Thumbsucking is a normal activity with its peak occurrence at about age two. Thumbsucking can be an important source of pleasure for an infant and is usually nothing to worry about since a child will usually grow out of the habit. If thumbsucking occurs past age 4, dental problems may occur such as malocclusion. Malocclusion is the abnormal contact between the teeth of the upper and lower jaw.
Review Date 8/10/2021
Updated by: Neil K. Kaneshiro, MD, MHA, Clinical Professor of Pediatrics, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.