What should a parent do? If possible, try to switch them to a properly designed pacifier that fits the shape of the mouth. Pacifiers are less likely to create the same developmental problems [by distributing forces over greater area], are usually discarded by the child at an earlier age and are easier to hide than a thumb. If the thumb sucking is during the day, discuss the problem with them to discourage the habit. Placing a band-aid on their thumb as a reminder may help. Be positive and praise them when they remember. And reward them for their success.
It is more difficult to control thumb sucking when the child is asleep, because the child is unaware of this involuntary action. So, try this habit-breaking technique that is usually successful within two weeks. Before your child goes to bed, wrap a 2-inch wide ace bandage lightly around their fully extended arm [straight]. Start about 3 inches from their armpit and continue down past the elbow. This will not prevent your child from putting their thumb into their mouth. However, as soon as they fall asleep, the tension created by bending the elbow will pull the thumb from their mouth.
If your child is still sucking on their thumb or anything else by the time their permanent teeth erupt [around age 6], please call it to the attention of our office.