An underbite occurs when the lower front teeth extend beyond the upper front teeth, leading to a misalignment of the bite. This dental condition, formally known as a Class III malocclusion, can range in severity from a subtle overlap to a more pronounced protrusion of the lower jaw.
Understanding Underbites
An underbite is characterized by the lower jaw and teeth protruding past the upper teeth, creating an abnormal alignment. This condition is distinct from an overbite, where the upper teeth significantly overlap the lower teeth. Underbites are classified into two main types: dental and skeletal.
Dental underbites involve misaligned teeth, where the lower front teeth are angled improperly in front of the upper teeth, even if the jaw structure is relatively balanced. Skeletal underbites stem from a misalignment of the jaw bones. This occurs when the lower jaw (mandible) is oversized or positioned too far forward, or when the upper jaw (maxilla) is underdeveloped.
Factors contributing to an underbite include genetics, as jaw size and shape can be inherited. Childhood habits like prolonged thumb-sucking, pacifier use, or bottle-feeding beyond infancy can exert pressure on developing jaws and teeth. Injuries to the face or jaw, or rare instances of tumors, can also lead to an underbite.
How Braces Correct Underbites
Braces are a common and effective method for correcting underbites, particularly in mild to moderate cases. They work by applying consistent, gentle pressure to gradually shift teeth into their proper alignment. For underbites, braces move the upper teeth forward while guiding the lower teeth backward to achieve a balanced bite.
This process often involves specific orthodontic appliances used with braces. Elastics, or rubber bands, are frequently utilized, attached to brackets on both upper and lower braces to exert additional force and align the jaws. Palatal expanders may be used to widen the upper jaw, especially in younger patients whose bones are still developing.
Reverse-pull headgear (also known as a protraction facemask) is particularly effective for growing children. This external device consists of a frame with pads on the forehead and chin, connected by elastics to the upper teeth or an internal dental appliance. It gently pulls the upper jaw forward, encouraging its growth to catch up with the lower jaw, which can prevent the need for more invasive treatments later.
Other Treatment Options for Underbites
While braces are a primary treatment, other approaches are available. Early intervention, known as interceptive orthodontics, addresses jaw development issues in children before full growth. This phase-one treatment, often started around age seven, takes advantage of a child’s still-developing bones to guide jaw growth.
Functional appliances, such as reverse-pull headgear, are frequently used in interceptive orthodontics to encourage forward growth of the upper jaw or restrict lower jaw growth. This early treatment can significantly reduce the complexity or even eliminate the need for more extensive procedures later.
For severe skeletal underbites, especially in adults whose jawbones are fully formed, surgical options like orthognathic surgery may be necessary. This procedure involves reshaping and repositioning the jawbone to achieve proper alignment. Jaw surgery is typically recommended when the jaw misalignment is too significant for orthodontics alone to correct, or when it causes difficulties with chewing, speaking, or chronic jaw pain.
The Underbite Correction Process
Correcting an underbite typically begins with an initial consultation and thorough diagnosis by an orthodontist. This involves a detailed examination of the patient’s dental and skeletal structure, often including imaging techniques like X-rays and 3D scans to assess the severity and underlying causes. Based on this assessment, a personalized treatment plan is developed.
Once the treatment plan is established, braces and any necessary auxiliary appliances, such as elastics or expanders, are placed. Regular adjustments occur every few weeks to apply continuous, controlled forces that gradually shift teeth and guide jaw alignment. The duration of treatment varies depending on the underbite’s severity and the chosen methods. Mild dental underbites might be corrected in as little as 6 to 12 months, while severe skeletal cases requiring surgery could take 18 to 36 months for complete correction. Most patients complete treatment within 12 to 30 months.
After the active treatment phase with braces is complete, a retention phase follows. This involves wearing retainers, either removable or fixed, to maintain the newly achieved alignment of teeth and jaws. Retainers are important for preventing teeth from shifting back to their original positions and ensuring the long-term stability of the treatment results.
Importance of Correcting an Underbite
Correcting an underbite extends beyond aesthetic improvements, offering functional benefits and mitigating potential long-term health issues. A properly aligned bite improves chewing efficiency, aiding digestion and leading to clearer speech by optimizing the positioning of the tongue and teeth.
Leaving an underbite untreated can lead to various complications. The misalignment can cause uneven wear and tear on teeth, increasing the risk of enamel erosion, tooth decay, and tooth loss. Chronic jaw pain and temporomandibular joint (TMJ) disorders are also potential consequences, stemming from the strain placed on the jaw joints and muscles due to the improper bite. Untreated underbites may also contribute to gum disease, chronic bad breath, and in some cases, sleep apnea. Addressing an underbite early can prevent these problems from worsening and lead to improved oral health and overall well-being.