A pneumatically operated, simplified valve actuating device for dental equipment, the valve being capable of avoiding an undesirable dripping of dental instruments at the end of the work. The device includes a valve actuating element identified in a four-way valve, whose body includes a housing for a piston connected to a bobbin, wherein said casing is on one side connected to a selector unit and on the other side to a one-way retention valve, capable of receiving pressurized air from a reducer unit and passing it from said selector unit to a constantly pressurized air line coming directly from said reducer unit and to at least one dental instrument.