What Is a Bi-maxillary Osteotomy?
Often corrective jaw surgery is performed on one jaw at a time. But when the upper and lower jaws are both operated on simultaneously, it is called “double jaw surgery”, two jaw surgery, or bi-maxillary osteotomy. Double jaw surgery may also involve a maxillomandibular advancement – moving the upper jaw (maxilla) and the lower jaw (mandible) forward.
What Are “Degrees of Freedom” in Orthognathic Surgery?
Often your surgeon will talk about “degrees of freedom” within jaw surgery. This refers to defining the directions in which the jaw can be moved into new, more beneficial positions.
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With double jaw surgery, we have the most “degrees of freedom”: increased creative freedom to shape the face and move the jaws – giving the patient the best chance for a favorable outcome.
For example, when we perform lower jaw surgery only, we use the upper jaw as a template for how the jaws fit together. Similarly with the upper jaw, the only degree of freedom is what the orthodontist has previously set up for the lower jaw.
However, with double jaw surgery, we have all possible degrees of freedom including vertical facial height which may also be altered if necessary.
Case Study: Double Jaw Surgery Alleviates Sleep Apnea
A 55-year-old woman was suffering from a long history of sleep apnea – a potentially serious sleep disorder in which breathing repeatedly stops and starts while sleeping. She had had multiple nasal surgeries and chin surgeries with another surgeon designed to improve her sleep apnea. These surgeries left her with a drooping chin, continued sleep apnea, and a poor shape to her face. In addition, she also suffered from a Class II malocclusion – a severe overbite wherein the upper teeth and jaw significantly overlap the lower jaw and teeth. Prior to surgery, Dr. Deschamps-Braly used a combination of old-fashioned x-ray tracing along with virtual surgery planning on CT scans to ensure an accurate result. Intra-operative splints were then fashioned using 3D printers rather than making them by hand. Dr. Deschamps-Braly then performed bimaxillary surgery which involved advancing the maxilla 4mm forward and down 4mm, while bringing the lower jaw forward 7mm and moving the chin backward 3mm and also performing a Chin Ptosis correction. As a result of the surgery, the patient’s sleep apnea has now been nearly totally resolved. She reports that her daytime sleepiness has abated and that she loves her new appearance.