ALEXANDRIA, Va., April 20 -- 3M Innovative Properties, St. Paul, Minnesota, has been assigned a patent (No. 9,943,465, initially filed Dec. 12, 2007) developed by seven co-inventors for "methods of using a dental composition having an acidic component and a photobleachable dye." The co-inventors are Afshin Falsafi, Woodbury, Minnesota, Joel D. Oxman, Minneapolis, Minnesota, Tiffany T. Ton, Woodbury, Minnesota, Joan V. Brennan, Sierra Madre, California, David K. Cinader Jr., Walnut, California, B . . .