thumb sucking

One of the thing that attracted me is his thumb sucking. So much like a baby. HE sucked quietly to sleep.
Out of the blue, I feel sucking is not right. So, I browsed the internet to look for more information. To my horror, it is not right!
What I found?

Does thumb-sucking cause any problems?
Prolonged thumb-sucking may cause a child to develop dental problems. Thumb-sucking can cause a child's teeth to become improperly aligned (malocclusion) or push the teeth outward, sometimes malforming the roof (upper palate) of the mouth. Malocclusion usually corrects itself when the child stops thumb-sucking. But the longer thumb-sucking continues, the more likely it is that orthodontic treatment will be needed to correct any resulting dental problems.
A child may also develop speech problems, including mispronouncing Ts and Ds, lisping, and thrusting out the tongue when talking.

I guess I should be thinking of how to get rid of this habit..and I really believe, it won't be easy..*sigh...another nightmare beings..