My 2 1/2 year old still sucks her thumb.how can i get her to stop and will this cause any permanant damage to her teeth?

Difficult problem: When a toddler has a consistent self soothing activity such as thumb sucking it is difficult to change.Sometimes finding a stuffed animal , blanket, or doll can provide a substitute. generally it will resolve on it's own when your child is ready. It can lead to overbite problems but most children get braces which can correct this issue

Try the "Thumbguard": Thumb-sucking in children younger than 5 is usually not a problem. Try the Thumbguard. It is one of the most recommended benign solutions to break and stop the thumb sucking habit.

Thumb: no it does not cause permanent damage to the teeth, usually you need to try some other diversionary methods when they try to suck on their thumbs, application of bitter tasting stuff can also help