Thumbsucking can affect a child's smile.
D002648:Child; D002652:Child Behavior; D002657:Child Development; D002675:Child, Preschool; D005386:Fingersucking / Q000009:adverse effects*; D006801:Humans; D007223:Infant; D008310:Malocclusion / Q000209:etiology*; D012904:Smiling