Good theory on how snakes might have evolved a hollow tooth.
To me, however, the bigger mystery is how a snake would develop a venom sack coupled to the hollow tooth containing poison harmless to the snake but deadly to prey.
It doesnt say they are hollow like a needle, it says and shows in the diagram cross sections that it has a deep groove on the back side as the fang penetrates , which keeps the venom from being wiped off.
Which was my understanding before, snake fangs are not really like hypodermic needles.
You know what, you are right, that last cross section is halfway down and is like a hypodermic. mea culpa.
Genesis 49:17
Dan shall be a serpent by the way, an adder in the path, that biteth the horse heels, so that his rider shall fall backward.