crowding

What is an Expander? How Does it Work?

July 14th, 2016

The 2 most common names used to describe this orthodontic device are an expander or a jaw widener.  There are, in fact, many different types of expanders – an RPE (Rapid Palatal Expander), a Quad Helix, a Haas Expander, a Schwartz Appliance, and a W-arch to name just a few.   Each one has a slightly different indication, but the overall purpose of most expanders is to make the jaw wider.

How does an expander work?  Through adolescence the upper jaw is composed of 2 separate bones.  An expander pushes the two halves of the jaw apart, the cartilage between the bones is stretched, and new bone is formed.  Ultimately, the jaw ends up wider than it’s starting point, which ultimately makes more room for the teeth.

The lower jaw is a little different; although it started as two separate bones while developing in the womb, the two bones of the lower jaw fuse into one prior to birth. Thus, while lower expanders can make more room by pushing the teeth apart or by tipping them, they don’t actually make the jaw bone itself wider.

The 2 most common orthodontic problems addressed by expanders are Crossbites and Crowding:

1 – Crossbite:   When the upper jaw is too narrow, this can result in upper teeth that are inside lower teeth;  an expander widens the jaw to ensure the proper relationship of the upper jaw being wider than the lower jaw;
2 – Crowding:  If the jaw isn’t large enough to accommodate all the teeth, an expander can be used to make more room for permanent teeth.

Let’s use an analogy:  imagine you have a box of crayons and you accidentally place too many crayons into the box.  The result is crayons that are all jumbled up.  If straight crayons are your goal, you can either remove some crayons ~or~ make the box bigger.  Your jaw is like the box and your teeth are like the crayons:  if your teeth are all jumbled up because the jaw isn’t big enough, you can either remove some teeth ~or~ make the jaw bigger by using an expander.

In previous generations, extractions were often preferred to expansion.  However, extracting teeth unnecessarily can result in poor facial esthetics.  A Board Certified Orthodontist is the best practitioner to determine whether or not your child would benefit from expansion to help avoid extractions and to ascertain the ideal timing for its use.

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