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Underbite: Symptoms, Causes, Treatment, Diagnosis, and More

Underbites, while the least common form of malocclusion, can still affect many individuals. Underbites are usually classified as part of Angle’s classification III. Globally 6.5% of individuals are affected with an underbite, or class III occlusion (1). While the percentage may seem slight, compared to other forms of malocclusion, underbites can have severe health impacts depending on their severity.

What is an Underbite?

An underbite is a classification of malocclusion characterized by the lower front teeth extending beyond the upper front teeth when the jaws are at rest or closed. This misalignment can vary in severity, ranging from mild to severe. Underbites can result from either, dental or skeletal discrepancies or be a combination of both (2). While some cases may only be of cosmetic concern, others cases can lead to functional problems affecting speech, chewing, and overall oral health.

Symptoms of Underbites

Identifying the symptoms of an underbite is crucial for timely intervention and treatment. Early intervention and treatment may be beneficial. Early treatment may allow dental providers to manipulate the patient’s bones during the growth phases, an option that is usually not available to adults.

  • Misaligned teeth: The most apparent indication of an underbite is the lower teeth extending beyond the upper teeth when the mouth is closed.
  • Difficulty chewing or biting: Underbites can disrupt the proper functioning of the jaws, leading to difficulty chewing food (3). This can be critical in young children if it affects an infant’s ability to nurse.
  • Speech difficulties: Severe underbites may alter the alignment of the jaw, impacting speech articulation and clarity (4).
  • Facial asymmetry: In some cases, underbites can cause noticeable facial asymmetry due to the protrusion of the lower jaw.
  • Temporomandibular joint (TMJ) pain: The misalignment of the jaws in underbite cases may contribute to TMJ disorders, resulting in pain and discomfort in the jaw joint. However, this may not always be the case and some patients can remain asymptomatic (6).

Causes and Risk factors of Underbites

Several factors contribute to the development of underbites. While underbites can occur in individuals of any age or background, certain factors may increase the risk of developing this dental condition.

  • Genetic factors – these factors play a significant role, as underbites tend to run in families. A family history of malocclusions, including underbites, predisposes individuals to inheritable jaw and teeth misalignments (7, 8). Jaw structure and shape, as well as facial structures, can be passed down hereditarily amongst family members. Some genetic conditions can also affect the growth of the jaw which can lead to underbites.
  • Structural issues – these issues include an oversized lower jaw or an undersized upper jaw (9).
  • Childhood Habits – Prolonged thumb sucking, pacifier use, or tongue thrusting during childhood can influence the development of underbites by exerting pressure on the teeth and jaws (10). Early habit prevention and intervention can help prevent the teeth from moving to a poor alignment.
  • Facial trauma: Traumatic injuries to the face or jaw region can disrupt the natural alignment of the jaws (11), potentially leading to underbites. Injuries, if severe enough can require surgical interventions.
  • Skeletal abnormalities: Conditions such as mandibular prognathism or maxillary hypoplasia can contribute to underbites by altering the shape and size of the jaws (12).

Treatment Options for Underbites

The treatment approach for underbites varies depending on the severity of the condition and the individual’s age. Your dental provider will examine and determine the appropriate treatment modalities. If you suspect you or your child have an underbite getting early intervention is preferable. Going to see a dental provider at an earlier age can help with treatment and may result in less invasive treatment options as well.

  • Orthodontic treatment: Mild to moderate underbites may be corrected using braces or clear aligners (13). Braces and aligners will gradually shift the teeth into proper alignment.
  • Orthognathic surgery: In cases of severe skeletal discrepancies, orthognathic surgery may be necessary to reposition the jaws and achieve proper occlusion. The most common type of orthognathic surgery in this case is referred to as a bilateral sagittal split osteotomy, BSSO (14). This surgery will involve collaboration between several dental specialists.
  • Dental appliances: Functional appliances such as headgear or palate expanders may be prescribed to guide jaw growth and correct underbite in growing children (15). During the growth phases, the bones can be manipulated as they have not fully fused.
  • Tooth extraction: In some instances, removing one or more teeth may be necessary to alleviate crowding and facilitate orthodontic treatment (16).

Diagnosis of Underbites

Diagnosing underbites involves a comprehensive evaluation by a qualified dental or orthodontic professional. An examination and diagnostic images may be taken during the evaluation process.

  • Clinical examination: The dentist or orthodontist will visually inspect the alignment of the teeth and jaws, assessing for signs of malocclusion such as underbites. Clinical examinations may also involve taking photographs to determine if the patient requires surgical intervention or if skeletal structure can be camouflaged with the patient’s soft tissue structure.
  • Dental imaging: X-rays, panoramic radiographs, or cone-beam computed tomography (CBCT) scans, and cephalographs may be utilized to obtain detailed images of the teeth, jaws, and facial structures.
  • Bite analysis: Functional assessments, such as bite impressions or intraoral scans, help determine the extent of the underbite and its impact on oral function. Dental professionals can examine a patient’s occlusion to determine if the tooth alignment may lead to damage due to an inappropriate occlusal load.

Prevention of Underbites

While some factors contributing to underbites, such as genetics, cannot be controlled, several preventive measures can help minimize the risk of developing an underbite.

  • Early orthodontic evaluation: Children should undergo routine dental check-ups starting from an early age, allowing for timely detection and intervention in case of developing malocclusions.
  • Breaking harmful habits: Parents should discourage habits like thumb sucking or prolonged pacifier use in young children to prevent adverse effects on dental and jaw development.
  • Protecting against trauma: Wearing appropriate protective gear during sports or activities that pose a risk of facial injury can help prevent traumatic facial fractures that may lead to underbites.
  • Seeking prompt treatment: Addressing dental issues promptly, including overcrowding or abnormal tooth eruption, can prevent complications that may contribute to underbite development.

Conclusion

Understanding the causes, symptoms, treatment options, risk factors, diagnosis methods, and preventive measures associated with underbites is essential for maintaining optimal dental health. By raising awareness and implementing appropriate interventions, individuals can effectively manage underbites and achieve healthy, well-aligned smiles.