how to plumbing: What's the best way to get rid of roots in the sewer line other than snaking it?

I have partial clog in my main sewer line from roots from an adjacent tree. I since removed the tree so essentially the remnant roots will eventually die and decompose. However, I want to get rid of the roots before the drain clogs up once more. I was advised not to use a drain root cleaner containing copper sulphate.