Teeth Underbites- when is the right time to see an orthodontist for this?

Sunday, 15 Jul 2018 Andrew Chang 680 hits Print it

Teeth Underbites- when is the right time to see an orthodontist for this?

Smiles Faces Orthodontics

I recently presented to a group of general dentists on teeth underbites, showing them how orthodontic treatment to improve their smile increases with complexity as we see them later. Your dentist may not be aware that early treatment of an underbite before the age of 10 years has a big impact on their orthodontic treatment plan choices. This is because the upper face growth is largely complete by 8-10 years.

The lower jaw growth may not be complete till 18-21 years. Treatment to prevent the lower jaw growing forwards is a long process that would need to continue till 18-21 years. Therefore, correcting underbites early where there is a jaw structure mismatch is focused on moving the upper jaw forwards. Treatment time ranges from 12-15 months and the appliances are comfortable and easy for your child to manage. This is usually sufficient time to obtain a slight overcorrection, which provides a buffer for further lower jaw growth later.

What this means for parents is that for 12-15 year olds with an underbite, when it is too late to move the upper jaw forwards and yet there is a good chance of further lower jaw growth, it is better to straighten the teeth at a later age, when more of the lower jaw growth has established. This can be a problem if your child is already quite self conscious of their smile if their teeth are also very crowded and there should be some discussion between you and the orthodontist about the pros and cons of commencing braces treatment at this time.

Why is an underbite a problem

As the upper front teeth are inside of the lower front teeth, certain foods like biting unto an apple may be hard. Large underbites can also cause a lisping when speaking.

A much more common picture we see are underbites where the upper and lower front teeth edges are able to meet initially (this can be checked by moving your lower jaw as far back as possible, closing the teeth, and seeing the first area of contact), but where the lower jaw then slides forward so the back teeth can meet together. This movement of the lower jaw happens many times throughout the day as we chew, eat and swallow, and often leads to noticeable chipping and wear of the upper and lower front teeth edges.

Underbite in a young teenager showing chipping and wear of the upper adult front teeth edges

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How successful is the early underbite treatment approach?

Elastics would need to be worn by your child to the upper expander plate. Sleep time wear of the elastics is usually sufficient to correct the underbite. These elastics are attached either to a removable chin & forehead cup (worn during sleep) or to a lower plate. The duration of treatment is usually 12-15 months. See below for a typical example.


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After (12 months)

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Braces are used to straighten teeth and not correct jaw structure mismatch, so braces are not usually placed for early underbite treatment.

Large studies have now been completed on this where they compared early treatment of underbites with no early treatment. What they found is early treatment of underbites does reduce the need for jaw surgery later. 2/3rds of the early treated group continued to maintain an overbite during their mid to late teenage years.

Orthodontic treatment options to correct an adult underbite. When is jaw surgery needed?

Where possible, our approach has been to avoid jaw surgery, or as a last measure. However, jaw surgery has the biggest improvement in facial changes.

As an older teen or adult, other options to correct a teeth underbite range from lower side teeth removal and braces or using temporary plates or screws to correct the teeth underbite with braces or aligners. The latter option is simpler with far less risks compared with jaw surgery, though  improvements in the chin & lip positions are mild.

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