Bending of the distraction site during mandibular distraction osteogenesis in the rabbit: a model for studying segment control and side effects.
OBJECTIVE
The purpose of this investigation was to develop an animal model for studying and correcting mandibular distraction side effects.


METHODS
Twenty-nine rabbits underwent bilateral mandibular distraction. Bending of the mandible was accomplished by offsetting a linear distraction by 35 degrees from the occlusal plane (4 screws per distractor), rotating the anterior segment inferiorly (2 screws per distractor), and removing a 3- or 6-mm wedge of the distraction site. The amount of bite opening varied according to the surgical design. Direct measurements, radiographs, and histology samples were compared.


RESULTS
Linear distraction produced a 4-mm anterior open bite and a Class III malocclusion after 2 weeks of distraction. Segmental rotation produced an 8-mm anterior open bite without complications. Removal of a wedge initiated rotation of the anterior segment. A large wedge (6 mm) produced fibrous union in the distraction site. The amount of bite opening or closure depended on the number of surgical screws and position of the distractor. Serial histologic sections showed bone formation at the rotated, triangular distraction site.


CONCLUSIONS
Bite opening or closure can occur from loss of segment control or by altering surgical design. This information is needed to counter unwanted side effects or to plan segment rotations.
Yen
S L
SL
Department of Oral and Maxillofacial Surgery and the Center for Craniofacial Molecular Biology, University of Southern California, Los Angeles, CA, USA. syen@hsc.usc.edu
Wei
S
S
Li
S
S
Shuler
C
C
Yamashita
D D
DD
D000704:Analysis of Variance; D000818:Animals; D001863:Bone Screws; D004195:Disease Models, Animal; D005355:Fibrosis; D008310:Malocclusion / Q000000981:diagnostic imaging / Q000209:etiology* / Q000473:pathology / Q000517:prevention & control; D008313:Malocclusion, Angle Class III / Q000000981:diagnostic imaging / Q000209:etiology / Q000473:pathology; D008334:Mandible / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery; D019857:Osteogenesis, Distraction / Q000009:adverse effects* / Q000295:instrumentation / Q000379:methods; D010027:Osteotomy; D011817:Rabbits; D011859:Radiography; D012399:Rotation; D013314:Stress, Mechanical; D013997:Time Factors; D014945:Wound Healing