Unsafe Sex

[JodieTs]

HIV is very fragile & would most likely be destroyed by enzymes in the mouth.
The real risk of HIV transmission {& other STI's}
is if you have a bleeding gum or mouth ulser as that is an infection route.

HIV via mouth is between very very unlikely or the pattern of infection in the population demographic would look totally different to that seen.

As guiltydreamer points out, though, a lot of other STI's regularly get transferred via mouth.