If I am taking penicillin for a tooth infection, is intercourse with my boyfriend a risk if he is allergic?

Probably not. There isn't a lot of transmission of fluids from women to men during intercourse; this is more likely to be a problem for a penicillin-allergic woman whose male partner is taking penicillin.
No. Your boyfriend will have to ingest the penicillin himself. It is very unlikely for the penicillin to spread through body fluids to your partner.