root canal teeth are 99.9% always infected. However pulling the tooth most of the time won't cure the problem, because the infection spreads to the bone. And if the extraction is done poorly and results in a cavitation you are no better off than having the tooth still there. It is vital that the dentist thoroughly cleans the surrouding bone away from the tooth, preferably with hand tools. If it bleeds a lot after surgery, that's not a bad thing. Means hopefully it'll heal successfully.