Tongue ulcers are painful sores that appear on the tongue. They vary in size. They are usually harmless but can be very uncomfortable especially while eating. Causes Ulcers in the tongue may arise from a variety of reasons. Some of the causes are: 1. Trauma Injury from accidentally biting your tongue eating scalding food improper brushing chewing hard foods and ill-fitting dental implants such as braces can cause tongue ulcers. A misaligned or crooked tooth can rub against your tongue causing ulcer and pain. 2. Stress Stress releases a host of chemicals in the body that affects the entire body