The tongue is a very strong muscle. It can exert pressure of 400 to 800 grams per square centimetre. Moving a tooth requires a minimum force of just 30 grams. Normal tongue movements don't move our teeth if the bone around them is completely healthy. This is because the tongue pushes on the teeth from the inside, but on the outside this force is balanced by the muscles of the lips and cheeks. If the tongue sits in an abnormal position or presses constantly on the teeth in one direction, then given how much force it can apply to a tooth, we can expect it to shift the teeth. Not only that – the force the tongue exerts is greater than that of braces. That is why, when an incorrect tongue position or faulty swallowing pattern is found and the problem isn't corrected, orthodontic treatment may not be effective, or part of the result may be lost after treatment ends.
This answer is for general information. Your own case needs an examination by an orthodontist.