###Human: Why do I have increased pain and pressure in the tooth after undergoing root canal treatment? ###Assistant: Hi. You have an infection still lingering in your tooth undergoing root canal treatment. It causes pain. Your dentist should place a calcium hydroxide dressing in the tooth, and it disinfects the canals. A course of antibiotics should be given. Also, the tooth should be trimmed to avoid contact with opposite jaw tooth. If the pain does not get better, get an X-ray done and upload it to me. So that, I can advise you appropriately.