Dental dams are just that, barriers used during dental work to isolate a tooth. So what does that have to do with sex?
Back in the day, when safer sex was first being discussed, no one thought that oral sex could pass infections. But after a while it became apparent that it could. Using a condom for oral sex on a penis seemed pretty straight forward. But what about protection when going down on a woman? Or when having anal / oral contact? That's where the dental dam came in. Some clever folks realized that the same device that could protect your mouth, could also be used to protect your genitals.
But the original dental dams weren't made for sex. They were kind of small, rubbery and didn't taste too good. Plus they were hard to find. Some people gave Saran Wrap a try, others modified condoms. Pretty soon manufacturers took notice.
These days, a few companies produce dams that are specifically for sex. Pictured here is the Sheer Glyde Dam. According to their website this is the only, "latex dam cleared by the Food and Drug Administration (FDA) for protection against STDs for oral / vaginal-oral / anal (rimming) sex."
Though oral sex is lower risk activity for STD's than are vaginal and anal sex, infections like herpes and even syphilis can easily be spread from mouth to genitals. Using a dam can definitely help reduce your risk!
More Information: Learn how to use a dental dam