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Figure 7-2.—Typical endodontic instrument tray setup.
usually tapered and pointed, with spiral cutting edges.
Since the cutting edges of reamers are farther apart
then those found on files, reamers are more flexible
than files. This same distance between the cutting
edges causes reamers to cut slower than files. Reamers
can also be used to remove old, softened gutta-percha
filling, or as a paste carrier to place cement near the
apex.
Reamers are available in many sizes beginning
with size 10 and continuing in intervals of 5 to size 60.
Beginning with size 60, they are also available in
intervals of 10 through size 140. The dentist may use
several reamers in one operation, usually beginning
with a relatively small size, then the next larger size
each time the canal has been reamed to the desired
diameter.
Files
Root canal files normally are used after the
broaches and reamers. The root canal files look much
like those of the reamers. However, the file threads or
cutting edges are much finer and closer together. Files
come in two different types (H and K types) and are
different in terms of physical properties, such as
flexibility, resistance to fracture in rotation, and
method of manufacture. The designation of "K-type"
7-7
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