Cleaning & Shaping Flashcards
SHAPING: PRINCIPLES
1. A constantly — funnel from crown to WL
2. Curves of canal respected w/o “—”
3. Retention of the “—”
4. Enlargement of the canal system to create —
5. Adequate “—” for proper obturation
tapering
transportation
apical constriction
clean white filings (adequate cleaning)
deep space
Evaluate the degree & location of
curvature: How can we TELL ?
- Radiographs will generally show mesial and
distal curves. - Facial and lingual curves will NOT
generally be seen:
- Facial and lingual curves will NOT
generally be seen:
(3)
– Try angled radiographs (SLOB)
– Look for “bulls eye” radiograph (root tip
turns to F or L)
– If your initial #10 SS scouting file bends
(it follows the anatomy of the canal)
“Bulls eye” configuration may reveal
apex curving severely to Facial or L.
Creating Ledges and Blockages
* When we place a straight SS hand file in a curved canal:
- Physics dictates it must track the OUTSIDE (convex) wall of the canal at some point. What does this do?
- Tends to gouge and lean against the outside wall of the canal creating the a Ledge, which can be the first step to Blockage or Transportation
- If we keep Pushing & Grinding on the file, we can eventually force it through the root to create a Perforation
As our shaping proceeded to
the larger sizes of SS hand
files above #15 :
(2)
- Increase in Stiffness*
- Decrease in Flexibility
ransportation of apex occurs within
the root. The result is called a
Zip
If the Zip occurs the through apex to
the exterior of the root
We have
an apical strip perforation
—, etc. is one of
the MAIN REASONS that we
selected the current technique
in which hand files used are
generally no larger than #–
Transportation
15
The Curved File is to be oriented
correctly to
coincide or slightly exceed
the curvature of the canal , introduced
in a gentle watch-winding motion and
then flexed in a rasping pull motion
with circumferential filing after the
path is negotiated.
If done carefully, many canals may be
safely enlarged to a reasonable —
MAF
Loose Resistance to Apical Advancement
* You are encountering a ledge or a possibly
abrupt bend or curve:
- Do Not Force File: Instead STOP Irrigate, and
Bend the Tip - The most apical flutes of the file must be
bent & 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 & BYPASS the obstruction/
ledge to join the TRUE canal.
skipped
Transportation can still OCCUR
* If there is a severe curve in the canal –
especially
if the curve occurs in the apical 1/3 and a very
smooth glide path was not perfected and the
operator tries to PUSH or Force the Wave One Gold
file to WL
F you develop
RESISTANCE when
approaching a curve such
as this,
STOP AND CALL
AN INSTRUCTOR
Transportation can still OCCUR
* By allowing the Vortex Blue finishing files to rotate
at or slightly short of WL for more than 1 moment
- KEEP THE VORTEX BLUE FILE MOVING using a smooth
in-out motion in the canal while flexing it on the
out stroke to smooth and further flare the walls.
- Strip –Perforation
* Occurs when files used are
- Commonly the (3)
either too large or too
aggressively used for a small or thin walled canal.
distal of the mesial root of lower molars,
MF of upper molars ,
2 canal max. PM .
Strip-perforation
Overzealous use of shaping instrument or selection of
an instrument which is too large. Failure to move
canal AWAY FROM danger area (toM&B or M&L)
The 9 STEP PREP
(following proper access)
- Scouting (#10 hand file)
- Patency (#10 hand file)
- Working Length (#15 hand file) TIGHT file
- Glide Path (#15 hand file) LOOSE file ONLY HAND FILES to this point
- Shaping of coronal 1/3 of canal (Wave One Gold)
- Shaping of middle 1/3 of canal (Wave One Gold)
- Perfecting Straight-Line-Access to mid-root (.25/.12 carefully)
- Shaping of apical 1/3 of canal (Wave One Gold)
- Final Shaping Objective Vortex Blue or
Serial Step Back (SSB) using HAND FILES if MAF >#50
watch winding
arched arrow indicates a gentle right and left rocking motion, which causes the instrument to cut while a light inward pressure (straight arrow) keeps the file engaged and progressing toward the apex
arc of rotation is indicated by the shaded region in the circle
30 degrees each way
- Obtain Patency
* The canal is “PATENT” when
a #10 file goes slightly
beyond the canal exit (.5 mm.) = Long = into the
Periodontal Ligament. The Apex Locator will help us locate
the canal exit clinically.
The canal is “PATENT” when a #10 file goes slightly
beyond the canal exit (.5 mm.) = Long = into the
Periodontal Ligament. The Apex Locator will help us locate
the canal exit clinically.
* In lab, measure — you mount
BEFORE
his tiny passageway can clog easily as
soon as we start C&S, resulting in blockage
= loss of patency. We want to
keep a small
hole out the end of the root (#10 file is ideal
– no larger)
Patency is maintained by
“Recapitulation” (irrigating and revisiting
patency after Wave One with the patency
file #10 only)
HOWEVER: NOT ALWAYS EASY TO IMMEDIATELY GO TO PATENCY*
If it is TIGHT RESISTANCE to apical advancement,
you probably have a
small canal which must be enlarged carefully to reach patency.
f 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.
ALL Shaping is done @
WL = 1 mm. short of the
Canal Exit
Working length confirmed
radiographically
Accurate WL is CRITICAL to RCT success
Reference point:
Anteriors:
Posteriors:
Incisal edge
Cusp for which canal is named, flatten cusp when possible
Create a smooth “Glide Path”
(only after the WL is confirmed) #15 SS file
* Purposes:
(3)
– To smooth curves & 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.
The Glide Path is created using
hand files (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 enlarge the canal to a
size #15 at the WL. (#15 File should end up SLOPPY LOOSE)
Always take each working file to
WL. Never file SHORT of WL (prevent
Blockage & Ledging)
– Irrigate following
each active instrument (revisit patency 2-3 times
during cleaning and shaping)
How do you TELL if canals converge or are simply 2
canals in close proximity? . . . The “2 File Technique”
- Establish working length of
“each canal” separately. - Attempt to place 2 files to WL
in ea. Canal @ same time
– If both go to WL = 2 canals
– If one goes & the other is
short – reverse the placement
sequence. If still one is short =
converging Class II canals
(see next slide)
Once the WL is confirmed and the Glide Path
(#15) is smooth and unobstructed,
You are ready to
select the first machine
driven file to begin canal shaping
You will choose the size of Wave One file to be used based on the diameter
of the canal you are treating:
(3)
- If a 10 K-file was very resistant to movement, use Wave One Gold Small file.
- If a 10 K-file moves to length easily, is loose or very loose, use Wave One Gold Primary file. (85%)
- If a 20 hand file or larger goes to length, use WaveOne Gold Large file.
Wave One files come
in lengths of
21, 25.
and 31 mm. Select the
appropriate length for
your tooth.
The Crown usually is about — of total tooth length. The root
is mentally divided into
10mm
thirds (each is 3mm. If total tooth length
is 19mm and each is 5mm. If total tooth length is 25mm)
Think of the canal as
comprised of – distinct
sections to consider in
shaping with the Wave
One File.
3
We will be shaping the canal
1/3 at a time:
-coronal (13-15mm)
-middle (16-20mm)
-apical (19-25mm)
- Shaping of coronal 1/3 of canal:
- Shaping of middle 1/3 of canal:
- Perfecting Straight-Line-Access to mid-root:
(Wave One Gold)
(Wave One Gold)
(.25/.12 carefully)
Small:
— mm. @ tip
— overall taper
Maximum Flute Diameter — mm.
.20 mm. @ tip
.07 overall taper
Maximum Flute Diameter .8 mm.
Primary:
.25 mm. at tip
.07 overall taper
MFD = .8 mm.
Large:
.45 mm. at tip
.05 overall taper
MFD = .8 mm.
Wave One Gold files are used only with the Dentsply motor on
the Wave One setting. The operator action is a light “—-”
motion
pecking
It is important to note that one must be vigilant as the
Wave One action tends to 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.
- Perfecting STA (Straight-Line Access) to
mid-root (Following 2nd 1/3 (Wave One shaping)
Place a .25/.12 Vortex Orifice opener in the Pro-Mark
motor and adjust the action to Vortex and leave the
speed at 500 rpm. MFD is 1.20mm
- Allow the 25/.12 to mill to the depth of —
ONLY .
Any lateral motion should be — FROM the
furcal area (ex. In max/mand. MB canal pull toward
the mesial & buccal only). - RECAPULATE: IRRIGATE
mid root
AWAY
Shaping the apical 1/3 of Canal
- Set the Wave One Gold file at the confirmed
WL (Working Length) and reset the Pro-Mark
motor to reciprocal action and guide it to
advance to the WL. - Confirm patency & smooth glide path with
#15 hand file & then irrigate and continue to
WL with Wave One. - IRRIGATE
Small Roots about #— MAF
Medium Roots about #— MAF
Large Roots are #— MAF or
more
30-35
40-45
45-50
Teeth with moderate to severe
curvature require — MAF to
avoid transportation of canal.
smaller
Younger teeth will have larger
canals & require — MAF to clean
larger
Small =
(4)
Mand. Incisors,
2 canal Premolars,
M. canals of Mand. molars,
B. canals of Max. Molars
Medium =
(2)
Palatal canals of Max. Molars,
Single Distal canals of Mand. Molars
Large =
(3)
Max. Anteriors,
M/M Cuspids,
Single canal M/M Premolars
Final Shaping Objective : HOW BIG?
■ We will be using Vortex Blue Files for the final shaping and
smoothing of the canal. Sizes
.30/.04 through .50/04
available.
Each Vortex Blue file should be KEPT MOVING and go completely
to WL on each of
10 strokes. They should be flexed while
rotating & being drawn out to increase the flare of the canal
in an appropriate direction - away from furca or toward the
greater dimension of the canal. Shaping is complete when
dentinal filings are on apical 1/3 of the instrument
■ IRRIGATE after each active file
serial step back
method of producing greater taper at the apical control zone
this technique is to be used when the canal requires a large diameter than the .45/.04 vortex blue file
rather than stocking a number of expensive rotary files for the less common large canals, one can accomplish an excellent increased apical taper by using SS hand files
