DJS, or double jaw surgery, is an operation that repositions both your upper and lower jaws to correct problems with how they fit together. Known clinically as bimaxillary orthognathic surgery, it’s not a quick fix. The full process, including the orthodontic work before and after the operation, typically spans two to three years.
The surgery itself addresses structural issues that braces alone can’t solve. When the bones of the jaw are significantly misaligned, no amount of tooth movement will create a proper bite, a clear airway, or a balanced face. That’s where DJS comes in.
Why DJS Is Performed
Double jaw surgery corrects deformities in one or both jaws that cause real functional problems. The most common reasons include a bite so far off that chewing is ineffective, an airway narrowed enough to cause obstructive sleep apnea, speech difficulties from severe underbite or overbite, jaw joint disorders, and significant facial asymmetry. Some patients have all of these at once.
The jaw problems treated by DJS can be present from birth, as in conditions like hemifacial microsomia, or develop during adolescence when one side of the jaw grows more than the other. Functional impairments go beyond cosmetics: poorly chewed food can cause choking, a retruded jaw can collapse the airway during sleep, and chronic mouth breathing from a narrow upper jaw can lead to persistent gum disease. Many patients also experience meaningful impacts on self-esteem and quality of life from visible facial imbalance.
What Happens During Surgery
DJS involves two separate procedures performed in the same session, one on the upper jaw (maxilla) and one on the lower jaw (mandible). All incisions are made inside the mouth, so there are no visible scars on the face.
Repositioning the Upper Jaw
The surgeon cuts through the bone above your teeth using a specialized saw, separating the upper jaw from the rest of the skull. This cut runs horizontally across both sides of the face, through the bone just above the roots of the upper teeth. Once freed, the jaw is gently pulled downward, then shifted into its planned position. It could move forward, backward, up, down, or be rotated to correct a tilt. Titanium plates and screws hold it in place while the bone heals.
Repositioning the Lower Jaw
The lower jaw is split on both sides behind the back teeth, a technique called a bilateral sagittal split. The surgeon makes three cuts on each side: one on the inner surface of the jaw, one along the outer ridge, and one vertically through the outer surface. This creates a controlled split that separates the tooth-bearing portion of the jaw from the joint portion, allowing the surgeon to slide the lower jaw forward or back without disturbing the jaw joints. A prefabricated splint, made from detailed surgical planning, guides the jaw into its exact target position before it’s secured with titanium plates and screws.
The entire operation usually takes three to five hours under general anesthesia.
The Orthodontic Timeline
Surgery is only the middle chapter. Most patients wear braces for 12 to 18 months before the operation. This pre-surgical orthodontic phase isn’t about making your teeth look nice. It’s about moving your teeth into positions that will fit together correctly once the jaws are in their new alignment. Your bite may actually look and feel worse during this period, which can be discouraging, but it’s a necessary step.
After surgery, braces stay on for another six to nine months to fine-tune the bite and lock teeth into their final positions. Some patients are candidates for a “surgery first” approach that shortens the pre-surgical orthodontic phase, but the traditional route remains more common.
Hospital Stay and Early Recovery
Hospital stays for DJS typically range from one to four days. About two-thirds of patients go straight to a regular ward after the operation rather than an intensive care unit, though some hospitals reserve an ICU bed as a precaution for double jaw cases. Surgeons assess each case individually, and patients without significant bleeding, progressive swelling, or other complications generally don’t need intensive monitoring.
The first week is the hardest. Your face will be significantly swollen, your jaw will feel stiff, and opening your mouth wide won’t be possible. You’ll be on a liquid-only diet, taking everything through a syringe, straw, or small spoon. Think smooth soups, protein shakes, and anything that pours without lumps.
By week two, most people can graduate to fork-mashable foods: soft, moist items with small lumps that require minimal chewing. Some patients need to wait until week three for this stage. From weeks three through eight, gentle chewing of soft foods is allowed, but tough or fibrous things like nuts, raw vegetables, and chewy meat are still off limits. Full return to a normal diet happens gradually after that.
Nerve Sensation Changes
The most talked-about risk of DJS is numbness in the lower lip and chin. A major nerve runs through the center of each side of the lower jaw, directly in the path of the surgical split. Reported rates of altered sensation range from 8% to 32%, with one recent study finding a 21.5% rate of some lingering deficit at six months.
The good news is that when the nerve remains intact during surgery, most patients recover full sensation within six months. Mild cases where the nerve is simply bruised often resolve within days to weeks. More significant injuries, particularly when the nerve needs to be physically detached from bone during the split, can take eight months or longer. A small percentage of patients experience some permanent change in sensation, though complete permanent numbness is rare.
Titanium Hardware
The plates and screws used to hold your jaws in place are made of titanium and are designed to stay permanently. Most people never notice them. However, roughly 13% of patients eventually need at least one plate removed. The most common reason is infection (about 7% of patients), followed by a plate becoming exposed through the gum tissue, sensitivity to cold, or the hardware being noticeable to the touch. Plate removal is a much smaller procedure than the original surgery.
DJS for Sleep Apnea
For patients with obstructive sleep apnea caused by a recessed jaw, DJS (often called maxillomandibular advancement in this context) is one of the most effective surgical options available. A large meta-analysis of 627 adults found that the average number of breathing interruptions per hour dropped from about 64 to under 10 after surgery. The surgical success rate was 86%, and those results held steady at nearly four years of follow-up.
Complete cure, meaning breathing interruptions dropped below five per hour, occurred in about 43% of patients. For many others, the improvement was dramatic enough to eliminate or significantly reduce dependence on a CPAP machine, even if their numbers didn’t reach the strict “cure” threshold.