Anyway, getting back to the original question, the smile stretches or thins the lips in the Z axis possibly providing an insufficient buffer to the mouthpiece pressure that is inherent in trumpet playing. Additionally, if you consider the analogy of a rubber band: if we stretch it and twang it, we get a pitch; stretch it further, we get a higher pitch. How far can you stretch it before it breaks? The lips aren't rubber bands but the smile causes them to work similarly to that analogy. Thus, there will be a finite range and a finite endurance for that player. Dangerous? Maybe, if you attempt to play beyond those factors. I can't say. I will state emphatically that a cushioned embouchure resists pressure and controls the buzzing tube, per my previous post. This approach works for me.