Dr. Rafael L. Bowen, director of the American Dental Association Health Foundation (ADAHF) Paffenbarger Research Center (PRC) at NBS, consults with a volunteer patient in the center’s 5-year clinical trial of an adhesive material to bond composite restorations to dentin and enamel. Bowen, who invented a dental resin known as BIS-GMA, also is developing glass inserts for composite restorations which will improve their wear resistance and reduce leakage around such restorations.