A device and a method for delivering UVA light to the mouth in which a photocatalytic agent is distributed in the mouth and a UVA light source is located contiguously to the head of the device so that the photocatalytic agent distributed in the mouth is efficiently activated by UVA light produced by the device. The UVA light delivery device of the invention may be, inter alia, a toothbrush, a tongue scraper, an interdental toothbrush, a denture brush, a flossing device, a dental hand tool, or a wand adapted exclusively to applying UVA light to photocatalyst coated surfaces.