It may affect dental health

(HealthDay News) — Thumbsucking is more than an unsightly habit that most toddlers easily outgrow. The practice can permanently damage their teeth.

The American Dental Association explains:

Children who suck their thumbs vigorously may have more dental problems than those who just hold the thumb in their mouths.
Thumbsucking affects the way permanent teeth align as they come in. Kids who suck thumbs aggressively can even damage baby teeth.
Most children stop sucking their thumbs before they are 4 years old, before the permanent teeth come in.
Speak with your dentist if you are concerned about your child’s thumbsucking and its effects on dental health.