I'd for sure have your son seen by a pediatric dentist just to be sure.
our daughter, who is very active and rough and tumble, fell on her face running when she was 21 months. one front tooth chipped, the other one bled a little at the top and while she really cried for a bit, we gave her some ice and she was fine in 5-10 min. we took her to the regular dentist who thought it was fine, they are baby teeth anyways, but we got a referral to a really good pediatric dentist in our area (the non-chipped tooth started to turn grey after a week or two).
one tooth is dead, the other might be and it's recommended for her to have a root canal to avoid infection. it's scheduled in a couple of weeks, wish us luck!