Abstract: An information and control system for use in a dental environment has a dental unit with a number of selectable dental instruments and a control member for controlling their operation, a patient's rest and working positions for a dentist and a dental nurse. A computer is provided for storing treatment protocols listing selectable dental treatments, and for each treatment sequential steps to be performed in the treatment. Treatment and actions are displayed, and protocol control means are provided for inputting commands to the computer means for selection of treatments and actions listed in said protocols.

Abstract: In the process, water, in which organic carbon, ammonium and nitrate are contained, is biologically purified. In a first reaction vessel (10) forming a denitrifying biofilm reactor the carbon is to a large extent eliminated under partly anoxic, partly aerobic conditions by the use of nitrate-containing oxygen, and molecular oxygen respectively. In a second, ventilated reaction vessel (20) the ammonium is converted at least partially by nitric bacteria into nitrates. Water containing nitrates is recirculated from the second into the first reaction vessel. In the first reaction vessel the water to be treated is conveyed from the top to the bottom via a flooded fixed bed. To supplement a deficiency in nitrate-containing oxygen in the elimination of carbon the fixed bed is ventilated in the base region with a gas which contains a metered amount of molecular oxygen. The process according to the invention is particularly suitable for the purification of waste water having a variable ammonium concentration.

Abstract: In a dental apparatus, in which each of a number of instruments is controlled by a control circuit common to the instruments, which are connected with a common operator unit having a control member which is movable in planar directions out of a home position, auxiliary functions not related to the instrument operation may be carried out by means of the common operator unit by switching the apparatus to a second mode of operation, when all the instruments assume respective resting positions in an instrument carrier. Moreover, also auxiliary functions directly related to the instrument operation may be carried out by the common operator unit in a first mode of operation by actuating the control member thereof with a movement different from the instrument energizing movement. The movement for energizing such an auxiliary function may have another direction and/or a shorter duration than the instrument energizing movement.

Abstract: In a dental apparatus, in which each of a number of instruments is controlled by a control circuit common to the instruments, which are connected with a common operator unit having a control member which is movable in planar directions out of a home position, auxiliary functions not related to the instrument operation may be carried out by means of the common operator unit by switching the apparatus to a second mode of operation, when all the instruments assume respective resting positions in an instrument carrier. Moreover, also auxiliary functions directly related to the instrument operation may be carried out by the common operator unit in a first mode of operation by actuating the control member thereof with a movement different from the instrument energizing movement. The movement for energizing such an auxiliary function may have another direction and/or a shorter duration than the instrument energizing movement.