L2- Cleaning and Shaping Flashcards by Olivia Bellantoni

what are the shaping principles

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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what is the 9 step prep

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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what is the motion in scouting

watch winding- move right and left rocking motion

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

30 degrees

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the canal is patent when:

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

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what helps find the canal exit clinically

apex locator

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when do you measure patency in lab

before you mount

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patency is maintained by:

recapitulation

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if it is a tight resistance to apical advancement:

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

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if it is loose resistance to apical advancement:

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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what is the reference point for working length on anteriors

incisal edge

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what is the reference point for working length for posteriors

cusp for which canal is named, flatten cusp when possible

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what file number do you take to patency

10 only

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

the 2 file technique

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what is the 2 file technique

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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what is the purpose of creating a smooth glide path

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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what is the glide path created using

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

sloppy loose

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

youll have blockage and ledging

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how many times should you revist patency during cleaning and shaping

2-3

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describe the small wave one gold reciprocal file

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

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describe the primary wave one gold reciprocal file

0.25mm at tip
0.07 overall taper
MFD = 0.9mmd

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describe the large wave one gold reciprocal file

0.45mm at tip
0.05 overall taper
MFD = 0.8mm

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wave one gold files are used only with:

the dentsply motor on the wave one setting

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what is the operator action for a wave one reciprocal file

a light pecking motion

what is a downside of the wave one gold reciprocal files

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

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

the diameter of the canal you are treating

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

small

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

primary - 85%

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

large

wave one gold files come in what lengths

21,25, and 31mm

the crown is usually about how long

10mm

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

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

how do you perfect straight line access to mid root

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

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

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

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

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

what is the MAF for small roots

#30-#35

what is the MAF for medium roots

#40-#45

what is the MAF for large roots

#45-#50

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

smaller

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

larger; larger

what are examples of teeth with small MAFs

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

what are examples of teeth with medium MAFs

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

what are examples of teeth with large MAFs

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

what is used for final shaping

vortex blue files sizes 0.30/0.04 through 0.50/0.04

describe final shaping with the vortex blue files

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

final shaping is complete when:

dentinal filings are on apical 1/3 of instrument

when is serial step back used

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

how are ledges and blockages created

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

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

- increase in stiffness - decrease in flexibility

what is a zip

when transportation of apex occurs within the root

what is an apical strip perforation

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

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

#15; transportation

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

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

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

- 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

the curved file is to be oriented correctly to:

coincide or slightly exceed the curvature of the canal

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

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

when does strip perforation occur

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

where is strip perforation common

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

how do you fix strip perforation

gutta percha and PC sealer

how can transportation occur with wave one gold file

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

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

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