The effect of ultrasound on osteogenesis in the vertically distracted edentulous mandible: a double-blind trial.

Whether low intensity pulsed ultrasound therapy stimulates osteogenesis in mandibular distraction was investigated in a double-blind trial. Nine patients underwent a vertical mandibular distraction over a distance of 5.1+/-1.2mm. Ultrasound or placebo therapy was started daily from the first day of distraction. After 46+/-8.1 days consolidation, two endosseous implants were inserted and a transmandibular biopsy was taken. Ultrasonographs were taken regularly to follow osteogenesis inside the gap. There were no complications during the 44+/-7.1 months of follow-up. Microradiographic measurements of the biopsies revealed no differences in the area of mineralized tissue in the distraction gap. The cranially distracted bone segment appeared significantly more radiolucent than the caudal bone. Histological examination showed large lacunae inside the cranially distracted bone segment, filled with clusters of osteoclasts and surrounded by clear tetracycline double labels. Within the distraction gap, woven bone was present, with no apparent differences between the treatment groups. Ultrasonographic follow-up revealed that osteogenesis inside the distraction gap progresses from 4 to 20 weeks post distraction, with no differences between the ultrasound and the placebo groups. In summary, ultrasound treatment does not appear to stimulate bone formation in the severely resorbed vertical distracted mandible.