What are the risks of thumb sucking?

Thumb and finger sucking can lead to a variety of concerns, of both a physical and a social nature. 

A child who sucks their thumb may be teased by their peers, for both the habit and the secondary effects of the habit. For example, a child with a sucking habit may develop poor speech, unattractive bite concerns, or have difficulty managing food and saliva. Sucking is a subconscious habit, and most children do not even realize the thumb has entered until it is too late...this can be tormenting if it occurs in public in the presence of taunting classmates. Thus, many children are ostracized for a habit they often have little control over. Many may be prone to develop self-esteem issues as a result. Fortunately, by addressing the habit in a positive manner with trained professionals, most children will experience an increase in self-esteem and self-worth post habit. 

The physical risks are well documented. The obvious ones that come to mind are dental and bony jaw changes. The pressure of the sucking process can lead to narrowing of the upper arch, and the pressure from the sucking muscles within the cheeks can cause a further collapse against the sides of the upper arch. This often results in a vaulted or v-shaped upper arch. Pressure on upper teeth outward and lower teeth inward further complicates these oral changes.

New research now shows a link between the thumb and the tongue posture as well. The vast majority of children over age 5 with a thumb habit have a low rest posture of the tongue and a "tongue thrust swallow". All children are born with low postured tongues that begin to change at age 4-6 years of age. However, thumb sucking behavior may impede this natural transition. Some researchers are exploring the idea that the tongue actually plays a significant role in growth and development changes in the jaw in the young child and may potentially impact the growth of the facial structure over time. These issues can be addressed as a team effort between the dental team and an orofacial myologist. Eliminating the habit and then addressing any resulting issues at an early age allows the best chance for the reversal of any structural or muscular concerns.