The answer is painfully simple. If you do not wish your teeth, and or tooth, shot out because you were playing airsoft; if you are not interested in paying the exorbitant funds needed to replace said tooth, or simply do not wish to appear as a tooth-less simpleton - wear mouth protection. I wear the bitterend mesh mask and love it, Andy: a.k.a.- Hard Drive wears the Iron Face, and he likes that. There are alternatives; of course, evike.com, ehobbyasia.com, and ebaybanned.com all sell steel mesh masks for half the price of the bitterend.
Then there's option two, do not wear mouth protection - and risk having one, or all of your teeth shot out. The choice is, and always has been, yours. As stated, in another thread regarding mouth protection, I personally have seen two separate players get teeth SHOT OUT at two separate games.
Fight hard. Fight safe. Fight strong. Fight with honor.
Best regards,
Kevin: a.k.a.- Book
p.s. As if you need any more reason to protect your teeth... let's say, for argument's sake, that a lost tooth costs upwards of 1,000 - 2,000 dollars to replace. Think of all the airsoft swag you can acquire with 1,000, or even 2,000 dollars!

If'n you ain't diein'... you ain't tryin'.