Effects of low intensity pulsed ultrasound stimulation on bone regeneration in rat parietal bone defect model

Abstract

Purpose: Low intensity pulsed ultrasound stimulation (LIPUS) has been clinically applied to promote bone fracture healing in the orthopedic field. Thus, it is likely that LIPUS also stimulates bone regeneration in bone defects in the cranial-maxillofacial area. However, this has not been clearly proved. Furthermore, optimal time point and period of the application after the surgery has not been reported. The purpose of the present study was to evaluate the effect of LIPUS on bone regeneration in the rat parietal bone defects especially focusing on time and period of the application. Materials and Methods: Eighteen Wistar rats (14 weeks old) were divided into 6 groups: 5 experimental groups and a control group. Bone defect of 5 mm diameter was prepared on each side of the parietal bone and customized gelatin membranes were placed over the bone defects. LIPUS (160 mW/cm 2 , 15 min/day) was applied to the defect area with an active transducer externally in the experimental groups according to the schedules of the applications: Group 1 (day 6 -12), group 2 (day 13 -19), group 3 (day 20 -26), group 4 (day 6 -19) and group 5 (day 6 -26). All the animals were sacrificed at 28 days. The defects were analyzed with micro CT and then histologically. Results: In Group 1, new bone formation was significantly promoted and the newly-formed bone was thick and matured compared to the one of the control group. In other experimental groups there were tendencies of stimulation of new bone formation; however, they were not statistically significant. Discussion and Conclusion: The present study demonstrated that amount of new bone formation in the bone defect depended on the time and period of LIPUS application. It has been suggested that application of LIPUS at an early healing period, the second week after the surgery, effectively accelerated new bone formation.

The Effect of Low Intensity Pulsed Ultrasound Therapy on Osseointegration and Marginal Bone Loss Around Dental Implants

“…4 and 5). These findings were consistent with a previous study by Chen et al 13) who investigated the effect of LIPUS on bone regeneration in the rat parietal bone defects. These defects were analyzed with micro CT (µCT) and histological, demonstrating enhanced new bone formation fi lling the parietal defect whereby the newly-formed bone was thick and matured compared to the one in the control group.…”

“…It reveals that LIPUS has positive eff ect on the healing of bone and the loss of marginal bone in the control group was contributed to not using US therapy 13,26,27) . The justifi cation of using LIPUS in this study is to accelerate the bone healing processes around the newly placed dental implant.…”

“…Della Rocca 11) in her study on the eff ect of LIPUS on bone regeneration on Wister rats confi rmed that LIPUS can consolidate fractures and reduce bone healing time. It has also been shown that LIPUS enhances bone regeneration based on its angiogenic and osteogenic values both before and after dental implant placement 12,13) . Stimulation of the implant wound site using LIPUS may be a suitable chair-side (office) technique to achieve quality osseointegration and prevention of marginal bone loss…”

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

“…Their results showed that the amount of new bone formation in the bone defect was dependent on the time and period of LIPU application and was accelerated effectively at the second week after surgery. 23 As stated earlier, the second week after surgery is associated with the angiogenesis phase of the bone healing process. The intensity of LIPU and percentage of duty cycles should also be taken into account as factors influencing the healing results.…”

“…Ultrasound stimulation is considered to favour this phase as well. 23 The general clinical regimen for LIPU application is 20 min/day, 1 MHz sine waves repeating at 1 KHz, average intensity 30 mW/cm 2 , and pulse width 200 ms. However, there is no consensus regarding the therapeutic LIPU intensity.…”