34. Tip Design.
Instrument tips have
been described as
1. cutting
2. noncutting
3. partially cutting
The instrument tip has
two functions:
1. to enlarge the canal
2. and to guide the file
through the canal
35. A clinician who is unfamiliar with the tip design
of a particular instrument is apt to do either
of the following:
(1) transport the canal (if the tip is capable of
enlarging the canal and remains too long in
one position)
Or
(2) encounter excessive torsion and break
the file (if a noncutting tip is forced into a
canal with a smaller diameter than the tip).
36. A good beginner’s rule is this:
1. If the canal is smaller than the file, a cutting
tip is more efficient.
2. If the canal is larger than the file, using a
less effective cutting tip can help prevent
transportation
37.
38.
39.
40.
41.
42.
43.
44. Hand Instruments for Canal
identification
The endodontic
explorer: has two
straight, very sharp
ends that are angled in
two different directions
from the long axis of the
instrument
45. endodontic spoons:
These spoons have a
much longer offset from
the long axis of the
instrument (for better
reach inside constricted
pulp chambers) than
regular dental spoons.
The spoons are used to
remove carious material
and to excise pulp
tissue
46.
47.
48.
49.
50.
51.
52. The number of sides
and the number of
spirals determine
whether the
instrument is best
suite for filing or
reaming.
A file has more flutes
per length unit than a
reamer.
53. Besides their configuration,
the difference between files
and reamers is their
intended use.
Files are manipulated with
a rasping, or push-pull
planing motion.
Reamers are twisted and
withdrawn; therefore,
cutting takes place during
rotation.
54. The use of reamers has declined in
popularity because of
1. their lack of flexibility (especially in larger
sizes),
2. their inability to prepare canals with
anything other than a round crosssection,
3. and their lack of cutting efficiency when
compared with other instruments.
55. K-Type Instruments
made from a steel wire
that is ground to a
tapered square or
triangular cross section
the wire then was
rotated to form the
spiral instrument
56. Permanent deformation occurs
when the flutes become wound
more tightly or opened more
widely
failure occurs in the
counterclockwise direction more
often the clockwise direction.
Therefore K-type instruments
should be operated more carefully
when pressure is applied in a
counterclockwise direction.
