I can't believe it! After 7+ years of trying, my son has stopped sucking his thumb. Not only that, but my daughter stopped sucking her fingers too! It was a little more difficult with my daughter, since she switched to each thumb after stopping her fingers, but we managed to stop all sucking!
How did we do it? Band-aids. We spent 2 weeks in band-aids. My daughter had 4 on and my son just had one, but they were on all day and all night for 2 weeks straight. I think the constant part was my problem before when I tried them. Before we would take them off in the morning and when I caught them I would put another one on. This time as soon as they got up, they took them off to eat, washed up and immediately put another band-aid on. There was no opportunity for them to suck at all.
It's been a week since we stopped putting on band-aids and there is no sign of sucking. I've checked when they've gone to bed and there has been no secret sucking going on. I can't begin to tell you how relieved I am! My daughter's fingers have started healing from the teeth indentations and my son's thumb nail is growing properly again. Can you see me dancing my happy dance from where you are? On second thought, maybe you don't want to see me dancing!