An underbite, also known as a Class III malocclusion, is a dental condition where the lower teeth extend beyond the upper teeth when the mouth is closed. This misalignment can range from barely noticeable to quite pronounced, affecting both appearance and oral function. This article explores its causes, when it needs attention, and available correction approaches.
Understanding Underbites
An underbite describes a specific type of bite misalignment where the lower jaw and teeth are positioned in front of the upper teeth. This contrasts with an ideal bite, where the upper front teeth slightly overlap the lower front teeth, allowing the back molars to meet properly. In a mild underbite, the protrusion of the lower teeth might be subtle, while in more severe cases, the lower jaw can visibly jut out, preventing the teeth from touching. This condition is also referred to as prognathism by dental professionals. It can create a distinct facial profile and impact how the teeth come together.
Why Underbites Develop
Underbites frequently have a genetic component, often inherited from family members. The shape and size of an individual’s jaw and teeth are largely determined by genes, increasing the likelihood if parents or other relatives have an underbite.
Environmental and behavioral factors during childhood can also contribute. Prolonged habits such as thumb-sucking, extended pacifier use beyond age three, and persistent bottle-feeding can exert pressure on developing teeth and jaws. Tongue thrusting, where the tongue presses against the front teeth during speech or swallowing, can also play a role. Injuries to the face or jaw can sometimes lead to misalignment. Tumors in the jawbone or mouth may also cause the jaw to protrude.
When an Underbite Needs Attention
While a mild underbite might not cause significant issues, more severe cases can lead to various functional and health problems. Difficulty with chewing is a common concern, as the misaligned bite can prevent proper food breakdown, leading to discomfort during meals. Speech difficulties, such as lisping or trouble pronouncing certain sounds, can also arise due to the improper positioning of the teeth and jaw.
Underbites can also cause chronic jaw pain or contribute to temporomandibular joint (TMJ) disorders. This occurs when uneven pressure is placed on the jaw joint, potentially leading to pain, stiffness, clicking, or a locked jaw sensation. The misalignment can also result in excessive wear on the front teeth, making them more susceptible to chipping, cracking, or breakage. An underbite can create areas where bacteria accumulate, increasing the risk of dental problems like tooth decay, cavities, and gum disease. Individuals may also experience chronic mouth breathing, snoring, or sleep apnea due to airway obstruction caused by jaw misalignment.
Addressing Underbites
The approach to correcting an underbite varies depending on its severity, the patient’s age, and the underlying cause. For children and adolescents whose jaws are still developing, early intervention often yields more effective results. Common orthodontic treatments include a palatal expander, which gradually widens the upper jaw, and reverse-pull headgear (face mask) to encourage forward growth of the upper jaw.
Traditional braces, consisting of metal or ceramic brackets and wires, are frequently used to reposition teeth and correct jaw alignment in both children and adults. Clear aligners, such as Invisalign, offer a more discreet option for mild to moderate underbites by gradually shifting teeth into place using custom-fitted trays. When overcrowding of the lower teeth contributes to the underbite, tooth extraction may be considered to create space. For severe skeletal underbites, particularly in adults where jaw growth is complete, orthognathic surgery may be recommended. This surgery reshapes and repositions the jawbones to achieve proper alignment and improve facial balance.