RCT with laser (endodontics ) is needed when the blood or nerve supply of the tooth (pulp) is damaged due to decay or injury .it is most often needed in teeth which have deep fillings , or in teeth which have deep dental decay. It may cause very severe pain and lead to infection of the tissue surrounding the root tip.
RCT removes infected or damaged pulp from the diseased tooth . after that the hollow pulp chamber and root canals are cleaned & sealed.