An open bite is a dental misalignment, or malocclusion, characterized by a lack of vertical overlap between the upper and lower teeth when the back teeth are closed together. This creates a visible gap, most commonly in the front of the mouth, which affects a person’s ability to bite, chew, and speak clearly. Effective treatment depends on identifying the underlying cause, which dictates whether correction requires simple tooth movement, advanced orthodontics, or jaw surgery.
Determining the Cause of the Open Bite
Determining the origin of the vertical gap is the first step in planning correction, and it typically falls into one of three categories. A dental open bite originates from issues with the teeth themselves, such as improper eruption or position. A habitual open bite results from repetitive behaviors like prolonged thumb sucking, pacifier use, or a tongue thrust, where the tongue pushes against the front teeth. These habits create constant pressure that pushes the teeth out of alignment.
The most complex type is the skeletal open bite, caused by an abnormal growth pattern of the maxilla (upper jaw) or the mandible (lower jaw). In these cases, the jaws are vertically misaligned, often resulting in a long lower facial height. Diagnosis requires a clinical examination combined with specialized X-rays, such as a lateral cephalometric analysis. This analysis measures the angles and relationships between the jawbones, helping to distinguish between a dental and a skeletal discrepancy. Early detection in children is beneficial because addressing a habitual cause can prevent a mild dental issue from progressing into a complicated skeletal problem.
Non-Surgical Orthodontic Corrections
Non-surgical approaches treat dental and habitual open bites, or mild to moderate skeletal cases in patients whose growth is complete. Traditional braces and clear aligners reposition the teeth by applying continuous forces. The goal is often to intrude, or push, the back teeth into the jawbone, which allows the mandible to rotate slightly forward and upward, effectively closing the gap.
Clear aligners achieve this movement by incorporating bite ramps that direct forces for posterior intrusion. Extrusion, which pulls the front teeth downward, is a secondary mechanism used cautiously, especially if the patient shows a lot of gum when smiling. This method is most successful when the underlying jaw relationship is normal.
To address habitual open bites, specific fixed or removable appliances are used. A tongue crib or spurs are bonded behind the upper front teeth to physically block the tongue from thrusting forward during swallowing. This device acts as a barrier, helping to retrain the tongue posture and eliminate the pressure keeping the bite open.
Temporary Anchorage Devices (TADs)
For challenging cases avoiding surgery, Temporary Anchorage Devices (TADs) are used. These are small, biocompatible screws temporarily placed into the jawbone to act as stable anchors. TADs allow the orthodontist to apply precise, intrusive forces directly to the posterior teeth. By intruding the molars, TADs encourage the lower jaw to autorotate counter-clockwise, which reduces the lower facial height and closes the open bite efficiently. This technique allows for the successful treatment of some moderate skeletal open bites that previously required orthognathic surgery.
Treatments for Skeletal Open Bites
When the open bite is due to a significant mismatch in jaw growth or position, correction requires a combined approach involving orthodontics and orthognathic surgery. This severe skeletal discrepancy is often characterized by excessive vertical growth of the posterior maxilla, causing the lower jaw to rotate downward and backward. The standard treatment is orthognathic surgery, or corrective jaw surgery.
The surgical phase typically involves a Le Fort I osteotomy on the maxilla, allowing the surgeon to separate and reposition the upper jaw. For open bite correction, the surgeon performs a differential posterior impaction, moving the back part of the maxilla upward significantly more than the front. This superior movement results in the counter-clockwise autorotation of the mandible, bringing the lower jaw forward and upward to close the vertical gap.
Skeletal correction is a two-phase process, starting with preparatory orthodontics lasting 12 to 18 months before surgery. This pre-surgical phase aligns the teeth within each jawbone so they fit together perfectly once the jaws are repositioned. After surgery, a final phase of post-surgical orthodontics is necessary to fine-tune the bite relationship. This comprehensive treatment is reserved for adult patients whose skeletal growth is complete, ensuring stability.
Retaining the Corrected Bite
The retention phase is a permanent component of open bite correction, regardless of the initial treatment method. After active appliances are removed, the teeth and surrounding tissues have a strong tendency to return to their original positions, known as relapse. Open bites are particularly susceptible to relapse, especially if the original cause, such as improper tongue posture, was not fully eliminated.
To maintain the corrected bite, a combination of fixed and removable retainers is prescribed for long-term wear. Fixed retainers are thin wires bonded to the back surface of the front teeth, providing continuous support. Removable retainers, such as clear aligners or traditional Hawley retainers, are worn full-time initially and then transitioned to indefinite nighttime use. If a tongue thrust was the cause, the removable retainer may incorporate a tongue guard to help maintain corrected tongue posture and ensure stability.