A Answers (3)
You should brush your teeth and floss even if you have a painful canker sore. You don't want to create another problem like an infection or sore gums on top of your canker sore. Use a soft toothbrush and be very gentle around the sore area, but do your best to maintain good dental hygiene.
American Dental Association answered
It is important to maintain a good oral health regimen even during mouth sores to prevent other problems. Not brushing can lead to bacteria and plaque that can lead to cavities and other problems. Be sure to continue brushing your teeth twice daily for two minutes with a fluoride toothpaste and floss once daily. Canker sores often heal on their own.
Honor Society of Nursing (STTI) answered
Good oral hygiene during an outbreak of aphthous stomatitis (canker sore) is important. Keeping your teeth and mouth clean will help keep food particles from irritating the ulcers. Use a soft toothbrush and a mild toothpaste or baking soda to gently brush your teeth. Be sure to rinse thoroughly.