(IMAGE) Tohoku University Caption Using a small prism, it is possible to irradiate the oral mucosa of inner lips. Credit Yuji Matsuura Usage Restrictions Credit: Yuji Matsuura License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.