At night before bed, I take a half cup of bleach and pour it into the toilet. Then I take about 18 inches of dental floss, I tie one end of it to the bottom of my tooth brush and tie the other end to the front of the toilet seat. When I lower the seat, the toothbrush goes into the water and bleach. When I get up in the morning, I flush the toilet which rinses off the toothbrush. I can then brush my teeth with a clean toothbrush and floss with the dental floss used to tie the toothbrush to the toilet seat. The bonus is that my toilet bowl stays nice and fresh too!
Much safer that using the microwave and it works even when there isn't any electricity available (storms, hurricanes, blackouts, etc.)

AHAHAHAHAHAHAHAHAHAHA WTF THAT IS AWESOME.