An inside mouth guard will most definitely protect your teeth from chipping and breaking no question! and after wearing one playing hockey for 20+ years, breathing is not a problem either...talking with one well ya that is noticeable, that can be relieved by cutting off some of the rear portion (over the molars) since you are only realy worried about the front 4 upper and lower anyway!
In 9 years of play, I have had my front tooth broken completely off and a couple over ripe cherry split lips until my brain matter absorbed the cost of dental work and unnecessary discomfort, I have been wearing a face mask covering just my mouth area for a long while now and with all the BBs that have smashed off that, I am sure it saved me 100s of dollars!!
In the last 2 years I have seen 4 others loose front teeth, 1 dig a BB out of their nose and half a dozen cherry popped lips, if the cool factor tugs at one's ego and protection is out (these are the same guys that would wear ballistic sunglasses if they could get away with it!) it is only a matter of time...unless of course you are with the Arty boys and MED is from 200ft or more:wink:
Bottom line, dont let the wanna be "hard corps" players that tell you it ain't cool, my mouth guard has never got in the way of any of my BBs, slowed them down or put a hook to the left or right on them!