The document discusses the evolution of endodontic file designs from manual stainless steel files to rotary nickel-titanium files. It describes how early manual stainless steel files had limitations like ledge formation and inability to negotiate curved canals. The introduction of greater taper and flexible nickel-titanium files addressed these issues and allowed for faster and more predictable root canal shaping. Modern rotary file systems further improved on these designs with features like progressive tapers and unique cross sections for better debris removal and canal centering.

1. Non ISO File
Technique
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2. Use stainless steel instruments - files
files used manually
files made by twisting wires of square,
triangular or diamond cross section
These have ISO taper
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3. ISO stands for
International Standards Organization
Taper is the amount by which the
diameter of an instrument
increases from tip to handle
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4. This is the taper set by the ISO
It is set at 0.02 per mm
This is commonly referred to
as
02 taper
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5. 02 taper does not match the
taper of root canals
Root canals have tapers close to
04, 06 or even 08
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6. By using a lot of instruments (files)
in complex protocols e.g.
Crown Down, Step Back
Techniques
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7. A series of files used from coronal to
apical sequentially with recapitulation
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8. S/S instruments have to be
used in reciprocating action
i.e. rotate clockwise, then anti-clockwise
or in push - pull action
If these are rotated continually
in one direction, these fracture
Not very flexible
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9. Push - pull action leads to
ledge formation in root canals
This action also pushes debris
into the canal causing
blockages
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10. By using these files manually in
reciprocating action
i.e. Balanced Force Technique
But this is a very slow process
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11. By using Greater Taper GT files
The Greater Tapers matchhRRoot Canal tapers
tC
needing fewer files
By making them of Nickel Titanium instead
of S / S so that these are flexible and can be
rotated continually in one direction without
risk of fracture
Thus NiTi GT Rotary instruments
were born
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12. Made of Nickel Titanium alloy
NiTi wires cannot be twisted
Therefore, made by machining - makes
these files very expensive
These have a Taper > ISO Taper
Tapers of 04, 06, 08, 10 & even 12
These tapers are similar to taper of root
canals
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14. ISO Greater Taper
02 04 06
08
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15. A ProFile Rotary File kit
Note the large no. of files with different
tapers and tip diameters
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16. A ProFile
instrument
Cross-section is similar to that
of system GT with Triple U
Endo12
shape
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17. 06 taper
08 taper
10 taper
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18. Invented by Dr. Stephen
Buchanan of USA in the
1980’s
Has revolutionised
Endodontic Practice
Used in rotating action
with special hand piece
with a low speed, high
torque motor
Now several designs and
brands available
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20. NiTi exists in 2 forms with different
properties
Martensite
Low temp form, low modulus, high strain
Austenite
High temp form, high modulus, low strain
Shape memory
NiTi exhibits super elasticity
Under stress, martensite austenite
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21. Bends and returns to original shape
Martensite Austenite Martensite
Can negotiate curved root canals better
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22. A curved canal
prepared with
NiTi files
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22

23. System GT (Buchanan,Tulsa Dental)
ProTaper (Dentsply)
ProFile (Dentsply)
RaCe (Schotlander)
K3 (Sybron Kerr)
Quantec
FlexiMaster
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24. Note Triple U
cross-section of
the rotary file
collect debris
Flat radial lands
keep the file
centred on the
natural root
canal while
enlarging it
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25. RaCe files have a
triangular cross-
section
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26. File tip is dome-
shaped to prevent
ledge formation &
canallttransportation
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27. Progressively Tapered files
Differing percentage of taper along
the length of the file
Makes the file even more flexible
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28. Note convex
triangular
cross-
section
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29. Active cutting
blades
speed up
cutting of
root canal wall
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30. Blunt tip prevents
ledge formation &
perforations
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31. Six files
3 Shapers
SX S1 S2
3 Finishers
F1 F2 F3
Finishing File F3 recognisable by Blue band on handle
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32. Same basic file shapes and tapers but
designed to be used manually
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33. Unique handle allows ease of use
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34. Fewer files needed due to better taper
Faster completion of canal preparation
Flexible, enabling easy use in curved
canals
More predictable outcome
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35. Mandibular
second molar with
abrupt curvature
of the distal canal.
Note the apical
control despite
the conservative
canal enlargement
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36. Before and after
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37. Before and after
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