Abstract: A dental treatment apparatus having a plurality of dental instruments releasably retained in an instrument-holding device. A control and display arrangement controls the operation of an instrument upon extraction from the holding device, and displays the magnitude of an operating parameter of the instrument on a display device. A control data store is arranged to store pre-determined fixed control data values for the operating parameters of the instruments. To enable the user to alter the predetermined fixed values, a forward-backward counter is connected to the data store which can also store the altered values. A data converter is connected to the counter and to the display device for converting the instantaneous value stored in the data store to a corresponding service datum instantaneous value to be displayed by the display device.