Late to the discussion, but I believe the true definition of a fang is a specialized tooth used in the delivery of venom. Garter snakes don't have teeth specialized for this purpose, but their venom is delivered via bite wound caused by the teeth. This is probably stretching the definition of course and I think we all agree as the above consensus would show. While Jesse's tree boa has very long teeth, some of which may be specialized for grasping, they wouldn't be fangs ( I know you weren't suggesting they were really fangs) due to the lack of venom to be delivered.

A stronger definition of what a fang is includes it including a groove or hollow duct for venom delivery. With the massive array of dentition, this narrow definition may exclude some dangerously venomous animals, but of that I am uncertain.

Ian

ps, thanks for sharing the diagram