What is an underbite?

What is an underbite?

Class III malocclusion (more commonly referred to as an underbite or an anterior crossbite) affects approximately 10% of the population, where the lower jaw outgrows the upper jaw, causing the lower teeth to overlap the upper teeth. In a normal or ideal bite, the upper front teeth should slightly overlap the lower front teeth. Approximately 20 - 25 percent of our patients at Chatswood and St Ives Orthodontics seek treatment for an underbite.   

Underbites often have a genetic origin and can be identified by excessive growth of the lower jaw, a smaller upper jaw, or a combination of both. These characteristic features typically manifest at an early age, sometimes as early as 4-5 years old. If left untreated, Class III malocclusion tends to worsen as the individual grows, and does not self-correct, often leading to the need for jaw orthognathic (jaw) surgery in adulthood. This is due to the fact that the lower jaw continues to grow forward for a longer period than the upper jaw.

Untreated underbites can lead to various problems, such as compromised dental function, dental wear, aesthetic concerns, gum recession and speech difficulties.  

For effective treatment, early intervention is often recommended to achieve a more normal jaw relationship. In growing children this would involve growth modification to develop the upper and lower jaw together, aiming for facial and dental harmony, improved function, and better breathing. This is typically achieved using facemasks and jaw expanders or in in more severe cases temporary anchorage device (TADs) can be used as an alternative.

In adults, correction of an underbite can vary depending on the severity of the malocclusion (misaligned bite) and their specific dental and skeletal needs. In mild cases, correction can be accomplished with braces, while more severe cases a combination of orthodontic treatment and orthognathic (jaw) surgery is necessary to achieve optimal results for adult Class III correction.

It's essential for adults considering Class III correction to consult with a specialist orthodontist or an oral and maxillofacial surgeon with experience in treating adult malocclusions. They can assess your specific condition and create a personalised treatment plan that addresses your needs and goals for achieving a more functional bite and to improve dental and facial aesthetics.