I use one as a precaution, but there's no gap between the teeth and the guard so if the BB does hit it it could shatter the tooth. All that force has got to go somewhere. Mouth guards are built for contact sport, to protect your teeth from hitting each other, not getting shot at. There's videos online of dental models getting hit and the guard didn't help one bit. But if you're not going to use a mesh mask, some protection is better than nothing I guess.