hello, 5 years of mouth ulcers may due to various reasons, 1. peptic ulcers 2. under any many medication for systemic problems 3. sharp tooth 4. wearing denture initially check with a dentist to rule out the cause of ulcer and if necessary we can take a biopsy since its a chronic issue, the dentist will give you treatment option after the reports obtained.

Hello. It's not possible to know the cause of your ulcers without clinically checking your case...there are many reasons for mouth ulcers like vitamin deficiency, improper diet, stress, sharp teeth., systemic  reasons etc. If you haven't visited a dentist then please do so immediately... preferably meet an oral medicine specialist near your area...happy to help. Dr Zankhana Mody Mohile