Endo Flashcards
When would you root canal teeth with healthy pulps?
- If tooth can’t be restored without seriously endangering pulp
- Tooth cannot be restored without using pulp chamber and canal system to retain restoration (post)
- There is intractable dentine hypersensitivity
On what teeth are RCTs not possible?
- Gross caries
- Vertical fracture
- Advanced perio disease
How can you help teeth to not fracture during treatment?
Flatten cusps or matrix band around tooth
Why is shaping done?
To enlarge the original canals for:
- Mechanical cleaning
- Irrigant exchange
- Ease and control of filling
After access what are the stages of canal preparation and filling the canal?
- Find electronic working length
- Establish glide path
- Coronal flare
- Confirm WL
- Deep flare
- Apical stop preparation
- Irrigation
- Master GP point
- Cold lateral condensation - spreader and accessary points
- Cut off and warm compaction with plugger
What burs are used in access cavity preparation?
- Medium tapered diamond
- Endo Z and Batt bur (safe ended for unroofing pulp chamber)
- Gooseneck and LN pin burs (for locating pulp spaces and canal entrances)
What is a Gates Glidden bur used for and how do you know its size?
Slow speed for canal preparation
Bands on shank
Flame shaped bur
What are barbed broaches made of and what way to twist?
Stainless steel
Clockwise engages and removes pulp
For the ISO hand files, what is the length, taper and diameter of the active part of the file?
16mm
0.02mm/mm taper - 2% taper
Depends on ISO size e.g. ISO 35 = 0.35mm
When were the ISO regulations?
1961
What is the cutting motion for
a) ISO K hand files
b) ISO Hedstroem files?
a) Rotation - watchwind or balanced force motion. Rasping - filing on outward stroke
b) Rasping not rotation. Milled to have a sharp angle so aggressive but fragile
For the non ISO Protaper hand files/ engine driven rotary files, what is the tip size and taper of Shaper 1 (Purple)?
0.17mm
2-11% taper
For the non ISO Protaper hand files/ engine driven rotary files, what is the tip size and taper of Shaper 2 (White)?
0.2mm
4-11.5% taper
For the non ISO Protaper hand files/ engine driven rotary files, what is the tip size and taper of Finisher 1 (Yellow)?
0.2mm
7% taper
For the reciprocating files (Reciproc, WaveOne) what is the tip size, taper and max diameter?
25
8% taper in apical 3mm, 4% taper in remainder
1.05mm
What materials can be used as lubricants and chelating agents?
a) EDTA/ peroxide paste (glyde)
b) Medicated soap (hibiscrub)
What materials can be used as irrigants?
a) Sodium hypochlorite (NaOCl) 0.5-5% - kills microorganisms and dissolves organic matter but must have seal on rubber dam
b) Chlorhexidine gluconate 0.2-2% - antimicrobial but no solvent action
c) Sterile saline or local anaesthetic - flushes debris and lubricates but no other action
What is the reason for antimicrobial dressings?
- Clean and disinfect canals between appointments
- Kill microorganisms that leak around temporary dressings
- Prevent pain after canal prep
What is it called when there is disruption of perfusion that causes pulp death?
Ischaemic pulp necrosis
In reversible pulpitis, what fibres cause pain? and in irreversible pulpitis?
A delta
C fibres
What is the success rate of RCT in necrotic pulps for healing AP?
70-90%
How does AP occur?
Necrotic pulp - toxins leak into PA tissues, host inflammatory and immune defenses cannot enter tooth but attempt to contain infection - bone loss consequence
Why do we use a rubber dam?
- Prevents saliva entry to tooth
- Protects airway
- Allows use of strong disinfectants
- Retracts cheeks and tongue
- Stops pt talking/rinsing
- Improved pt comfort?
What pH is non-setting calcium hydroxide paste? How long does it last? What else can be used? How are they placed?
pH11/12. 3 months
Odontopaste (steroid/antibiotic paste)
File rotated anticlockwise
What allergy should you check for before placing gutta percha?
What sealer cements are used with gutta percha?
Latex
ZOE, resin, silicone, calcium silicate etc
What is the disadvantages of using zinc oxide eugenol sealers in root canal filling?
- Can stain teeth yellow
- Can interfere with composite restorations (inhibits polymerisation so no direct contact)
What sealer is widely used for root canal fillings? What is its setting time?
Resin (AH plus). 8 hours (slow)
What qualities should the temporary filling have?
- Cotton wool to secure canal orifices
- No whisps of cotton wool exposed
- 3 mm thick
- Well adapted to cavity wall
What temporary filling materials can be used in retentive, non-load bearing areas?
Cavit
Sedanol (clove taste)
What temporary filling materials can be used in load-bearing areas?
GIC - good for unretentive
Intermediate restorative material (IRM)
For maxillary central incisors
a) What is the average length
b) How many canals
a) 23.5mm
b) 1
For maxillary lateral incisors
a) What is the average length
b) How many canals
a) 22.5mm
b) 1 canal - distal curve apex
Fishtail shape pulp horns
For maxillary canines
a) What is the average length
b) How many canals
a) 26.5mm
b) 1
Candle flame shape pulp horn
For maxillary first premolars
a) What is the average length
b) How many canals
a) 21mm
b) 2 roots and 2 canals in 90%
For maxillary second premolars
a) What is the average length
b) How many canals
a) 21.5mm
b) 1 canal in 60%
2 pulp horns
For maxillary first molar
a) What is the average length
b) How many canals
a) 21mm
b) 4 in 60%, 3 in 40% (palatal, distal and 2 MB)
When preparing the access cavity for a maxillary first molar, what should be preserved?
Mesial marginal ridge and transverse oblique ridge (no pulp horns underneath)
For maxillary second molars
a) What is the average length
b) How many canals
a) 21mm
b) 3, but 2 MB in 10%. DB canal entrance more central than first molar
For mandibular central incisors
a) What is the average length
b) How many canals
a) 21mm
b) 1, but 2 in 30%
For mandibular lateral incisors
a) What is the average length
b) How many canals
a) 21mm
b) 1 or 2 in 45% (extend lingually to find)
For mandibular canines
a) What is the average length
b) How many canals
a) 22.5mm
b) 1, but 2 in 30%
Flame shaped pulp chamber
For mandibular first and second premolars
a) What is the average length
b) How many canals
a) 21mm
b) 1, but 4s have 2 in 30%, 5s have 2 in 12%
For mandibular first molars
a) What is the average length
b) How many canals
a) 21mm
b) 3, but 2 distal canals in 30%
For mandibular second molars
a) What is the average length
b) How many canals
a) 20mm
b) 3, but 2 distal canals in 8%
When cutting an access cavity, how should you start and when should you stop?
- Measure how far on PA to pulp chamber
- Outline shape of access
- Stop at 5mm and reassess if not in pulp chamber
What are the effects of under-preparation of an access cavity?
- Infected tissue remains in pulp horns = reinfection
- Stressed access for instrumentation = ledging, instrument fracture
- Missed canal
What are the effects of overpreparation of an access cavity?
- Weakened tooth structure
- Unrestorable
How should you enter calcified/sclerosed pulp chambers?
Once reached 6mm stop, use gooseneck for direct vision
Use long thin ultrasonic tip to shatter pulp stone but beware may drop into canals
What are the 5 complications of shaping?
1) Apical transportation (file flexing away from canal)
2) Ledging
3) Perforation
4) Stripping (inside-out)
5) Blockage
What is the working length?
Zero reading -0.5mm measured from reference points
Why should you not exceed size 20 K file when establishing glide path?
Transportation risk
What should you use to take the master file radiograph?
Gutta percha- circular in cross section, size of GP varies in pack
What is deep flaring?
Shaping to working length (S1, S2 then F1)
How should you approach if canals are narrow or a complex curve?
Scout with size 10/15 K file
Pre-flare and irrigate before thinking of entering apical third
What are the causes/aetiology of pulpitis?
Microbial - caries
Cracked tooth
Trauma - mechanical, thermal, chemical, barotrauma (aerodontalgia - air bubbles in tubules from high altitudes or diving)
Perio-endo lesion
Attrition/abrasion/erosion
Dens en dente
What is the pathogenesis of pulpitis?
Ingress of bacteria vs the host immune response:
- Acute pulpitis has acute inflammatory response with neutrophils and supparation
- Increase in pulpal pressure, venous stasis, ischemia, thrombosis, necrosis - chronic
What is the pulpal response to mild insult?
Inflammatory response with no suppuration. Repair, organization and replacement with granulation tissue, fibrosis and scarring. Tertiary dentine deposition.
What does pulpitis look like histologically?
- Rich inflammatory cell infiltrate (neutrophils, lymphocytes, macrophages)
- Diluted blood vessels and hyperaemic
- Tertiary dentine
- Pus (dead neutrophils)
What is the aim of pulp capping?
To induce dentine bridge
What is a pulp polyp? How does it occur? What happens if you touch it?
Hyperplastic granulation tissue forming from a wide open carious cavity usually in deciduois molars. Covered with epithelial lining.
Will bleed very easily
What changes occur in pulpal degeneration that means endodontic treatment sometimes doesnt work?
- Oedema - odontoblasts less numerous and wheat sheafing (stick together)
- Fatty changes (adipocytes)
- Fibrosis
- Calcifications
What is the difference between a true pulp stone and a false pulp stone?
True = tubules
False = no tubules
What are the types of calcification that occur in the root canal system?
a) Diffuse/dystrophic = in root canal
b) Pulp stones/denticles = coronal pulp, irregular or laminated, free adherent or interstitial
c) Pulp obliteration by secondary or tertiary dentine
What are the requirements of a root filling material?
- Biocompatible
- Inert (doesn’t breakdown over time)
- Removable
- Compaction/condensation
- Doesnt support microbial growth
- Radiopaque
What should you do if your master gutta percha point is too short?
Canal usually blocked with dentine mud or CA(OH)2 so irrigate, gently use K file to WL, irrigate and try cone again
May be poor size match between flies and GP
What should you do if your master gutta percha point is too long?
No apical stop or poor sizing of cone so try another GP or trim tip for better fit (stops taper)
What finger spreader should be selected when doing a cold lateral condensation?
Biggest FM (green) - pack full length of filling and slide in easily. If not use smaller MF or B spreader (red)
Always use vertical force and leave for 10 seconds then remove with watch-winding motion
Why does the canal need to be dry before placing sealer?
AH plus hypoxyresin is hydrophobic
What is the process of warm vertical condensation?
Cut off GP points at or below cervical margin with Glick (heated) - or to canal entrances in molar teeth
Pack with cold plugger
When should you next radiograph after RCT and at what point should you see complete radiographic evidence of healing?
6 months
4 years
What are the options when there is an open root apex and length control is difficult?
MTA
What is condensing osteitis?
Diffuse radiopaque lesion - localised bony reaction to low grade inflammatory stimulus, usually seen at apex of tooth
What is the theory of vital pulp therapy?
To excise irreversibly inflamed tissue to control inflammation
Stimulation of dentine bridge formation - reduces bacterial contamination and allows pulp to form layer of odontoblasts against it
What is the stepwise modified approach to caries management?
Margins to hard dentine, pulp wall to firm dentine, pulp deposits reactive dentine, second stage up to 6 months later where caries arrested and firmer - less risk of exposure
What is selective caries removal?
Clear ADJ, excavate to soft or firm dentine, apply biomaterial.
Why should calcium hydroxide not be used as a cavity lining?
It is soluable - leaves hole under amalgam.
Use biodentine (calcium silicate cement)
What is a direct pulp cap?
Application of biomaterial directly onto exposed pulp prior to placement of permanent restoration in an aseptic working field. Must be a healthy pulp
What factors influence predictability of direct pulp capping?
- Site of exposure less than 2.5mm
- Age - young more predictable
- Isolation - must use rubber dam
What materials are used in vital pulp therapy to promote formation of dentine bridge?
MTA or calcium silicate cement - less soluble and higher compressive strength than calcium hydroxide
But MTA takes 24 hrs to set
You are removing a composite that has secondary caries and there is pulp exposure with bleeding. What should you do?
Put pressure and wait for 5 mins - bleeding stops
MTA pack
GIC cap as etch would wash away MTA
Restore with composite
What are the indications for a pulpotomy?
- Trauma with open apices
- Carious exposure with open apices
What is the technique for pulpotomy?
Rubber dam
Cut back to healthy pulp - judge by bleeding by using hypochlorite on cotton wool pledget for 5 mins, if no arrest then further pulp removal
Use magnification
Place CSC (or CH but CSC better dentine bridge)
Restore immediately to reduce microbial contamination
What are the forces acting on posterior and anterior teeth?
Post = compression
Ant = shearing
What are the aims of restoring root treated teeth?
- Preserve as much tooth structure as possible
- Minimise damaging internal stresses
- Protect remaining tissue from fracture
- Maintain as much peri-cervical dentine as possible
What are the 3 ways of achieving cuspal coverage?
1) Direct onlay/restoration with amalgam or composite (flatten off cusps but hard to restore contact points)
2) Metal, composite or ceramic onlay
3) Full coverage crown
What are the pros/cons of cores with a) amalgam b) composite
a) High strength, forgiving technique. But post teeth only, delayed crown prep, being phased down
b) High strength, immediate crown/onlay preparation, any tooth, good seal. But shrinkage and technique sensitive
What is a nayyar core preparation?
GG used to cut back GP 3-4mm to provide anchorage and increased SA for adhesion. Clean internal walls and ensure no debris and direct amalgam.
What are the requirements of a ferrule and why is it necessary?
Ideally 2+mm circumferential dentine: 2mm height, 1mm width
Resists fracture
What materials can be used as a temporary restoration in RCT?
IRM - zinc oxide 2-3 weeks
Cavit - 7-10 days
GIC - weeks
Ensure adequate thickness, reduce cusp height and if vulnerable consider ortho band to reduce flexion
For what reasons would a fibre post fail?
- Moisture control - must have good isolation as very technique sensitive
- Not encased in composite core so posts wicks moisture and swells
- Debonding - when ferrule not observed or microleakage
What factors determine the success of a post?
1) Accuracy of fit - not against rubber, thin section of cement
2) Length - longer retains better leave 4-5mm root filling but care in curved canals
3) Shape - parallel more retentive
4) Surface - sandblasted/roughened best, threaed is very retentive but creates internal stresses
5) Width - wider have more SA for bonding but dont remove more dentine than requires
6) Cementation - composite cements most retentive (but zinc phosphate used for metal posts)
What is the process for placing a fibre post?
1) Cut back GP
2) Post channel enlarged with post drill prep so post just engages with walls
3) Etch tooth and wash
4) Size 60 paper point
5) PTFE table to adjacent tooth then bond, paper point to remove excess
6) Insert post and build up core with DT light kin
What is the method for placing an indirect post?
1) Prepare post channel and shape coronal tooth tissue for crown
2) insert smooth plastic impression post and take impression
3) make temporary post crown
4) Cast the impression and remove impression post from model
5) Insert size matched burnout post and wax up core
6) Cast in hard gold or non-precious metal
7) Fit and cement post and take imp for permanent crown
What are the histological features of periapical granuloma?
Granulation tissue, blood vessels, inflammatory cells, whisps of hyperplastic epithelium left over from rests of malassez, cholesterol clefts, haemosiderin
What is condensing osteitis/focal sclerosing osteitis?
Radiopaque mass of sclerotic bone associated with root apex
In what situations or indirect post systems used?
Very wide and tapered canals
