A device for the application of light treatment at a body structure is provided. The device could also be referred to as (dental) floss and be used for body structures in an oral cavity. The device distinguishes a container and a filament. The container hosts one or more light sources each capable of delivering a light beam with a unique light treatment. A user could select between the different light sources and/or parameters. The filament is a strand or fiber of a material transparent to the light beam. The filament is optically connected to a light source (or selected light source) such that the light beam could radiate through the filament at a body structure. The filament could be used in direct or not in direct contact with a body surface as long as the light treatment can be applied to the body structure.