Sorry to hear the bad luck buddy. I've seen that dog jump and is the most athletic lab I've personally seen. Just glad he didn't have the usual rock in his mouth or it would have knocked you out.
Ends up several more teeth are cracked and broken than I thought. Going to try to see a dentist tomorrow.
You are 100% correct on the rock. Either that or a block of wood. Guess the bumper was good enough right at that moment.