If you’ve visited your dentist in the last few years, she may have shown a light in your mouth as a way of screening for cancer. The technology of using certain wavelengths of light to more easily detect cancer in the mouth has been used for about ten years. It works by using powerful shortwave lighting, which causes the normal tissue to glow. Any dark areas could be an early sign of cancer. Damaged or abnormal cells don’t glow the same way as healthy tissue. So if your dentist shines an unusual light in your mouth, know they're checking your mouth, to catch cancer early. Early detection can help your treatment prognosis.