Joe Louis certainly gave Marciano a fair bit of stick with that jab. Marciano's eye was bruised, blackened and swollen, and there was blood.
"the onus is on you to present evidence" Yes. I have never heard anyone claim before that Louis knocked out Marciano's teeth. I don't have my front teeth. I have worn a permanent bridge for years. When a teenager I wore removable false teeth. I lost my teeth in an accident when I was nine or so. Marciano could have lost his front teeth anytime playing football or something.