One of the most menacing features of the vampire is their fangs, threatening to sink into flesh and drain victims of blood. The origination of the fang mythology has several roots, but perhaps the most popular stems from the vampire bat, and that these creatures can carry a disease, similar to rabies that could infect someone and potentially turn them into a vampire.
With the morphology that the vampire has undergone through over the years, their most iconic part of them has come gone under changes too. In Dracula by Bram Stoker, fangs were used like a proboscis, and were needle thin elongations. When he drank blood from his victims, they were easily confused with pinpricks possibly received during the fastening of a cloak. The fangs were sunk into the flesh and the blood suckled through the hollow interior of the teeth.
Over the years, fangs changed into instruments to rip flesh open so that the vampire could feed on the blood that was gushing from the wounds, a more messy and less productive, albeit faster feeding process. The ripping open of throats would also be much more difficult to hide, and it is a widely understood and accepted characteristic that vampires prefer to keep their existence hidden.
The position of fangs are thought of classically in the canine position, but historically, fangs have been the lateral as well as even the central incisors. Nosferatu, the quintessential classic vampire film has the two front teeth is extended into fangs. Sometimes fangs appear on the top and bottom of the mouth. Sometimes there are two sets of fangs. For some stories, but mainly only those where the vampire is still a grotesque and evil monstrosity, every tooth is a sharpened fang.
One modern idea is that fangs are retractable and only come out when the vampire wills it or becomes so blood thirsty – and in some cases horny – that they come out on their own. Some retract into the gum line, while others actually fold up into the roof of the mouth. This idea makes the possibility of vampires blending into normal life more believable.
In Twilight, Stephenie Meyer completely did away with much of the accepted vampire mythology, including fangs. Thus, when bitten by a vampire, they leave behind a crescent shaped scar like any other homo-sapiens.
Another common thought is that vampires contain an anticoagulant in their fangs that they inject like a mosquito, or a paralytic like a snake, that thins the blood so they can drain as much blood as possible. In some cases, the vampire’s saliva contains a healing agent that seals the wound closed when they’re done feeding. Again, this would be a defensive use to keep their anonymity. After all, if people kept turning up with two open puncture wounds it might give away the presence of vampires.
Fangs are so inextricably linked with vampires that regardless of placement, amount, size, or retractability, if you do away with them completely, the thing you are left with is only is a poor imitation of a vampire.
All images taken from Yahoo! Images