This is a subject very close to my heart because I am your sons!! I am 33 and I still have my comfort blanket from childhood! If I'm upset or stressed I hold it and it completely calms me down and it was really helpful when I had my babies as it relieved that awful anxiety you get at night just by holding it! Back when I was young my mum was worried about my teeth, as you are, and she said that she would either take it away or I could use it to rub my face but I mustn't suck my thumb as it was ruining my teeth. I did as I was told and voila! I still have it
maybe you could try this tactic? Rubbing their face with the label is okay right? It's just the sucking bit that's a problem. Tell them all the facts about their teeth, they will know you are serious as you've taken them away already.
Also, I would ask your dentist for further advice on this as my mother in law is a dentist and she said that unless you inhertitantly have a misshapen palatte then sucking your thumb won't make it misshapen. Might be best to ask for detailed info as its important for you to know exactly. I sucked my thumb for 6 years plus, my thumb even shrunk, but my teeth are perfectly straight naturally I never had a brace, they were not at all effected.
Anyway, I hope you appreciate my highly embarrassing post!! I thought I should bare my soul just in case my mums tactic works for you
hope so. Xoxo