How to stop receding gums?

Of course I cannot know anything for sure without actually seeing it, but it sounds as if you have some "gum recession" That can be caused by a number of different things. Is that the ONLY place you see that happening? Nowhere else, even your back teeth that you might not be able to see as easily? If you had it going on other places I might suspect you tot be using a medium or hard toothbrush. Or possibly "scrubbing back and forth" instead of trying to gently massage the gum area in a circular motion with the toothbrush bristles slightly angled towards the gumline.

Do you get your teeth cleaned regularly by a Hygienist at your Dentist office? If not, it is possible that you have a buildup of hard mineralized material covered with soft bacterial plaque right at, or slightly beneath your gums.. If tartar and/or plaque is present, your gum tissue does not like that and will recede a bit. Then if plaque clings onto the Tartar it can be difficult to remove. Once the hard material called Tartar has developed you can not get that off yourself, it prevents your gum tissues from healing properly and once recession begins it is not reversible.

I would try brushing the area EXTREMELY gently, but thoroughly, with a SOFT toothbrush for a couple of days. Use a salt water rinse if you like to soothe any irritated feeling in your gums.(1/4 teaspoon salt to 1/2 cup of lukewarm water) If it does not improve or begin to look "normal" within a couple of days I would encourage you to call and schedule a cleaning with a Hygienist if you have not had one within the last 6 months. If you have and it still does not go away I'd ask for an apopintment with either your Dentist or your Hygienist for evaluation.