Mandibular deficiency is one of the most common facial deformities the orthodontist and maxillofacial surgeon encounter. Traditional orthognathic surgery addresses such cases with generally acceptable results. The stability of the advancement and integrity of the sensory nerve of the lower face remain an area of concern in cases where the patient needs a significant amount of mandibular advancement.
Factors that contribute to relapse of this surgical procedure and possible nerve damage include, but are not limited to: trauma at time of surgery, connective tissue tension, control of proximal segment, magnitude of distal segment advancement, age of patient at operation, method of fixation, and quality of bone healing.
Distraction osteogenesis surgery can be used to advance a patient’s deficient lower jaw in a relatively atraumatic manner. Distraction surgery has been shown to preserve the integrity and function of the nerve which provides sensation to the lower jaw and face in cases of more significant advancement. Long term stability of the advancement in distraction surgery is more likely because of the gradual movement forward of the lower jaw followed by bone formation in the distraction gap.
While the patient is under general anesthesia the lower jaw is gently fractured and then the distraction devices are affixed to the bone. A small part of the device protrudes through the gum tissue in order that the doctor can activate the device later.
After about a week of healing the patient returns to the office for activation of the device. This will be done almost daily until the lower jaw is in the proper position. Once the lower jaw is in the correct position the devices are left in place for 3 to 6 months while the bone consolidates. Then, while the patient is under general anesthesia, the devices are removed.