Very simple. H2o2 hydrogen peroxide use on swab to clean the area. .
Mouth sores. A number of home remedies or otc preps can help: rinsing mouth with mixture of warm salt water, alcohol-based mouthwash, & peroxide (don't swallow!) can soothe & help heal sores. Topical oragel/anbesol can numb pain, as can lozenges with benzocaine. Glyoxide (otc) gel forms foamy peroxide inside your mouth. If not improving, see fp to make sure more isn't going on.