To treat a Root Canal infection, the bacteria needs to be removed. This can be done by the root canal specialist by either removing the tooth (extraction) or attempting to save it by removing the bacteria from the root canal system.
After the bacteria have been removed, the root canal will be filled and the tooth sealed with a filling or crown. In most cases, the inflamed tissue at the end of the tooth will heal naturally.
Before having a root canal procedure to replace a missing tooth, you will usually be given a local anesthetic. This means the treatment shouldn't be painful and should be no more unpleasant than having a filling.