REDIRECTED TO MAYBEMAIMED.COM: Maybe Maimed but Never Harmed

Safety: Face slapping, is a very detailed article about the physical dangers of face slapping in BDSM play that both submissives and dominants should read and understand before playing with strong face slapping in their scenes. Face slapping can be dangerous. For instance, the article advises:

Of course, if hitting hard enough, you will break the cheekbone (damaging almost inevitably some nerves), or dislodge or break the jaw articulation, which, even when being very strong, is not designed for receiving a lateral impact. For diminishing the possibility of this damage your sub should close forcefully the mouth.