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Endo II > L2- Cleaning and Shaping > Flashcards

L2- Cleaning and Shaping Flashcards

1
Q

what are the shaping principles

A
  • a constantly tapering funnel from crown to WL
  • curves of canal respected w/o “transportation”
  • retention of the apical constriction
  • enlargement of the canal system to create clean white fillings
  • adequate “deep space” for proper obturation
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2
Q

what is the 9 step prep

A
  • scouting (#10 hand file)
  • patency (#10 hand file)
  • working length (#15 hand file) TIGHT file
  • glide path (#15 hand file) Loose file
  • shaping of coronal 1/3 of canal (wave one gold)
  • shaping of middle 1/3 of canal (wave one gold)
  • perfect straight line access to mis root (.25/.12 carefully)
  • shaping of apical 1/3 of canal (wave one gold)
  • final shaping objective (vortex blue or SSB with hand files
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3
Q

what is the motion in scouting

A

watch winding- move right and left rocking motion

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4
Q

how many degrees each way does the watch winding motion move in

A

30 degrees

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5
Q

the canal is patent when:

A

a #10 file goes slightly beyond the canal exit (.5mm) = long = into the PDL

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6
Q

what helps find the canal exit clinically

A

apex locator

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7
Q

when do you measure patency in lab

A

before you mount

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8
Q

patency is maintained by:

A

recapitulation

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9
Q

if it is a tight resistance to apical advancement:

A

you probably have a small canal which must be enlarged carefully to reach patency

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10
Q

if it is loose resistance to apical advancement:

A

you have encountered a canal curvature and you must bend the terminal flute of your file and search for the path to negotiate the curve

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11
Q

what is the reference point for working length on anteriors

A

incisal edge

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12
Q

what is the reference point for working length for posteriors

A

cusp for which canal is named, flatten cusp when possible

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13
Q

what file number do you take to patency

A

10 only

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14
Q

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

A

the 2 file technique

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15
Q

what is the 2 file technique

A
  • establish working length of each canal separately
  • attempt to place 2 files to WL in each canal at same time
  • if both go to working length = 2 canals
  • if one goes and the other is short reverse the placement sequence and if it is still short then you have a converging class II canal
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16
Q

what is the purpose of creating a smooth glide path

A
  • to smooth curves and make sure there are no canal obstructions
  • to create space for rotary instruments to be used safely without excessive torque requirements
  • to relieve stress on tip of rotary file to minimize fracture
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17
Q

what is the glide path created using

A

hand files that are pre-curved to match or slightly exceed the curvature of the canal
- using watch wind entry followed by pull strokes directed in a circumferential manner to enalrge the canal to a size #15 at the WLd

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18
Q

in creating a smooth glide path the #15 file should end up:

A

sloppy loose

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19
Q

why do you not want to take a working file short of WL

A

youll have blockage and ledging

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20
Q

how many times should you revist patency during cleaning and shaping

A

2-3

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21
Q

describe the small wave one gold reciprocal file

A

.20mm at tip
0.7 overall taper
- maximum flute diameter 0.8mm

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22
Q

describe the primary wave one gold reciprocal file

A

0.25mm at tip
0.07 overall taper
MFD = 0.9mmd

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23
Q

describe the large wave one gold reciprocal file

A

0.45mm at tip
0.05 overall taper
MFD = 0.8mm

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24
Q

wave one gold files are used only with:

A

the dentsply motor on the wave one setting

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25
Q

what is the operator action for a wave one reciprocal file

A

a light pecking motion

26
Q

what is a downside of the wave one gold reciprocal files

A

they push debris ahead of the file so stop action at 1/3 and 2/3 of the operation approaching the apex to clean the file and to irrigate thoroughly at these stages of shaping

27
Q

what do you choose the size of wave one file based on

A

the diameter of the canal you are treating

28
Q

if a 10 K-file was very resistant to movement what wave one gold file would you choose

A

small

29
Q

if a 10 K-file moves easy to length, is loose or very loose what wave one gold file do you choose

A

primary - 85%

30
Q

if a 20 hand file or larger goes to length what wave one gold file do you use

A

large

31
Q

wave one gold files come in what lengths

A

21,25, and 31mm

32
Q

the crown is usually about how long

A

10mm

33
Q

what are the 1/3s of the canal divided into and about how long are each

A

coronal (13-15mm)
- middle (16-20mm)
- apical (19-25mm)

34
Q

how do you perfect straight line access to mid root

A

place a 0.25/0.12 vortex orifice opener in the pro-mark motor and adjust the action to vortex and leave the speed at 500 rpm
MFD is 1.2mm

35
Q

describe the action used with the .25/.12 straight line access to mid root

A

allow the .25/.12 to mill to the depth of mid root only. any lateral motion should be away from the furcal area

36
Q

how do you shape the apical 1/3 of the canal

A

set the wave one gold file at the confirmed WL and reset the pro-mark motor to reciprocal action and guide it to advance to the WL

37
Q

what is the MAF for small roots

A

30-#35

38
Q

what is the MAF for medium roots

A

40-#45

39
Q

what is the MAF for large roots

A

45-#50

40
Q

teeth with moderate to severe curvature require ___ MAF to avoid transportation of canal

A

smaller

41
Q

younger teeth will have _____ canals and required ____ MAF to clean

A

larger; larger

42
Q

what are examples of teeth with small MAFs

A

mandibular incisors, 2 canal premoalrs, mesial canals of madnibular molars and buccal canals of maxillary molars

43
Q

what are examples of teeth with medium MAFs

A

palatal canals of maxillary molars, single distal canals of mandibular molars

44
Q

what are examples of teeth with large MAFs

A

maxillary anteriors, M/M cuspids, single canal M/M premolars

45
Q

what is used for final shaping

A

vortex blue files sizes 0.30/0.04 through 0.50/0.04

46
Q

describe final shaping with the vortex blue files

A

it needs to keep moving and go completely to WL on each of 10 strokes
- they should be flexed while rotating and being drawn out to increase the flare of the canal n an appropriate direction away from furca or towards the greater dimension of the canal

47
Q

final shaping is complete when:

A

dentinal filings are on apical 1/3 of instrument

48
Q

when is serial step back used

A

with big canals larger than the .45/0.4 vortex blue file and need to open in the middle

49
Q

how are ledges and blockages created

A

when we place a straight SS hand file in a curved canal
- tends to gouge and lean against the outside wall of the canal creating a ledge which can be the first step to blockage or transportation

50
Q

as our shaping proceeded to the larger sizes of SS hand files above #15:

A
  • increase in stiffness
  • decrease in flexibility
51
Q

what is a zip

A

when transportation of apex occurs within the root

52
Q

what is an apical strip perforation

A

if the zip occurs through the apex to the exterior of the root

53
Q

hand files are generally no larger than ______ because mainly of ______

A

15; transportation

54
Q

what does it mean when there is loose resistance to apical advancement

A

you are encountering a ledge or a possibly abrupt bend or curve

55
Q

what do you do if you find loose resistance to apical advancement

A
  • do not force file
  • stop irrigate and bend a #10 file at the tip- approximately 2mm
  • the most apical flutes of the file must be bent and rotated to track the inside wall of the canal
  • gently enter canal rotate and advance the file a little at a time through the full 360 degrees until you fall into a tight area
  • this is the canal and the file can now often advance and bypass the obstruction/ledge to join the true canal
56
Q

the curved file is to be oriented correctly to:

A

coincide or slightly exceed the curvature of the canal

57
Q

how is the curved file used in a bend in a canal

A

in a watch winding motion and then flexed in a rasping pull motion with circumferential filing after the path is negotiated

58
Q

when does strip perforation occur

A

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

59
Q

where is strip perforation common

A

the distal of the mesial root of lower molars
- MF of upper molars
- 2 canal maxillary premolars

60
Q

how do you fix strip perforation

A

gutta percha and PC sealer

61
Q

how can transportation occur with wave one gold file

A

if there is a curve in the apical 1/3 and the glide path is not smooth and the operator tries to push or force the wave one gold file to WL

62
Q

how can transportation occur with vortex blue files and how can it be avoided

A

allowing them to rotate at or slightly short of WL for more than 1 moment
- must keep moving using a smooth in-out motion in the canal while flexing it on the out stroke to smooth and further flare the walls

Endo II (11 decks)

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