A Palate Expander (also called a Palatal Expander or simply an Expander) is an appliance that helps to widen the upper jaw so that the bottom and top teeth fit together properly. In children who are still growing, the Palate is divided into two halves (left and right) which fuse together after puberty (usually by age 18 or 19). Before the two halves fuse together, an Orthodontist can affix a Palate Expander to gently and gradually widen the palate and create more space in the upper jaw. You usually need to wear a Palate Expander for a period of several months.
The device fits over several of the top teeth at the back of the mouth. It’s designed to exert a gentle force when a screw on the device is turned a little bit each day with a special Expander Key. (Some types of Expanders don’t use a key, but have built-in springs or other mechanisms). The continual force gradually moves the Palate apart in small amounts. It may sound uncomfortable, but it’s really a lot less painful than an orthodontic adjustment! Most children get used to the device being in their mouth and experience only a small amount of discomfort.
There are two main types of Palate Expanders used for different purposes:
- Tissue-borne – These apply the force directly to the tissues of the palate instead of the teeth. One example is the Haas Appliance.
- Tooth-borne – These apply the force directly to the teeth of the upper arch instead of the palate tissue. One example is the Hyrax Expander.
Within these two types, expanders can act on the palate in different ways:
- Slow Maxillary Expansion (SME) – These expand the palate in a slow manner, to allow time for jaw and facial growth.
- Rapid Maxillary Expansion (RPE) – These expand the palate in a fast manner, if that is what is necessary.
- Bone-Anchored – These require the expander to be screwed into the bone of both sides of the palate with micro screws. One example is a Maxillary Skeletal Expander (MSE)
In some cases, when the Orthodontist sees that the appropriate amount of expansion has been achieved, the device is stays in place for a few more months (without turning the screw). This allows enough time for new bone to grow inside the gap and stabilize the Palate.