I recently picked up these "Horror Fangs" at an estate sale. I believe I paid $1 for them.
I'm not sure when they date from, but my first thought was they were in awful fancy packaging compared to plastic teeth I remember:
These plastic fangs bought back so many memories from my childhood and lead me to research the company that created them, Imagineering (not to be confused with Disney's Imagineers).
Imagineering was founded in the 1960's by Larry Liff, a drama teacher at Central High School in Flagstaff, Arizona. Their first product was a monster make-up kit containing "Evil Teeth", the first pair of hinged fangs that have become so familiar.
By the early 1970's, the company was selling millions of kits and had expanded their lines with additional products. The first to follow "Evil Teeth" was "Vampire Blood". It could be bought alone or purchased in their "Vampire Kit".
I have personal memories of "Vampire Blood", having purchased some when I was about 10. It was used for multiple Halloweens and I still have the tube.
Green Dragon's Blood was a variant of Vampire Blood
This was quickly followed by Scar Stuf, a product so fondly remembered, there are blogs named after it. I remember buying Scar Stuf, but I was never able to replicate the effects they promised.
Some other kits and variant teeth from Imagineering:
One of my favorite things about these packages and why they remain so fresh in my memory is the artwork. It was done by Gordon Vigus (sp?). He brought a simplistic, whimsical almost childlike quality to the backing cards.
This is an excellent documentary short on the company including an interview with Larry Liff.