What causes mouth sores or kanker sores? is it caused by bacteria in your mouth, food you've eaten or by simply not brushing your teeth?

Trauma or viral?: Depending on location, this generally will tell you if your ulcer is traumatic or viral. Recurring ulcers are either herpetic or aphthous. Only a blood test can tell for sure. Herpetic ulcers harbor the herpes virus and are transferable; aphthous are not. Most ulcers will heal within 2 weeks of first occurrence. Consult your dentist for proper treatment.

Stress: Canker sores are associated with stress and sometimes having dental treatment done (also stressful for many patients). The condition behaves like a virus, however we do not know which one yet. The condition is self limiting and lasts 7-10 days. I have found that lasers help reduce pain and speed up healing. I have used both diode and er:yag lasers to treat canker sores. Zylactin-b is also good.