Teeth+and+fangs

Vampires have fangs in which the use to inject venom or suck blood here is how they work. They main idea is that the teeth or fangs are hollow and have venom sacks in them so when the vampire is feeding the sacks contract forcing the venom into the blood stream, paralysing the victim, or putting the victim in a great amount of pain so they cant go anywhere fast. The fangs are retractable.