Methods for controlling and/or regulating of a compressed-gas-operable medical or dental drive device and a control and/or regulating device for performing such methods are described. In one method according to a first embodiment, a rotor of the drive device is operated at an essentially constant rotational speed (n.sub.1) by adjusting the gas pressure and/or the flow rate of the compressed gas through a valve and the rotational speed is reduced on reaching a pressure value (p.sub.2) of the compressed gas which is lower than the maximum gas pressure (p.sub.max) of the compressed gas. In the case of a method according to a second embodiment, the gas pressure of the compressed gas and the rotational speed of the rotor are altered on reaching a rotational speed limit value (n.sub.2, n.sub.3) of the rotor by adjusting the valve.

The invention relates to a device for the controlled supply of compressed air to at least one pneumatically operated dental instrument (5, 5, 5, 5) from a supply and control unit (2), in which a dental instrument (5, 5, 5, 5) is connected by a supply hose (4, 4, 4, 4) for supplying compressed air with a valve mechanism (6) provided in the supply and control unit (2), the valve mechanism (6) having a plurality of pneumatic sliding valve units (9, 9, 9, 9). The pneumatic sliding valve units (9, 9, 9, 9) of the valve mechanism (6) are accommodated in at least one valve body (10) and the valve body (10) has a plurality of control connections (12, 12, 12, 12), whereby each pneumatic sliding valve unit (9, 9, 9, 9) corresponds to a control input (12, 12, 12, 12) and pressurization of a control input (12, 12, 12, 12) with switching compressed air opens the corresponding sliding valve unit (9) and locks the additional, closed sliding valve units (9, 9, 9).

Embodiments of the invention include a handpiece system including a detachable cable that can receive at least power, and a detachable cable connector, where the detachable cable connector and detachable cable are reversibly attachable to each other. In some embodiments, the system includes an interchangeable laser module, where the laser module and detachable cable connector are reversibly attachable to each other. Further, the interchangeable laser module is configured and arranged to receive at least the power via the cable connector when coupled to the cable connector, and to be removed from the detachable cable connector and replaced with another laser module. In some embodiments, the system further includes an interchangeable handpiece which is reversibly attachable to the interchangeable laser module. Further, the interchangeable handpiece is configured and arranged to be removed from the interchangeable laser module and replaced with another interchangeable handpiece.