Page 30
Operation 12. 21. ’04
Problem
Check Points
Responses
Canal length
indicator is
unstable.
Refer to manual for
Canal
Measurement
Module.
Is contrary electrode making
good contact with oral mucosa?
Is the file holder dirty?
Make sure the contrary electrode makes
good contact with the oral mucosa.
Clean the file holder with ethanol.
Canal length
indicator bar does
not move.
(except when very
near the apical
foramen)
Is root canal blocked?
Is root canal extremely dry?
Impossible to make a
measurement.
A small file in a large root canal.
Canal length indicator will return to
normal when the file reaches apical
constriction.
Moisten the inside of the root canal with
hydrogen peroxide or saline solution.
Determine the working length by taking
an x-ray. Put a rubber stopper on the
file and use the unit in manual mode.
Increase the size of the file.
Canal length
indicator
overreacts or is too
sensitive.
・
Measurements
are too short.
・
Poor accuracy.
・
Erratic results.
Is blood or saliva overflowing
from the opening at the crown?
Is the root canal filled with
blood or chemical solutions?
Is the tooth surface covered
with cutting debris or chemical
solutions?
Is the file touching the gingival
tissue?
Is there pulp tissue left inside
the root canal?
Is the file touching a metal
prosthesis?
Are proximal surfaces infected
with caries?
Are there lateral canals or is
the tooth fractured.
Does a broken crown allow the
leakage of electric current?
Is there a lesion at the apex?
Is the file holder broken or dirty?
Blood, saliva or chemical solutions that
overflow and leak onto the crown or neck
can cause an electrical shortage. Clean
away all overflowing fluids.
The canal length indicator bar may
suddenly swing when it breaks the
surface of fluids inside the root canal,
but it will return to normal as it
approaches the apex.
Clean entire tooth surface.
This will cause the canal length
indicator bar to suddenly jump all the
way to “APEX”.
An accurate measurement cannot be
obtained if a large amount of pulp tissue
is left inside the root canal.
Touching a metal prosthesis with the file
allow the current to flow to the gingival
tissue or periodontal pocket and will
cause the meter to jump to “APEX”.
Caries on proximal surfaces can allow
the current to flow to the gingival tissue
and make it impossible to measure the
length of a root canal.
The canal length indicator bar may jump
to apex when it reaches the opening of a
lateral root canal or the opening of a
fractured tooth which allows the current
to flow to the gingival tissue.
Build up an insulating barrier to stop
the leakage.
A lesion can destroy the apical foramen
through absorption and an accurate
measurement cannot be obtained.
Replace or clean the file holder.