Quick ways to heal a canker sore?

Home remedy. Nothing cures canker sores or prevents recurrence. However, the best home remedy for canker sore is to put a chip of alum on top of the sore. Alum removes the moisture from the ulcer and promotes the healing.
Prevention. Canker sore or more specifically aphthous ulcer can be prevented by avoiding a common foam detergent found in most toothpastes called sodium laurel sulfate. Switching to Biotene or other toothpaste not containing this ingredient can be the cure in preventing this painful condition.