I have a nice set of big old buckteeth; I always just wore shooting glasses playing airsoft....needless to say I bought an Empire E-vent mask not too long ago. It's a paintball setup but it's very nice, it's not very good if you use sight's but that doesnt bother me though...I dont use the sights anyways, I just line my shots with the barrel.
The thing I really like about this mask is that it uses a lens much like a half face hockey visor. I can also wear my glasses underneath it. I have asthma so I breath fairly heavy and I havent had a single issue with it fogging up.