Effect of electrical stimulation on mandibular distraction osteogenesis.

This study was designed to examine whether the use of electrical stimulation during mandibular lengthening accelerates new bone formation. Twenty adult female rabbits weighing between 2800 g and 3200 g underwent left mandibular body osteotomy. After a 3 day latency period, an external fixation device was activated at a rate of 0.7 mm per day for 10 days. Direct current electrical stimulation of 10 microA was applied to 10 rabbit mandibles. Two of the screws were used as electrodes during the distraction phase. The other 10 rabbits (control group) were not stimulated. The device was then stabilized for periods of 10, 20, 30 and 60 days in both groups. The distraction segment was evaluated radiographically by assessing the proportion of bone mineral density using a dichroma scan. The amount of new bone formation was studied histologically with an image analyzer to evaluate the bone formation in the distraction gap. Histological examination showed that the new bone formation 10 and 20 days after distraction was greater in the electrical stimulation group than in the control group. Ten and 20 days after distraction, image analysis and analysis of bone mineral density in areas of newly formed bone indicated that there was a greater amount of new bone formation in the stimulation group than in the control group. The radiographic evaluation, however, did not demonstrate significantly different images between the stimulation group and the control group. Thirty and 60 days after distraction, no difference in the amount of new bone formation was noted in either the experimental or the control groups. These results indicate that electrical stimulation during gradual distraction promotes new bone formation in the early retention period in a rabbit model.