3 trans-polyisoprene with zinc oxide
List two reasons why GP should terminate well down below the crown
- Avoid staining
- Reduce the possibility of coronal leakage
What is AH plus made from
Epoxy resin
What is the short version of sodium hypochlorite
NaOCl
What is the difference between NaOCl and Chx as an irrigant?
NaOCl has antibacterial properties AND dissolves organic material. Chlorhexidine is antibacterial but wont dissolve organic material.
What is EDTA used for?
Chelate calcium and therefore remove the smear layer.
What are the advantages of calcium hydroxide as a medication in canals?
- Antibacterial
- Promoted calcific repair
What does MTA consist of?
- Tricalcium silicate
- Tricalcium aluminate
- Tricalcium oxide
- Silicate oxide
- Formulation and setting chemistry is similar to portland cement.
Set MTA has a pH of 12.5. It is a water-based chemistry which means it can:
Set in the presence of blood - big advantage
6 indications of MTA
- Repair of perforactions
- Management of open apices in immature roots with non-vital pulps
- Direct pulp capping
- Pulpotomy
- Paediatric pulpotomy
- As a root filling on its own in selected teeth
What is CAVIT
Zinc Oxide/Calcium phosphate
Cold test illicits a response from what type of nerve fibers?
a delta
EPT illicits a response from what type of nerve fiber
C fiber
Diffuse radiopaque lesion sometimes seen at apex of tooth. Represents a localized bony reaciton to a low grade inflammatory stimulus.
Condensing Osteitis
Which teeth display the highest rates of fracture?
a) Maxillary Anterior
b) Mandibular Anterior
c) Maxillary Posterior
d) Mandibular Posterior
d) Mandibular Posterior
Aquilino and Caplan (2002) found that RCT teeth have …..x greater survival rate when the cusps are covered.
6x
Why do we not crown anterior teeth after RCT?
Does not improve outcomes. Remaining tooth structure MORE significant for preventing tooth fracture and retention of restoration.
Describe the ferrule effect
Miniumum 1-2mm of tooth height for restoration to band around will double fracture resistence
Ideally a ferrule will have how many walls?
4
What does a core do?
Provide retention for crown restoration. So needed for non bonded restorations.
What does a post do?
Retain a core.
Do posts increase or reduce fracture resistance
Reduce
When placing a post, you need at least how much GP left in tooth
4mm
Should you use threaded posts?
No
What is the ideal post design
- 1:1 crown root ratio (longer is better for retention)
- Parallel sided, small diameter
- Serrated
- Passive fit
Endodontically treated teeth as abutments in order ot preference:
- Crown
- Denture abutment
- Bridge abutment
- Single crown
- Bridge abutment
- Partial denture
(poorer prognosis when reduced bone support)
What is a distinct disadvantage of ceramic posts?
They aren’t easily retrievable
If there is a crack in the tooth, there will be a narrow deep pocket in just one spot. If it is wider it is likely to be:
What is the accuracy of cold test vs EPC
Cold test 90%
EPT 84%
But EPT better if pulp calcified
What pulpal diagnosis is indicated by:
Tooth very tender to touch, biting, percussion, palpation
Acute apical periodontitis
Cracked tooth syndrome must be differentiated from:
Apical periodontitis
What periapical diagnosis is this:
Apical radiolucency, (widening of PDL or obvious PA lesion) symptom free tooth or slightly tender to chewing
Chronic apical periodontitis
What periapical diagnosis is this:
Rapid onset spontaneous severe throbbing. Tooth may be mobile.
Extreme TT pressure.
May be palatal fluctuating swelling.
May have malaise and fever.
Acute apical abscess
What periapical diagnosis is this?
Intermittent discharge of pus through an associated sinus tract
Chronic apical abscess
Trace tract with GP
What periapical diagnosis is this?
Diffuse radiopaque lesion at apex of tooth, localised bony reaction to low grade inflammatory stimulus
Condensing osteitis
What size file should you use for recapitulation
Size 10
RCT have the same fracture resistance as vital teeth.
True or false
True
What is an ideal ferrule?
1.5 to 2mm
What bacteria are involved in extra-radicular infection
Propionibacterium and Actinomyces
What is another name for cyst which are associated with canals
Bay cyst or pocket cyst
In the pulp chamber the wall should be translucent and the floor should be opaque.
True or false.
FALSE
Flood is translucent. Walls are opaque.
6 reasons to prepare a tapered canal
- Promote healing
- Create space for irrigants/medicament
- Preserve location of canal anatomy
- Avoid transportation
- Preserve dentine
- Facilitate filling
Which of these is not a type of transportation
a) Ledges
b) Zip
c) Perforation
d) Cavity
d) Cavity
Why is excessive RC taper bad
It removes excessive dentine at the CEJ which is most prone to fracture
Why does 30% of the canal wall remain untouched after instrumentation?
because canals are ovoid and files are round
Unwinding of the flutes on rotary files is due to
a) Cyclic fatigue
b) Torsional load
b) Torsional load
The patency (recapitulation) file should be a size and should be longer than WL.
10
0.5mm
If a radiolucency is large or there is a very infected tooth, what would you do?
Medicate for longer
What should you do when the rotary file doesn’t go to length?
- Remove file
- Clean flutes
- Irrigate, recapitulate, reirrigate
- Check glide path with proglider
- X1 or X2 but DO NOT PUSH or will get a ledge
What order of GP condensation:
Vertical or lateral first?
Lateral and use size 20-25 accessory points as needed, then vertical.
When anesthetising maxillary molars it is a good idea to do palatal infiltration as well. Why?
Palatal roots often most inflammated.
hyperaemic meaning:
increased blood flow
What is in odontopaste?
Triamcinolone + Clindamycin
Can an acute apical abscess be diagnosed from a radiograph?
No
5 reasons for pain mid-way through RCT
- Incomplete pulp removal
- Over instrumentation
- Extrusion of debris/irrigants/meds
- Procedural accidents
- Occlusion
4 indications for RCT antibiotics:
- Systemic involvement
- Compromised host (diabetes, organ transplant)
- Fascial space involvement
- Inadequate surgical drainage
How to manage hypochlorite accident:
- Reassure
- Long acting local if you have
- Analgesics
- Advise to avoid aspirin/NSAIDs (can cause bleeding)
- Warn of bruising, swelling, ulceration
- Follow up
What will a vertical root fracture look like on a radiograph?
J shaped radiolucency
What are some age related changes which affect endo as people get older
- Tubules become occluded
- Can be difficult to determine working length
- Reduced pulp chamber size
- Vascularity decreases
- Complex anatomy
How long before you should see radiographic healing following RCT:
6-12 months
WHy don’t we use success and failure as terms for RCT anymore?
Doesn’t acknowledge host response. Use healing, healed, persistent periapical disease.
Some lesions take 4-5 years to heal.
What is the likelihood of healing following RCT?
90%
5 indications for surgical endo retreatment
- Following non healing of non surgical RCT
- Iatrogenic or developmental anomalies
- Root filled tooth where NS RCT has failed and conventional retreatmetn not viable
- Visualisation of periapical tissues and root surface
- Patient factors where non-surgical tx may prolong tx
What does this show?
Healing by scar following apicectomy.
Appears as a black punchhole.
