选区激光熔化和电子束熔化制作上颌全口义齿钛合金基托适合性及微观结构的比较

Comparison of adaptation and microstructure of titanium upper complete denture base fabricatedby selecting laser melting and electron beam melting

目的对比选区激光熔化（selectivelasermelting，SLM）和电子束熔化（electronbeammelting，EBM）制作的上颌全VI义齿钛合金基托的适合性和微观结构差异，为三维打印的口腔临床应用提供实验依据。方法采用标准上颌无牙颌模型，计算机辅助设计（computeraideddesign，CAD）上颌全口义齿基托，使用SLM、EBM设备三维打印钛合金基托各10个，即SLM组和EBM组；以传统手工铸造的上颌全口义齿钛合金基托lO个（铸造组）作为对照。将每个基托从前至后分成3个区段：尖牙远中区、第一磨牙中央区和边缘封闭区。体视显微镜测量并记录基托与石膏模型的间隙，以间隙量作为评估适合性的指标。用扫描电镜观察3组钛合金试件微观结构。结果铸造组尖牙远中区、第一磨牙中央区和边缘封闭区的间隙量为（99．4±17．0）、（98．2±26．1）、（99．6±16．1）μm；SLM组为（99．4±22．8）、（83．1±19．3）、（103．3±13．8）μm；EBM组为（248．3±70．3）、（279．1±71．9）、（189．1±31．6）μm。对于相同测量区域，SLM组与铸造组间隙量差异均无统计学意义（P〉O．05）；EBM组与SLM组、铸造组间隙量差异均有统计学意义（P〈0．05）。铸造组钛合金基托表面光滑均匀，仍有一部分铸造缺陷。SLM组钛合金基托表面光滑均匀，少有烧结缺陷。EBM组钛合金基托表面粗糙，条索状分布，存在明显的烧结缺陷。结论SLM制作的上颌全口义齿钛合金基托在形态、适合性、微观结构方面均可达到临床要求，可进一步进行临床应用研究；且相比于传统铸造方法，其在微观结构方面更具优势。而EBM钛合金基托的适合性和微观结构仍有所欠缺，尚待改进。

Objective To fabricate Ti alloy frameworks for a maxillary complete denture with three-dimensional printing （3DP） technique, such as selective laser melting （SLM） and electron beam melting （EBM）, and to evaluate the microstrueture of these frameworks and their adaptation to the die stone models. Methods Thirty pairs of edentulous casts were divided into 3 groups randomly and equally. In each group, one of the three techniques （SLM, EBM, conventional technique） was used to fabricate Ti alloy frameworks. The base-cast sets were transversally sectioned into 3 sections at the distal of canines, mesial of first molars, and the posterior palatal zone. The gap between the metal base and cast was measured in the 3 sections. Stereoscopic microscope was used to measure the gap. Three pieces of specimens of 5 mm diameter were fabricated with Ti alloy by SLM, EBM and the traditional casting technology （as mentioned above）. Scanning electron microscope （SEM） was used to evaluate the differences of microstructure among thesespecimens. Results The gaps between tile metal base and east were （99.4± 17.0）. （98.2±26.1）. and （99.6± 16.1） txm in conventional method; （99.4±22.8）. （83.1 ± 19.3）, and （103.3± 13.8） ixm in SLM technique： （248.3±70.3）. （279.1±71.9）, and （189.1±31.6） μm in EBM technique.