Hi Root canal is not at all scary or dangerous and doesn't lead to cancers also I think you might have got wrong information Root canal treatment usually done for decay tooth involving nerve of that particular tooth to avoid extraction and preserving it to maintain the normal function like chewing and speech Thanks & Regards Dr Katta R Venkatesh

Root canal is not dangerous neither it causes cancer. its a procedure to replace the infected tissue in the tooth with inert and safe material. only aspect of root canal with cancer is the use of formaldehyde as a pulp devitalizer, most clinics don't use it anymore. Symptoms are meant for diseases not for treatment procedures. so the second part of question needs to be rephrased.