Neither. Fangs have only a Hollywood affiliation with vampires. Properly, it would be the canines, or eye teeth. Sometimes the filmmakers portray vampires as having their second teeth enlarged, and sometimes they show multiple sharp teeth. It's all fictional.
While it is unusual for people to have fangs (though nothing like Hollywood's fangs), it is not unheard of. There are a few vampires who claim to have fangs of varying degrees — and I, myself, had fangy teeth of a sort growing up — but overall, it doesn't seem to be a vampire trait in and of itself.
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