Why is my Orthodontist Using the Nance Appliance for my Upper Jaw?

While it is difficult from your description to know for certain, my guess is that your orthodontist's analysis shows that the best outcome will be achieved if the upper back teeth do not move forward. The Nance holding arch is designed to ensure that such undesired tooth movement does not happen. If you are only six months in to treatment that involves extraction of four teeth, it is too early to make a judgement about outcome. Full space closure can take a year, or in some cases longer, before it is complete. So your treatment is a work in progress!

I suggest that you ask at your next orthodontic visit for an update on treatment progress and whether or not it is within the expected range. If things are moving slowly, your orthodontist might suggest more frequent appointments to be certain that you stay on schedule.

You mention that you have had four bicuspids extracted and that there are spaces remaining.  I assume that the spaces are being closed or are soon to be closed.  The process of closing the spaces can take up to a year in some cases. The purpose of the Nance is to "anchor" the upper molars so that they do not slip forward as the space closes. This may be necessary to allow the development of an ideal bite.  You should definitely discuss your concerns with your orthodontist.  There may be a simple explanation for what you are seeing.  He/she should be happy to go over any details of your treatment with you.  If you are not satisfied with the discussion you are always free to seek an opinion from another orthodontist.

A concept that is critical to successful orthodontics is to be able to anchor some teeth in place while being able to move others.  In other words anchorage helps control undesirable side effects.  The Nance is a great appliance for holding upper molars in their place.  Other forms of anchorage include headgears, elastics, and mini-screw implants.  Although a Nance can be very helpful in extraction cases, I have found that in some cases, as the space closes, it gets in the way. The gums on the palate can bunch up at the edge of the acrylic button.  I would certainly discuss with your orthodontist if the Nance is still necessary, is any anchorage still necessary, and if it is,  if there is another from of anchorage that can be used in your case.