I don't wear any lower face protection, I accept the risk and keep my mouth closed to help prevent it happening. The only time I wear any is indoor games, and it is simple a 4" pentagonal mouth protector. I have had several close calls, hole in my nose, fat lips, a couple bbs in the mouth, I still prefer no lower face protection.
Not much except a mesh lower protector will fully protect. There have been several instances of a mouth guard (boxing/hockey style) of merely containing the broken teeth.
A problem with balaclavas/shemaghs/keffiyeh for teeth protection is the fogging issues cause by the moisture in your breath being pushed up into the goggles/glasses.
"Those who have long enjoyed such privileges as we enjoy, forget in time that men have died to win them"
Franklin D. Roosevelt