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Shaping canals safely, effectively and economically
by Barry Musikant
I'’ve read so much about the beautiful results one can get by
incorporating rotary NiTi into one’s practice that
I thought I would demonstrate another way to produce excellent
results that have the added advantages of virtually
eliminating instrument separation, gives the dentist the
ability to widen canals to a minimum of 35, allows for
multiple uses of the instruments and reduces the costs of
endodontic shaping by about 90% compared to rotary NiTi.
We use relieved reamers (SafeSiders) to make both the initial
glide path as well as the entire preparation thru
a minimum of 35 and an overlayed taper of 25/06. In wider
canals we, of course, will make wider preparations to
assure adequate cleansing and irrigation of the canals.
The advantages of relieved reamers versus K-files are as follows:
1. The relieved reamers have fewer and more vertically oriented
flutes. The fewer number of flutes produce less engagement
along length that translates into less resistance when
negotiating the canals. The more vertical orientation makes
them more efficient at shaving dentin away from the canal
walls when used with the typical watch winding motion than
the more horizontally oriented flutes of the K-file that
tend to embed into the dentin rather than shaving it away.
With K-files the dentin is removed only when the pull stroke
is incorporated. Used in curved canals this pull stroke tends
to remove dentin from the outer wall causing distortions that
are best avoided.
2. The relieved reamers are also more flexible and record the
curvature of canals better than the non-relieved stiffer K-files.
3. Greater flexibility, less engagement along length and more
efficient cutting blades produce a superior tactile perception
compared to K-files giving the dentist the ability to discern
when he is in a tight canal and when he is hitting a wall.
The ability to make this distinction tells the dentist when
he must remove the instrument from the canal, prebend it and
negotiate around the blockage.
4. These instruments may be used manually or in a 30º reciprocating
handpiece at 3000-4000 cycles/minute.The reciprocating action
simulates the same watch winding motion that is used manually
and does not lead to separation while appreciably accelerating
the shaping process.
5. These instruments work so effectively that they replace the
subsequent work that has been done with rotary NiTi after the
glide path has been created. The entire shaping procedure is
done with first regular non-relieved reamers and then after 10,
with the relieved reamers doing away with the more vulnerable
use of NiTi made even more vulnerable when they are used in a
Below are several examples of the type of shaping we achieve with
the relieved reamers used both manually and in the reciprocating
These cases demonstrate there is more than one way to shape
complex anatomy. That fact that the technique we employ
virtually eliminates instrument separation while preparating
canals to a greater width producing superior cleanliness
and more effective irrigation can only be considered pluses.
That they produce these results at a cost approximately
90% less than that of rotary NiTi is something else that
logically should be pondered. Regards, Barry