An underbite, a Class III malocclusion, is a dental condition where the lower teeth overlap the upper teeth when the mouth is closed. While a slight underbite may be subtle, more severe cases can cause significant oral health issues, including chewing, speaking, and breathing difficulties. Understanding what causes underbite is essential for both prevention and effective treatment. This blog post will delve into the various factors contributing to underbites, discuss potential complications, and explore the range of treatments available.

Genetic Factors: The Role of Inherited Traits

One of the primary causes of underbite is genetics. If your parents or close relatives have an underbite, you may also be more likely to develop one. This is because the size and shape of a person’s jaw are often inherited. A protruding lower jaw, characteristic of an underbite, can be passed down through generations. When the lower jaw is larger, or the upper jaw is smaller than average, the lower jaw overlaps the upper, causing an underbite. This imbalance in jaw alignment is a common reason why underbites occur in families.

Genetic factors can also influence the size and positioning of the teeth themselves. For instance, if a person has an unusually large set of lower teeth or an unusually small set of upper teeth, it can contribute to developing an underbite. Additionally, the way permanent teeth erupt can also play a role. In some cases, the upper teeth may not fully develop or be misaligned, causing the lower teeth to protrude slightly forward, leading to an underbite.

Developmental Issues: The Impact of Childhood Habits

While genetics play a significant role, developmental factors during childhood can also cause an underbite. Certain childhood habits, such as thumb sucking, prolonged use of a pacifier, or bottle-feeding beyond infancy, can exert pressure on the developing jaw and teeth, leading to misalignment. Tongue thrust, where the tongue pushes against the lower teeth instead of the upper teeth during swallowing, can also contribute to developing an underbite. These habits can cause the lower jaw to grow more prominently than the upper jaw, resulting in a slight underbite or even a more prominent underbite in severe cases.

Mouth breathing, often due to chronic nasal congestion or allergies, can also affect jaw development. When a child breathes through their mouth instead of their nose, it can alter the position of the tongue and the growth of the dental arch, potentially leading to an underbite. This is because mouth breathing tends to keep the tongue in a lower position, which can contribute to the protruding lower jaw seen in underbite cases.

Medical Conditions and Syndromes: When Underbite is a Symptom

Sometimes, an underbite can be a symptom of a more complex medical condition or syndrome. For example, cleft lip and palate, a congenital condition where the upper lip and palate tissues do not fuse properly during fetal development, can cause an underbite. This is because the misalignment of the upper jaw’s rear and upper back teeth can contribute to a skeletal underbite. Additionally, certain genetic syndromes, such as Crouzon syndrome or Treacher-Collins syndrome, can affect the development of the bones in the face, leading to jaw misalignment and an underbite.

Temporomandibular joint disorder (TMJ) is another condition that can contribute to underbites. TMJ affects the joint connecting the lower jaw to the skull, leading to pain, discomfort, and difficulties in jaw movement. In some cases, TMJ can cause the lower jaw to shift forward, resulting in an underbite. This shift can occur gradually over time, making it a progressive issue that may require treatment to prevent further complications.

Injuries and Trauma: The Aftermath of Severe Injuries

Injuries to the face or jaw can also cause an underbite. A fractured jawbone, for example, can alter the alignment of the teeth and jaw, leading to an underbite. Severe injuries to the jaw can disrupt the normal growth and development of the bones, causing a misalignment between the upper and lower jaws. This is particularly true if the injury occurs during childhood when the bones are still growing and developing.

Orthognathic surgery is sometimes required to correct an underbite caused by injury. This type of jaw surgery involves repositioning the bones of the upper and lower jaws to achieve proper alignment. In severe cases, orthognathic surgery may be the only way to correct the misalignment and restore proper jaw function.

Dental Issues: The Role of Tooth Development and Oral Health

Dental factors can also play a significant role in the development of an underbite. For instance, if a child’s primary teeth do not fall out in the correct sequence, it can affect the alignment of the permanent teeth, leading to an underbite. Additionally, if the upper jaw’s rear teeth or upper back teeth are misaligned or if the lower teeth overgrow, it can contribute to the development of an underbite.

Tooth decay and gum disease can also impact the alignment of teeth and jaws. Severe tooth decay can lead to tooth loss, which can cause the remaining teeth to shift out of place, potentially leading to an underbite. Also, gum disease can cause the gums and bone supporting the teeth to deteriorate, leading to misalignment.

Orthodontic treatments, such as braces or an upper jaw expander, are often used to correct an underbite caused by dental issues. These treatments can help reposition the teeth and jaws, improving the smile’s function and appearance. In some cases, tooth extraction may be necessary to create space for the remaining teeth to be properly aligned.

Treatment Options: How to Correct an Underbite

Several treatment options are available for correcting an underbite, ranging from noninvasive orthodontic treatments to more complex surgical procedures. The best option will depend on the severity of the underbite and the underlying cause.

Orthodontic Treatments

Orthodontic treatments are often the first line of defence in correcting an underbite. Braces, for example, can gradually reposition the teeth and jaw, improving the alignment of the bite. An upper jaw expander may also be used with braces to widen the upper jaw, creating more space for the upper teeth and correcting the misalignment.

In some cases, an orthodontic treatment headgear may be recommended to help guide jaw and teeth growth. This dental device is typically used in children and adolescents whose bones are still developing. Orthodontic treatments can take several months to a few years to achieve the desired results, but they are often highly effective in correcting mild to moderate underbites.

Jaw Surgery

Jaw surgery may be necessary for more severe cases of underbite. Orthognathic surgery, in particular, is a common procedure used to correct severe underbites. This surgery involves repositioning the bones of the upper and lower jaws to achieve proper alignment. In some cases, jaw surgery and orthodontic treatments may be required to achieve the best results.

Jaw surgery is typically recommended for adults whose bones have stopped growing, as it is a more permanent solution to correcting an underbite. However, it is important to note that jaw surgery is a major procedure that requires careful planning and recovery time. Patients who undergo jaw surgery may need to follow a special diet and take precautions to ensure proper healing.

Dental Appliances

In addition to orthodontic treatments and surgery, dental appliances can also be used to correct an underbite. For example, a retainer or an upper jaw expander can gradually shift the teeth and jaw into the correct position. These appliances are typically used with braces or other orthodontic treatments to achieve the desired results.

In some cases, tooth extraction may be necessary to create space for the remaining teeth to be properly aligned. This is often the case when the bottom teeth are overcrowded, which can contribute to the development of an underbite. After tooth extraction, orthodontic treatments can be used to close the gaps and improve the alignment of the teeth.

Conclusion: The Importance of Early Intervention

Understanding what causes an underbite is the first step in preventing and treating this dental condition. Early intervention is crucial in achieving the best outcomes if genetic factors, childhood habits, injuries, or dental issues cause the underbite. Orthodontic treatments, jaw surgery, and dental appliances offer effective solutions for correcting an underbite and improving oral health.

If you or your child has a severe underbite, it is important to seek the advice of a dental professional. Early diagnosis and treatment can help prevent more severe complications and ensure a healthier, more functional smile. By addressing the underlying causes of an underbite and choosing the appropriate treatment, you can achieve long-lasting results and enjoy better oral health for years to come.

References

https://www.healthline.com/health/underbite

https://my.clevelandclinic.org/health/diseases/24985-underbite#:~:text=These%20actions%20include%20prolonged%20thumb,jaw%20can%20cause%20an%20underbite.

https://www.webmd.com/oral-health/what-to-know-about-underbite