Minimal planning is required. It is only necessary to determine that there is sufficient bone stock to perform the osteotomies and place the distraction device.
Orthodontic appliances or arch bars are necessary to control the occlusion during distraction.
If any screws or other fixation devices are present in this part of the mandible from previous surgery, these should now be removed. An Obwegeser-Dal Pont type sagittal split osteotomy is performed. It should be remembered that previous surgery will have been performed in this area and the bone quality and quantity may be deficient.
The procedure starts with three corticotomies.
The first cut is made through the lingual cortex just above the mandibular foramen parallel to the occlusion. The corticotomy is extended from the anterior to the posterior borders of the ramus.
The second corticotomy is made through the buccal cortex in a vertical direction at the level of the first or second molar.
The third corticotomy connects the first two osteotomy lines along the anterior border of the ascending ramus.
The sagittal split
The final split is completed with a thin osteotome, splitting the entire ascending ramus from the anterior to the posterior border of the ramus.
5. Placement of the distraction device
Insertion of pins
One pair of pins is inserted bicortically in the distal segment anterior to the vertical osteotomy through the lower border of the mandible. The distance between the pins is determined by the distraction device using a special drill guide.
A second pair of pins is inserted monocortically into the lower border of the proximal fragment. The distance between the pins is determined by the distraction device using a special drill guide.
MMF is established.
The pins are attached to a special distraction device that functions by drawing the pins attached to the proximal fragment laterally.
An antibiotic ointment is placed at the junction of the pins and the skin.
After a suitable latency period, the ramus is distracted at a rate of 1.0 mm per day.
Frequent review of the patient is valuable until such time as the required distraction has been achieved. The occlusion must be monitored and intermaxillary elastics used as necessary.
This endpoint for distraction can be difficult to determine because the patient will inevitably be a little swollen following surgery. In addition it is not known how far the ramus can be lateralized before the patient will experience problems with the TMJ. We do know that approximately 1 cm of lateralization can be produced without causing any sequelae.
After reaching the desired distraction the device is left in place to retain the distraction and to allow for bone consolidation.
Consolidation will take approximately 8 weeks and the regeneration of bone into the distraction gap can also be verified with radiographs. When sufficient bone is present in the gap, the distraction device is removed.
7. Aftercare following distraction osteogenesis
Apply ice packs (may be effective in a short term to minimize edema).
The sterile dressing placed over the skin incisions is maintained for a minimum of 48 hours. Thereafter routine wound care should be instituted around the activation rod.
Antibiotic prophylaxis is continued for 1-5 days depending on the nature, complexity, and duration of the surgical procedure.
Patients with intraoral wounds must be instructed in appropriate oral hygiene procedures. A small soft toothbrush with toothpaste should be used. Antiseptic rinses can be used in the early postoperative period. If a Waterpik is used, care should be taken not to direct the jet stream directly over intraoral incisions to prevent wound dehiscence in the early postoperative phase.
Early post-operative x-rays are obtained to verify correct device placement. Additional postoperative imaging is performed as needed.
Remove sutures from skin after approximately 5 days if nonresorbable sutures have been used.
Regular follow up examinations to monitor healing and the postoperative occlusion are required.
Avoid sun exposure and tanning to skin incisions for several months.