MTI integrated mirrors are part of the overall MEMS device/actuator, which is about 40um thick. The pivot point is somewhere in the middle of that thickness, about 20um below the reflecting surface.
Bonded mirrors with no pedestal are mounted on top of the actuator tip/tilt stage, raising the reflective surface of the device. The pivot point of bonded mirror with a 300um pedestal usually lies about 360um below its reflecting surface.