A tooth ache is a feeling of pain in a tooth itself or around a tooth. While tooth decay is often the cause of tooth ache, other causes may include sinus or ear infections. Should your tooth ache persist, you should contact your dentist as soon as possible to prevent the infection and pain from getting worse. Your dentist will conduct tests, including an xray to diagnose the cause of the pain and suggest treatment options which may include a filling, a root canal or in some cases extraction.