Ml. Samchukov et al., BIOMECHANICAL CONSIDERATIONS OF MANDIBULAR LENGTHENING AND WIDENING BY GRADUAL DISTRACTION USING A COMPUTER-MODEL, Journal of oral and maxillofacial surgery, 56(1), 1998, pp. 51-59
Purpose: Experience using distraction osteogenesis for limb lengthenin
g has shown the importance of appliance orientation. Although successf
ul results of mandibular lengthening using osteodistraction have been
reported, optimal orientation of the distracters relative to the mandi
ble has not been determined. The purpose of this study was to evaluate
the biomechanical effects of linear distracters placed parallel to th
e body of the mandible or parallel to the axis of distraction. Materia
ls and Methods: A two-dimensional model of the human mandible was gene
rated for computer simulation of mandibular osteodistraction. Linear d
istracters were then analyzed based on their orientation, either paral
lel to the body of the mandible or parallel to the axis of distraction
. In addition, two types of distraction osteogenesis procedures for ma
ndibular reconstruction were analyzed: 1) bilateral mandibular lengthe
ning, and 2) bilateral mandibular lengthening in combination with midl
ine mandibular widening. Results: Distracters oriented parallel to the
body of the mandible caused a lateral displacement of the posterior c
omponents of the distraction devices and a reduction of the midline di
straction gap during mandibular lengthening. These effects were elimin
ated when the device was oriented parallel to the axis of distraction.
Midline symphyseal widening created axial rotation of the mandibular
condyles regardless of the orientation of the distracters. Conclusions
: Distraction appliances must be oriented parallel to the axis of dist
raction to prevent adverse biomechanical effects during bilateral mand
ibular lengthening. Additional ramus osteotomies, using hinged devices
for angular correction, may be necessary to compensate for rotational
movements of the mandibular condyles secondary to midline osteodistra
ction.