Text this: Interactions between oral tissues and external light and matters

  ______   _    _   __    __    _____     ______  
 /_   _// | || | || \ \\ / //  |  ___||  /_____// 
 `-| |,-  | || | ||  \ \/ //   | ||__    `____ `  
   | ||   | \\_/ ||   \  //    | ||__    /___//   
   |_||    \____//     \//     |_____||  `__ `    
   `-`'     `---`       `      `-----`   /_//     
                                         `-`