May Be. Ledermix, is an anti inflammatory medication that would be best used at the onset of the symptoms, at this time your endodontist could either introduce ledermix to the tooth or use the traditional way to finish the treatment. Ledermiix may be a good idea but it will take longer to complete the treatment. Right now you should be on antibiotics to contain the infection.
Possibly. Ledermix is usually used to prevent root canal therapy... Since it sounds like you have had root canal therapy started, you could try having the ledermix applied directly on to the puld to reduced pain. I would also get traumeel liquid which is a homeopathic remedy from a health food store and take 6 drops 4x per day..That will also reduce nerve pain.
Quickest relief by.. In my opinion, the quickest and best method to start and treat any tooth that requires rct is to carefully and completely remove all tissue and debris to or just shy of the apex, irrigate and then dry the canals complete, place either eugenol for a vital tooth, or formocresol for a non-vital tooth and then seal the access hole. Follow with antibiotics and pain medication as appropriate.