Biomechanical properties of regenerated bone by mandibular distraction osteogenesis

Objective: To study the biomechanical properties of the new bone generated by mandibular distractionosteogenesis (DO).Methods: A total of 11 healthy adult goats wererandomly divided into 2 groups, the experimental group (n=9) and the control group (n = 2). For the goats in theexperimental group, the bilateral mandibles were graduallylengthened for 10 mm with distraction appliances. Threegoats were sacrificed respectively at 2, 4 and 8 weeks aftercompletion of distraction. Compressive, three-pointbending and shearing tests were conducted on the standardregenerated bone samples and the whole unilateralmandibular specimens. For the goats in the control group,no operation was made and the whole unilateral mandiblewas taken as the test specimen.Results: The compressive strength and bendingstiffness of the new bone reached the normal level at 4 and 8weeks after completion of distraction, respectively. But theshearing strength remained significantly weaker than that of the controls at 8 weeks after distraction.Conclusions: The distraction appliance can beremoved and the lengthened mandible should be exposed toadaptive functional exercise at 8 weeks after completion ofdistraction.