This looks interesting, but none of the 7 search options that 4chan X provides came back with the pic. Must be cropped or something. So if you would, OP, please sauce me on this one.
it's Dead Tube
The OP is the latest chapter, probably why it doesn't show up with img search
There's nothing horrifying about this smile!
I don't remember anyone who's alive missing teeth. They seem to lose it when they die, though.
With that said, I don't think she's ever been hit in the jaw or mouth.