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2TRN Endodontics > Root Canal Instrumentation > Flashcards

Root Canal Instrumentation Flashcards

1
Q

one anatomical consideration when thinking of instrumentation

A

root canal naturally tapers apically

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2
Q

time for disease resolution (eg. apical periodontitis) after RCT

A

months to yrs

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3
Q

what 2 things need be mentioned to pt

A
  1. success rate of procedure

2. in case it fails… what happens

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4
Q

gold standard for chemical preparation of the canal

A

2% Hypochlorite (bleach)

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5
Q

precautions when using Hypochlorite

A
  1. keep within rubber dam pocket - stains clothes
  2. burns tissue is ingested (hence rubber dam)
  3. dissolves pulp - this property is what also makes it so suitable
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6
Q

why avoid overpreparing

A

not enough structure remaining - RCT will break

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7
Q

first 3 aims of preparation

A
  1. complete yet conservative access to pulp chamber
  2. straight-line access to root canals
  3. creation of continuous taper corono-apically
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8
Q

next 3 aims of preparation

A
  1. maintaining original canal anatomy
  2. minimal enlargement of apical constriction
  3. disinfection of root canal system using Irrigants and Instruments
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9
Q

Bystrom 1981

A
  1. saline irrigant - not sufficient, 50% only bacteria free at visit 5
  2. cannot use instrument disinfection alone
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10
Q

why cannot use instrumentation alone for disinfection

A

files contact only 60% of walls of canal

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11
Q

what must one always use in combination with instrument disinfection

A

1.antimicrobial irrigant (and medicament if necessary)

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12
Q

what can be said then about the role of instrumentation?

A

provides the MECHANICAL ACCESS for disinfection

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13
Q

two metals used in endo files

A 
Stainless steel
Nickel titanium (1988)
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14
Q

types of stainless steel files

A
  1. Barbed broaches
  2. Hedstrom files
  3. K files
  4. Reamers (hand or engine driven)
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15
Q

disadvantage of stainless steel files + one advantage

A

very stiff, not flexible enough through root canal at greater thicknesses.
+greater cutting efficiency than Nickel Titanium files

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16
Q

taper used on stainless steel files

A

0.2 (2%). anything higher will make it too rigid

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17
Q

ideal taper for a file

A

6 - 8% mimicking biological taper

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18
Q

advantage of Nickel titanium

A

more flexible - can make use of 6-7% taper efficiently

19
Q

what sort of standardization are K files subjected to

A

ISO standardization

20
Q

what does ISO standardization comprise

A
  1. color coded APICAL size
  2. length
  3. taper
  4. length of cutting shaft
21
Q

3 commonly used lengths of K files

A

21
25
31 mm

22
Q

3 common APICAL sizes

A 
#10
#15
#20
23
Q

brand of K file used in DDUH

A

Maillefer Flexofile (Dentsply)

24
Q

two hand filing techniques

A
  1. watch-winding: reciprocal for negotiation

2. Balanced-Force Technique

25
Q

who + when introduced balanced force technique?

A

Roane

1985

26
Q

second category of instrumentation?

A

rotary (NiTi) files

27
Q

disadvantage of rotary NiTi files

A
  1. don’t cut as well

2. more difficult to see when damaged

28
Q

advantage of NiTi rotary files

A

greater taper possible

29
Q

“Crown Down Preparation”

A

removal of bacteria starting coronally and moving down apically (as opposed to starting at the apex and moving out)

30
Q

why not ‘true’ Crown Down preparation?

A

as we step back from the apex

31
Q

4 advantages of crown down prep

A
  1. rapid irrigant penetration
  2. prevents instruments from binding coronally
  3. consistent LENGTH CONTROL
  4. straight line access to apex
32
Q

what technique we use for crown down prepping

A

‘Modified double-flare technique’ with Balanced force

33
Q

3 preparation errors

A
  1. zipping of apex (transportation)
  2. ledge formation
  3. stripping
34
Q

stripping /strip perforations

A

caused by excessive flaring of canal w rotary instruments; mostly inaccessible; treated w MTA

35
Q

zipping

A

transportation of apical portion of canal.

causes: existing curved canal that has been straightened

36
Q

ledge formation

A
  1. inadequate straight line access
  2. inadequate irrigation/lubrication
  3. using straight instruments in curved canal.
  4. packing debris in apical portion of canal.
  5. rapid advancement in file sizes
  6. skipping file sizes
37
Q

how to avoid these (x5)

A
  1. use NiTi files
  2. Balanced force technique
  3. smaller files in curved canals
  4. irrigate profusely
  5. ensuring patency (condition of being open or unobstructed)
38
Q

list 3 endo burs

A
  1. Trans-metal bur [aka beaver bur]
  2. Endo-Z bur (blunt end)
  3. long shank bur [aka Goose neck bur]
39
Q

advantage of long shank bur on plastic teeth

A

less damage

40
Q

how to detect canal that bifurcates close to apex

A

need of microscope

41
Q

principle of Bleeding technique for determining working length

A

necrotised pulp does not bleed. bone will. introduce file until meet resistance (aka bone) take out and check for bleeding

42
Q

first 4 steps in RCT

A
  1. tooth assessment
  2. LA
  3. rubber dam
  4. access opening
43
Q

next 3 steps in RCT

A
  1. Explore anatomy & locate/negotiate canals
  2. achieve straight line access to canals
  3. chemo-mechanical debridement
44
Q

last 3 steps in RCT

A
  1. +/- interim dressing
  2. obturation
  3. permanent restoration

2TRN Endodontics (2 decks)

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