The invention relates to a medical device (1), in particular a dental device, for determining the quality of a bone by cutting a thread into the bone using a rotating threaded element (3). The medical device (1), in particular the dental device, has a controller (2) with a measuring circuit (6), and the measuring circuit (6) is designed: (i) to determine values of the motor current supplied to the motor drive (5) in order to rotate the threaded element (3) that can be connected to the motor drive (5) via the first electric contact device (2A), wherein the motor current values are a measurement of the bone quality, (ii) to monitor and/or to ascertain the penetration depth of the threaded element (3) into the bone, and (iii) to generate measurement signals which relate the determined motor current values or parameters derived therefrom to the penetration depth and transmit said measurement signals to a display unit (4) which reproduces the relationship between the determined motor current values or the parameters derived therefrom, in particular the quality of a bone, and the penetration depth.
