Answer by
primatefreak (1616)
There are two types of canker sores: Simple canker sore, between 10-20 of age and can have 3-4 times per year.Real cause is unknown,probably due to stress or tissue injury. Second: Complex canker sore caused by an underlying health condition. Both can last 1-2 weeks. Call dentist if 3 weeks or more. Avoid acidic foods and good oral hygiene helpful.