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BDS3 - Endodontics > Instrumentation of the Root Canal System > Flashcards

Instrumentation of the Root Canal System Flashcards

1
Q

what is the purpose of instrumentation

A
  • Remove infected soft and hard tissue
  • Give disinfecting irrigants access to apical canal space
  • Create space for the delivery of medicaments and subsequent obturation
  • Retain the integrity of radicular structures
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2
Q

what is the purpose of instrumentation

A
  • Remove infected soft and hard tissue
  • Give disinfecting irrigants access to apical canal space
  • Create space for the delivery of medicaments and subsequent obturation
  • Retain the integrity of radicular structures
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3
Q

what is the purpose of keeping the apical opening as small as possible

A

○ Over enlarging it allows for extrusion of materials into the apical tissues

○ If hypochlorite gets into the tissues it can have serious consequences for your patient

○ Also affects the long term prognosis of the tooth as it makes it harder to obturate it as it is more difficult to obtain an apical seal to maintain a sealer within the tooth

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4
Q

what are the design objectives of a root canal space

A
  • Create a continuously tapering funnel shape
  • Maintain apical foramen in original position
  • Keep apical opening as small as possible
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5
Q

what is the purpose of keeping the apical opening as small as possible

A

○ Over enlarging it allows for extrusion of materials into the apical tissues

○ If hypochlorite gets into the tissues it can have serious consequences for your patient

○ Also affects the long term prognosis of the tooth as it makes it harder to obturate it as it is more difficult to obtain an apical seal to maintain a sealer within the tooth

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6
Q

what is the purpose of chemomechanical preparation

A

• Chemo
○ Irrigate to kill micro-organisms
○ Remove smear layer

• Mechanical
○ Prepare shape
○ Flush out debris and micro-organisms

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7
Q

what is the aim of mechanical preparation

A
  • Shape the canal
  • Allows delivery of sodium hypochlorite to working length
  • Creates shape to obturate
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8
Q

name some challenges to root canal preparation

A

• The root canal system is very complex

○ Difficult to get sodium hypochlorite to penetrate all the smaller / lateral / accessory canals

  • The number, length, curvature and diameter of canals can vary considerably
  • Teeth are weird
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9
Q

what size of apical diameter to you want and why

A

an apical diameter of ISO 25 (0.25mm) or ISO 30 (0.3mm) in order to deliver the syringe and the irrigant it contains into the apical portion of the tooth, to try and get some penetration into the little lateral canals

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10
Q

define estimated working length

and how is it got

A

Estimated length at which instrumentation should be limited

Obtained by measuring pre-operative radiograph to determine distance between coronal reference point and radiographic apex then subtracting 1mm

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11
Q

define corrected working length

and how is it got

A

Length at which instrumentation and subsequent obturation should be limited

Obtained by the use of an electronic apex locator and / or working length radiograph
Confirmation of the estimated working length

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12
Q

what is the master apical file

A

The largest diameter file taken to working length and therefore represents the final prepared size of the apical portion of the canal at the working length

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13
Q

what are the different types of motion

A
  • Filing
  • Reaming (warning)
  • Watch-winding
  • Balance forced motion
  • Envelope of motion
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14
Q

explain what is meant by watching winding motion and when are they used

A
  • Back and forward oscillation of 30-60 degrees
  • Light apical pressure
  • Effective with K files

Useful for passing small files through canals

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15
Q

explain the balanced force technique

A
  • insert file and engage clockwise into the dentine, 1/4 turn (90 degrees)
  • with continued pressure, go counter clockwise 1/2 (180 degrees) turn to strip the dentine away
  • do this 1 to 3 times before removing the file to remove debris and check the file
  • then reintroduce the file to the canal and repeat until working length
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16
Q

explain the envelop of motion

A

honestly no clue lol sorry fix this if yous know the answer but my notes is legit just a picture of a file with arrows that i dont understand but feel free to look that up hehe

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17
Q

what is the barbed broach instrument
when is it used
what are the negatives to it
how is it used

A
  • Used for extirpating, not enlarging - can be useful for lifting bits of debris or cotton wool from a canal
  • Formed from a tapered round shaft by lifting up portions of metal of the shaft almost at a right angle to the shaft
  • Must not engage the canal walls
  • Extremely fragile instrument, and will break easily if misused
  • Not used very often
  • Elevated barbs engage the pulp tissue and remove it from the canal
  • The largest size broach that will fit freely in the canal is selected
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18
Q

after shaping is complete, what is the irrigation protocol

A

• EDTA 17% for 1 minute
○ To remove the smear layer

• Sodium hypochlorite 3%, 30ml for 10minutes
Slow injection, don’t use thumb

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19
Q

what is the barbed broach instrument
when is it used
what are the negatives to it
how is it used

A

• Used for extirpating, not enlarging - can be useful for lifting bits of debris or cotton wool from a canal

• Formed from a tapered round shaft by lifting up portions of metal of the shaft almost at a right angle to the shaft
• Must not engage the canal walls
• Extremely fragile instrument, and will break easily if misused
• Not used very often
• Elevated barbs engage the pulp tissue and remove it from the canal
The largest size broach that will fit freely in the canal is selected

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20
Q

what are the ISO colour codes

A 
06 - pink
08 - grey
10 - puple
15 - white
20 - yellow
25 - red
30 - blue
35 - green
40 - black
45 - white
50 - yellow
55 - red
60 - blue
70 - green
80 - black
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21
Q

ISO 35 file has a tip size of what

A

0.35 mm

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22
Q

what are stainless steel instruments
when are they used
explain the diameters

A

• ISO-sized instruments

○ All have 16mm cutting flutes

○ Each file is named according to its diameter at the first rake angle [tip] - D1

○ Taper is 0.32 over the 16mm / 0.02 per millimetre

○ Diameter at D2 = apical size + 0.32mm

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23
Q

what is the cross section of K-reamers

A

triangular

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24
Q

what is the cross section of K files

A

square

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25
Q

what is the cross section of H files

A

kind of comma shape

26
Q

what are Hedstrom files

A

H files

  • Machined steel blank
  • Used in a filing motion, cuts on withdrawal
  • Good cutting efficiency but can cause iatrogenic damage
  • No longer used for canal preparation
  • Useful for removing gutta-percha or fractured instruments in cases of retreatment
27
Q

what are reamer files

A

K-Reamers

  • Manufactured by twisting a tapered triangular shaft
  • Cutting edges nearly parallel to long axis
  • Rotate 1/4 to 1/2 turn clockwise to cut as advanced to length
  • Must be in contact with the walls of the canal in order to be effective, must not bind or it may break
  • More aggressive than K files
28
Q

what are K files

A
  • Manufactured by twisting or grinding a square tapered shaft
  • Cutting edges almost perpendicular to the long axis of the instrument

• Can be used in a filing motion - advanced to the full working length rotated 1/4 to 1/2 turn clockwise, and withdrawn while applying lateral pressure
○ Repeated circumferentially until canal enlarged
○ Most useful with balanced force motion

• Do not use larger instrument too quickly
This will cause ledges or the instrument to bind within the canal and separate

29
Q

what are the 2 main properties of Nickel Titanium which are very useful for endodontic instruments

A
  • super elasticity

- high resistance to fatigue

30
Q

name the features of endodontic instrument

[sorry unsure what instrument this even is but it is a diagram in my notes so better include it xox]

A
  • positive rake angle
    provides the acting cutting acting of the K3
  • third radial land
    stabilises and keeps instruments centred in the canal and minimises over engagement
  • wide radial land
    provides blade support while adding peripheral strength to resist torsional and rotary stresses
  • radial land relief
    reduces friction on the canal wall
31
Q

name the different components of endodontic rotary instrument and their function

A

• Taper
○ Diameter change along working surface

• Flute
○ Groove to collect dentine and soft tissue

• Leading / cutting edge
○ Forms and deflects dentine chips

• Land
○ Surface extending between flutes

• Relief
○ Reduction in surface of land

• Helix angle
Angle cutting axis forms with long axis of file

32
Q

name the features of endodontic instrument

[sorry unsure what instrument this even is but it is a diagram in my notes so better include it xox]

A
  • positive rake angle
    provides the acting cutting acting of the K3
  • third radial land stabilises and keeps instruments centred in the canal and minimises over engagement
33
Q

what are the advantages of NiTi Vs Stainless steel

A
  • Increased flexibility in larger sizes and tapers= can have greater tapers
  • Increased cutting efficiency
  • If used appropriately good safety in use
  • Can be more user friendly with less instruments and simple sequences
34
Q

what are disadvantages of NiTi preparation

A

• Instrument fracture
○ Misuse of operator
○ Over-forcing it into the canal
○ Instrumenting the canal with a larger instrument too early

  • Expense
  • Access can be difficult in posterior teeth
  • Unsuitable for complex canal anatomy
35
Q

when are the ProTaper Hand Files S1, S2 and Sx used

A

S1 (purple) = coronally third [tip = 17]
S2 (white) = middle third [tip = 20]
these 2 are almost always used

Sx (orange) = can be used to open up the orifice when it is difficult to get straight line access [tip = 19]

{i’m not 100% sure those are the tips, thats the numbers beside the files in the diagram so i’m assuming that what it means but if i am wrong let me know xx)

36
Q

what does the “S” in the protaper hand files stand for

A

shaping

37
Q

what does the “F” in F files in the pro taper hand files represent

A

finishing files

38
Q

explain the F files of the protaper hand files

A

follow ISO codes
all have a varying degree of taper
eg F2 has the same tip size as ISO 25

39
Q

what is the downside of the protaper hand files

A

Downside of using these is if you have a particularly large root canal, {for example; an immature central incisor in a young patient} and you find that the F5 (tip size of 0.5mm) does not engage the dentine then perhaps you need to revert to a modified double flare technique and use a 60 / 70 / 80 ISO file to clear that root canal

Ie very big canals and these files may not be of a lot of use

40
Q

what is the ProTaper Sequence

A
  • `ISO 10 (k file I think)
    [to 3/4 EWL - double check diagram for all these just in case I have messed up haha can’t hack the pressure]
  • ISO 15
  • S1
    [little shorter than ISO 10]
  • (Sx)
    [little shorter again if used]
  • ISO 10
  • ISO 15
  • S1
  • S2
  • F1
    [to WL]

optional

  • F2
  • F3
  • F4
  • F5
41
Q

what are the different colours of F files

A 
F1 = yellow [ISO 20]
F2 = red [ISO 25]
F3 = blue [ISO 30]
F4 = black [ISO 40]
F5 = yellow [ISO 50]
42
Q

what is the ProTaper Sequence

A
  • `ISO 10 (k file I think)
  • ISO 15
    [to 3/4 EWL]
  • S1
  • ## (Sx)
43
Q

explain true reciprocation

A

• Mimics manual movement

• Reduces risks associated with continuously rotating a file through canal curvatures
○ Continuously cutting 360 degrees will cause the file to cut its own path within the tooth and can create a ledge

  • Decreased cutting efficiency
  • Requires increased inward pressure
  • Limited capacity to auger debris out of a canal
44
Q

what are the guidelines for rotary instrumentation

A
  • Straight line access
  • Cross-sectional diameter
  • Root canal system anatomy
  • Speed and sequencing
  • Lubrication and a “light touch”
45
Q

how do you create a glide path

A
  • Confirm straight line access
  • Explore anatomy
  • Always introduce files 10-25 to resistance only (coronal only)
  • Coronal flare
  • Size 10 with watch winding establish apex
  • Irrigate and repeat using size 15 (WW) and 20 (BF)
46
Q

what is reciproc

A

Kind of like a balanced force, but controlled by the computer

angles of reciprocation:
150 degrees counterclockwise
30 degrees clockwise

47
Q

rotary reciprocation

A

lots of slides explaining this step by step but do we need to know it all???

48
Q

how can instrument separation occur

A
  • torsional stress

- flexural stress

49
Q

how can cyclic fatigue occur

A

• Freely rotating in a curvature
• Generation of tension / compression cycles
• Cyclic fatigue
- Failure

50
Q

how can flexural stress occur

A

○ Repeated cyclic metal fatigue

Cannot be influenced by clinician

51
Q

what is torsional fatigue

A

Elastic phase up to around 400 rotation and after that it is the elastic limit

After that you are then into the plastic phase where the instrument starts to deform

52
Q

what is included in the aseptic technique

A

dental dam

use of hypochlorite

53
Q

what is watch winding technique

A

back and forward (clockwise/anticlockwise) oscillation of 30 - 60 degrees, used with small diameter files

54
Q

what is the modified double flare technique

A

The process involves development of an initial coronal flare, followed by an apical flare.
These distinct regions of preparation, upon intersection create a continuous taper. Preparation involves the use of Gate Glidden drills and stainless steel K-files.

55
Q

what is recapitulation

A

Using a small hand file to ensure patency and dislodge debris into solution prior to introducing a larger file into the root canal system.
Essential to prevent blockages or iatrogenic damage to canals

56
Q

what is the balanced force technique

A

60 degree clockwise rotation, maintaining apical pressure rotate anticlockwise at least 60 but not more than 120 degrees, repeating the cycle 3 times.

57
Q

what is reciprocation

A

a file working motion consisting of a counterclockwise (cutting direction) and a clockwise motion (release of the instrument) whereby the angle of the counter-clockwise direction is greater than the angle of the reverse direction

58
Q

what is filing

A

A dynamic movement of a hand file to optimally effect canal debridement; predominantly a push- pull (rasping), rotational (reaming) movement or a combination of the two.
Engine-driven filing motions can be rotary, reciprocating or oscillating

59
Q

what is patency filing

A

Passing a small hand file thorugh the apical constriction and apical foramen to contact the apical tissues

60
Q

what is the apical foramen

A

the main apical opening of the root canal

61
Q

what is the apical constriction

A

the apical portion of the root canal having the narrowest diameter
position may vary but is usually 0.5-1mm short of the center of the apical foramen

BDS3 - Endodontics (10 decks)

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