One of the casualties of being a hockey player is that you often lose your teeth. Whether you take a puck to the mouth or lose them in a fight, at one point or another there is a good chance that you will lose a few.
I’m going to assume that all the years of fighting were what contributed to Paul Bissonnette losing some of his front teeth. I tried to search online for confirmation of when he may of lost them and the searches turned up empty. His wikipedia page wasn’t any help: