successfully STOPS this behavior:
But because he is no longer able to lull himself to sleep with his thumb, he may do this when he is supposed to be napping:
but I will venture to say that NOT moving bone structure in his mouth (per the dentist) is better than not napping.
I haven't fully decided on that one yet. ;-)
(Do NOT leave this product in your house with a 2 year old little girl. Said girl can, to your surprise take off the top, put the little brush thingy in her mouth, drool profusely, vomit her breakfast, make you dial Poison Control, stuff ice cream down her mouth, which she will gladly take, gag a few times and tell you at least 100 times, "mommy, yuckies" as she claws at her tongue. but otherwise be just fine.)