骨科植入材中使用的材料最常見為金屬材料，其中鈦及其合金擁有良好的抗腐蝕性、延展性、高強度、抗疲勞強度及低密度，因此被廣泛的應用在骨科植入材中。近年來3D列印技術成熟被廣泛應用在研究中，在牙科材料也不例外，3D列印鈦金屬我們可以製造出特定病人的永久植體，以達到較短的手術時間及降低發病率；並利用3D列印列印出不同結構，達到更接近人體骨骼之機械性質，增加植體的生物相容性。由於3D列印的製作方法有別於傳統的熔煉及鑄造的技術，在材料微結構的部分經金相觀察可以發現不同的微結構；且鈦金屬為生物惰性材料，不易與骨細胞產生良好的結合，經過適當表面改質後，能夠使表面的生物活性提高，有助於骨細胞與植入材的結合。本實驗使用微弧氧化(Micro-arc oxidation, MAO)法，利用鈣磷電解液通入高壓電，於材料表面形成微弧火花進而形成氧化層，目的為探討鈦金屬分別利用3D列印經過MAO製程前後是否與醫療級鈦合金之差異，並進行體外試驗觀察。經光學顯微鏡以及XRD分析觀察可以知道不同製程的試片有不同的微結構組成及相組成。本實驗也開發出Ti-6Al-4V之MAO最佳參數，應用在不同試片中無明顯差異，在生物活性分析及體外試驗中可以知道經表面改質後擁有較高之生物活性及細胞活性。為增加植體之臨床生物相容性，解決應力遮蔽效應問題，本實驗也設計低彈性模術之支架結構解決臨床應用之問題。

Metal is the most common material used in orthopedic implants. Among those materials, titanium and its alloys are widely used in orthopedic implants because of great ductility, high strength, and fatigue strength. Moreover, the most frequently used alloy is Ti-6Al-4V, which has high strength, high wear resistance, good corrosion resistance, etc. In recent years, 3D printing has been widely used in our life, and there is no exception in dental materials, such as dental implants. With 3D printing titanium, people can produce permanent implants for specific patients, and arrange better surgeries for shorter operation time and lower relapse rate. Furthermore, using 3D printer to print a special structure to make the implants have better biocompatibility. Since the 3D printing process differs from traditional smelting and casting, there are some differences in the microstructures of materials that we can observe by OM. Plus, titanium and its alloys cannot bond well with bone cells due to their biological inertness; as a result, with appropriate surface modification, the biological activity of the surface will be increased, which enables the implants to bond better with bond cells. There are various methods for surface modifications, such as alkali treatment, acid treatment, anodizing and calcium phosphate coating. In this experiment, with micro-arc oxidation (MAO) method, high-voltage electricity is steered into the electrolyte of calcium and phosphorus to make micro-arc spark and then form the oxide layer on the surface of the material. The purpose of this experiment is to see whether there is a difference between medical-grade Ti alloys and 3D printing Ti alloys before and after MAO treatment in vitro. It can be seen by optical microscopy and XRD analysis that the test pieces of different processes have different microstructure compositions and phase compositions. This experiment also developed the optimal parameters of MAO for Ti-6Al-4V. There is no significant difference in the application of different test strips. It can be known in biological activity analysis and in vitro tests that it has higher biological activity and cell activity after surface modification. . In order to increase the clinical biocompatibility of implants and solve the problem of stress shielding effect, this experiment also designed the scaffold structure of low elastic molding to solve the clinical application problems.Ti-6Al-4V, 3D printed EBM and 3D printed SLM, and the surface was modified and the biological activity was explored.
Extended Abstract
1. Under the observation of the microstructure of the substrate, the phase of the traditional medical grade Ti-6Al-4V is a spherical phase structure, the phase of EBM is a layered phase structure, and the phase of SLM is acicular organization. The difference in the different phase organization is due to the difference in the early effects of the heat effects in the three different processes. And in the microhardness test, it can be found that the hardness is Ti-6Al-4V<3D printing EBM<3D printing SLM.
2. Ti metal is a biologically inert material. In this experiment, the micro-arc oxidation (MAO) surface treatment method was successfully used, and the positive voltage, negative voltage frequency and duty ratio were adjusted to the optimal parameters, respectively, the positive voltage was 350 V, and the negative voltage was -150 V, frequency is 100 Hz, duty cycle 90% is the best parameter of traditional medical grade Ti-6Al-4V, and it is found that there is no significant difference between the three on the 3D printed test piece, indicating that the process is very Good applicability.
3. The micro-arc oxidation process developed in this experiment will not be different due to the difference in substrate process and shape. In the future, the treatment effect will be changed regardless of the difference in the label, shape, microstructure and trace elements of the implant.
4. Sr has been found to have good biological activity in the literature [40], and at the same time, in addition to the MAO reaction, elements such as Ca, P and Sr have been added, and the surface-modified group has been proved in the biological activity experiment. Biological activity was significantly higher than the untreated group.
5. In in vitro cell experiments, the cells are more evenly attached to the MAO-treated surface, meaning that the cells are compared to the unmodified group. In the cell proliferation experiment, it is further explained that the number of cell proliferation after surface modification is larger than that of the untreated test piece, and has statistical significance.
Keywords: 3D printing, Ti-6Al-4V, Micro-arc oxidation, Elastic modulus, Biocompatibility

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