Effects of low intensity ultrasound on mandibular fracture healing

Pulsed ultrasonic waves have been shown to accelerate fracture healing of the long bones. The aim of this study was to evaluate the effects of low-intensity pulsed ultrasound on healing of mandibular fractures. Thirty skeletally mature male New Zealand rabbits were used. Animals underwent unilateral mandibular osteotomy. The bone segments were repositioned and fixed with miniplates and miniscrews. The animals in the experiment group received daily ultrasound treatment, 20 min/day, for 20 days. Ultrasound signals consisted of a 1.5-MHz pressure wave administered in pulses of 200 microseconds with an average temporal and spatial intensity of 30 mW/cm2. Animals in control group received sham application. All of the subjects were sacrificed at 22nd postoperative day. Three point bending test, digital radiodensitometric analysis, histological and histomorphometrical examinations were performed on the harvested hemimandibles. The data were statistically analyzed. Biomechanical tests revealed significant improvement in the mechanical properties of the healing bone in the ultrasound treated group. This was supported by histological and radiological findings. Results of this study suggest that low-intensity pulsed ultrasound improves the bone healing of mandibular fractures in rabbits.