Effect of preflaring on Root ZX apex locators

The Root ZX apex locator is an example of a generation of apex locators that identify the terminus of the canal by measuring a ratio between two electrical impedances. Studies have shown this device to have a high degree of accuracy. However, the manufacturer warns that the performance of these devices is limited by the presence of calcifications and dentinal shaving obstructions. An in vitro study was designed to determine if preflaring of canals would facilitate the passage of files to the apical foramen by eliminating cervical interferences and to see what effect this would have on the performance of the Root ZX apex locator. Thirty-two canals were divided into two groups. Group 1 was not manipulated before use of the Root ZX apex locator and served as control. In group 2, the canals were preflared before the use of the Root Zx apex locator. The working length files were secured in place and measured with the linear measurement tool used by the Visilog 5 imaging program. Results of this study suggest that preflaring of canals will allow working length files to more consistently reach the apical foramen (p = 0.015), which in turn increases the efficacy of the Root ZX apex locator.