An overbite, known clinically as a Class II malocclusion, occurs when the upper front teeth significantly overlap the lower front teeth. While a minor overlap is normal, a severe overbite can signal an underlying structural issue with the jawbones. Many mild to moderate overbites are effectively corrected using traditional orthodontic methods, such as braces or clear aligners, which focus on moving the teeth. However, when the misalignment stems from the size or position of the upper and lower jaws themselves, a more comprehensive treatment involving orthognathic surgery is often necessary. This type of jaw surgery is specifically designed to correct skeletal discrepancies that non-surgical methods cannot adequately address.
Recognizing Functional and Aesthetic Issues
A severe overbite often presents with noticeable functional challenges. Patients frequently report difficulty when biting and chewing food, as the upper and lower teeth do not meet correctly. This improper alignment can also contribute to speech impediments because the tongue placement is affected by the jaw structure. The constant strain can lead to chronic temporomandibular joint (TMJ) dysfunction, manifesting as jaw pain, clicking, or headaches.
Furthermore, the misaligned bite can cause abnormal and excessive wear on teeth surfaces, potentially leading to premature dental damage. From an aesthetic standpoint, overbite often results in mandibular retrognathia, giving the appearance of a recessed chin because the lower jaw is positioned too far back. The skeletal mismatch can also make it difficult to comfortably close the lips, a condition known as lip incompetence. The presence of these issues suggests a need for a professional evaluation that considers surgical options.
Determining Skeletal Discrepancy Severity
The decision to pursue surgery rests on differentiating between a dental overbite and a skeletal overbite. A dental overbite involves misaligned teeth on correctly positioned jawbones, treatable with orthodontics alone. A skeletal overbite involves a mismatch in the size or position of the maxilla (upper jaw) and the mandible (lower jaw), requiring repositioning of the bony structure.
The most common skeletal cause is mandibular retrognathia, where the lower jaw is positioned too far back. Once a patient has finished their adolescent growth phase (typically around age 16 for females and 18 for males), major skeletal discrepancies cannot be corrected by moving teeth. Only orthognathic surgery can physically reposition the jawbones to achieve proper alignment and stability.
Surgical intervention is considered when the horizontal discrepancy between the jaws is significant, often exceeding 8 to 10 millimeters. This mismatch cannot be compensated for by tilting the teeth with braces. Orthodontists use cephalometric analyses to quantify this gap, indicating a severe misalignment that promises a poor outcome with orthodontics alone.
If the teeth are straightened without correcting the jaw position, the bite remains unstable, leading to persistent functional issues. Excessively moving the teeth to compensate for the discrepancy risks placing them outside the supporting bone, potentially causing root resorption and gum recession. Surgery is necessary to correct the foundational problem and ensure long-term stability.
Diagnostic Tools Used in Jaw Evaluation
Clinicians rely on objective measurements and advanced imaging to quantify the skeletal discrepancy and precisely plan the treatment. A standard tool is the panoramic X-ray, which provides a broad two-dimensional view of the entire dentition, jawbones, and temporomandibular joints. This initial image helps assess root health and rule out underlying pathology before advanced planning begins.
The lateral cephalometric X-ray is the foundation for determining skeletal severity, capturing a precise side-view of the skull and facial structures. Orthodontists take numerous measurements, such as the ANB angle, which quantifies the relationship between the maxilla and the mandible. An ANB angle significantly higher than the normal range (typically 2 to 4 degrees) strongly indicates a Class II skeletal problem, suggesting the lower jaw is positioned too far back.
For comprehensive planning, a three-dimensional Cone Beam Computed Tomography (CBCT) scan is utilized to visualize the bone in all planes of space. The CBCT provides detailed cross-sectional images, allowing the surgical team to assess bone volume and precisely map the intended movements of the jaw segments. High-resolution dental impressions are also taken to create accurate models of the bite, simulating the final tooth and jaw relationship post-surgery.
Planning the Surgical Consultation
Once imaging confirms a skeletal issue warranting surgery, the treatment shifts into a planning phase involving a multidisciplinary team. This requires close collaboration between the treating orthodontist and the oral and maxillofacial surgeon. The orthodontist begins the pre-surgical orthodontic phase, called decompensation, using braces to align the teeth over their misaligned jawbones.
This pre-surgical alignment often makes the overbite look temporarily worse, but it is necessary to ensure the teeth fit together perfectly when the jaws are surgically moved into position. During the surgical consultation, the surgeon reviews the virtual surgical plan, discusses the specific osteotomies (bone cuts) to be performed, and outlines the expected timeline.
Discussions cover the potential benefits of improved function and aesthetics, along with a detailed overview of the procedure’s risks, hospital stay, and post-operative recovery protocol. This final planning phase ensures both the patient and the clinical team are aligned on the goals and sequence of the complex treatment.