An underbite occurs when the lower front teeth sit in front of the upper front teeth when the mouth is closed. While mild cases may cause minimal concern, more significant underbites can affect bite function and jaw alignment.
In a typical bite, the upper front teeth sit slightly in front of the lower front teeth. When this relationship is reversed — with the lower teeth protruding beyond the upper teeth — it is referred to as an underbite, sometimes called a reverse bite or Class III malocclusion.
The severity of an underbite can vary considerably. Some individuals have a very mild reverse bite that causes no functional difficulty, while others may experience problems with chewing, jaw comfort, or tooth wear. The underlying cause — whether related to tooth positioning, jaw size, or a combination of both — also influences the most appropriate management approach.
Professional assessment by a dentist is important for understanding the nature and severity of an underbite and for determining whether treatment may be beneficial. This page provides an overview of what an underbite involves, its possible causes, and the assessment and treatment options that may be available.
In a normal bite relationship, the upper front teeth overlap the lower front teeth slightly, with the upper arch sitting just outside the lower arch. This allows the teeth to come together comfortably for biting and chewing.
An underbite reverses this relationship, with the lower front teeth positioned ahead of the upper front teeth. This can range from a very mild edge-to-edge bite to a more pronounced protrusion of the lower jaw.
It is helpful to distinguish between an underbite and a crossbite, as the terms are sometimes confused. An underbite specifically involves the lower front teeth sitting ahead of the upper front teeth. A crossbite, by contrast, typically affects the teeth on the sides of the mouth, where one or more upper teeth bite inside the lower teeth.
Underbites can be broadly categorised as dental or skeletal. A dental underbite is primarily caused by the positioning of the teeth, while a skeletal underbite relates to differences in the size or position of the jaws themselves. In many cases, a combination of dental and skeletal factors may be present.
An underbite can develop for a variety of reasons, and the underlying cause often differs from person to person. In many cases, a combination of factors may contribute to the development of a reverse bite.
Inherited traits can influence the size and position of the upper and lower jaws. If the lower jaw grows larger or more forward than the upper jaw, an underbite may develop as a result of these natural growth patterns.
Certain habits during early development — such as prolonged thumb sucking, tongue thrusting, or extended use of a dummy — may influence jaw growth and tooth positioning, potentially contributing to an underbite.
Missing teeth, particularly in the upper arch, can allow surrounding teeth to shift over time. This gradual movement may alter the bite relationship and contribute to the lower teeth sitting further forward.
In some individuals, the upper and lower jaws develop at different rates or to different proportions. A relatively smaller upper jaw or a larger lower jaw can result in the lower teeth protruding beyond the upper teeth.
A professional assessment can help identify the likely contributing factors in your individual case and inform any recommendations for management.
Not all underbites produce noticeable symptoms. However, when the reverse bite is more pronounced, the following effects may be experienced:
When the lower teeth sit in front of the upper teeth, the normal biting mechanism is disrupted. This can make it more difficult to bite into food effectively or chew evenly on both sides.
In some cases, a significant underbite may affect the positioning of the tongue and lips during speech, potentially influencing the clarity of certain sounds.
An imbalanced bite can place additional stress on the jaw joint and surrounding muscles, which may contribute to aching, stiffness, or fatigue in the jaw area.
When the teeth do not meet in their intended positions, certain teeth may bear more force than others during biting and chewing, leading to accelerated or uneven wear patterns.
Some individuals may feel self-conscious about the appearance of their lower jaw or teeth when the bite relationship is visibly reversed.
If you are experiencing any of these effects, a dental assessment can help determine whether they are related to your bite alignment and what options may be available.
A dentist can evaluate your bite relationship through a clinical examination, which may include digital scans or imaging to provide a detailed view of how your teeth and jaws relate to one another. This assessment helps determine the type and severity of the underbite and whether it is primarily dental, skeletal, or a combination of both.
Understanding the nature of the underbite is essential for determining the most appropriate course of action. A dental underbite may be manageable through orthodontic tooth movement alone, while a skeletal underbite may require a more comprehensive approach.
Early evaluation — particularly during adolescence when the jaws are still developing — may support more predictable outcomes by taking advantage of natural growth patterns. However, orthodontic treatment for underbite can also be effective in adults.
Professional evaluation ensures that any underlying factors are identified and that treatment recommendations are tailored to your individual needs and circumstances.
The most suitable approach to managing an underbite depends on its type, severity, and the underlying cause. Treatment aims to create a balanced jaw relationship that may improve bite function and comfort. Options may include:
Traditional fixed braces use brackets and wires to gradually reposition teeth and improve bite alignment. This approach can address a range of underbite severities and allows precise control over tooth movement.
For suitable cases — typically mild to moderate dental underbites — clear removable aligners may be used to adjust tooth positioning with a more discreet treatment approach.
Your dentist or orthodontist will develop an individualised treatment plan that aims to create a balanced jaw relationship, taking into account the type, severity, and underlying cause of the underbite.
After active orthodontic treatment, retainers are typically recommended to maintain the corrected tooth positions and prevent the bite from reverting to its previous alignment.
In more significant skeletal underbites where jaw size or position is a primary factor, a combined approach involving orthodontics and other specialties may be considered to achieve a balanced outcome.
Your dentist or orthodontist will discuss which approach may be most appropriate for your situation and explain what each option involves in terms of the treatment process.
If you are concerned about bite alignment or lower jaw positioning, a dental assessment can determine whether orthodontic treatment may be appropriate. Our dental team can evaluate your bite and discuss the options that may be suitable for your needs.
Orthodontic assessment and underbite treatment are available at our London clinics. You can attend our South Kensington dental clinic or our City of London clinic near St Paul's for a professional dental evaluation.
South Kensington Medical & Dental is registered with the Care Quality Commission (CQC) and our clinicians are registered with the relevant UK regulatory bodies, including the GDC and GMC. Our dentists, dental nurses and medical professionals deliver care that meets the highest clinical, safety and ethical standards, because our patients deserve nothing less.
