Well, Tai is a lesbian, so condoms aren't really her problem...
And no, I have never heard of Polyurethane dental dams. I'm sure there are nitril ones, but still...
Having a latex allergy can be a bitch (trust me, I have one). You can't accept (well you can, but you can't use them) free condoms, polyurethane isn't as elastic as latex and more susceptible to breakage, and they aren't PROVEN to 100% protect against STDs, even when used properly. They are pretty sure that they do, but they're not totally positive. Or at least that's what I heard the last time I read up on it. ...I feel as though I've had this discussion before.
Edit:
Wiki can answer everything. For those of us with latex allergies, dental dams are also made of silicone.
But silicone tastes yucky...blegh.