A new cordless engine-driven root canal preparation system has been developed that electronically monitors the location of the file tip and the torque applied to the file during all instrumentation procedures, The Root ZX is mounted inside the handpiece to measure the canal length, The engine is driven with a rechargeable battery, and it works more than 40 minutes without a recharge. Nickel-titanium files are used for this preparation system, The file is rotated at 240 to 280 rpms, When the file tip reaches the apical constriction, the revolution of the file can be automatically reversed (Auto-apical-reverse mechanism). If there is too much torque, the rotation is automatically reversed (Auto-torque-reverse mechanism). These automatic functions promise a safer engine preparation of the canal with nickel-titanium files.