There is a natural tendency for very young babies to comfort the feeling of having something in their mouth, this is why many babies can develop a habit of sucking the thumb or finger, the baby actually been photographed and scanned doing this in the womb!
As babies begin to develop, it is a normal developmental stage for excursions oral. The mouth is very sensitive and when the baby is put in everyday objects in their mouth allows them to begin to find the texture and taste of the world around them. You can purchase thumb sucking prevention devices for your toddler online via amazon.
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A baby who made their thumbs in their mouths could be a problem because of the constant pressure on the roof of the mouth, which is caused as the baby sucks, can begin to move the bone.
If this habit continues through to the beginning, middle or even the end of the bone will continue to move at this pressure. This is a process that is very similar to orthodontics; orthodontic braces work by applying pressure to the teeth to move through the bone when the baby sucks very hard pressure is only applied to the bone directly by their mothers.
If this habit continues, swallowing and speech may also be affected as moving a bone in the oral environment. If you believe that your child has sucked their thumb and move the bones then it is recommended that you visit a dentist as early as possible, even as young as 5 years old.