Enhancement of Maturation Using Low-intensity Pulsed Ultrasound on Bone Formation Induced by rhGDF-5

在我们以前的研究中，我们能够通过使用rhGDF-5诱导骨形成。然而，该研究的结果表明，即使骨形成发生，所产生的骨生长是不成熟的。本研究评估了低强度脉冲超声刺激（LIPUs）促进重组人生长分化因子5（rhGDF-5）诱导的骨成熟的有效性。本研究使用体重约12 kg的成年比格犬。β-TCP基质与rhGDF-5的复合物由每克β-TCP颗粒含有500 μ g的rhGDF-5制成。本研究中使用了直径为3.7 mm、长度为8 mm的Ti-6A 1 -4V牙科种植体。LIPU的强度为100 mW/cm ^2，波长为3.0 MHz，脉冲宽度为1.0 msec，脉冲周期为10.0 msec。双侧暴露额窦，并接受2克rhGDF-5复合物。术后4、8和12周，将种植体放置在窦移植区域。1周后，实验组一侧鼻窦每天用LIPUs刺激10或20 min，对照组一侧不刺激。种植体植入8周后切除额窦。组织学评价LIPU对骨成熟的反应，并测量牙种植体表面周围的骨接触率。实验组有促进新骨形成的作用。结果显示：4周组骨结合率均高于对照组，但3组间骨结合率无显著性差异。

In our previous study, we were able to induce bone formation by using rhGDF-5. However, the results of that study showed that even though bone formation occurred, the resulting bone growth was immature. This study assessed the efficacy of the low-intensity pulsed ultrasound stimulation (LIPUs)to enhance the bone maturation that was induced by the recombinant human growth differentiation factor 5 (rhGDF-5). This study used adult beagle dogs that weighed about 12 kg. The composite of β-TCP matrix with rhGDF-5 is made of rhGDF-5 which contained 500 micro-gram per gram of β-TCP particles. A Ti-6A1-4V dental implant with a 3.7 mm diameter and an 8 mm length was used in this study. The LIPUs had an intensity of 100mW/cm^2, a wave length of 3.0 MHz, a pulse width of 1.0 msec, a pulse cycle of 10.0 msec. Exposure of the frontal sinus was carried out bilaterally and received 2 grams of the rhGDF-5 composite. After 4, 8 and 12 weeks postsurgery, the implants were placed in the sinus graft regions. For 1 week, one sinus was stimulated by LIPUs for 10 or 20 minutes a day as the experimental group and the other sinus was not stimulated as the control group. The frontal sinuses were excised 8 weeks after dental implants placement. The bone maturation in response to LIPUs was evaluated histologically and bone contact ratio around the dental implant surface was measured. It seemed that the promoting of new bone formation was observed in the experimental groups. It was shown that the bone contact ratio of 4 weeks groups was higher the experimental groups than the control group, however there were no significant differences of bone contact ratio among three groups.