Facial symmetry, where features on one side of the face mirror the other, is a key component of facial balance and aesthetics. While no human face is perfectly symmetrical, noticeable imbalances often stem from the underlying skeletal structure and dental alignment. The effectiveness of orthodontic treatment depends heavily on the cause and severity of the imbalance. For asymmetries rooted in dental issues, braces can offer significant improvements, but their ability to change bone structure is limited.
The Connection Between Bite Alignment and Facial Symmetry
The relationship between how your upper and lower teeth meet, known as the bite or occlusion, has a profound influence on the appearance of the lower third of the face. An aligned bite ensures that the jaw rests in a balanced, central position, promoting a harmonious appearance. Conversely, a misaligned bite, or malocclusion, can force the jaw to shift or compensate, leading to a visible imbalance.
One common cause of asymmetry is a posterior crossbite, where the upper back teeth sit inside the lower back teeth on one side. This can cause the lower jaw, or mandible, to functionally shift to one side to find a comfortable closing position. Over time, this constant shift can lead to uneven development of the jaw joint and muscles, resulting in a visible deviation of the chin and dental midline.
Other bite problems, like a severe overbite or underbite, also contribute to an unbalanced facial profile. An excessive underbite, where the lower jaw protrudes, can make the lower face appear unduly prominent, while a deep overbite can make the chin look recessed. By correcting these front-to-back discrepancies, braces help the jaw find a more natural and centered position. When teeth are crowded or unevenly spaced, the jaw may settle slightly off-center to achieve a functional bite, which affects the perception of symmetry.
Mechanisms of Facial Change Through Braces
Braces primarily work by applying continuous, gentle force to move the teeth within the supportive alveolar bone. This movement, known as dental compensation, allows the orthodontist to realign the dental arches and improve the relationship between the upper and lower teeth. Correcting dental crowding or gaps can improve the support structure for the lips and cheeks, which in turn enhances overall facial aesthetics.
For asymmetries that are primarily dental or functional, meaning they result from a shifted jaw position due to a bad bite, braces can be highly effective. By correcting a unilateral crossbite, for instance, the underlying dental interference is removed, which allows the jaw to settle into a more symmetrical, non-shifted position. This realignment can immediately reduce the appearance of a deviated chin or a crooked smile line.
The repositioning of the teeth has a direct effect on the overlying soft tissues, such as the lips and cheeks. When teeth that were flared outward are brought inward, the profile can become less convex, and the lips may rest more naturally. Correcting a deep bite can allow the lower jaw to rotate slightly, often making the jawline appear clearer and the chin more defined. These changes improve the harmony of the smile and bring the dental midline into alignment with the facial midline.
When Braces Alone Are Not Enough
While braces are powerful tools for moving teeth and influencing the jaw’s resting position, they have limitations when the asymmetry is caused by a significant skeletal discrepancy. Skeletal asymmetry refers to a true difference in the size, shape, or position of the facial bones, particularly the upper jaw (maxilla) or the lower jaw (mandible). Braces move teeth within the bone, but they cannot fundamentally alter the underlying size or shape of the jawbones themselves.
If one side of the jaw has grown significantly longer or shorter than the other due to developmental issues, braces can only attempt to camouflage the issue by tilting the teeth to achieve a functional bite. This process, known as orthodontic camouflage, can improve the bite and dental appearance, but the underlying skeletal imbalance will remain. For instance, in an adult with a large skeletal jaw difference, the facial asymmetry may persist despite perfectly aligned teeth.
In cases of severe skeletal asymmetry, the most effective treatment involves orthognathic surgery, commonly known as jaw surgery. This procedure is performed by an oral and maxillofacial surgeon to physically reposition the jawbones into a symmetrical alignment. Braces are a necessary part of this treatment, used before and after surgery to ensure the teeth align correctly once the bones are repositioned. Braces are also unable to correct asymmetry caused by soft tissue issues, such as uneven muscle tone, fat distribution, or congenital defects unrelated to the bone structure.