Working lenght

Working length is measured always before preparation. Correct working length is a key to problemfree preparation. Working length measurement is based on the following methods:
1) measuring from the preoperative radiograph before any preparation
2) using apex locator
3) taking a working length radiograph.
A correct way of determining the working length is usually a combination of methods 1 and 3 or 1 and 2, or all three together. Working length of each canal and the reference points chosen must be written down in the patient journal. Schematic drawings may also be used to mark the reference points.