The objective of working length determination is to establish the length (distance from the apex)
at which canal preparation and subsequent obturation are to be terminated.
Importance of accurate working length determination:
· Confine the instrumentation to the canal system (within dentin).
· Create and maintain an apical stop or seat at the minor constriction.
· Prevent under-instrumentation that could leave tissue and debris in the apical segment.
· Prevent over-instrumentation which could cause patient discomfort, damage periapical
tissue, or potentially cause an infection or cyst development from the placement of
irritating materials beyond the apex.
Methods for determining working length:
· Radiographs
· Electronic apex locators
· Tactile sense
Additional adjunctive methods:
· Paper points
· Microscopic magnification
· Average tooth length
