My dentist accidentally over prepped my #3 molar for a crown, mechanically exposing the pulp. What should I do?

I had a large filling from childhood fall out. The dentist removed a very small amount of decay & placed another filling, which came loose again. There was no decay, but I was told I needed a crown since the fillings wouldn't hold. During crown prep, the dentist mechanically exposed my pulp. He placed a temp crown and treated the tooth with Dycal. I'm concerned that I'll need a root canal. Should I get a 2nd opinion/get him to pay for any endodontics I may need? How should I treat the tooth?