Tongue thrusting is a habit which can end up in abnormal bone development leading to an open bite and crooked teeth. There are many speculations as to what causes it such as breathing problems, large tongue, genetics, etc. But one theory which I found interesting and wanted to share as food for thought was the 'gushing milk from baby bottle' theory - I gave it this name after attending a seminar on the benefits of breastfeeding related to Orthodontics.
Babies when fed through a bottle, in order to prevent the 'gushing milk' from the nipple of the bottle, will start to push back with their little tongues. This eventually becomes a habit. Some babies overcome this once they grow up. Some babies don't.
Breastfeeding has more benefits than the contents which give babies necessary immune-related antibodies. The act of suckling on mommy's breast takes a greater amount of effort to obtain breast-milk for the baby compared to the nipple of a bottle. Therefore, the baby won't have the problem of having to push back the 'gushing milk' with their tongue. This not only gives the baby's musculature, the needed normal level of exercise for proper/natural development of the muscles and bone, teeth positioning, and speech, but also promotes better circulation to the head and neck region.
Proper development to the head and neck may even aid in preventing certain breathing disorders such as Obstructive Sleep Apnea which is becoming more and more prevalent. Proper teeth positioning may reduce the need for complex orthodontic treatment for your child.
So working moms who choose to use pumps for bottles, this is a great choice for when you are not with your baby. But if time allows, I encourage you to try breastfeeding directly for your baby.