Need advice on what is the the best remedy for a mouth ulcer?

Time + warm salt H2O: In time mouth ulcers will go away on there own. Warm salt water helps expedite healing. A dental laser is great as well. Prevention is the best medicine. Be careful with sharp foods like nacho chips, they can scrape your gums and cause ulcerations . Also slipping with your toothbrush can injure your gums.

Mouth ulcers: It really depends on what the cause of the ulcer is - it could be one of several different entities, and without a true diagnosis, you would just be guessing (as well as not knowing why/how it got there). An aphthous ulcer is an immune-type reaction; some ulcers come from trauma due to a sharp edge of a tooth or dentistry; others can be due to a chronic infection - you should see your dentist.