Aphthae (or canker sores) are ulcers that are typically round or oval and occur on the inside of the lips or underneath the tongue. They are very common and affect between 30-60% of the population.
The cause of aphthae is still uncertain but hereditary factors are certainly significant with approximately 40% of people who get them having a family history of aphthae.
The main causes of aphthous ulcers include: emotional stress and lack of sleep, local injury by an accidental self-inflicted bite, nutritional/vitamin deficiencies (especially iron and folic acid, vitamins B1, B2, B6, B12 and vitamin C), the menstrual cycle and certain foods (including coffee and chocolate). Aphthae can be divided into three types of ulcers.