I know many boxers that have all their teeth. Most of them that i know, in fact, from guys with a handful of fights to world champions. Almost all of the street guys that i grew up with are missing teeth. Many of the guys that I know that do bareknuckle boxing are missing teeth.
My back teeth are messed up on the left side, and my bottom teeth are piling up on themselves. This is because of a distinct misalignment of my jaw on the left side, which is a result of me getting cracked by a right hand in a non sanctioned bout. I got jumped on the street at some stupid hour when I was 18 and it didn't hurt at the time, or ever, really.