Ds is 3 and a half and is increasingly sucking/biting his bottom lip, especially when tired and seemingly almost all the time when asleep. I've noticed he has quite an overbite now and the bottom teeth are clearly angled inwards. We are off to the dentist anyway next week, but I wondered if anyone has any experience of this and what they did (if anything). He seems so young to have it corrected and obviously still has his baby teeth, but on the other hand it is having quite a clear effect on his jaw.