I too say leave him My first was a thumb sucker but I think he stopped before he turned 2. We used to flick it out of his mouth and made it funny with a "pop" noise and he just kinda stopped on his own. I prefer thumb to dummy too cos they're attached and easily found in the middle of the night Oh and I can't remember if there's a thread somewhere or not, but apparently so long as they stop by the time they're around 3 you shouldn't have teeth issues - so I've heard on some show on tv.