Nasal Breathing and Braces?! Will Rubber Bands Help??

I love palatal expanders. I use a lot of them. The success of palatal expanders to increase the size of the nasal cavity and therefore improve breathing is directly related to the amount of suture separation that is achieved during activation. The mid-palatal suture (the junction between the two halves of your palate) usually matures or fuses between 14 and 16 years of age. Prior to suture maturation, palatal expanders can actually push the bones apart and increase the size of the nasal cavity. After the suture is mature, however, the expansion that is achieved is primarily dental in nature. In other words, the teeth move in the bone, but the palate remains the same size! You might actually have more room for your tongue, but it is doubtful that without surgery a palatal expander in a 20-year-old would actually change your breathing. For this reason, it is important to perform expansion on patients who need it BEFORE that suture is fused (i.e. 12 or 13 years old).

Expansion of your palate may have lead to an increase in volume of your nasal cavities, thus making breathing easier...at rest. Usually, especially as an adult, if you have been a mouthbreather through development, this initiates a change in your central nervous system that is permanent, and thus, even though you may be able to breath easy at rest when you are awake, when you fall asleep, the body will revert back to what it knows.

In addition, when on your back, your pharyngeal tissues collapse a little on your throat, reducing your functional airway. Unless your rubberband are pushing your lower jaw forward, chances are, you will still have difficulty breathing.

It sounds llike you are well informed about your treatment and the condition it's supposed to improve.  If you've noticed easier breathing from the treatment so far (including the palate expander) you are doing well.  After a lifetime of breathing a certain way it might take a few months to adapt to having more nasal airway available.  It's also possible that you could still have some obstruction to nasal breathing such as adenoids.  Ask your orthodontist about this possibility.  Perhaps a referral to an ENT doctor might be in order.