Not sure which tomato you are growing, but the plant should send out a sucker at the top remaining side stems. It will become the new main stem. I grow mine in cages, so I usually allow 2 suckers to grow anyway.

You should have put the stem in a 5 gallon bucket of potting soil and totally soaked it. I have accidentally pruned some big stems on my plants this year and I always stick them in some buckets and they always root and in most cases even keep the blossoms on them. If you don't have a place for them leave them in the bucket or give them away as I do.

I did the exact same thing.....by accident. Well, on-purpose but i did not mean to get the main stem......my victim was one of my three cherokee purple plants :(
I wanted to pinch off the flower cluster to keep it from blossom too early ( i want BIG toms) and i did not realize that they were not flowers, but leaves that were rolled up and being born :(
my plant is fine..alive, but slowed, so i guess i did more harm than good....the other 2 CP i kept my hands off of and they are twice the size of the one i "pinched". But he is still gorwing - so i don't think it kills them per say - just shocks them?

Tina

Just curious as to why you are pruning one of the dwarf varieties?