From the AWESOME Science Channel show "Science Of The Movies", which is really a great program if you have the Science Channel (note, that it is not the SciFi/SyFy channel). Part 2 of 2, host Nar Williams goes to ZOIC studios where they go in-depth on how they get the vampire fangs to "run out" (as Charliane Harris would say) and how they were inspired to give them such a unique appearance. All rights belong to the Science Channel and HBO
Appears on these pages
I don't know how much help this is but it is a video on how the fangs work (retract etc) I don't...