Lower Arch Expanders

A lower arch expander is an orthodontic appliance that is used at a young age, most often in elementary school, to gradually widen the lower dental arch. At 103 Orthodontics, we have found the design pictured above to provide the most predictable, efficient, and successful results.

Over the course of around nine months, we use the expander to gradually widen the lower arch to be the appropriate width. We teach the parent how to turn the expander, and we guide the frequency of the turns. Each turn of the expander accomplishes a very small amount of expansion, but many turns over time add up to be significant, typically in the range of 5-10 millimeters. We follow the progress closely with routine appointments, as the parent turns at home once or twice per week over numerous months.

First and foremost, the expansion creates significantly more space for adult teeth to come into the mouth. If utilized at a young age, a lower expander makes a substantial change in the development and shape of the lower dental arch.

Orthodontics has changed dramatically over the past twenty to thirty years. Many years ago, orthodontists used to first see a patient when all of the baby teeth had fallen out – at this age, the window for expanders had already passed; as a result, in a very crowded mouth, orthodontists would often remove adult teeth to create space to align the teeth. When removing adult teeth, the arch ends up being constricted, rather than widened. Although removing adult teeth is still indicated in some rare situations, our philosophy at 103 Orthodontics is to expand early at a young age when the jaws are malleable with the intent of avoiding adult teeth removal in the future.

Expanding the dental arches has also been shown to have a significant and favorable impact on the airway. In a crowded mouth with narrow arches, the tongue may be forced downward and backward, blocking the airway and making the patient potentially more prone to snore. Early expansion provides more room for the tongue, allowing the tongue to be more properly positioned. As a result, airway-focused orthodontic treatment has been shown to help children get a more restful sleep. Simply put, orthodontic treatment at 103 Ortho revolves around the airway.

Furthermore, expanding the lower arch allows for even further expansion of the upper arch. This can be extremely helpful in a severely crowded mouth when you need as much space to be created as possible.

Please note that a lower expander will not make the teeth perfectly straight. An expander makes generalized room in the mouth. In the future, braces or Invisalign can be utilized to align each individual tooth. In our office, we try to avoid braces and Invisalign when baby teeth are still present. Generally speaking, we wait for all of the baby teeth to fall out before starting braces or Invisalign, which is typically around 10-13 years old.

Unlike upper jaw expansion, which often separates the mid-palatal suture, the lower jaw consists of one bone that is bone-solid, so lower arch expansion focuses on guiding growth and reshaping the lower dental arch.

Many factors determine jaw structure and can contribute to a lower jaw being smaller than normal.

The most important factor to determine jaw structure is genetics. In our office, one of the first questions that we ask at every initial consultation appointment is “Has anyone in the family had orthodontics?” We want to know the family history because this information can help predict future jaw growth. For example, if both parents report that their upper canines were impacted due to lack of space, we need to factor this into decisions and be more apt to intervene orthodontically at a young age.

Habits (such as an improper swallow pattern) also affect jaw growth and teeth positioning. For example, some people use their lower lip to create a seal whenever swallowing. This means that the patient puts the lower lip upwards and behind their upper front teeth when swallowing. With this improper swallowing technique, the lower lip puts pressure to move the upper front teeth forward and the lower front teeth inward toward the tongue. In this case, the lower dental arch develops improperly with significantly less space available for adult teeth to properly come into the mouth. This likely would be an ideal case to use a lower expander to recreate lost space; we would also refer to a speech therapist and myofunctional therapist to teach the proper swallowing technique.

Diet also plays a significant role in proper arch shape. A softer, mushier diet of processed food has actually been shown to lead to the development of narrower and more constricted dental arches. On the other hand, a diet filled with challenging-to-eat foods (like raw vegetables and tough meat) has been shown to lead to wider dental arches during development. For example, if you analyzed the jaw structure of cavemen that ate only raw vegetables and hearty meat, you would see broad arches with nicely aligned teeth and adequate space available for all teeth, even including wisdom teeth. If you are interested in learning more about this theory, please read about Orthotropics (aka “Mewing”) developed by British Orthodontist Dr. Mew.

Premature loss of baby teeth can also contribute to dental crowding on the lower arch. Sometimes, a baby tooth is lost before its natural time due to trauma (like being knocked by a ball) or due to a large cavity. Baby teeth serve many purposes. They aid in chewing, speaking, brightening a smile, and holding space for future adult teeth. When a baby tooth is lost prematurely, the adjacent teeth typically drift towards each other, leading to space loss for future adult teeth.

Generally speaking, expanders were not common 20-30 years ago because kids saw orthodontists for the first time too late in age. Expanders are most effective in elementary school. However, two to three decades ago, kids saw the orthodontist for the first time as a teenager when all of the baby teeth had fallen out, often missing the window for expansion to be overly effective.