7. CROWN-DOWN/STEP-DOWN
TECHNIQUE
• Corono-apical
• Originally advocated for hand-file (NiTi files)
• A #10 file is placed in the canal to establish patency
To assess morphology (curvature).
• WL can be established at this time
• coronal third of the canal
with progressively smaller GG drills
greater taper instruments
NiTi orifice shapers
8.
9.
10. • Avoid carrying all the GG drills to same level which may result in
excessive cutting of dentin
weakening of roots
and “coke-bottle appearance” in the radiographs
• The amount of dentin removed in the coronal third
makes Gates-Glidden drills an
unsuitable instrument for modern endodontics.
• Nos. 3 and 2 (diameters 0.7 and .9 mm, respectively)
• Gates-Glidden drills should not be
placed apical to canal curvatures
11. • A large file (such as No. 60) is then placed in the canal, and a watch-
winding motion is used
• until resistance is encountered
• The process is repeated with sequentially smaller files until the apical portion
of the canal
• Irrigation and recapitulation after every instrumentation
• WL and the IAF (the first file that binds at WL) can be determined
• apical portion of the canal can now be prepared by enlarging the
canal to the MAF at the WL.
• Apical taper is accomplished using a step-back technique.
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19.
20. COMPONENTS OF AN
ENDODONTIC FILE
Taper:
Taper denotes the per millimeter increase in file diameter from the tip
toward the file handle. The taper is denoted either in
• numerical or in percentile.
• #.02 taper or 2% taper.
• a size #20 ISO file will have a tip diameter of 0.20 mm and would have a 0.22
mm diameter 1 mm from the tip and 0.24 mm diameter 2 mm from the tip
Flute:
Blade (cutting edge):
Pitch:
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25. • Greater tapered instruments have been developed
with 4, 6, 8, and even 10% taper.
• Tapered instruments help in preparing canals of wider diameter without over
enlarging the canal at working length.
• Thus, a 30 size file with 2% taper, 30 size file with 4% taper, and 30 size file with
6% taper all would have the same tip diameter of 0.30 mm.
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33.
34. NITI ROTARY INSTRUMENTS
One instrument sequence uses NiTi files in a crown down approach,
• with a constant taper/ variable ISO tip sizes:
a 0.06 taper is selected. Initially a size .06/45 file
is used until resistance, followed by the .06/40, .06/35, .06/30,
.06/25, and .06/20.
• In a second technique, NiTi files with a constant tip diameter are used also in
a crown down sequence.
• The initial file is a .10/20 instrument, the second a .08/20, the third a .06/20,
and the fourth a .04/20
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39. ULTRASONIC SYSTEMS
• Ultrasonic systems involve a power source to which an endodontic file (K file)
is attached with a holder and an adapter.
• Before a size 15 can be freely used with ultrasonics, canal must be enlarged
with hand instruments to a size Nos. 30–40 file
• Irrigants are emitted from cords on the power source and travel down the
file into the canal to be energized by the vibrations.
40. • Advantages of Ultrasonics
• ‰
. Clean canals free of smear layer and debris
• ‰
. Enhanced action of NaOCl because of increased temperature and
ultrasonic energy.
