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endo II > lecture 4: cleaning and shaping with curved canals > Flashcards

lecture 4: cleaning and shaping with curved canals Flashcards

1
Q

are there any straight lines in human anatomy

A

no, all canals are curved. that is why you should curve your SS files before placement in a canal.

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2
Q

new shaping and electric torque control motors should

A

eliminate ledging and canal transportation

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3
Q

hand files are still necessary to appreciate and develop

A
  • scouting the canal to patency and establishing WL
  • negotiating severe curves, blockages and ledging
  • creating a smooth #15 glide path
  • SSB in larger canals
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4
Q

when should you refer

A

basically if greater than 30 degrees

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5
Q

radiographs will show which types of curves

A

M and D curves

F and L curves will NOT generally be seen

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6
Q

what should you do to XR to try to see F and L curves

A
  • SLOB
  • look for “bulls eye”
  • see if your #10 SS scouting file bends
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7
Q

NA and some other Asians have a higher chance of having what

A

D-L md 1M (3rd root)

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8
Q

as our shaping proceeded to the larger sizesof ss hand files above #15

A

we have increase in stiffness and decrease of flexibility

which means that it can straighten out the canal and result in

ledges and blockages
canal transportation

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9
Q

what is a zip

A

the result of transportation of apex occurs within the root

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10
Q

what is one of the main reason we do not have hand lives larger than #15

A

because of transportation

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11
Q

what is a elbow

A

the smaller part of the funnel created by the apical failure to follow the curved canal

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12
Q

can a zip occurs through the apex to the exterior of the root, what is this called

A

apical strip perforation

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13
Q

with the ss hand files increasing in diameter and stiffness it resists what

A

resists adaptation to the natural curve of the canal

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14
Q

if you develop resistance when approaching a curve what should you do

A

stop and call an instructor.

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15
Q

can transportation still occur with vortex blue files

A

yes.. by leaving it rotating for more than a moment, YOU NEED TO KEEP THE VORTEX MOVING while flexing it on the out stroke to further flare the walls.

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16
Q

can transportation still occure with wave one gold file

A

yes.. if the operator tries to push or force the wave one gold file to WL because a very smooth glide path was not perfected.

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17
Q

why did we change to modern Ni-Ti files, new technique and expensive motors

A

because of ledging and transportation

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18
Q

Ni-Ti are straight but-

A
  • EXTREMELY FLEXIBLE but will transport if inattentive and pushed
  • SUPER-ELASTIC AND EXPENSIVE will only follow a smooth glide path
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19
Q

to avoid blockage

A

irrigate

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20
Q

to avoid ledging

A

curve and insert files correctly and irrigate

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21
Q

to avoid file separation

A

single use files inspect and don’t skip sizes or force

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22
Q

once a ledge or blockage is created it is…

A

very difficult and time consuming to regain the canal

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23
Q

if a ledge is created or if we encounter loose resistance to apical advancement, we modify the curvation to include what

A

the very terminal flute of the SMALL FILE to about 45 degree curve to bypass the curve toward the inner wall or to scout for the direction of the curve

24
Q

a simple ledge which is ignored will soon create what

A

sufficient debris in the canal to create a blockage

25
Q

most common causes of blockages:

A
  • failure of recapitulate
  • failure to gain and maintain patency
  • failure to recognize loss of length ledge/blockage/curve
26
Q

what is dentin mud

A

it can rapidly become harder than dentin especially in vital cases

27
Q

when do we use strip - perforation

A

when files used are either too large or too aggressively used for a small or thin walled canal

28
Q

in maxillary molars how many canals are there

A

MB1 and MB2 95% of the time

29
Q

mandibular molars have what type of canals

A

DF and DL about 60% Type II

MF and ML 40% type II

30
Q

what type of canals do max 1PM have

A

85% have two roots

31
Q

types of canal configurations

A

I, II, III, IV

i, o, u, y

32
Q

what is the 2 file technique

A

how you tell if canals converge or are simply 2 canals in close proximity?

  • establish WL of each canal
  • attempt to place 2 files to WL in ea canal @ same time
33
Q

in the 2 file technique if both go to WL then what does that mean

A

2 canals

34
Q

in the 2 file technique if one goes and the other is short what does that mean

A

reverse the placement sequence if still one is short then it is a converging Class II canal

35
Q

the “high cervical break” what is it

A
  • using .25/.12 to create a smooth glide path in the MB canal,
  • insert it about 3 to 4mm into the canal
  • the purpose is to remove the dentin triangle and align the access to a more advantageous path to the canal
36
Q

which teeth can benefit from the high cervical break

A
  • MB canals from max molars
  • both mesial canal of md molars
  • any time that we can eliminate/minimize a cervical curve it will give better access to mid root and make apical curves easier and file separation will be less likely
37
Q

why do files break aka separate

A
  • judgment erros
  • cyclic fatigue (inside)
  • torsional stress (outside)
38
Q

what is torsional stress

A

the larger the instrument or the tighter the curve, the greater the stretching on the outer diameter of the curved instrument and the greater the compression on the inner diameter of the curve

39
Q

what is cyclic fatigue

A

greater acceleration of the curve results in increased stress from stretching and compressing resulting in increased cyclic fatigue

40
Q

if you feel that you need to push the rotary file what should you do

A

go back and smooth or carefully enlarge the glide path with a small properly curved hand file

41
Q

anytime obturation is not yet accomplished what should you do

A

place intracanal medication

42
Q

any time a temp restoration is placed, it a good idea to do what

A

medicate and seal with proper interim temporization

43
Q

what is the most popular intra-canal medication to use for between RCT visits

A

CaOH

44
Q

where should you place the interim placement

A

-2mm short of the WL (do NOT allow to BIND) and then CaOH is expressed as the syringe is retracted from the canal

  • fill the canal to cervical line
  • clear excess CaOH from chamber
  • place sterile cotton pellet in chamber to prevent clogging of the canal with temp filling material after the cotton pellet
45
Q

what do you place over the cotton

A

cavit, IRM, amalgam or composite

46
Q

what is cavit

and when is it best used

A

comes from the tuber or jar ready to place in the tooth. No mixing. Seals better than IRM (1-2 weeks) but deteriorates rapidly

best used for 1 surface access

47
Q

what is IRM

A

1-4 week duration of seal = stronger = use when 2 or more surfaces are missing

48
Q

what is composite, amalgam and temp crowns

A

when considerable tooth structure is compromised of a greater delay to next tx visit is anticipated.

49
Q

temporization following obturation

A

use “vitrebond”

50
Q

what is vitrebond

A

a resin modified glass ionomer

it is recommended to seal the obturated canal against leakage following successful RCT completion while awaiting perm restoration.

51
Q

if saliva remains in contact with GP for 72 hours what will happen

A

re tx will be required

52
Q

follow “vitrebond” with what

A

composite, amalgam, temp crown etc, as a base for crown to follow or as directed by restorative faculty

53
Q

if your tx plan calls for a post what should you do

A

place cotton over obturation

no vitrebond.

instead place substantial IRM/amalgam/composite or temp crown over cotton –> XR –> Completed RCT film without rubber dam

place rubber dam, remove IRM/amalgam/composite and cotton and proceed with post and planned restoration

54
Q

if your tx plan calls for a crown

A
  • DO NOT PLACE COTTON over obturation

- place amalgam or vitrebond and composite as a build up –> XR –> RCT without rubber damn

55
Q

restorations of RCT ant teeth that need to be done ASAP

A

minimal structural loss –> vitrebond and composite

significant structural loss –> crown or post and crown

56
Q

restorations of RCT post teeth that need to be done ASAP

A

minimal structural loss: Crown ALL POST

significant structural loss: post and crown

57
Q

2 things to remember about posts

A
  • posts do NOT strengthen tooth (they weaken it)

- posts provide ONLY RETENTION of coronal restoration

endo II (7 decks)

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