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.
While hydrogen peroxide is an irritant for gums, salt water is soothing for gums, especially the first few times, and it also kills dental bacteria. To reduce hydrogen peroxide usage you could swish with hydrogen peroxide MWF and swish with salt water T-Th-Sa and neither on Sundays.