A medical or dental device for determining a bone's quality by cutting a thread into the bone with a rotating threaded element comprises a control unit having a measurement circuit configured: (i) to determine values of the motor current via a first electrical contact device with which the motor drive is supplied for rotational drive of the threaded element that can be connected to the motor drive, the current values being a measure of the bone's quality； (ii) to monitor and/or to determine the penetration depth of the threaded element into the bone, and (iii) to generate measurement signals which show the relationship between the penetration depth and the determined current values or parameters derived therefrom, and to transmit these signals to a display unit, which displays the relationship between the determined current values or parameters derived therefrom, in particular the bone's quality, and the penetration depth.
