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Endodontics > Canal preparation 1 > Flashcards

Canal preparation 1 Flashcards

1
Q

List two phases of canal preparation

A
  1. Debridement

2. Shaping

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2
Q

Debridement

A

Removal of all tissue and bacteria from root canal system

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3
Q

Shaping

A

Create shape to facilitate obturation

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4
Q

Describe warnings of debridement

A
  • MUST confine instruments within root canal
  • Avoid pushing debris out root apex
  • Create shape within canal for chemical irrigant
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5
Q

Describe warnings of shaping canal

A
  • Maintain special relationship of root canal within dentine
  • Establish a “seat/stop” at apical termination
  • Create tapering funnel
  • Eliminate all surface irregularities along root canal walls
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6
Q

Endodontic failure is usually due to?

A

Colonizing of the filled canal system after treatment.

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7
Q

Primary goal of endodontic treatment?

A

Optimize root canal debridement and disinfection

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8
Q

Most favourable prognosis of end of canal instrumentation

A

Terminate at apical constriction

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9
Q

Least favourable prognosis of end of canal instrumentation

A

Working beyond apical constriction

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10
Q

List end of canal instrumentation aim and reference point

A
  • End instrumentation at transition point between pulp and periodontal tissue (cemento-dentinal junction)
  • Reference point: 0.5 - 1.5 mm inside apical foramen
  • Aim to create smallest wound surface
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11
Q

In general, file is _____ to apex than it appears in the radiograph

A

Closer

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12
Q

When file is placed _____ in radiograph, it is actually ______ to apical foramen than it appears.

A

Short; closer

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13
Q

When file is placed __________ in radiograph, it is actually _______ past apical foramen than it appears.

A

Long; further

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14
Q

List landmarks of end of canal instrumentation

A
  • Apical constriction
  • Apical foramen
  • Radiograph vertex
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15
Q

List recommended apical termination points

A
  • 1.0 mm from radiographic vertex where no bone resorption occurs
  • 1.5 mm from radiographic vertex where only bone resorption occurs
  • 2.0 mm from radiographic vertex where bone and root resorption occurs
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16
Q

List goals of preparation

A
  • Create continuously tapering funnel
  • Minimize canal transportation
  • Apical termination point of canal preparation should be kept as small as possible.
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17
Q

Minimizing canal transportation

A

Position of apical foramen and apical constriction should remain unchanged.

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18
Q

File

A

Tapered and pointed metal instrument with cutting edges used to enlarge the root canal by filing action

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19
Q

K-file

A
  • File with square cross-section
  • USed in all zones, but mostly in apical zone
  • Use “Watch-winding” technique and “push-pull” action
20
Q

H-file

A
  • File with circular cross-section
  • Used in coronal and middle zone only
  • Use “pulling” action only
21
Q

Flexofile

A
  • File with triangular cross-section
  • Flexible
  • None-aggressive tip
22
Q

Taper

A

The increase in file diameter with every 1 mm from the tip.

23
Q

0.02 Taper means?

A

The filer gets 0.02 mm wider with every 1 mm from the tip

24
Q

Circumferential (perimetre) filing

A

Repeat filing motion along entire inner perimeter of canal

25
Q

Gates-Gliddens burs used when? Fracture rate?

A

Used only in Coronal zone.

- Easy to fracture in canal

26
Q

Speed of Gates-Gliddens burs?

A

Use at low speed

27
Q

Action of Gates-Gliddens burs?

A
  • Passively insert into canal
  • Withdraw from canal with light “paint-stroke” action along a wall
  • Keep GG bur spinning until fully removed
28
Q

Only use No. 2 GG bur when?

A

Only use No. 2 GG bur after #40 H-file has been used. Then sequentially use No. 3 GG bur and No. 4 GG bur (only in large canals)

29
Q

List benefits of crown-down instrumentation

A
  • Most important benefit -> provides a glide path
  • Facilitates irrigant exchange
  • Provides coronal escape-way for filing debris
  • Reduces piston-pump effect
  • Reduces apical extrusion of debris
  • Improves instrument and irrigant access to apical canal
  • Reduces potential for vapour lock
30
Q

Lsit the steps of modified crown-down technique

A
  1. Access cavity preparation
  2. Determine working length (allows checking of canal patency and prep. configuration)
  3. Coronal one-third preparation
  4. Middle one-third preparation
  5. Apical one-third preparation
31
Q

Describe file size choice

A
  • 3 sizes bigger than the first file that binds

- Variation depends highly on curvature of root

32
Q

List the preparation zones (only applies when Working length WL < 19 mm)

A
  • Coronal one-third = WL - 8 mm
  • Middle one-third = WL - 4 mm
  • Apical one-third = WL
33
Q

Phases of canal preparation: describe access cavity

A
  • Access cavity should mirror the coronal pulp chamber
  • Follows the long axis of tooth, not just crown long-axis
  • Law of concentricity = Walls of pulp chamber are concentric to the external outline of tooth at level of CEJ
34
Q

Define “Law of concentricity”

A

Walls of pulp chamber are concentric to the external outline of tooth at level of CEJ

35
Q

Instrumentation for access cavity

A
  • Pre-curve instrument: Match curvature of radiographic image
  • ALWAYS have irrigant in the canal during instrumentation (need fluid for lubrication)
36
Q

Define “Stem winding action”

A

CW/CCW twisting of file no more than 30 deg with positive apical pressure

  • Pre-curved files can be rotated less or none
  • Pre-curved files have increased risk of transporting canal
37
Q

Phase of canal preparation: tactile negotiation

A
  • Use Stem-winding action
  • Stem-winding insertion to working length
  • Do NOT screw instrument into canal
  • Only use with K-Files
38
Q

How to establish working legnth?

A

Use radiograph with file in canal

39
Q

Describe circumferential filling

A
  • Stem winding insertion to working length
  • Cutting stroke on withdrawal of file
  • No rotation of file in circumferential filing
40
Q

After each incremental size increase in file, the ___________- is re-introduced for what?

A

Recapitulation file (i.e. original file used to measure working length) is re-introduced to working length to ensure canal remains patent and check for wall irregularities.

41
Q

Recapitulation purposes?

A
  • checks canal configuration
  • Reduces vapour lock
  • Facilitates irrigant transfer to apical zone of canal
  • Prevents compaction of debris at bottom of canal
42
Q

Apical patency

A

Technique where apical portion of canal is maintained free of debris by recapitulation with a small file through the apical foramen

43
Q

Never re-use a _____ file and why?

A

Never reuse a loaded file therefore tooth debris file flutes.

  • Clean file with gauze
  • check the length of file
44
Q

Equipment for canal preparation in coronal one-third?

A

Gates glidden burs or Hedstroem Files

45
Q

Equipment for canal preparation in middle one-third?

A

Use Hedstroem Files and K Files

46
Q

Equipment for canal preparation in apical one-third?

A

Use K-files only

Endodontics (9 decks)

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