Effects of low-intensity pulsed ultrasound on healing of mandibular bone defects: an experimental study in rabbits

Research evidence suggests that low-intensity pulsed ultrasound (LIPU) produces significant osteoinductive effects, accelerating the healing of bone defects. The authors investigated the effects of LIPU on mandibular bone defects in a rabbit model. Fifty-six adult Dutch rabbits were divided randomly into control, LIPU-1 (1MHz), and LIPU-3 (3MHz) groups. A mandibular defect was created in all rabbits. The effect of LIPU on mandibular defects was assessed by frequency (1 or 3MHz) and timing (2 and 4 weeks). Bone mineral density (BMD) was measured and stereology and histology performed; results were compared at the end of 2 and 4 weeks. LIPU-3 resulted in significantly higher bone formation compared to the control group at the end of week 4 on histological assessment (P=0.008). BMD was significantly higher at 4 weeks than at 2 weeks (P=0.03). LIPU-3 increased the numerical density of osteoblasts and osteocytes at the end of week 4 (P=0.05 and P=0.001, respectively). The results of this study are in favour of using LIPU 3MHz to accelerate mandibular bone healing. However, this study suggests that a frequency of 3MHz and the longer application of LIPU 3MHz for 4 weeks can only promote 8% mandibular bone healing in rabbits. Therefore, the use of LIPU has no really convincing, consistent clinical effects on maxillofacial bone healing.