Nozzle unit (10, 20, 30, 40, 50, 100) comprising at least one nozzle orifice, which nozzle unit (10, 20, 30, 40, 50, 100) is designed to be used as part of an oral irrigator, for emitting a flow of irrigation fluid to be directed towards periodontal pockets in a subject's mouth, and which nozzle unit (10, 20, 30, 40, 50, 100) has at least one constructional feature configured to contribute to realizing a predetermined orientation of a flow of irrigation fluid with respect to a subject's respective teeth (2, 3) and periodontal pockets in an operational situation involving functional placement of the nozzle unit (10, 20, 30, 40, 50, 100) with the at least one nozzle orifice in the vicinity of the subject's respective teeth (2, 3) at the position of interdental interfaces, namely an orientation from the at least one nozzle orifice towards the periodontal pockets at a pocket inflow angle (α) in a range of 10° to 50° and from the at least one nozzle orifice towards the surface of the subject's respective teeth (2, 3) at a surface impact angle (β) in a range of 0° to 50°, the pocket inflow angle (α) being defined in a first plane extending parallel to a central vertical axis of the subject's respective teeth (2, 3) and having an interdental orientation, and the surface impact angle (β) being defined in a second plane extending both parallel to the central vertical axis of the subject's respective teeth (2, 3) and perpendicular to the first plane, wherein the pocket inflow angle (α) is an angle between a direction of the flow of irrigation fluid as projected on the first plane and a direction of the central vertical axis of the subject's respective teeth (2, 3), and wherein the surface impact angle (β) is an angle between a direction of the flow of irrigation fluid as projected on the second plane and the direction of the central vertical axis of the subject's respective teeth (2, 3), characterized by the at least one nozzle orifice and/or portion of the nozzle unit (10, 20, 30, 40, 50, 60, 100) accommodating the at least one nozzle orifice having an adjustable positioning in the nozzle unit (10, 20, 30, 40, 50, 60, 100), and the nozzle unit further comprising a sensor arrangement which is configured and arranged to sense oral configuration features, and which is configured and arranged to generate input suitable to be received and processed by a controller which is configured and arranged to control positioning of the at least one nozzle orifice and/or the portion of the nozzle unit (10, 20, 30, 40, 50, 100) accommodating the at least one nozzle orifice on the basis of the input from the sensor arrangement. which nozzle unit (10, 20, 30, 40, 50, 100) has at least one constructional feature configured to contribute to realizing a predetermined orientation of a flow of irrigation fluid with respect to a subject's respective teeth (2, 3) and periodontal pockets in an operational situation involving functional placement of the nozzle unit (10, 20, 30, 40, 50, 100) with the at least one nozzle orifice in the vicinity of the subject's respective teeth (2, 3) at the position of interdental interfaces, namely an orientation from the at least one nozzle orifice towards the periodontal pockets at a pocket inflow angle (α) in a range of 10° to 50° and from the at least one nozzle orifice towards the surface of the subject's respective teeth (2, 3) at a surface impact angle (β) in a range of 0° to 50°, the pocket inflow angle (α) being defined in a first plane extending parallel to a central vertical axis of the subject's respective teeth (2, 3) and having an interdental orientation, and the surface impact angle (β) being defined in a second plane extending both parallel to the central vertical axis of the subject's respective teeth (2, 3) and perpendicular to the first plane, wherein the pocket inflow angle (α) is an angle between a direction of the flow of irrigation fluid as projected on the first plane and a direction of the central vertical axis of the subject's respective teeth (2, 3), and wherein the surface impact angle (β) is an angle between a direction of the flow of irrigation fluid as projected on the second plane and the direction of the central vertical axis of the subject's respective teeth (2, 3), characterized by the at least one nozzle orifice and/or portion of the nozzle unit (10, 20, 30, 40, 50, 60, 100) accommodating the at least one nozzle orifice having an adjustable positioning in the nozzle unit (10, 20, 30, 40, 50, 60, 100), and the nozzle unit further comprising a sensor arrangement which is configured and arranged to sense oral configuration features, and which is configured and arranged to generate input suitable to be received and processed by a controller which is configured and arranged to control positioning of the at least one nozzle orifice and/or the portion of the nozzle unit (10, 20, 30, 40, 50, 100) accommodating the at least one nozzle orifice on the basis of the input from the sensor arrangement.