Mandibular Bi-directional Distraction Osteogenesis: A Technique to Manage both Transversal and Sagittal Mandibular Diameters via a Lingual Tooth-Borne Acrylic Plate and Double-Hinge Bone Anchorage

Objectives: In orthognathic surgical practice both transversal and sagittal mandibular expansion can be required.
An original technique for mandibular transversal-plus-sagittal distraction osteogenesis is presented.

Methods: The procedure has been planned as follows.
An anterior dento-alveolar osteotomy comprising 4 or 6 teeth is performed. Moreover, a vertical symphysiotomy is done in the basal bone.
A T-shaped mini-plate is fixed on the basal bone with one screw on each side of the ymphysiotomy, so the two mandibular halves are fastened together. The last hole of the T-plate vertical arm, which is mobile from the rest of the plate, is secured to the frontal dento-alveolar segment.
The distraction procedure is performed via lingual tooth-borne devices An acrylic plate with a transversal expansion screw is fixed first to the teeth lingually.
After a week latency, the daily activation of the screw begins and is continued till the planned expansion is obtained; the two fixation screws act as hinges on the basal bone.
Then, the lingual plate is removed and a second plate with two sagittal-acting screws is applied. The two screws are activated daily till the sagittal distraction of the frontal block is achieved.

Results: Ten patients have been treated with the described technique in the last two years. The distraction procedures were carried on as planned without inconveniences. The orthodontic treatment continued then as usual.

Conclusion: Bi-directional mandibular distraction is difficult to perform because of both mechanical and surgical reasons. An original procedure for mandibular bi-directional simultaneous distraction is presented.
The osteotomy is performed in the symphyseal area, comprising both a dento-alveolar osteotomy and a vertical symphysiotomy underneath; two fixation screws work as hinges on basal bone. The distraction procedure is performed in two stages: first via a transversal acrylic plate, then with a sagittal acting distraction device.