激光选区熔化技术制作纯钛可摘义齿支架的可行性研究

目的    探讨激光选区熔化技术制作牙科纯钛义齿支架的可行性，并评价不同打印支撑方向对纯钛支架适合性、力学性能和显微结构的影响。方法    采用激光三维金属打印机按照垂直支撑和横向支撑方向各打印制作15个哑铃状拉伸试件，经真空热处理后，测试其力学性能，并使用激光共聚焦显微镜观察拉伸试件的内部组织结构。用3shape D2000扫描仪对一个上颌无牙颌和一个下颌牙列缺损标准模型进行扫描，建立通用的模型设计文件。采用3shape相应的可摘义齿设计软件包设计义齿支架的数字化模型，按照拉伸试件相同条件，各打印6个纯钛义齿支架，经热处理后在标准模型上检查支架的就位情况，用X线检测纯钛支架内部的气孔。结果   打印支撑方向对拉伸试件的力学性能有显著影响，横向支撑打印试件的弹性模量、屈服强度、极限拉伸强度高于垂直支撑打印试件，但试件的延伸率结果则相反，且各个机械性能数值之间的差异均有统计学意义（均P < 0.05）。纯钛义齿支架在上下颌标准模型上的适合性良好，常规X线检测未发现钛试件内有气孔存在，但2种支撑方向打印的纯钛试件组织致密性都欠佳，内部存在散在气孔。结论   激光选区熔化技术制作的纯钛可摘义齿支架适合性良好，机械性能够满足临床要求，但打印支撑设计显著影响试件的力学性能和显微结构。

Pure Ti denture framework in feasibility study report on the selective laser melting

Objective To fabricate the removable denture pure Ti framework with a selective laser melting(SLM)system and to evaluate their mechanical properties,fitness and microstructure when the different building orientation directions were used. Methods Totally 30 dumbbell-shaped pure Ti test specimens(n=15/group)were printed with a vertical and a horizontal building orientation respectively,their mechanical properties were evaluated after a vacuum heating treatment by using a test for tensile strength. The metal tissue structure was analyzed with the laser focus microscope. A cast of an edentulous maxilla and a cast of partial edentulous mandible were respectively scanned with 3 shape D2000 scanner. Two types of pure Ti frameworks(n=6/group)for the upper complete denture and the lower partial removable denture were designed with 3 shape design software and then these designs were fabricated with SLM. The fitness of pure Ti denture frameworks was checked on stone cast. Results Thin pure Ti frameworks for maxillary complete denture and mandibular partial denture could be fabricated by SLM,and its fitness on cast was appropriate for dental clinic use. However,the mechanical properties and microstructure were affected when the different building orientation were used. The elastic modules,yield strength and tensile strength for the horizontal building were higher than for the vertical building,but its elongation was lower. There were significant differences among the mechanical properties(P < 0.05). However no pores were found by X ray detection,but there were many micro pores of different sizes in the pure Ti specimens. Conclusion The mechanical properties and fitness of the pure Ti removable denture frameworks prepared by SLM,indicate that these pure Ti framework are suitable to dental clinic use,but the different building orientation designs affected the mechanical properties and microstructure.