<s>[INST] I had a root canal about 8 years ago and recently the same tooth has started throbbing. I did go to my dentist who  took an ex ray and saw some dark areas at the root. He put me on an antibiotic and provided pain meds until I can get in to see the endodontist next week.  I am taking 3 Advil every 3 hours plus the pain pills and the throbbing is still killing me. Any suggestions and what can cause this since I already had a root canal on this took? Thank you [/INST] Hello,Thanks for consulting HCM, Read your query , as you have pain in rct treated tooth and your x ray reveals radiolucent area at apex of root means infection is present for this I will suggest you to do warm saline gargle two - three times a day , for pain you can take dispersable tablets like ketrol dt or paracetamol tablet in water for releif . Consult oral surgeon and go for re rct if pain persists .Hope this will help you. Wishing you good health.Regards, Dr. Priyanka tiwari </s>