I got a phone call from my mom the other night - my brother was out doing intervals, and coming down a slight incline at maybe 35 miles an hour, he took a hard corner, hit a patch of gravel, and his wheel kicked out from under him and he hit the ground face-first.
I talked to him last night, and he's going to be fine (and more importantly, his sense of humor is starting to come back, and he's already talking about his next race), but he's pretty banged up. His face is pretty road burned, he's pretty sure he didn't actually chip his teeth, but rather ground them down a against the pavement, and then after he started to roll he basically covered his entire side and leg in road burn. Additionally, he thinks he may have sprained his wrist too, but it's tough to say for sure because he's so cut up that his whole body aches anyway.
More to the point, he hit the ground so hard that not only did he shatter his helmet, he actually has a large bruise on his forehead from where his helmet was when he hit. Without that helmet, he'd either be in critical care recovering from reconstructive surgery to his skull, or way more likely dead.
The human body is a pretty remarkably tough thing, but it wasn't really built to hit anything at 35 miles an hour, much less the equivalent of a giant rock-hard sanding block. I don't care how stupid you feel in one, just fuckin' put it on, ok?
Yikes. Good to hear that he's OK!