An apparatus for dental tissue treatment, the apparatus comprising: a laser source for generating a laser beam at a wavelength in the range from 5 μm up to 15 μm that is absorbed by hydroxyapatite in dental tissue; a system for directing the laser beam to an area of dental tissue to be treated; a fluid-delivery system (8, 9, 20) comprising: a nozzle comprising a plurality of orifices that are oriented and configured to direct a flow of a cooling fluid in a direction toward the area to be treated and to form a coolant film on the area to be treated, while minimising pooling of the cooling fluid and intersection of the flow of cooling fluid with the laser beam prior to impingement thereof on the dental tissue to be treated; and a fluid controller to direct a flow (7, 12) of the cooling fluid to at least a portion of the area to be treated and to limit the amount of fluid delivered to the area to be treated, characterized in that the fluid controller is configured so as to minimise pooling of the cooling fluid and prevent interference with the laser beam to avoid a reduction in laser energy absorption by the dental tissue resulting in a hard tissue removal rate of less than fifteen percent of a peak hard tissue removal rate. a laser source for generating a laser beam at a wavelength in the range from 5 μm up to 15 μm that is absorbed by hydroxyapatite in dental tissue; a system for directing the laser beam to an area of dental tissue to be treated; a fluid-delivery system (8, 9, 20) comprising: a nozzle comprising a plurality of orifices that are oriented and configured to direct a flow of a cooling fluid in a direction toward the area to be treated and to form a coolant film on the area to be treated, while minimising pooling of the cooling fluid and intersection of the flow of cooling fluid with the laser beam prior to impingement thereof on the dental tissue to be treated; and a fluid controller to direct a flow (7, 12) of the cooling fluid to at least a portion of the area to be treated and to limit the amount of fluid delivered to the area to be treated, characterized in that the fluid controller is configured so as to minimise pooling of the cooling fluid and prevent interference with the laser beam to avoid a reduction in laser energy absorption by the dental tissue resulting in a hard tissue removal rate of less than fifteen percent of a peak hard tissue removal rate. a nozzle comprising a plurality of orifices that are oriented and configured to direct a flow of a cooling fluid in a direction toward the area to be treated and to form a coolant film on the area to be treated, while minimising pooling of the cooling fluid and intersection of the flow of cooling fluid with the laser beam prior to impingement thereof on the dental tissue to be treated; and a fluid controller to direct a flow (7, 12) of the cooling fluid to at least a portion of the area to be treated and to limit the amount of fluid delivered to the area to be treated, characterized in that the fluid controller is configured so as to minimise pooling of the cooling fluid and prevent interference with the laser beam to avoid a reduction in laser energy absorption by the dental tissue resulting in a hard tissue removal rate of less than fifteen percent of a peak hard tissue removal rate.