Underbite Treatment in Kent and Sammamish

In a healthy bite, the upper front teeth sit slightly in front of the lower front teeth, the upper arch overlaps the lower like a lid over a box. In an underbite, also called a Class III malocclusion, that relationship is reversed: the lower front teeth and often the lower jaw itself sit forward of the upper.

An estimated 1 to 5% of the population is affected, and underbite carries a strong genetic influence. If a parent, grandparent, or sibling had an underbite or jaw surgery, the odds that a child in the family will develop one are significantly higher.

Underbite is not a single condition with a single fix. The cause can be purely dental (only the teeth are tipped wrong), purely skeletal (the jawbones themselves are mismatched), or a combination of both.

That distinction is the most important call an orthodontist makes on this diagnosis, because it determines whether braces alone will do the job, whether growth modification can redirect the jaw in a child, or whether orthognathic surgery will be part of the plan in an adult.

A child who is seven and still growing has options an adult of thirty does not.

For skeletal underbites, the single most important variable in treatment outcome is timing. At age 10 and younger, the midpalatal suture that runs along the roof of the mouth is more open, and the maxilla is responsive to protraction forces transmitted through the upper jaw.

This is the window when a facemask (reverse-pull headgear) combined with a bonded palatal expander can physically pull the upper jaw forward and redirect facial growth. It is a narrow window, but when it is used well, it can turn a case that would otherwise require surgery into one that needs only braces.

What the Research Shows

A 2024 Cochrane systematic review (29 studies, 1,169 children) found that facemask therapy improved both the bite and the underlying jaw relationship immediately after treatment. Long-term follow-up is more nuanced: skeletal improvements tended to diminish by the three-year mark and appeared largely lost by six years.

However, clinicians consistently judged that children who received early facemask treatment were less likely to require orthognathic surgery in adulthood. Early intervention does not always permanently eliminate the jaw discrepancy, but it very often reduces its severity enough that an adult-stage surgical plan becomes unnecessary.

Family History Matters, Often More Than the Bite Itself at Age 7

Underbite has a strong hereditary pattern. When a parent or grandparent has an underbite or a history of jaw surgery, a child’s risk of developing one is significantly elevated.

A child’s bite at age 7 may still look acceptable even when the underlying growth pattern is already pointing toward Class III. The lower jaw continues to grow through puberty and can outpace the upper jaw, turning a subtle age-10 tendency into a severe age-15 problem.

When there is family history, Dr. Freelove recommends that evaluation happen no later than age 7 regardless of how the child’s bite looks at the time.

Children Under 10: Facemask Plus Palatal Expansion (Phase 1)

The gold standard for skeletal underbite in a growing child is the facemask + palatal expander combination. A bonded expander is placed first to widen the upper jaw and loosen the midpalatal suture. The facemask, a padded framework that rests on the forehead and chin, is worn at home and connected to the expander with elastic bands.

Those elastics apply a steady forward pull on the maxilla, redirecting growth of the upper jaw into a more normal anterior position relative to the lower.

At Freelove, a typical Phase 1 underbite protocol runs roughly six to twelve months: two to three weeks of active expansion, followed by retention of the expander while the facemask does its skeletal work, then removal once the bite is corrected and over-corrected slightly to account for continued mandibular growth.

Facemask wear is asked for during evenings and overnight, approximately 12–14 hours per day, and children adapt faster than most parents expect. The appliance is removed for school, sports, and meals.

These appliances are often better tolerated socially because nothing sits outside the mouth, and in cooperative patients they can produce meaningful skeletal change. Dr. Freelove selects the appliance based on the severity of the skeletal discrepancy, the child’s dental development, and, honestly, the family’s assessment of what the child will actually wear consistently.

Teens: MARPE, Braces, Class III Elastics, and Watchful Monitoring

Once the early growth window has slowed down, the skeletal component cannot be changed without skeletal anchorage or surgery. MARPE expansion extends the window of growth. Even adults have had positive orthopedic change with their use. Combined with dental compensation with braces/clear aligners, class III elastics (rubber bands stretched from the upper back teeth to the lower front teeth) tip the upper teeth forward and the lower teeth back relative to the jaws, or TADs, many class 3 bites can be treated non-surgically.

For teens with severe underlying skeletal underbites who are still growing, watchful monitoring through puberty is essential, if the lower jaw continues to outgrow the upper, a surgical plan may become necessary once skeletal maturity is reached.

Waiting to make the final call until growth is complete protects the patient from committing to surgery prematurely.

Adults: Camouflage or Orthognathic Surgery

Orthopedic growth with MARPE and/or orthodontic camouflage is appropriate for adults with mild skeletal underbites. MARPE with or without facemask can produce forward maxillary growth. Braces or clear aligners tip the upper front teeth forward and the lower front teeth back, disguising the jaw discrepancy at the dental level. The jaws themselves do not move without skeletal anchorage.

This works well when the skeletal discrepancy is small (ANB within one to two degrees of normal), the facial profile is acceptable to the patient, and there is no significant functional problem from the bite itself.

Orthognathic surgery is the correct choice for moderate-to-severe adult skeletal underbites. A Le Fort I osteotomy advances the upper jaw, a bilateral sagittal split osteotomy sets back the lower jaw, or both procedures are combined, depending on the analysis.

Orthodontic treatment is done before surgery to align the teeth into position for the jaws to meet correctly after repositioning, and a second phase of orthodontics refines the bite after healing. Dr. Freelove coordinates these cases directly with Kent and Sammamish-area oral and maxillofacial surgeons. Dr. Freelove handles the pre-surgical and post-surgical orthodontics in-house; the surgery itself is performed at the surgeon’s facility.