Ledge reduction on the 90-degree curvature wall with the T-mode of a new Ai motor.

Martensitic phased NiTi file is used to bypass a ledge and place the rotating file back into the original pathway over the ledge with the T-mode of a new Ai motor shifting from the 90-degree watch-winding motion (SGP) at 100 RPM to the ATR rotation at 300 RPM once it is placed into the original canal. Then the next size file is sequentially used the same way until the ledge is significantly reduced.