Yes, it is safe to use external whiteners such as whitening strips on a tooth with a root canal.In some cases, however, external teeth whiteners will not work on root canal teeth at all because discoloration is mainly caused by internal factors inside the teeth. After a root canal procedure, especially on an anterior tooth, tooth discoloration sometimes occurs even if the root canal work was done properly. If you really want to whiten your root canal tooth, you will probably need internal beaching. Internal bleaching can be performed by your dentist or endodontist to whiten the darkened tooth from the inside out by placing a whitening agent deep inside the tooth. It’s important to note that there are risks associated with internal bleaching treatment such as tooth loss. You should always consult your dentist if you are concerned about discolored, root canal teeth.