LA/ Isolation for root treatment

Question 1

Mechanical prep stages

Answer 1

1. LA
2. Isolation
3. Access cavity prep
4. Location of canal orifices
5. Straight line access
6. Prepare ‘glide path’ coronal 2/3
7. Opening of corornla 2/3
8. Prepare ‘glide path’ full length
   9/ Working length determination
9. Shape canal to working length (apical prep)
10. Determination of MAF
11. Step-back prep (every 1mm)

Question 2

Chemical prep

Answer 2

To flush out remnants of pulp tissue & debris created during mechanical prep
To dissolve residual pulpal tissue
To kill bacteria and remove bacterial biofilm
To clean parts of RC system which are inaccessible to mechanical instrumentation
To faciliate instrumentation and prevent RC blockages by acting as lubricant
To remove smear layer

Question 3

Obturation

Answer 3

Filling canal with 3-dimensional filling
Completely seal all anatomical parts
Prevent reinfection of RC system by denying access to oral bacteria
Resolution of signs and symptoms of disease
Restore integrity of tooth

Question 4

LA: maxillary teeth

Answer 4

Labial infiltration
Expect blanching
Around apex of tooth being worked on
Palatal infiltration only recommended if px still feels pain

Question 5

LA: mandibular molars

Answer 5

ID block (IAN block)
Long needle
Px should feel tingling sensation in corner of lip and part of tongue

Question 6

LA: Mandibular premolars

Answer 6

Mental nerve block & ID block

Mental nerve block like infiltration

Question 7

Isolation

Answer 7

RD/ Clamp/ Oraseal

• control of saliva
• before access into pulp chamber

Question 8

LA: maxillary incisors/ canines

Answer 8

Infiltration

Question 9

Isolation: Before commencing RCT

Answer 9

• fully restore tooth

- evaluate possibility of placing efficient RD

Question 10

Access cavity prep

Answer 10

1. Clinical assessment
2. Radiographic assessment
3. Dismantle coronal restorations
4. Access cavity prep
   - no undercuts
   - smooth axial walls
   - all canal orifices visible

Question 11

RD placement after access cavity prep

Answer 11

Indirect restoration
Position of tooth
Having visibility of neighbouring teeth will help align long axis of bur correctly

Question 12

Access cavity

Answer 12

To create smooth, straight-line path to canal system and, ultimately, the apical third

Question 13

Cutting access through full coverage restorations

Answer 13

Crown may mask actual orientation
Vision may be limited
Excessive cutting
Lateral perforation

Question 14

Removal of extra-coronal restorations

Answer 14

Considered when:
-caries is extensive and restorability questionable
Marginal deficiencies result in leakage
Difficulty locating canals
New crown planned after RCT

Question 15

Locating canal orifices: magnification and instruments

Answer 15

Magnification
-loupes
-dental operating microscope
Instruments
-endodontic explorer
-rose-head bur
-gates glidden drills
-stainless steel files
-nickel-titanium files

Question 16

Straight line access

Answer 16

Reduces stress on instruments to reduce chance of instrument fracture
< chance of procedural errors
Simplifies treatment by providing clear path of insertion for instruments

Question 17

Opening of coronal 2/3

Answer 17

Removal bulk of infected pulp tissue and dentine
< risk of pushing infected debris apically or through to peri-radicular tissues
Elimination of interferences in coronal 1/3, thus minimising risk of blockage apically
Early introduction of irrigants into apical portion of canal
Easier negotiation to working length
> tactile feedback apically

Question 18

Prepare glide path

Answer 18

Smooth radicular tunnel from canal orifice to apical constriction
Minimal size should be ‘super loose n.10’ endodontic file (purple)

Question 19

Lack of glide path

Answer 19

Ledge formation
Transportation
Zip formation
Perforation

Question 20

Working length determination

Answer 20

To enable root canal to be prepared as close to apical constriction as possible
Ideal terminus for RC prep is junction between RC and periodontium - only identifiable histologically
-root morphology
-radiographic interpretation

Question 21

Root treatment should end at

Answer 21

Apical constrictions

0.5-1mm shorter than radiographic apex

Question 22

Over-instrumentation

Answer 22

Damage to root apex and periapical tissues
Extrusion of debris which may contain micro-organisms, elements of necrotic pulp, and infected dentine chips
Presence of excess root filling material in PA tissue which may act as foreign matter

Question 23

Method of determining working length

Answer 23

Measure pre-op radiograph
Tactile feedback of apical constriction
Diagnostic or working length radiograph
Electronic Apex Locator (EAL)
Paper point

Question 24

Paper point

Answer 24

Observe blood/fluids on instrument tip or anywhere on a paper point

Question 25

Locating apex

Answer 25

Careful study of high quality radiographs
Magnification of radiographs, changing contrast and light
Keeping apical anatomy foremost in your mind
Use tactile sense to locate apical constriction
Observe blood/ fluids on instrument tip or anywhere on paper point
Use and understand apex locator