Combined Unilateral Mandibular Body and Ramus Lengthening by Intraoral Distraction Osteogenesis

Statement of the problem: Severe unilateral mandibular deficiency remains a challenge in facial reconstruction. The problem is 3-D and needs to be approached by increasing the mandible morphology by ramus and body lengthening and asymmetric genioplasty, adjunctive functional or cosmetic procedures are performed in a second stage; the surgical approach is based on the unilateral mandibular diagnosis: temporo-mandibular anquilosis, craniofacial microsomia type I, II or patients with CFM type III.

Material and Methods:  15 patients ages 6 to 18 years old average 9. 5 y.o., with unilateral mandibular deficiencies were divided in three categories. Group one, temporo-mandibular ankylosis were treated by increasing the mandibular frame by ramus and body lengthening, then in a second surgical stage distractor removal, TMJ gap arthroplasty, Le Fort I (in the adult patient, orthodontics in children to level the occlusal plane) and genioplasty were performed. Group two, Craniofacial microsomia type I or II with small functional condyles underwent mandibular ramus and body lengthening; the TMJ was fixated to the zygoma body with rigid fixation to avoid disc compression and damage. The plate was removed at the distraction appliance removal stage, Group three, Craniofacial microsomia type III were treated by condylar bone transport and body lengthening with intraoral distractors, on a second surgical phase the distractor is removed, genioplasty completed and dental implants were inserted.

Methods of data analysis: Detailed clinical analysis, facial radiographs (panoramic, lateral and P-A cephalic) and careful occlusal evaluation.

Results: The patient mandibular frame was increased by lengthening the ramus 12 to 30 mm average 20 mm, body lengthening 10 to 30 mm average 16 mm. The chin was asymmetrically advanced 10 mm, 8-12mm, to increased the deficient side and vertically reduces the longer side. On the second surgical stage, the distractors were removed, complementary procedures wee executed, secondary genioplasty (if needed), Le Fort I leveling osteotomy, orthodontics, dental implants insertion and TMJ arthroplasty in the TMJ ankylosis group.

Conclusions: The unilateral mandibular deficiency patients were differently treated according to: TMJ ankylosis, small functional condyle or absent condyle.  Facial symmetry, function and esthetics were obtained combining intraoral distraction osteogenesis and complementary procedures at distraction devices removal.

References:

Guerrero CA, Bell WH, Meza LS: Intraoral distraction osteogenesis. Maxillary and mandibular lengthening. In McCormick SU, guest editor: Atlas of the oral and maxillofacial Surgery Clinics of North America (distraction osteogenesis), 1999 , pp 111-151.

Guerrero CA, Figueroa F, Bell WH, et al: Surgical orthodontics in mandibular lengthening. In Bell WH, Guerrero CA, editors: Distraction osteogenesis of the facial skeleton, Hamilton, Ontario, 2007, BC Decker, pp 373-388