A dental machining device (1) having at least one shaft (2) which projects into a machining chamber (4) and is displaceable in both axial and radial directions includes a sealing element (7) having at least two axially spaced sealing lips (8, 9) bearing against the shaft (2) in its peripheral direction and enclosing an annular chamber (10) with the shaft (2). At least one fluid conduit (11) opens into the annular chamber (10) to supply a fluid (16) thereto. A pressure sensor (14) is provided for detecting a state variable of the fluid, which is detected and held ready for transmission to a control unit (14″).