A.M.
My daughter is now fourteen and had been sucking her thumb since Pre-birth, our first sonogram showed her sucking her thumb. She did it to comfort herself and when she was tired. As she got older she would only do it before bed time, around trusted friends or when no one was looking. To make a long story short, she gave it up when she was ten. We never made a "Big Deal" of it because it brought her comfort. Trust me on this, don’t sweat the small stuff or make her feel guilty or she will just feel as she needs to hide it and be ashamed (as my daughter did when she went to the in-laws) She could not understand why people were so cruel when she was not doing anything to hurt anyone else. By the way, she has beautiful teeth. Love your daughter no matter what and this too will pass.