Hey Hamster. Hope I can help.

Oral sex as far as STD's go carries roughly the same risk as vaginal, more or less. If you have an open sore, that can serve as a point of transmission. And of course there's herpes, but to be rather blunt, I think you'd have noticed by now, no? While that can be transferred even without an outbreak present, you sound based on the post that you've been with him long enough that I wouldn't be overly concerned, tbqh. I don't discourage you from asking a doctor though.

Dental dams I know very little about...I know what they are and how they're used, but not effectiveness. Honestly, they seem a little...awkward. But I know that they make condoms that're specifically designed for oral sex (and are even flavored ). As far as you go, while they may be a bit of a turn off, if you're concerned, use the dam, and do speak to your doctor. If he's willing, why not get tested? If you can know for sure he's clean, you needn't worry, I wouldn't think.

And, while I know you said it's not something you're into, if you ever make the leap to it, a condom is an ABSOLUTE MUST for ****. He runs the risk of severe infection to...well, himself, if you take my meaning...if anything gets in there, so to speak. I won't really go into the details there...just a friendly heads up.

Anyway, have fun, and be safe.

My best,
Harley