Aphthous ulcers (Canker Sores)

Let's talk about something unpleasant: canker sores. Twenty percent (20%) of the general population has them, and so do I. They hurt like hell, but they go away on their own. For me, they happen a few times per year, sometimes I don't have them for a few years at a time. When I do get them, they go away on their own in a few weeks. I have two right now. One just healed after a week, but then, annoyingly, another is just starting. The pain makes me cranky.

They aren't contagious.

Causes:

Large sores one those which last more than two weeks can be a sign of some other disease, but the small ones, in otherwise healthy people, seem to be an auto-immune problem which may have many different triggers.

A common trigger is physical injury or damage to the mouth's protective coating of special cells, the oral mucosa. -  In my case, being so intent on a project that I forgot to eat or drink for 7 hours, probably did it.  The type of cells lining much of the mouth dry out and die if they are not kept moist by bodily secretions. [ See: Non-keratinizing stratified squamous epithelium (SSNKE).] Damage to the protective lining is also caused by toothpastes with sodium lauryl sulfate.  This detergent attacks the upper layers of the mucosa and denaturates the mucin layer, exposure of the underlying epithelium. In other words, it strips away your mouth's natural protection.

The damage in step 1 ramps up your body's immune system.

Fixes:

Salt water (a mild antiseptic - 1 tsp (5 g) of salt in 1 cup (250 mL) of warm
water, rinse & spit, don't drink!), mouthwash (listerine) and other safe mouth disinfectants like licorice root will give the mouth a chance to heal.  Deglycyrrhizinated licorice (DGL) seems to be the best.

Shooting the sore with a red laser pointer for 30 seconds per day will reduce pain immediately and effect good healing in 1-2 days. ( 632 nm and  670 nm lasers were tested, I'm not sure of the power used.)