Morbius is one of those pesky Marvel characters that invades the story lines of otherwise respectable titles in order for Marvel to maintain their copyright. He first appeared for a short time in the mid 70s and then promptly vanished from existence for nearly two decades. Then for some reason, in 1992, they decided to revive the already “Living Vampire” and give him his own series. To promote this return of a character 90% of their audience had never heard of, they distributed these plastic fangs to comics stores who then passed them out for free to their customers. I got my pair, but of course never opened them. (They’re worth more sealed).
I’m not really sure why Marvel thought handing these out would lead to sales, but this was the early 90s, the comics industry was in free fall, and there was no limit to the kind of wacky tricks they were willing to try to turn their numbers around. In an era of issue #0’s, multi-variant gatefold covers, and polybags, this little item was barely even visible on the hype radar.
The Morbius series lasted a full three years, ending in 1995. Since then he has had numerous cameo appearances. I’ve never read any of them.