Bimaxillary osteotomy, often referred to as double jaw surgery, is a specialized type of orthognathic surgery. This procedure focuses on correcting significant misalignments of both the upper jaw, known as the maxilla, and the lower jaw, or mandible. The primary aim of bimaxillary osteotomy is to realign these jaws, leading to improved bite function and enhanced facial symmetry.
Conditions Treated by Bimaxillary Surgery
Bimaxillary surgery addresses jaw and bite irregularities, particularly skeletal discrepancies where the upper and lower jaws do not align properly, which cannot be corrected with orthodontics alone. Common issues include prognathism (a protruding lower jaw) and retrognathism (a receding lower jaw).
Other conditions include an open bite, where front teeth do not meet, or a crossbite, where upper and lower teeth do not align laterally. Facial asymmetry, caused by uneven jaw growth, can also be corrected to restore balance. These misalignments can impact functional aspects such as chewing, speaking clearly, and even breathing, with some patients experiencing conditions like obstructive sleep apnea.
The Bimaxillary Surgery Procedure
Bimaxillary surgery is performed under general anesthesia. Incisions are typically made inside the mouth to avoid any visible external facial scars. The surgical process involves repositioning both the upper and lower jaws to their pre-planned positions.
The first component, a maxillary osteotomy, usually involves a Le Fort I osteotomy technique. The upper jaw (maxilla) is carefully cut and separated from the rest of the facial skeleton. The surgeon then mobilizes the maxilla, moving it into its new, precise alignment, which can involve movements in vertical, horizontal, or rotational planes. Once repositioned, the upper jaw is secured with small titanium plates and screws to maintain its position.
Following the maxillary repositioning, a mandibular osteotomy is performed, often using a bilateral sagittal split osteotomy (BSSO) technique. This involves surgically splitting the lower jaw (mandible) on both sides. The lower jaw segments are then repositioned forward or backward, or rotated, to achieve the desired alignment with the newly positioned upper jaw. Similar to the upper jaw, the repositioned mandibular segments are then secured with plates and screws to ensure stability during healing.
The precise movements and final jaw positions are pre-planned using advanced 3D imaging and models for an accurate and harmonious outcome. This entire surgical process typically lasts several hours.
Recovery and Post-Operative Expectations
Immediately following bimaxillary surgery, patients can expect a hospital stay, typically lasting one to two days. Swelling and bruising around the jaw and face are common, typically peaking within 48 to 72 hours and gradually subsiding over the next two weeks. Pain is managed with prescribed medications for discomfort during this initial recovery phase.
Dietary restrictions are necessary in the initial weeks to protect the healing jaws. A liquid diet is required for the first 48 hours, progressing to pureed foods for about a week, and then soft foods for approximately three weeks. Chewing solid foods is not recommended for the first three to four weeks after surgery. Orthodontic elastics or wires may be used to guide and stabilize the jaws as they heal.
Patients commonly experience sensations such as numbness in the lips, chin, or cheeks due to nerve involvement during the surgery. This numbness is typically temporary, with sensation returning over several weeks to months, though in a small percentage of cases, it may be permanent. Temporary difficulty with speaking and eating is also expected. While initial healing takes about six weeks, complete healing and muscle firming can take between six to ten months. Follow-up appointments with the surgeon and orthodontist are important to monitor healing progress and continue any necessary post-surgical orthodontic treatment.
Potential Risks and Complications
As with any surgical procedure, bimaxillary surgery carries general risks such as adverse reactions to anesthesia, infection at the surgical sites, or bleeding. However, there are also specific risks associated with jaw surgery. Nerve damage, particularly to the inferior alveolar nerve, can occur, leading to temporary or, less commonly, permanent numbness in the lower lip and chin.
Another potential concern is relapse or instability of the jaw position, where the jaws shift from their corrected alignment over time. While modern fixation methods and precise planning have reduced this risk, it remains a consideration. Temporomandibular joint (TMJ) issues can arise, though surgery may improve pre-existing TMJ pain. Other rare complications include non-union or malunion of the bones, where segments do not heal correctly, and requiring revision surgery for unsatisfactory outcomes. Despite these potential risks, bimaxillary surgery is considered safe when performed by experienced oral and maxillofacial surgeons.