The present invention relates to methods, systems, kits and devices that emit light to the oral cavity. The device includes a light source a power source in electrical communication with the light source and a bite actuated switch in electrical communication with the power source and the light source. The device is a size or shape that fits within an oral cavity of an individual. Since the device along with the light and power source are self contained, the user have their hands-free and can perform other activities while using the device. The device, methods, systems, and kits, further include the use of an agent (e.g., antibacterial agents, tooth whitening agents, cleaning agents) that assists or enhances the efficacy of the light therapy.