Determination of Working Length of Root Canal.

BACKGROUND: This study was undertaken to determine the working length of root canal by microprocessor controlled impedance quotient apex locator and conventional radiographic method.
METHODS: Patients whose teeth were to be extracted were selected for this study. A total of 100 teeth in the same or different patients were identified. Biomechanical preparation of the canal was done for smooth negotiation of the entire canal. The electrode of the Root ZX™ was attached to the selected file and the length adjusted till the beep of the Root ZX™ indicated the apical foramen. The electrode was removed but the file was stabilized with the help of soft gutta percha. An intraoral periapical (IOPA) radiograph was taken using basic guidelines. The tooth was then extracted under local anaesthesia along with the file in the tooth. A window was cut on one surface of the root apex approximately 4mm from the apex to expose the root canal. The file tip was identified. The distance of the file tip from the apex was measured under 3X magnification and the reading recorded. Similarly the distance from the file tip to the radiographic apex was measured on the radiograph under magnification and the reading recorded. All the readings were tabulated. The actual distances measured between the extracted tooth, the electronic apex locator and on the radiograph were compared using a paired 't' test to determine the accuracy of each method in relation to the minor diameter. RESULT: It was observed that the radiographic method had a significant variation from the electronic method when compared to the actual measurement on the extracted tooth.
CONCLUSION: The electronic method is a more accurate method as compared to radiographic method for determination of working length of the root canal.