Biomechanical properties of regenerated bone by mandibular distraction osteogenesis.

OBJECTIVE

To study the biomechanical properties of the new bone generated by mandibular distraction osteogenesis (DO).

METHODS

A total of 11 healthy adult goats were randomly divided into 2 groups, the experimental group (n=9) and the control group (n=2). For the goats in the experimental group, the bilateral mandibles were gradually lengthened for 10 mm with distraction appliances. Three goats were sacrificed respectively at 2, 4 and 8 weeks after completion of distraction. Compressive, three-point bending and shearing tests were conducted on the standard regenerated bone samples and the whole unilateral mandibular specimens. For the goats in the cont rol group, no operation was made and the whole unilateral mandible was taken as the test specimen.

RESULTS

The compressive strength and bending stiffness of the new bone reached the normal level at 4 and 8 weeks after completion of distraction, respectively. But the shearing strength remained significantly weaker than that of the controls at 8 weeks after distraction.

CONCLUSIONS

The distraction appliance can be removed and the lengthened mandible should be exposed to adaptive functional exercise at 8 weeks after completion of distraction.