I have a smooth feeling, flat, circular patch on the roof of my mouth and it has been there for about 3 weeks now. It is not raised, or a bump, just a patch of flat abnormal skin with a red outline. I have been doing salt water rinses for about 3 days now 2-3x per day. I also changed toothpaste right before this abnormality occurred, and have recently changed back to my regular toothpaste to hopefully see improvement. But I was still hoping to get some other opinions on what it may be, and if it could be something serious. I went to my dentist the other day, and they just measured it and said to give it another month and see what happens.