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Re-treatment of a root filled with gutta-percha
The gutta-percha must be completely removed to eliminate its insulating
effect. After removing the gutta-percha, pass a small file all the way through
the apical foramen and then put a little saline in the canal, but do not let it
overflow the canal opening.
Crown or metal prosthesis touching gingival tissue
Accurate measurement cannot be obtained if the file touches a metal
prosthesis that is touching gingival tissue. In this case, widen the opening at
the top of the crown so that the file will not touch the metal prosthesis
before taking a measurement.
Cutting debris on tooth
Pulp inside canal
Thoroughly remove all cutting debris on the tooth.
Thoroughly remove all the pulp inside the canal. Otherwise an accurate
measurement cannot be obtained.
Caries touching the gums
In this case, electrical leakage through the caries infected area to the gums
will make it impossible to obtain an accurate measurement.
Blocked canal
The meter will not move if the canal is blocked.
Open the canal all the way to the apical constriction to measure it.
Extremely dry canal
If the canal is extremely dry, the meter may not move until it is quite close to
the apex. In this case, try moistening the canal with oxydol or saline.
