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Module 5 - Endodontics > Root Canal Instrumentation > Flashcards

Root Canal Instrumentation Flashcards

1
Q

What is the main aim of shaping?

A

Allow DISINFECTION and OBTURATION.

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2
Q

Define shaping.

A

controlled removal of dentine to produce a TAPERING shape that can be DISINFECTED and SEALED throughout its length with a root canal filling.

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3
Q

Why do we want to keep the apical opening as small as possible? How is this done?

A
  • To prevent extrusion of debris to the periapical tissues.
  • Work to the APICAL CONSTRICTION
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4
Q

What is DG16

A

Endodontic exploring probe

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5
Q

What type of mirror is used in endo?

A

Front facing mirror

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6
Q

What is the aim of the aseptic technique? What does it mean?

A
  • Exclude contamination with oral microbes.
  • Do not use instruments from the RCT kit until tooth has been isolated with rubber dam.
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7
Q

Endoblock?

A

Measures file length.

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8
Q

Endopot?

A

All dirt, used files placed onto it.

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9
Q

What are stainless steel hand files used for?

A

for INITIAL NEGOTIATION of the canal.

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10
Q

4 Drawbacks of Hand Files.

A
  • MISHAPS (ledges, canal blockade, zipping of foramen – no apical stop).
  • DEBRIS EXTRUSION with filing motion.
  • TIME CONSUMING.
  • LESS PREDICTABLE SHAPES IN CURVED CANALS.
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11
Q

What happens if curved canals are instrumented like they are straight?

A

Ledging thus apical few mms will remain unistrumented and infected.

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12
Q

Describe the balanced force technique.

A
  • PASSIVE 60 CW rotation.
  • CCW rotation with APICAL PRESSURE 120.
  • Remove file with another 60 CW.
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13
Q

When is balanced force technique REQUIRED? Give 2 examples.

A

When preparing canals that have apical diameter over size 50 (F5).

  • Immature apex, root resorption.
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14
Q

4 advantages of rotary NiTi files.

A
  • Less canal transportation.
  • Less debris extrusion (and thus less post op pain).
  • Faster than hand preparation.
  • More predictable results.
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15
Q

What is torque?

A
  • Forces that act in a ROTATIONAL MANNER.
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16
Q

What is a risk with higher torque?

A

File gets stuck within the canal and therefore separates.

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17
Q

How are torque values set?

A

Less than the value of torque at deformation and at separation of the rotary instruments

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18
Q

What is a downside of attempting to retrieve a broken file?

A

Excessive tooth structure removal can cause REDUCED ROOT STRENGTH or PERFORATION.

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19
Q

What are the 2 types of fracture that

A
  • Sheer/ torsional fracture.
  • Flexural fracture/ cyclical fatigue.
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20
Q

What is sheer fracture/ torsional fracture.

A
  • Fail by torsion when ULTIMATE SHEAR STRENGTH IS EXCEEDED.
  • Tip or other part of instrument bINDS TO CANAL WALL white handpiece keeps rotating.
  • POOR OPERATOR TECHNIQUE.
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21
Q

What is cyclical fatigue/ flexural fracture?

A
  • Caused by CONTINUOUS ROTATION IN CURVED CANALS.
  • Tension and compression at maximum flexure causes MICROCRACKS which propagate until FAILURE.
  • CANNOT BE INFLUENCED BY CLINICIAN.
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22
Q

Can we remove a file that broke in the apical third?

A

No, removal is not practical without risk of damage.

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23
Q

When would we consider removal of a file?

A
  • In middle/ coronal third. + straight line access possible.
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24
Q

Do we attempt removal of an instrument that can be bypassed?

A

No.

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25
Q

What is the first thing you do when a file has broken?

A
  • Find location using radiographs and tactile sensation.
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26
Q

What must we do if a file has broken (5)?

A
  • Establish location. (beyond curve = much more difficult to retrieve).
  • When did it fracture?, periradicular radiolucency?
  • Attemot to bypass.
  • Consider 3 factors above - are more invasive procedures needed.
  • INFORM PATIENT THAT THERE IS A FRAGMENT AND PROPOSE MANAGMENT (unless instrument is easily and successfully removed same appointment).
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27
Q

What must we do if a file has broken (patient)?

A

INFORM PATIENT THAT THERE IS A FRAGMENT AND PROPOSE MANAGMENT (unless instrument is easily and successfully removed same appointment).

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28
Q

Which of NiTi files were the first to have a variable taper?

A

ProTaper UNIVERSAL (2006).

29
Q

Variable taper?

A
  • Taper of file changes along its length.
  • progressive/ regressive taper.
30
Q

2 Advantages of variable taper.

A
  • File preferentially cuts a certain part of the canal.
  • Much less likely to have the file stick in the canal (shear fracture).
31
Q

2 reasons why we take a pretreatment radiograph for endo.

A
  • Measure tooth length (estimate WL).
  • Look at the anatomy of the canals.
32
Q

Complete sequence of treatment (9 steps)

A
  1. Pre treatment radiographs (EWL + tooth anatomy).
  2. Access cavity
  3. Rubber dam
  4. Locate canal
  5. Coronal flare with SX
  6. Initial negotiation, measure WL, confirm canal patency
  7. Create glide path
  8. Shape canal
  9. Apical preparation with F1- F5 as determined by apical gauging.
33
Q

Another word for tooth length

A

ESTIMATED working length

34
Q

What is used to locate the canal orifice (after access is complete)?

A

DG16 endodontic probe.

35
Q

What is used to induce coronal flare?

A
  • Coronal flare using SX FILE.
  • Place 2-3mm coronal and use brushing technique to remove palatal shoulder.
36
Q

Why is coronal flare useful?

A

Helps achieve straight line access.

37
Q

What file is used for initial negotiation?

A

Size 10 flexofile.

38
Q

What file is used to measure WL?

A

Size 10 flexofile.

39
Q

What file is used to confirm apical patency?

A

Size 10 flexofile.

40
Q

When is paste lubricant used? Named example.

A
  • Used with stainless steel files.
  • Glyde.
41
Q

2 components of Glyde

A
  • EDTA (chelates calcium).
  • Carbamide peroxide (emulsifies pulp remnants).
42
Q

What happens when Glyde and NaOCl are combined?

A

Bubbling action, no evidence this contributes to better cleansing.

43
Q

Where should the preparation end?

A
  • At the junction between the pulpal and periapical tissues.
44
Q

Where should the WL be as close as possible to?

A
  • CDJ/ apical constriction.
45
Q

Apical constriction?

A

Narrowest part of the canal.

46
Q

How does an electronic apex locator work?

A

Measures the difference in electrical impedance (resistance to acurrent in ohms) between the lip and the file in the mouth.

47
Q

2 disadvantages of using radiograph for WL?

A
  • Cannot determine position of AC.
  • True apex is sometimes not at the same place as radiographic apex.
48
Q

What is apical patency?

A

The ability to pass a size 10 flexofile through the apical constriction without widening it.

49
Q

What are 2 advantages/ functions of a glide path?

A
  • Gives information about canal morphology.
  • Creates a smooth, reproducible path of adequate diameter before rotary files.
50
Q

What is the glide path?

A

A pre-exisitng space once occupied by the pulp.

51
Q

2 types of glide path?

A
  • Micro: hand files (size 8 and 10 flexofiles files).
  • Macro: Enhanced micro using rotary instruments (proglider).
52
Q

What is proglider made of? Taper? Characteristics (2)?

A
  • M wire NiTi.
  • Progressive taper.
  • Flexible and resistant to cyclic fatigue.
52
Q

2 reasons why we must work in wet canals.

A
  • Prevent dentine dust buildup (blocks canal).
  • Prevent file breakage.
53
Q

What must be done between each rotary file?

A

Irrigate, recapitulate (size 10 flexofile), irrigate.

54
Q

Apical gauging?

A

Want tip of the file to be the same size/ a slightly larger than the apical constriction.

55
Q

Why do we perform apical preparation?

A

This is carried out todetermine the diameterof the canal at the ACand to finish the canalpreparation to this size

56
Q

How do you know apical preparation is complete?

A

When the flexofile that matches the file you have finished to (ex. Flexofile 20 for F1) FITS SNUG and HAS DEBRIS ON APICAL FLUTES.

57
Q

What can be used to assess how difficult an RCT will be/

A

BES assessment tool.

58
Q

What is the method for root treating CHALLENGING ANATOMY?

A

CROWN DOWN SEQUENCE.

59
Q

Describe the crown down sequence

A
  1. Access cavity + flare.
  2. SHAPE coronal 2/3rds.
  3. Determine WORKING LENGTH.
  4. Shape apical 1/3rd.
  5. Finish apical 1/3rd.
60
Q

What is the final irrigation?

A
  • 3mL NaOCl (with ultrasonic activation).
  • 3mL citric acid (with ultrasonic activation).
  • 3mL NaOCl.
61
Q

What do you do after final irrigation?

A
  • Dry with sterile paper points
  • Dress with non-setting calcium hydroxide.
  • Septotape
  • Coltosol
  • GI
62
Q

What is odontopaste based on and what does it contain?

A
  • Zinc oxide bases
  • corticosteroid (triamcinolone) + antibiotic (clindamycin).
63
Q

Functions of odontopaste (3)

A
  • anti-inflammatory causing rapid pain relief
  • inhibits clastic cells (osteoclasts, cementoclasts, dentinoclasts) - manage root resorption.
  • antimicrobial (limited).
64
Q

2 cases where odontopaste can be used.

A
  • Management of symptomatic irreversible pulpitis
  • pulpotomy agent in the emergency management of the above
65
Q

How long should odontopaste be used to resolve inflammation?

A

4-6 weeks.

66
Q

What must be avoided when using odontopaste?

A

Try to prevent paste contacting access cavity walls as this canlead to discolouration of the tooth

67
Q
A

Module 5 - Endodontics (11 decks)

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