The purpose of this study was to evaluate the mechanical strength and biodegradation of a ZK60 plate coated with poly(l-lactic)-acid polymer (PLLA) in a LeFort I osteotomy canine model for maxillofacial applications. The PLLA-coated ZK60 plate and screw were evaluated using a LeFort I osteotomy canine model based on five beagles. The presence of wound dehiscence, plate exposure, gas formation, inflammation, pus formation, occlusion, food intake, and fistula formation were evaluated. After 12 weeks, these dogs were sacrificed, and an X-ray micro-computed tomography (µCT) was conducted. Plate exposure, gas formation, and external fistula were not observed, and the occlusion remained stable. Wound dehiscence did not heal for 12 weeks. CT images did not show plates in all the five dogs. A few screw bodies fixed in the bone remained, and screw heads were completely absorbed after 12 weeks. These findings may be attributed to the inability to optimize the absorption rate with PLLA coating. Rapid biodegradation of the PLLA-coated ZK60 occurred due to the formation of microcracks during the bending process. Further improvement to the plate system with PLLA-coated ZK60 is required using other surface coating methods or alternative Mg alloys.

中文翻译：

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可生物降解镁合金（ZK60），具有上颌面外科手术的聚（乳酸）酸聚合物涂层。

这项研究的目的是评估在LeFort I截骨犬模型的颌面部应用中，涂有聚（l-乳酸）-酸聚合物（PLLA）的ZK60板的机械强度和生物降解性。使用基于五只小猎犬的LeFort I截骨犬模型评估了PLLA涂层的ZK60板和螺钉。评估伤口裂开，板暴露，气体形成，炎症，脓形成，闭塞，食物摄入和瘘管形成的存在。12周后，处死这些狗，并进行X射线计算机断层扫描（µCT）。未观察到板暴露，气体形成和外瘘，并且闭塞保持稳定。伤口裂开12周未愈合。CT图像未在所有五只狗中显示出板块。剩下一些固定在骨头上的螺丝，12周后，螺丝头完全吸收。这些发现可能归因于无法使用PLLA涂层优化吸收速率。由于在弯曲过程中形成了微裂纹，因此涂覆PLLA的ZK60发生了快速生物降解。需要使用其他表面涂层方法或替代的Mg合金进一步改进具有PLLA涂层的ZK60的板系统。