Wirkstoff, der Indocyaningrün und/oder Infracyaningrün enthält, zur Verwendung in der Behandlung dentaler oder paradontologischer Infektionserkrankungen unter Bestrahlung mit Licht, insbesondere Laserlicht, aus einem Wellenlängenbereich zwischen 790 nm und 830 nm.Active substance comprises indocyanine green and/or infracyanine green for the treatment of dental or paradental infections under irradiation with light, preferably laser light at a wavelength of 790-830 nm. An independent claim is also included for a system for the treatment of dental or paradental infectious diseases, comprising at least one active substance applicator for application of the active ingredient and at least one light applicator for irradiating the applied active ingredient with light, preferably laser light of wavelength 790-830 nm. ACTIVITY : Antibacterial; Fungicide; Antiinflammatory. No biological data given. MECHANISM OF ACTION : None given.