This spring, the Medical Marijuana Caregivers of Maine joined the usual coalition of anti-pot forces that includes active law-enforcement groups, social conservatives and public health advocates to oppose a state bill that would legalize possession of small quantities of the drug.
And it's not a good idea to use it as mouthwash. Hydrogen peroxide (in dilute form) is used as a tooth whitener (check the active ingredients on those gel-based tooth whiteners, they usually use H2O2). It also has the side effect of turning your gums pale temporarily, though it wears off in a few hours.
1 As an alternative, dip a cotton ball in peroxide and rub it on your teeth, making sure they get completely coated. Let it sit for about a minute, then rinse your mouth out with water.  Do not swallow the peroxide. It's safe to use peroxide on your teeth, but swallowing it could make you sick.