An underbite is when the lower front teeth sit in front of the upper ones as you bite together, usually because of how the jaws have grown. Children can have early treatment that guides the upper jaw's growth. Adults are treated with braces or aligners, or, for larger jaw differences, orthodontics combined with jaw surgery.
What causes an underbite
Most underbites are skeletal, which means the jaws rather than the teeth are the main cause. The lower jaw may have grown further forward than the upper, the upper jaw may have grown less, or both, and the pattern often runs in families. Some children only appear to have an underbite: one or two front teeth catch on the way in, and the lower jaw slides forward to close. These dental underbites are usually simpler to correct, and telling the two apart is the first job of an assessment.
Why it is worth treating
An underbite is rarely urgent, but it is worth having checked.
- When the front teeth meet the wrong way round, their edges can chip and wear.
- The lower front teeth can be pushed forward until the gum over them thins and recedes.
- Biting into food with the front teeth can be awkward, and some speech sounds may be harder to make.
- Many people feel self-conscious about the profile it creates.
How we assess it
The orthodontic consultation is complimentary and needs no referral. Dr Anand Srinivasa, our principal clinician, whose practice is restricted to orthodontics, passed the Membership in Orthodontics (MOrth) exams of the Royal Colleges of England, Glasgow and Edinburgh. His records (photos, digital scans and X-rays where needed) show whether the jaw closes forward from a shifted position. In a child, he also estimates how much growth is still to come, because the lower jaw can keep growing into the late teens, sometimes later. He plans treatment digitally, and you receive a written plan with the options, the timeframes they commonly take and the costs.
Growth guidance in children
Early treatment helps most when the upper jaw is the part lagging behind, and it is usually started before about age 10, while the upper jaw responds well. Depending on the case, that can mean a palate expander to widen the upper jaw, or a short course of partial braces to free teeth caught behind the lower ones. The aim is a normal overlap at the front and less need for complex treatment later. It cannot switch off an inherited growth pattern, so we keep checking until growth is complete. This phase commonly takes 6 to 12 months. Read more on early orthodontics and on front-tooth crossbites.
Options for teens and adults
Once growth has slowed, treatment moves teeth rather than jaws. For mild to moderate underbites, Damon™ braces or Invisalign®, often with elastics, can bring the front teeth back into a normal overlap, commonly over 12 to 24 months. When the jaw difference is large, moving teeth alone would tilt them to angles that are neither healthy nor stable, and orthodontics combined with jaw surgery is usually the more reliable path. Combined treatment commonly takes 18 to 30 months in total, including braces before and after the operation. See adult orthodontics.
Keeping the result
Retainers follow every case. Growing patients keep regular checks until the jaws settle, because late growth of the lower jaw can bring part of an underbite back, and some need a second phase. Our retainer guide explains the options. Individual results vary.
What it costs
As a guide, comprehensive treatment in Sydney is commonly quoted at roughly $4,500 to $8,000 for metal braces and $6,000 to $9,000 for Invisalign. Early treatment for a child is usually a smaller course. The surgeon and hospital quote their own fees separately. You get a written quote from us after an examination, with payment plans across treatment, and the Sydney braces cost guide explains what moves the price.