A dental dam, like a condom, is a barrier method. It is a thin, square piece of rubber which is placed over the labia or anus during oral-vaginal or oral-anal intercourse. Dental dams are most often made of thin latex rubber; however, for those allergic to latex, they are also available in silicone. Although specially-made rubber dental dams are sold in stores, plastic saran wrap from your kitchen can serve as an effective dental dam as well. A dental dam can help reduce the risk of STD transmission, including herpes, genital warts (HPV) and HIV.